new brunswick 2010 (mrr_2011-2)

Mine

ral R

esou

rce R

epor

t GEOLOGICAL

INVESTIGATIONS

IN NEW BRUNSWICK

FOR 2010

MRR 2011–2

Gwen L. Martin, editor

2011

Natural Resources

Lands, Minerals and Petroleum

Figures

Editing, design, layout

Translation

Report prepared by

Hon. Bruce Northrup

Terry Leonard, Gwen L. Martin

Gwen L. Martin

Le Bureau de traduction, Ministère de l’Approvisionnement et desServices du Nouveau-Brunswick (Translation Bureau, New BrunswickDepartment of Supply and Services)

Geological Surveys BranchLands, Minerals and Petroleum DivisionNew Brunswick Department of Natural Resources

Minister of Natural Resources

October 2011

Recommended citation Martin, G.L. (editor). 2011. Geological investigations in New Brunswickfor 2010. New Brunswick Department of Natural Resources; Lands,Minerals and Petroleum Division, Mineral Resource Report 2011-2,

p.146

Numbers on this location map referto papers listed in the

on the facing page

Table of

Contents .

Mineral Resource Report 2011-2

Print Edition

Online Edition

CD-ROM Edition

GEOLOGICAL INVESTIGATIONS

IN NEW BRUNSWICK FOR 2010

ISBNISSN 0548-4014

ISBN 978-1-55471-043-0ISSN 1717-1237

ISBN 978-1-55471-044-7ISSN 1911-7582

978-1-55471-042-3

Red conglomerate and sandstone of the Hopewell Cape Formation(Mabou Group) at Castle Cove, Hopewell Cape, in the SackvilleSubbasin, southeastern New Brunswick. Photograph by Gwen L. Martin.

Cover illustration

Bathurst

Edmundston

MiramichiCity

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TABLE OF CONTENTS

A Chemostratigraphic Assessment of Core from the

Discovery Hole of the Halfmile Lake Deep VMS Zone,

Bathurst Mining Camp, Northeastern New Brunswick

James A. Walker and Steven R. McCutcheon1 2

1

2

Geological Surveys Branch, New Brunswick Department

of Natural Resources

MGC GeoConsulting, Bathurst, New Brunswick

Stratigraphy and Structural Relationships in the

Western Sackville Subbasin of the Maritimes Basin,

Southeastern New Brunswick: A Petrographic,

Petrophysical, and Seismic Analysis

Holly J. StewartGeological Surveys BranchNew Brunswick Department of Natural Resources

11

3 75–126

2

Surficial Geology Mapping in New Brunswick:

Past, Present, and Future

Serge AllardGeological Surveys BranchNew Brunswick Department of Natural Resources

Trace-Element Values in Bedrock from the Burtts

Corner Formation in the Vicinity of the

Fredericksburg Basal Till Sb Anomaly, and from

Adjacent Formations in the Napadogan Map Area,

West-Central New Brunswick

Allen A. SeamanGeological Surveys BranchNew Brunswick Department of Natural Resources

Frontispiece. Glacially polished Precambrian granitic bedrock, showing striae and grooves in a pit near

Prince of Wales, just west of Saint John in southern New Brunswick. Photograph courtesy of Serge Allard.

ii

1

A Chemostratigraphic Assessment of Core from the Discovery Hole of the Halfmile Lake Deep VMS Zone, Bathurst Mining Camp, Northeastern New Brunswick

JAMES A. WALKER 1 AND STEVEN R. MCCUTCHEON

2 1 Geological Surveys Branch, New Brunswick Department of Natural Resources,

P.O. Box 50, Bathurst, New Brunswick, CANADA E2A 7C3 ([email protected]) 2 MGC GeoConsulting, 1935 Palmer Dr., Bathurst,

New Brunswick, CANADA E2A 4X7 ([email protected]) Walker, J.A., and McCutcheon, S.R. 2011. A chemostratigraphic assessment of core from the discovery hole of the Halfmile Lake Deep VMS Zone, Bathurst Mining Camp, northeastern New Brunswick. In Geological Investigations in New Brunswick for 2010. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Lands, Minerals and Petroleum Division, Mineral Resource Report 2011-2, p. 1–49.

______________________________________________________________________________

The Halfmile Lake Deep Zone is the most recently discovered part of the Halfmile Lake volcanogenic massive sulphide deposit in the Bathurst Mining Camp, northeastern New Brunswick. It was identified in 1999 during follow-up drilling of a 3-D seismic survey by Noranda Exploration Ltd. The Deep Zone was intersected at a vertical depth of about 1100 m and is interpreted to be a downdip extension of the Halfmile Lake Upper and Lower zones. Trevali Mining Corporation presently controls the property and has published an NI 43-101-compliant inferred resource estimate of 4.83 Mt grading 6.37% Zn, 1.6% Pb, 0.15% Cu, and 17.04 g/t Ag for the Deep Zone. The Deep Zone discovery drillhole, HN99-119, was collared in rhyolite (90 m) of the Ordovician Flat Landing Brook Formation (Tetagouche Group), about 1.5 km north-northwest of the surface exposure of the Upper Zone. The drillhole passes through the core of the Halfmile Lake Anticline, a southerly overturned, east–west-striking F1 structure. The hole penetrates a complete stratigraphic section (540 m) of conformably underlying crystal tuffs and volcaniclastic rocks of the Nepisiguit Falls Formation (Tetagouche Group) and about 550 m of sedimentary rocks of the Patrick Brook Formation (Miramichi Group). Earlier authors included these sedimentary rocks in the Nepisiguit Falls Formation. The Nepisiguit Falls Formation in the upward-facing, northern limb can be divided into five eruptive units that range in thickness from 26 m to 218 m. The present study confirms that, as with the other zones of the Halfmile Lake deposit, the Deep Zone occurs at or near the base of the Nepisiguit Falls Formation. However, the Deep Zone differs from the others in several respects. Oxide-facies iron formation was intersected in two drill cores at the Deep Zone in spatial association with massive sulphides but is unknown at other zones of the Halfmile Lake system. As well, the massive sulphide lens of the Deep Zone lacks breccia-matrix sulphides and stringer mineralization, indicating that this zone was deposited in a vent-distal setting; in contrast, the other zones clearly represent vent-proximal autochthonous mineralization.

_________________________________________________

2

La zone profonde du lac Halfmile est la partie la plus récemment découverte du gisement de sulfures massifs volcanogènes du lac Halfmile, situé dans le camp minier de Bathurst, dans le Nord-Est du Nouveau-Brunswick. Elle a été définie en 1999 au cours d’un forage de suivi d’un levé sismique tridimensionnel réalisé par Noranda Exploration. La zone profonde a été interceptée à une profondeur verticale d’environ 1 100 m et elle serait une extension en aval-pendage des zones supérieure et inférieure du gisement du lac Halfmile. Trevali Mining Corporation détient actuellement les droits miniers de cette propriété et a déposé une estimation de la ressource minérale présumée du gisement conforme à la Norme canadienne 43-101 de 4,83 Mt, d’une teneur de 6,37 % de Zn, de 1,6 % de Pb, de 0,15 % de Cu et de 17,04 g/t d’Ag pour la zone profonde. Le trou de forage HN99-119 effectué dans la zone profonde et qui a donné lieu à la découverte a été creusé dans de la rhyolite (90 m) de la Formation de Flat Landing Brook de l’Ordovicien (groupe de Tetagouche), à environ 1 500 m au nord de l’affleurement en surface de la zone supérieure du gisement. Le trou de forage HN99-119 traverse l’axe de l’anticlinal du lac Halfmile, une structure F1 déversée vers le sud et qui présente une orientation du est vers l’ouest. Le trou de forage a pénétré une section stratigraphique complète (540 m) de tufs cristallins et de roches volcanoclastiques sous-jacents et en concordance de la Formation de Nepisiguit Falls (groupe de Tetagouche), et environ 550 m de roches sédimentaires de la Formation de Patrick Brook (groupe de Miramichi). Ces roches sédimentaires faisaient auparavant partie de la Formation de Nepisiguit Falls. La face orientée vers le haut du flanc nord de la Formation de Nepisiguit Falls peut être répartie en cinq unités éruptives, dont l’épaisseur varie entre 26 m et 218 m. Cette étude confirme qu’à l’instar des autres zones du gisement du lac Halfmile, la zone profonde est observée à la base de la Formation de Nepisiguit Falls, ou à proximité. Par ailleurs, la zone profonde diffère des autres zones de plusieurs façons. Deux forages de sondage dans la zone profonde ont permis d’intercepter une formation de fer à faciès oxydé en association spatiale avec des sulfures massifs, mais cette formation ferrugineuse est absente des autres zones du système du lac Halfmile. En outre, les lentilles massives de la zone profonde ne contiennent pas de minéralisation filonienne et de sulfures de gangue bréchique, ce qui porterait à croire que la sédimentation de la zone a eu lieu en présence de cheminées distales, alors que par contraste, les autres zones présentent clairement une minéralisation autochtone de cheminée proximale.

_________________________________________________

INTRODUCTION

The Halfmile Lake volcanogenic massive sulphide (VMS) deposit is located in the western part of the Bathurst Mining Camp (BMC), northeastern New Brunswick (Fig. 1), and was discovered during the Bathurst staking rush of the 1950s (McCutcheon et al. 2003). Three fairly shallow sulphide zones were identified at the Halfmile Lake deposit in that era (Table 1). They are currently referred to as the Halfmile Lake Upper, Halfmile Lake Lower, and Halfmile Lake North zones (Kempster 2001; Bellefleur et al. 2004; Trevali Mining Corporation 2011a).

3

Figure 1. Simplified geological map of the Bathurst Mining Camp, northeastern New Brunswick,

showing the location of selected massive sulphide

deposits. Modified from van Staal et al. (2003).

the Halfmile Lake report area (Fig. 2) and

Various circumstances, including split ownership and the relatively small size of the deposit

as delineated at the time, precluded mine development for many decades. However, in 1999

Noranda Exploration sought to increase the deposit resource through a deep drilling program

designed to test targets identified in a 3-D seismic survey (Bellefleur et al. 2004). The

discovery hole, diamond drillhole HN99-119 (Fig. 2, 3), intersected about 40 m of massive to

semi-massive sulphides with additional minor stringer mineralization at a vertical depth of

about 1100 m (Kempster 2001; Bellefleur et al. 2004). This fourth zone—subsequently called

the Halfmile Lake Deep Zone, and the subject of the present report—contains an NI 43-101-

compliant inferred resource of 4.83 Mt grading 6.37% Zn, 1.6% Pb, 0.15% Cu, and 17.04 g/t

Ag (Table 2; Trevali Mining Corporation 2011a).

Mireku (2001) and Mireku and Stanley (2007) have previously described the

lithogeochemistry and hydrothermal alteration of the Deep Zone. The current study uses core

from drillhole HN99-119 to interpret the zone's stratigraphic position in the context of present

stratigraphic nomenclature for the BMC. This study also proposes a genetic model to

reconcile differences in characteristics between the Deep Zone and shallower parts of the

Halfmile Lake VMS system.

Canoe LandingLake deposit

OFLB

OSLfv

OBBs

Sulphide deposit

47°45’

66°3

0’

66°0

0’

47°00’

N e pi s i g u i t

N e pi s i g u i tR i v

e rR i v

e r

47°30’

SILURIAN to CARBONIFEROUS

Undivided sedimentaryand volcanic rocks

DEVONIAN

ORDOVICIAN

Felsic intrusions

Felsic intrusions

Fournier Group

Tetagouche Group

Sheephouse Brook Group

California Lake Group

Miramichi Group

CAMBRO–ORDOVICIAN

BrunswickNo. 6

HeathSteeleArea of

Figure 2

Nin

e M

ile B

rook

Synfo

rmMountFronsacNorth

0 15 km

MiramichiHighlands

Bathurst

Massive sulphide deposit

BrunswickNo.12

Teta

gouc

he

Antifo

rm

47°15’

Nepisiguit

Bay

NewBrunswick

Area ofFigure 1 Bathurst

Maine,USA

Bath

urs

t S

uperg

roup

HalfmileLake

BathurstMining Camp

BMC

BMC

4

Table 1. Sulphide zones of the Halfmile Lake VMS deposit, Bathurst Mining Camp.

Current Zone Name

Previous Zone Name

Current Property

Name

Claim Group

Number

Old Mining License

Original Owner

Upper A

Upper AB Halfmile Lake South

1900 998 Middle River Mining (Texas Gulf Sulphur)

Lower B

Lower AB Halfmile Lake Central

1681 1010 Bay Copper Mines (Conwest Exploration)

Deep – Halfmile Lake Central

1681 1010 Noranda Exploration

North Main Halfmile Lake North

1850 1281 Great Sweet Grass Oils

Table 2. Resource estimates for the Halfmile Lake VMS deposit, Bathurst Mining Camp, based on a 5.0% Zn-equivalent cut-off (data from Trevali Mining Corporation 2011a).

Indicated

Zone Tonnes ZnEq % Zn % Pb % Cu Ag (g/t)

Upper 1,192,700 7.96 6.72 2.31 0.43 16.95

Lower 4,472,200 9.65 8.68 2.81 0.12 37.94

North 597,200 7.56 6.78 1.4 0.49 4.84

Total 6,262,100 9.13 8.13 2.58 0.22 30.78

Inferred

Zone Tonnes ZnEq % Zn % Pb % Cu Ag (g/t)

Upper 156,100 8.08 7.2 2.64 0.17 6.19

Lower 1,071,000 9.01 8.06 2.76 0.08 38.55

Deep 4,825,700 6.86 6.37 1.6 0.15 17.04

North 25,400 7.46 6.19 1.55 0.73 6.19

Total 6,078,200 7.27 6.69 1.83 0.14 20.51

PREVIOUS EXPLORATION

Because the numerous assessment reports about the Halfmile Lake area contain large volumes of data that are too extensive to present here, the following account summarizes only the more important information. For a complete list of assessment work, please refer to New Brunswick Department of Natural Resources (NBDNR) (2011a).

5

1950s to 1970s

Initial mineral exploration in the vicinity of Halfmile Lake (Fig. 1, 2) was conducted in the 1950s by Middle River Mining Company, a subsidiary of Texas Gulf Sulphur Co. At the Halfmile Lake South property, sulphide mineralization of the Upper Zone (Fig. 2, 3; Table 1) was intersected during a drilling program designed to follow up on airborne electromagnetic and soil geochemical anomalies. Middle River Mining drilled 93 holes on the property in 1955 and 1956 (Texas Gulf Sulphur Co. 1957). Lowrie (1962) reported logs and locations for five additional holes drilled on the same property by Texas Gulf Sulphur (Table 1). In 1955 Bay Copper discovered sulphide mineralization of the Lower Zone (Fig. 2, 3; Table 1) at the Halfmile Lake Central property, downdip (Fig. 3) from the Middle River Mining discovery (Conwest Exploration Co. Ltd. 1955). Conwest reported logs for 26 holes drilled on the property by Bay Copper (Conwest Exploration Co. Ltd. 1955); locations of these holes are shown on a map filed by Noranda Exploration Ltd. (Adair 1988). Texasgulf Inc. drilled nine holes on the Halfmile Lake South property in 1966 (Clayton 1967). In the mid-1970s, Texas Gulf Sulphur drilled an additional 18 holes on that property (Vukovich 1975a) and nine holes on the Halfmile Lake Central property (Vukovich 1975b; Adair 1987), having optioned the latter property from Conwest. Between 1979 and 1982, Billiton optioned the Halfmile Lake South and Halfmile Lake Central properties from Texasgulf Canada Ltd. and Conwest, drilling 38 holes between the two properties. The logs and hole locations from this drill program do not appear in the Billiton assessment reports, but the drillhole collar locations are shown on a later map filed by Noranda Exploration Ltd. (Adair 1988). In 1955 Great Sweet Grass Oils drilled 48 holes outlining a sulphide deposit (the North Zone; Fig. 2, 3) at the Halfmile Lake North property. The ground was allowed to lapse and in 1975 was acquired by Mattagami Lake Mines Ltd. (Sutherland 1975).

1980s to Present

Brunswick Mining and Smelting Corp. Ltd., a subsidiary of Noranda Exploration, acquired the Halfmile Lake North property from Mattagami Lake Mines in 1984 and optioned the Halfmile Lake Central property from Conwest Exploration in 1985. In 1987 Noranda Exploration took over management of the Halfmile Lake Central property from Brunswick Mining and Smelting (Adair 1987, 1988). In 1985 Kidd Creek Mines Ltd. (formerly Texasgulf Canada Ltd.) assessed the gold potential of gossan at Halfmile Lake South (Hassard and Gardiner 1986). In 1986 Falconbridge Ltd. acquired Kidd Creek Mines, and in 1989 it restaked the Halfmile Lake South property as Claim Group Number 1900 (Table 1; Jerome 1989). Adair reported the results of a drillhole

6

compilation for all three properties and provided logs for 31 holes drilled on the Halfmile Lake Central property (Adair 1987, 1988, 1990, 1993, 1994a). In 1992 Brunswick Mining and Smelting acquired the Halfmile Lake South property from Falconbridge. Noranda Exploration drilled 12 holes on the property that year and an additional 14 holes in 1993 (Adair 1992a, 1994b). In 1999 Noranda Exploration (which in 2006 became Xstrata Zinc Canada) discovered another, deeper sulphide body during follow-up drilling of a 3-D seismic anomaly at the Halfmile Lake Central property (Bellefleur et al. 2004). The subsequently named Halfmile Lake Deep Zone (Table 1) was intersected at a vertical depth of about 1100 m below surface and was tested by the drilling of nine new holes (including the discovery hole, HN99-119) as well as by the deepening of two previously drilled holes (Kempster 2001). In 2008 Xstrata Zinc Canada entered into a property-sharing agreement with Kria Resources Ltd. involving the entire Halfmile Lake deposit, and in April 2011 Kria became a wholly owned subsidiary of Trevali Mining Corporation. The deposit is presently controlled and being developed by Trevali Mining. Resource estimates published in February 2009 report an NI 43-101-compliant indicated resource for the three shallower zones of the Halfmile Lake deposit (i.e., excluding the Deep Zone) of 6.26 Mt grading 8.13% Zn, 2.58% Pb, 0.22% Cu, and 30.78 g/t Ag using a 5.0% Zn-equivalent cut-off grade (Table 2). They also report an inferred resource for the entire deposit, including the Deep Zone, of 6.08 Mt grading 6.69% Zn, 1.83% Pb, 0.14% Cu, and 20.51 g/t Ag using a 5.0% Zn-equivalent cut-off grade. Trevali Mining is presently (July 2011) constructing a production adit at the Halfmile Lake deposit and is “on track to production in the third quarter of 2011….” (Trevali Mining Corporation 2011b). Regularly updated information about ongoing mine development at this deposit is available on the Trevali Mining Corporation website (Trevali Mining Corporation 2011a).

REGIONAL GEOLOGY

Bathurst Supergroup

Massive sulphide deposits of the Bathurst Mining Camp are hosted by submarine bimodal volcanic and intercalated sedimentary rocks of the Bathurst Supergroup, which underlies the northern Miramichi Highlands (Fig. 1). The rocks were deposited in the Tetagouche–Exploits back-arc basin during the Ordovician (van Staal et al. 2003). They stratigraphically overlie Cambro–Ordovician siliciclastic sedimentary rocks of the Miramichi Group that were deposited on the stable Gondwanan continental margin (van Staal and Fyffe 1991). Subsequent closure of the Tetagouche–Exploits basin in the Late Ordovician to Early Silurian resulted in rocks of the BMC being incorporated into an accretionary prism (the Brunswick Subduction Complex), in which polyphase deformation produced the complex tectonostratigraphic relationships recognized in the BMC today (de Roo and van Staal 1993; van Staal 1994).

7

The major tectonostratigraphic divisions of the Ordovician Bathurst Supergroup (Fig. 1) are the Sheephouse Brook, Tetagouche, California Lake, and Fournier groups (see McCutcheon et al. 1993, van Staal et al. 2003, and references therein for detailed descriptions). The Fournier Group is dominated by ocean-floor mafic volcanic rocks, whereas the more or less coeval Sheephouse Brook, Tetagouche, and California Lake groups are dominated by early felsic and later mafic volcanic and sedimentary rocks. Massive sulphide mineralization is genetically and spatially associated with the felsic volcanic rocks in all three groups. The Bathurst Supergroup contains 46 massive sulphide deposits that collectively account for a pre-mining resource of approximately 0.5 Bt of massive sulphides (Goodfellow and McCutcheon 2003). Most of these deposits are hosted by the Tetagouche Group, which in ascending stratigraphic order comprises the Nepisiguit Falls, Flat Landing Brook, Little River, and Tomogonops formations. Most deposits hosted by the Tetagouche Group, including the giant (>300 Mt) Brunswick No. 12 mine and the four sulphide zones at Halfmile Lake, are associated with the Nepisiguit Falls Formation (Fig. 2, 3).

Nepisiguit Falls Formation

The Nepisiguit Falls Formation represents the first-erupted felsic volcanic rocks in the Tetagouche Group (Goodfellow and McCutcheon 2003). Two facies of this formation have been recognized in the type section at Grand Falls on the Nepisiguit River and together constitute the Grand Falls Member (Langton and McCutcheon 1993). The lower facies includes massive, medium- to coarse-grained (0.2–2.0 cm) quartz–feldspar crystal tuff and cryptodomes. The overlying facies contains fine- to coarse-grained, granular, reworked volcanic debris (volcaniclastic rocks and ash) sourced from the lower, massive facies. Elsewhere, rocks assigned to the Grand Falls Member have consistently yielded U–Pb (zircon) ages of 469 Ma to 471 Ma (Sullivan and van Staal 1996). In areas where the Grand Falls Member is absent, very fine- to fine-grained volcaniclastic rocks devoid of quartz or feldspar phenoclasts occur at approximately the same stratigraphic position as the Grand Falls Member and have a similar chemistry. These latter rocks are assigned to the Little Falls Member (Langton and McCutcheon 1993; Downey et al. 2006). MacDonald (2001) and Downey (2005) showed that the internal stratigraphy of the Nepisiguit Falls Formation is more complex than was previously described by Langton and McCutcheon (1993) and may consist of up to seven eruptive units sourced from at least two volcanic centres in the eastern part of the BMC (Downey 2005). As well, up to five eruptive units were recognized in outcrop near the nose of the Tetagouche Antiform (Fig. 1; MacDonald 2001); and between five and seven eruptive units were identified in drill cores from the western part of the BMC (McCutcheon and Walker 2007).

Much of the massive sulphide tonnage in the Tetagouche Group is situated in the eastern BMC, at or near the top of the Nepisiguit Falls Formation, within the Austin Brook Member. This member hosts the Brunswick No. 12 and former No. 6 mines (Fig. 1), among others, and

HN99-119

HN99-123

Halfmile LakeNorth Zone:surface trace

B

A

47 19’00”o

66

17

’35

”o

Halfmile LakeUpper Zone:surface trace

Halfmile LakeDeep Zone:projectedto surface

Halfmile Lake

Anticline

HalfmileLake

Halfmile LakeLower Zone:projected to surface

Overturned fold(anticline; syncline)

Drillhole collar (discussedin text; other)

Fault (normal; high-anglereverse or thrust)

B

A

Line of cross-sectionon Figure 3

Flat Landing Brook Formation

Massive aphyric rhyolite andcrystal–lithic tuff

Basaltic flows, andesite, andminor rhyolite breccia

Medium- to coarse-grainedquartz–feldspar crystal tuff

Tetagouche Group

ORDOVICIAN

Fine- to coarse-grainedvolcaniclastic rocks and ash


Exhalite: massive sulphides andminor oxide-facies iron formation

Greyish green, fine-grainedsandstone, siltstone, and minorshale

Miramichi Group

CAMBRO–ORDOVICIAN

Patrick Brook Formation

0 1 km

Moody

Bro

ok

Chief’sPlateau

Figure 2. Geological map of the Halfmile Lake deposit, showing the distribution of all drillhole collars,

excluding those from recent drilling by Trevali Mining Corporation. Geology is complied and modified

from Adair (1992b) and Wilson (1993a). Drillhole database is provided by Dayle Rusk, Trevali Mining

Corporation. See Figure 3 (facing page) for geological cross-section A–B.

8

Approximate limit ofmassive sulphidemineralization projectedvertically to surface

Road

Figure 3. Geological cross-section A–B (looking westward) through the Halfmile Lake deposit of the

Bathurst Mining Camp, showing the Upper, Lower, and Deep zones. See Figure 2 for the line of section.

HN

99-1

19

Upper Zone

Lower Zone

Deep Zone

BA

HN

99-1

23

Stratigraphic contact

Axial trace of anticline

Axial trace of syncline

Drillhole HN99-119 (end of hole: 1409 m)

Other drillholes

Stringer mineralization

HalfmileLakeAnticline


Massive aphyric rhyolite andcrystal–lithic tuff

Basaltic flows, andesite, andminor rhyolite breccia

Medium- to coarse-grainedquartz–feldspar crystal tuff

Miramichi GroupTetagouche Group

CAMBRO–ORDOVICIANORDOVICIAN

Fine- to coarse-grainedvolcaniclastic rocks and ash


Exhalite: massive sulphides andminor oxide-facies iron formation


0 300 m

Thrust or reverse fault

9

Greyish green, fine-grainedsandstone, siltstone, and minor shale

10

consists of massive sulphides that are gradational with laterally continuous, chemically precipitated sedimentary rocks (exhalite) comprising silicate-, carbonate-, and oxide-facies iron formations (Peter and Goodfellow 1996). The New Brunswick Bedrock Lexicon (NBDNR 2011b) provides additional information about the Austin Brook Member under Nepisiguit Falls Formation. In contrast, the massive sulphide horizon and associated iron formation at the former Heath Steele mine in the central BMC (Fig. 1) occur near the base of the Nepisiguit Falls Formation (Lentz and Wilson 1997). Evidence presented below, interpreted from a relogging of drillhole HN99-119, suggests that the Halfmile Lake deposit also lies near the base of the Nepisiguit Falls Formation in a stratigraphic position similar to that at Heath Steele rather than higher in the sequence as proposed by Adair (1992a, 1992b) and Mireku and Stanley (2007).


The Austin Brook Member is overlain by massive rhyolite flows, domes, and related felsic and mafic volcanic rocks of the Flat Landing Brook Formation (Fig. 2, 3), which hosts the remainder of the massive sulphide deposits in the Tetagouche Group (McCutcheon et al. 2001). This formation has returned U–Pb zircon ages of 465 ± 2 Ma (van Staal et al. 2003 and references therein) and is younger than the Nepisiguit Falls Formation. The Flat Landing Brook Formation thus marks the end of a three- to five-million-year period of quiescence, during which massive sulphides of the Austin Brook Member were deposited.

DEPOSIT GEOLOGY

Earlier Investigations

The mineralization, stratigraphy, and structural geology of the shallower parts of the Halfmile Lake deposit (Upper, Lower, and North zones) were the subject of an M.Sc. thesis and report by Harley (1977, 1979) and a report by Adair (1992b). The lithogeochemistry of the Lower Zone was documented by Lentz (1996). The lithogeochemistry and hydrothermal alteration of rocks hosting the Deep Zone were described in an M.Sc. thesis by Mireku (2001) and subsequent paper by Mireku and Stanley (2007). Regional geological mapping by Wilson (1993a–c) was integrated with regional data to produce a 1:100 000 scale geological map (van Staal et al. 2002).

Structure

The geology in the vicinity of the Halfmile Lake deposit is structurally complex (Fig. 2, 3), as throughout other parts of the BMC. All of the earlier authors considered the entire stratigraphic section in the Halfmile Lake area to lie within the Tetagouche Group and to represent a consistently downward-facing homoclinal sequence, notwithstanding the fact that the section apparently is transected by a number of thrust faults. Wilson (1993a–c) demonstrated that the Halfmile Lake deposit occurs stratigraphically well down in the Nepisiguit Falls Formation and

11

is stratigraphically overlain by a relatively thick accumulation of quartz–feldspar crystal tuff (occupying the structural footwall), such as occurs at the Heath Steele deposit (Fig. 1; Lentz and Wilson 1997). The homoclinal sequence in the Halfmile Lake area was interpreted by these same authors to lie on the southern limb of a southerly overturned anticlinal structure, the axial trace of which was assumed to be situated within felsic volcanic rocks of the Nepisiguit Falls Formation about 1 km to the northwest of the Halfmile Lake deposit. Base metal zoning in the massive sulphides and rare younging indicators in the sedimentary rocks are both consistent with such an interpretation, as is the occurrence of stringer mineralization and associated hydrothermal alteration in the immediate structural hanging wall (i.e., lower in the stratigraphy) of the deposit. The presence of this stringer zone is strong evidence for a vent-proximal depositional setting for shallower zones of the deposit (Jambor 1979). As detailed below under Exhalite Characteristics, the massive sulphides in the Upper Zone of the Halfmile Lake deposit (Fig. 3) are hosted by chloritic volcaniclastic rocks of the Nepisiguit Falls Formation, whereas in the Lower Zone, they are hosted by crystal tuff of the same formation (Adair 1992b). In some drill cores, mafic to andesitic volcanic and locally felsic volcanic rocks of the younger Flat Landing Brook Formation have been interpreted to be in either normal stratigraphic (Adair 1992b; Wilson 1993c) or tectonic (Wilson 1993a) contact with the massive sulphide horizon. Locally, younger intrusions are interpreted to suture the contact between the massive sulphide lens and the Flat Landing Brook Formation in the structural footwall (Adair 1992b). Mapping by de Roo and van Staal (1991) delineated a major southerly overturned, east–west-striking, tight F1 fold with an axial trace situated immediately north-northwest of the surface exposure of the Halfmile Lake Upper Zone (Fig. 2). This structure, referred to by de Roo and van Staal (1991) as the ‘Halfmile Lake Fold,’ had been recognized earlier (on the basis of regional stratigraphy) as an anticline that exposes sedimentary rocks in its core (Helmstaedt 1973; Fyffe 1982). These sedimentary rocks have been correlated with the Patrick Brook Formation (Fig. 2, 3) by de Roo and van Staal (1991) and, if the correlation is correct, belong to the upper part of the Miramichi Group (Fyffe et al. 1997). According to such an interpretation, volcanic rocks of the Tetagouche Group are repeated on the flanks of the overturned Halfmile Lake Fold, which means that the stratigraphic sequence at the Halfmile Lake deposit cannot represent a homocline as proposed by Harley (1977, 1979) and Adair (1992b). It is noteworthy that sedimentary rocks exposed about 3 km along strike to the southwest of the fold were assigned to the Patrick Brook Formation by Wilson (1993b, 1993c). To date, all mapping and core-logging projects have defined the structural hanging wall of the Halfmile Lake deposit as comprising a 1 km to 2 km thick sequence of quartz–feldspar crystal tuff and related volcaniclastic rocks of the Nepisiguit Falls Formation. The sequence has been interpreted to be structurally thickened by three or more south-verging thrust faults that approximately parallel the massive sulphide horizon (Adair 1992b; Wilson 1993a–c).

12

However, if sedimentary rocks of the Patrick Brook Formation are, in fact, exposed in the core of the Halfmile Lake Fold as discussed above, then rocks of the Nepisiguit Falls Formation in the structural hanging wall are actually in a normal stratigraphic position, facing upward on the upright, northern limb of a tight anticlinal fold (Fig. 2, 3). Evidence presented below supports this alternative interpretation: namely, that the stratigraphic sequence at Halfmile Lake is repeated by folding rather than representing a continuous downward-facing homocline.

Relogged Core from Drillhole HN99-119

Drillhole HN99-119 (Kempster 2001) is located at the Halfmile Lake Central property about 1.5 km north-northwest of the surface exposure of the Upper Zone (Fig. 2). The hole was drilled toward the south-southeast (165º) with an initial dip of approximately 85º that flattens to 69º at the end of the hole at 1409 m (Fig. 3, 4). The rocks cored by drillhole HN99-119 display tectonostratigraphic relationships that are inconsistent with the homoclinal model previously interpreted for shallower parts of the Halfmile Lake deposit (i.e., those cited in Adair 1992b and Wilson 1993a–c). About 90 m of Flat Landing Brook Formation was intersected at the top of the hole, followed by a complete section (540 m) through the Nepisiguit Falls Formation, and approximately 550 m of Patrick Brook Formation (Fig. 3, 4; Table 3). This stratigraphic order is consistent with most of the sequence occupying the northern, upward-facing limb of the Halfmile Lake Fold (de Roo and van Staal 1993), which is herein named the ‘Halfmile Lake Anticline.’ The drill core showed no observable evidence of an anticlinal closure within the Nepisiguit Falls Formation high in the structural hanging wall, as would be required by the homoclinal model for the downward-facing Halfmile Lake deposit. Moreover, no thrust-related repetition of stratigraphy was apparent at depth, in contrast with previously interpreted tectonic imbrication by thrusting in the near-surface parts of the Halfmile Lake deposit (Adair 1992b; Wilson 1993b, 1993c; Mireku and Stanley 2007).

At the stratigraphic base of the sequence, in the core of the anticline, drillhole HN99-119 intersected about 550 m of interbedded greyish green, fine-grained sandstone, siltstone, and minor shale assigned to the Patrick Brook Formation (Fig. 3–5a). The estimated true stratigraphic thickness of these rocks in the drillhole is about 250 m. In the Lower Zone, the Patrick Brook Formation is approximately 125 m thick, whereas in the Upper Zone, two intervals (separated by Nepisiguit Falls rocks) account for a combined stratigraphic thickness of about 100 m (Fig. 3). The Patrick Brook Formation stratigraphically immediately underlies the Upper and Lower zones and reaches to within 10 m of the Deep Zone massive sulphide lens (Fig. 4). Hence, the Halfmile Lake deposit lies at or very close to the base of the Nepisiguit Falls Formation in a stratigraphic position similar to that of the Heath Steele deposit (Lentz and Wilson 1997). The sedimentary rocks of the Patrick Brook Formation show abundant evidence of sub-metre-scale faults and folds in addition to abundant quartz ± minor carbonate veins. However, no obvious evidence exists of any major tectonic break within the Patrick Brook

13

Formation. Furthermore, most of these rocks are chemically similar to sedimentary rocks of the Miramichi Group at Heath Steele (see Lithogeochemistry, below). Moving uphole in drillhole HN99-119, in the upward-facing limb of the Halfmile Lake Anticline, the sedimentary sequence of Patrick Brook Formation is conformably overlain by about 540 m (true stratigraphic thickness) of quartz–feldspar crystal tuff and related volcaniclastic rocks of the Nepisiguit Falls Formation (Fig. 5b). The latter formation is divided into five eruptive units referred to in ascending stratigraphic order as NF1 through NF5 (Fig. 4; Table 3). Unit boundaries are generally delineated by an interval of ash or fine-grained volcaniclastic rock, and some units are further divided into subunits. Unit descriptions are as follows. The basal unit, NF1, is about 80 m thick and divided into three subunits. At the base, 11.5 m

of quartz–feldspar crystal tuff is overlain by 7.1 m of ash and fine-grained volcaniclastic rock (represented by NF1 (vc) in Table 3) that is overlain in turn by 61.5 m of quartz–feldspar crystal tuff (Fig. 4, 6a).

Unit NF2 is separated from Unit NF1 by a thin bed of fine-grained volcaniclastic rock

(represented by NF2 (vc) in Table 3; Fig. 6a). The unit is approximately 218 m thick and is divided into two subunits. The lower subunit is a quartz–feldspar, crystal-rich pumiceous tuff with pumice clasts that increase in abundance downhole, whereas the upper subunit consists of 43 m of ash and coarse-grained volcaniclastic rock without obvious phenoclasts.

Unit NF3 is thin (approximately 26 m thick) and consists of medium-grained quartz–feldspar

crystal tuff. Unit NF4 consists of 91 m of fine- to medium-grained quartz–feldspar crystal tuff and minor

interlayered ash (Fig. 6b). Quartz phenocrysts are up to 3 mm in diameter and rounded, whereas feldspars are anhedral to subhedral.

Unit NF5 in the uppermost part of the Nepisiguit Falls Formation is divided into five

subunits. At the base, 91.5 m of medium-grained quartz–feldspar crystal tuff containing some pumice clasts is capped by a 5.5 m thick ash bed (Fig. 4, 6c). Overlying the ash bed is approximately 9 m of quartz–feldspar, phenoclast-rich and subordinate fine-grained, phenoclast-poor volcaniclastic rocks. The volcaniclastic unit is gradational upsection into approximately 7 m of mixed crystal-rich pumice and ash. The uppermost subunit consists of 11.4 m of ash and very minor thin lenses of volcaniclastic rock rich in quartz and feldspar phenoclasts.

Unit NF5 is conformably overlain by felsic volcanic rocks of the Flat Landing Brook Formation, of which approximately 90 m were intersected in drillhole HN99-119. The base of this formation consists of 40 m of massive to locally spherulitic, aphyric to sparsely feldspar-phyric rhyolite (Fig. 4, 7a), which is overlain by about 50 m of crystal–lapilli tuff (Fig. 7b).

14

Table 3. Samples from drillhole HN99-119 in the Deep Zone, Halfmile Lake deposit, Bathurst Mining Camp, listed in order of increasing drillhole depth (see Fig. 4). Appendix 1 (p. 41–49) presents the lithogeochemical analyses of these samples.

Upward-Facing Limb of Halfmile Lake Anticline

Downward-Facing Limb of Halfmile Lake Anticline

Sample No. Unit Data Source Sample No. Unit Data Source

HN-119-0050.3 FLB This study HN-119-0946.4 OM This study

HN-119-0082.8 FLB This study HN-119-0981 OM Mireku (2001)

HN-119-0138.7 NF5 This study HN-119-1033 OM Mireku (2001)

HN-119-0175.6 NF5 This study HN-119-1066.4 OM Mireku (2001)


HN-119-0221 NF4 This study HN-119-1141 OM This study



HN-119-0285 NF4 This study HN-119-1195 NF1 This study

HN-119-0304.7 NF4 This study HN-119-1196.6 NF1 Mireku (2001)

HN-119-0307.3 Basalt dyke This study Massive sulphide zone

HN-119-0308.8 NF3 This study HN-119-1263.6 NF1 (vc) Mireku (2001)

HN-119-0339.5 NF2 (vc) This study HN-119-1270 NF1 This study

HN-119-0376 NF2 (vc) This study HN-119-1271.1 NF1 (vc) Mireku (2001)


HN-119-0445 NF2 This study HN-119-1296.5 OM This study

HN-119-0482 NF2 This study HN-119-1319.5 OM Mireku (2001)


HN-119-0541 NF2 (vc) This study HN-119-1341.5 OM Mireku (2001)


HN-119-0580.6 NF1 This study HN-119-1403 NF1 This study

HN-119-0617 NF1 (vc) This study HN-119-1407.16 NF1 Mireku (2001)

HN-119-0629.5 NF1 This study

HN-119-0640 OM This study

Notes: OM = Patrick Brook Formation (Miramichi Group), NF = Nepisiguit Falls Formation (Tetagouche Group), FLB = Flat Landing Brook Formation (Tetagouche Group), (vc) = volcaniclastic rocks

Downhole, in the downward-facing limb of the Halfmile Lake Anticline (Table 3), sedimentary rocks of the Patrick Brook Formation are followed by a narrow interval (1192–1295 m) of rocks assigned to the Nepisiguit Falls Formation. This interval includes 60 m of crystal tuff and volcaniclastic rocks rich in quartz phenoclasts, and 40 m of massive to semi-massive sulphides that constitute the Deep Zone (Fig. 8).

Flat LandingBrook Formation

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0

EOH 1409 m

Nepisiguit FallsFormation



Patrick BrookFormation


Unit NF5

Unit NF1

Unit NF2

Unit NF3

Unit NF4

Crystal-lithic tuff

Massive aphyricrhyolite

981

1033

1066.4

1117.6

1165.81191.3

1196.6

1296.5

1403

50.3

82.8

138.7

175.6

202.2

221243.6256.6

285304.7307.3308.8

339.5

376385.6

445

482

541

554.6

580.6

517.6

617629.5

640

946.4

1141

1195

1270

Axis of minor syncline

Basalt dyke

Upw

ard

-facin

g lim

bD

ow

nw

ard

-facin

g lim

b

Axis of minor anticline

Figure 4. Simplified graphic log of drillhole HN99-119, intersecting the Deep Zone at the Halfmile Lake

deposit ( Log shows the position of lithogeochemical samples and

Samples plotted on the right are from Mireku (2001).

collar location on Fig. 2). stratigraphic

units. on the left are from this study; those

Lithogeochemical samplenumber (see Table 3and Appendix 1)

x xx x

x

x

xx

x

x

x

x

x

Approximate axis of

Halfmile Lake Anticline

Clastic sedimentary rocks


Quartz–feldspar crystaltuff and volcaniclasticrocks

MIRAMICHI GROUP

TETAGOUCHE GROUP


Massive sulphides


Stringer mineralization

629.5

Felsic volcanic rocks

Depth

(m

etr

es)

Pumice-rich base

xx

1263.61271.11286.3

1319.5

1341.51332.04

1386.8

1407.16

15

End of holeEOH

16

Figure 5.

a)

b)

Rocks of the Patrick Brook Formation (Miramichi Group) and Nepisiguit Falls Formation

(Tetagouche Group) intersected in drillhole HN99-119 at the Halfmile Lake deposit, Bathurst Mining

Camp. Greyish green, fine-grained sandstone and siltstone of the Patrick Brook Formation;

photograph shows part of the interval between about 638 m and 650 m. Transitional contact between

the Patrick Brook Formation (four lower cores) and Nepisiguit Falls Formation (Unit NF )

photograph shows part of the interval between 629.4 m and 632.5 m. Core diameters are 4.7 cm.1 (two upper

cores);

a

b

17

Figure 6. Rocks of the Nepisiguit

Falls Formation intersected in

dri l lhole HN99-119

Halfmile Lake deposit.

ine-

grained volcaniclastic rock

separates the two eruptive

units. Core diameter is 4.7 cm.

a) Contact between quartz–

feldspar crystal tuff of Unit NF

(right) and quartz–feldspar

crystal-rich pumiceous tuff at

the base of Unit NF (left) at

553.2 m. A thin bed of f

1

2

at the

b) Fine- to medium-grained

quartz–feldspar crystal tuff and

minor interlayered ash beds of

Unit NF at about 250 m. Core

diameter is 6.3 cm.4

c) Tuff and interbedded quartz–

feldspar crystal-rich pumice

clasts in Unit NF at about 105

m.5

Core diameter is 6.3 cm.

b

a

Crystaltuff

Pumiceoustuff

Volcaniclasticrock

c

Figure 7.

a)

b)

Rocks of the Flat Landing Brook Formation (Tetagouche Group)

Halfmile Lake deposit. Grey, massive to locally spherulitic, aphyric to sparsely feldspar-

phyric rhyolite at about 85 m. Crystal–lapilli tuff at about 45 m. Core diameters are 6.3 cm.

intersected in drillhole

HN99-119,

18

a

b

19

Figure 8. Basal contact of the massive sulphide lens from the Deep Zone, Halfmile Lake deposit. Core

is from drillhole HN99-119 at 1202.4 m. Core diameter is 4.7 cm.

Another interval of sedimentary rocks (1296–1341 m) is tentatively assigned to the Patrick

Brook Formation (Table 3) and likely represents a parasitic anticline on the southern limb of

the larger Halfmile Lake Anticline (Fig. 3, 4). The mixed sequence of volcaniclastic rock and

fine-grained felsic tuff, from 1341 m to the end of the hole at 1409 m, is tentatively assigned to

the Nepisiguit Falls Formation.

As part of this study, 30 core samples were collected for lithogeochemical analysis from

drillhole HN99-119, mainly from the upward-facing limb of the Halfmile Lake Anticline (Fig. 4;

Table 3). All samples were prepared and analyzed at Activation Laboratories Ltd. in Ancaster,

Ontario. Appendix 1 presents the lithogeochemical data, along with the analytical methods

and detection limits used. Analyses for an additional 15 samples from the downward-facing

limb were

LITHOGEOCHEMISTRY

compiled from Mireku (2001) and incorporated into the data set. However,

the higher detection limits for

some of the elements, as well as by the absence of data for other elements such as the rare

earths.

the

usefulness of the Mireku (2001) data is somewhat restricted by

20


Three samples were collected from the large interval of clastic sedimentary rocks of the Patrick Brook Formation (Miramichi Group) in the core of the Halfmile Lake Anticline. The formation there begins at approximately 630 m and continues downhole to about 1191 m, in the structural hanging wall of the Deep Zone (Fig. 4; Table 3). An additional sample was collected from the narrow interval of probable Patrick Brook Formation between 1296 m and 1341 m, in the structural footwall of the Deep Zone (Fig. 4; Table 3). Analyses for these four samples were augmented with data from Mireku (2001) for the structural hanging wall (n = 6) and structural footwall (n = 3). Data from these 13 Patrick Brook samples were assessed using lithogeochemical diagrams developed for the discrimination of sedimentary rocks in the BMC by Rogers et al. (2003) and McCutcheon (unpublished). On a V/Nb versus Zr/Cr diagram (Fig. 9a) and a V–Zr/2–Ni ternary diagram (Fig. 9b), all samples assigned to the Patrick Brook Formation fall within the field of older sedimentary rocks of the Miramichi Group. On a MnO versus Al2O3/SiO2 diagram (Fig. 9c), most samples fall in the field of the Knights Brook Formation, and two plot in the field of the Chain of Rocks Formation. (Note: The two last-named formations are from the Miramichi Group. Figure 9c does not include a field delineating rocks of the Patrick Brook Formation.) On a Ni/Nb versus Cr/Nb diagram (Fig. 9d), most samples fall in the field of sedimentary rocks of the Miramichi Group. Lithogeochemical diagrams developed to distinguish sedimentary rocks of the Miramichi Group from those intercalated with the lower part of the Nepisiguit Falls Formation at Heath Steele (Fig. 9e, 9f; Lentz and Wilson 1997) indicate that most sedimentary rocks in the structural hanging wall of the Deep Zone fall in the ‘older sedimentary rocks’ field and so should be assigned to the Miramichi Group. The downhole geochemical profiles (Fig. 10a, 10b) show that the sedimentary rock samples are quite varied in terms of their major element contents. For example, SiO2 (Fig. 10a) varies from 50 wt % to 80 wt %, whereas Al2O3 (Fig. 10b) ranges from <10 wt % to >18 wt %. Throughout the sedimentary section, Fe2O3 (Fig. 10a) is consistently <10 wt % but increases slightly with proximity to the massive sulphide zone from both the uphole and downhole sides. In contrast, MnO (Fig. 10a), which rarely exceeds 0.2 wt %, reaches its highest concentration within approximately 100 m of the massive sulphide lens but decreases in concentration immediately adjacent to the lens. The MgO content (Fig. 10a) in the sedimentary rocks is generally low but tends to be slightly higher in the structural footwall (downhole side) of the Deep Zone massive sulphide lens. The CaO content (Fig. 10a) also tends to be low but is elevated in the structural footwall of the massive sulphides. Likewise, the Sr content (Fig. 10a) is elevated in the structural footwall. (The apparent covariance of Sr with Ca is likely attributable to Sr substituting for Ca in carbonate minerals.) The Na2O content (Fig. 10a) of these rocks is low (<0.5 wt %) in samples from structurally above the sulphide lens but is elevated (1 wt % and 6 wt %) in the structural footwall, a trend similar to that for Ca.

Figure 9.

a)

b) c) d) e)

f)

Lithogeochemical discrimination diagrams for sedimentary and volcaniclastic rocks

intersected in drillhole HN99-119 at the Deep Zone, Halfmile Lake deposit. V/Nb versus Zr/Cr

diagram. V–Zr/2–Ni diagram. MnO versus Al O /SiO diagram. Ni/Nb versus Cr/Nb diagram.

Al O diagram. Al O diagram. Field boundaries in a) and b) are from McCutcheon

(unpublished), those in c) and d) are from Rogers et al. (2003), and those in e) and f) are from Lentz and

Wilson (1997).

2 3 2

2 3 2 3versus Ni versus TiO2

21

a)

0

10

20

30Z

r/C

r

V/Nb

Older sedimentary rocks

Younger sedimentary rocks

0 10 20

b)

V Ni

Zr/2

Older

sedimentary

rocks

Younger

sedimentary

rocks

d)

0.01 0.1 1 10 1000.1

1

10

100

1000

Cr/

Nb

Ni/Nb

Field of sedimentary rocksof the Miramichi Group

Field of sedimentary rocksof the Fournier, Tetagouche,and California Lake groups

c)

0.0 0.1 0.2 0.3 0.4

0.1

0.2

0.3

0.4

0.5

MnO wt %

AlO

/SiO

23

2

KnightsBrookFormation Chain of

RocksFormation

TiO

wt %

2

f)

Al O wt %2 3

00

1

2

10 20 30

Ni ppm

e)

Oldersedimentary rocks

Al O wt %2 3

0 10 20 300

10

20

30

40

50

Sedimentary RocksSedimentary sample fromformer Heath Steele mine (Fig. 1)(Lentz and Wilson 1997)

Youngersedimentary rocks

Patrick Brook Formation (Mireku 2001) Nepisiguit Falls Formation (Mireku 2001)

Volcaniclastic Rocks

Patrick Brook Formation (this study) Nepisiguit Falls Formation (this study)

Oldersedimentary rocks

Youngersedimentary rocks

42 77

0 5 10

MgO wt %

0 1 2

CaO wt %

8 1815

0 10 20 30

Fe O wt %2 3

0.0 0.1 0.2 0.3 0.4

MnO wt %

0 1 2 3 4 5 6

Na 0 wt %2

0 20 40

Sr ppm

60 80 100

40 50 60

SiO wt %2

70 80

TiO wt %2

0 0.5 1.0 1.5 0 2 4 6

Cs ppm

0 10 20 30

Th ppm

1500

0

500

1000

Dep

th

0

500

1000

Dep

th

NF1

NF2

NF3

NF4

NF5

NF1

NF1

NF2

NF3

NF4

NF5

NF1

NF1

NF1

NF1

NF1

8

10.5

Al O wt %2 3 Zn ppm

0 100 200 300 400

1500

Flat Landing Brook Formation Patrick Brook FormationNepisiguit Falls Formation

Figure 10a. Figure caption and symbol legend are on page 23.

a)

22

Massive sulphides

0 2 4 6Bi ppm Sc ppm

0 100 200

Cr ppm0

Ni ppm500 1 2 3

W ppm4 5 6 7

2 4 6

Sn ppm8 10 120 50 100 150

As ppm0 50

Co ppm0 50 100 150

Cu ppm0 100 200

Pb ppm300 400 500 0 100 200 300

Zn ppm400 500 600

1500

0

500

1000

1500

0

500

1000

0 10 20 30

NF1

NF1

NF2

NF3

NF4

NF5

NF1

NF1

NF1

NF1

NF2

NF3

NF4

NF5

NF1

NF1

40360146

NF1

NF2

NF3

NF4

NF5

Flat Landing BrookFormation



This study

Mireku (2001)

Basaltdyke

Dep

thD

ep

th

Figure 10b. Major- and trace-element lithogeochemical profiles from drillhole HN99-119 at the Halfmile Lake deposit. A more detailed version

of the stratigraphic column legend appears on Figure 2. See Appendix 1 for geochemical data, analytical methods, and detection limits.

b)

23

24

Mireku and Stanley (2007) recognized generally low Na content in sedimentary rocks of the structural hanging wall and generally high Na content in rocks of the structural footwall. They also noted an increase in Na2O in the structural hanging wall with proximity to the sulphide lens. The higher Na2O adjacent to the sulphide lens is attributed to an increase in the amount of intercalated felsic volcanic material. Mireku and Stanley (2007) suggested two possible explanations for low Na in the sedimentary rocks: 1) the source sediment for these rocks had low primary sodic plagioclase, or 2) the original sodic plagioclase was destroyed by subsequent hydrothermal alteration. The P2O5 content (not shown on Fig. 10) varies from 0.06 to >0.2 wt % and is higher in the structural footwall than in the structural hanging wall. The K2O content also varies (0.2–6 wt %), but no discernable trend is recognized. The considerable spread in the Zr and TiO2 contents and in the Zr/TiO2 value of the sedimentary rocks (Fig. 10a) is probably attributable to winnowing of zircon and Fe–Ti oxide phases in the marine environment. The concentrations of As, Co, Cu, W, and Zn are generally higher in the sedimentary rocks than in the felsic volcanic rocks, and a weak but noticeable trend of increasing Co, Cu, and Sn contents in the sedimentary rocks with proximity to the massive sulphide lens is interpreted to reflect hydrothermal input. The contents of rare earth elements (REEs) in sedimentary rocks from the Patrick Brook Formation are quite consistent. Typically, these samples have very flat REE profiles when normalized to the North American Shale Composite (Fig. 11a) and display no evidence of either a positive Ce or a positive Eu anomaly. The presence or absence of Ce and Eu anomalies can indicate the ambient conditions when the sediment was deposited. In the case of Ce, normally oxygenated (neutral to high pH) seawater readily oxidizes typical trivalent Ce+3 to Ce+4, which is highly insoluble (Toyada and Masuda 1991). Once oxidized, the Ce+4 readily fills octahedral sites in precipitated Fe–Mn oxides, thereby imparting a positive Ce anomaly to the seafloor sediment. Consequently, the absence of a positive Ce anomaly (Fig. 11a) indicates that the original sediments were likely deposited in poorly oxygenated (disoxic to anoxic) seawater. Normal seawater has a relatively low concentration of Eu, in line with the concentrations of other REEs (i.e., it is not anomalously high or low). However, Eu+3 is readily reduced to Eu+2 in high-temperature, low-pH hydrothermal fluids such as those associated with the formation of volcanogenic massive sulphide deposits. As a result, Eu+2 may reach relatively high concentrations in such fluids (see Gale et al. 1997 and Humphris 1984 for discussions about the calculation of Eu anomaly and Eu mobility). Consequently, marine sediment deposited coevally with seafloor-venting hydrothermal fluids may have strongly positive Eu anomalies, because Eu+2 in the hydrothermal fluids oxidizes and becomes insoluble Eu+3 and precipitates upon mixing with seawater. The absence of a positive Eu anomaly in samples of the Patrick Brook Formation suggests that the hydrothermal component in these rocks is negligible (Fig. 11a). Likewise, the absence of a strongly negative Eu anomaly in the samples indicates they did not interact with high-temperature, low-pH hydrothermal fluids.

Figure 11

a)

b)

. Lithogeochemical discrimination diagrams for sedimentary rocks of the Patrick Brook

Formation intersected in drillhole HN99-119 at the Deep Zone, Halfmile Lake deposit. North

American Shale Composite (NASC)-normalized REE profiles. Normalization factors are from Gromet

et al. (1984). Al/(Al+Fe+Mn) versus Fe/Ti diagram for the determination of hydrothermal input in

terrigenous sediments. Diagram is from Boström (1973).

The Al/(Al+Fe+Mn) versus Fe/Ti diagram

us sediments. On this diagram, sedimentary

rocks of the Patrick Brook Formation have Al/(Al+Fe+Mn) values that range between 0.45

and 0.7 and Fe/Ti values that are close to 10, clearly reflecting a sediment dominated by

terrigenous components. Furthermore, TiO , Cr, Ni and, to some degree, V concentrations in

these rocks are higher than would be expected for sedimentary rocks codeposited with, and

in part sourced from, felsic volcanic rocks near the base of the Nepisiguit Falls Formation

(Fig. 10a, 10b), as was suggested by Mireku and Stanley (2007).

In terms of elements related to magmatic fluid input into the hydrothermal system (Bi, Sb, Sn,

W), a few anomalous but sporadic values are present in samples immediately adjacent to the

massive sulphide lens. Note that data compiled from Mireku and

Stanley (2007) have higher detection limits than for the remainder of the data set and account

for the linear trends of these elements in some diagrams (Fig. 10a, 10b).

A total of 23 samples were collected from the five eruptive units of the Nepisiguit Falls

Formation in drillhole HN99-119 (Table 3). Samples of massive quartz–feldspar crystal tuff

from the more massive facies of the five eruptive units were collected as follows: NF (n = 6),

NF (n = 4), NF (n = 1), NF (n = 5), and NF (n = 3). Inter-eruptive volcaniclastic rocks were

sampled from Unit NF (n = 1) and Unit NF (n = 3). As well, data from Mireku (2001) were

compiled for four samples of crystal tuff and two samples of volcaniclastic rocks from unit NF

immediately adjacent to (structurally above and below) the Deep Zone massive sulphide

lens.

2

1

2 3 4 5

1 2

1


for some of these elements

(Fig. 11b) was devised by Boström (1973) to gauge

the degree of hydrothermal input in terrigeno

25

a) b)

Fe/T

i

Al/(Al+Fe+Mn)

Hydrothermal fluidfrom East Pacific Rise

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

10

100

1000

10000

Increasingterrigenouscomponent

Sedimentary rock (Mireku 2001)

0.01

0.1

1

10

La Ce Nd Sm Eu Gd Tb Dy Er Yb Lu

Sam

ple

/ N

AS

C

Sedimentary rock (this study)

26

In terms of their alkali element contents, most of the volcanic rocks fall outside the field of normal volcanic rocks on a 100*K2O/(Na2O+K2O) versus Na2O+K2O diagram (Fig. 12a), implying the addition of K2O and Na2O. However, all but two of the Nepisiguit Falls samples fall in the rhyolite field on a SiO2 versus Na2O+K2O diagram (Fig. 12b). It is unknown whether the alkali mobility is attributable to hydrothermal alteration or to normal interaction between hot volcanic rocks and ambient seawater at the time of deposition (see Hughes 1972). On a Zr versus TiO2 diagram (Fig. 12c), most of the massive crystal tuff samples fall in a very tight cluster along a line of Zr/Ti = 0.167. Conversely, the volcaniclastic rocks form a more scattered plot and have a generally higher TiO2 content, indicative of a detrital component associated with intercalation/contamination by sedimentary material. All of the felsic volcanic samples fall in or near the rhyodacite–dacite field on a Nb/Y versus Zr/TiO2 discrimination diagram (Fig. 12d). The REE contents of the massive tuff samples are remarkably consistent, in that all samples are enriched in light REE (LREE), have moderately negative Eu anomalies, and show gently sloping heavy REE profiles (Fig. 12e). The average Lan/Smn decreases from 7.29 (Unit NF1) to 7.04 (Unit NF5), suggesting a slight LREE depletion with ascending stratigraphic level in the Nepisiguit Falls Formation; additional sampling is required to confirm this trend. The overall REE slope also flattens with ascending stratigraphic level as Lan/Lun values decrease from 7.35 (Unit NF1) to 7.09 (Unit NF5). The Eun/Eu* for the Nepisiguit Falls data set averages 0.24; however, there is no obvious trend, as the average Eun/Eu* values for all units range from 0.22 to 0.27 regardless of stratigraphic level. Likewise, the average ΣREE content for each of the eruptive units is similar, with values ranging from 174 ppm to 191 ppm. The consistency of ΣREE and Eun/Eu* among the five units of the Nepisiguit Falls Formation suggests they all formed from a single magma that did not have time to fractionate between eruptions. Other interesting trace-element patterns were also recognized. Specifically, Sn and W both increase upsection through the Nepisiguit Falls Formation, whereas Cs decreases (Fig. 10a). Such systematic variation with respect to stratigraphic level in volcanic successions may be interpreted to reflect fractional crystallization processes in an evolving magma chamber. Several samples of volcaniclastic rocks that were interbedded with crystal tuff can be distinguished on the basis of their chemistry. In particular, samples collected at 339.5 m, 376 m, 541 m, and 617 m all have higher MgO, Sc, Zr, TiO2, and Co contents, similar to values in samples from the Miramichi Group (Fig. 9f, 10a, 10b). Higher MgO in these samples is explained by the relative abundance of chlorite. Elevated Sc is attributed to Sc substituting in the muscovite (phengite) structure, whereas elevated Zr and TiO2 may be related to crystal winnowing processes.

Figure 12.

a)

b)

c)

d)

e)

Lithogeochemical discrimination diagrams for felsic volcanic and volcaniclastic rocks of the

Nepisiguit Falls and Flat Landing Brook formations intersected in drillhole HN99-119 at the Deep Zone,

Halfmile Lake deposit. 100*K O/( K O) versus Na O+K O diagram for the determination of

altered volcanic rocks; field boundaries are from Hughes (1972). Na O+K O diagram;

field boundaries are from Le Bas et al. (1986). Zr versus TiO diagram; field boundaries are from

Winchester and Floyd (1977). Nb/Y versus Zr/TiO diagram; field boundaries are from Winchester

and Floyd (1977). Chondrite-normalized REE profiles; normalization factors are from Nakamura

(1974).

2 2 2 2

2 2

2

2

Na O+

SiO versus2

2

27

1

10

100

1000

LaCe

PrNd

PmSm

EuGd

TbDy

HoEr

TmYb

Lu

Sam

ple

/ c

hondrite

35 40 45 50 55 60 65 70 750

2

4

6

8

10

12

14

16

Pic

ro-

basalt

Basalt

Basaltic

andesite

Andesite Dacite

Rhyolite

Trachyte

Trachy-daciteTrachy-

andesite

Basaltictrachy-andesite

Trachy-basalt

Tephritebasanite

Phono-tephrite

Tephri-phonolite

Phonolite

Foidite

SiO wt %2

Na

O+

KO

wt

%2

2

0 20 40 60 80 1000

2

4

6

8

10

12

14

Keratophyre

Spillite

Na

O+

KO

wt

%2

2

100*K O/Na O+ )2 2 K O2

TiO

wt %

2

0.1 10.01

0.003

0.1

1

Subalkaline basalt

Andesite

Rhyodacite/dacite

Rhyolite

Alkalinebasalt

Tra

chyandesite

Comendite/pantellerite

Basanite /nephelinite

Zr/

TiO

2

Nb/Y

a)

b)

c)

d)

e)

0 100 200 300 4000

1

Zr ppm

Flat LandingBrook Formation

NepisiguitFalls Formation:flows and tuffs

r’ = 0.797

Igneous

spect

rum

NF1

NF2

NF3

NF4

NF5



Basalt dyke

80 85 90

r’ = correlationcoefficient

28


Two samples of felsic volcanic rock collected from the Flat Landing Brook Formation fall in the field of K-altered rocks on a 100*K2O/(Na2O+K2O) versus Na2O+K2O diagram (Fig. 12a). The two samples plot in the rhyolite field on a SiO2 versus Na2O+K2O diagram (Fig. 12b). On a Zr versus TiO2 diagram (Fig. 12c), the samples plot slightly below the line defining the Nepisiguit Falls trend (Zr/Ti = 0.167), because the Zr content is higher (by ~80–100 ppm) and the TiO2 content is slightly lower (by ~0.05 wt %) in the Flat Landing Brook samples. Together, the higher Zr and lower TiO2 contents of these samples account for a 0.01 to 0.02 increase in the Zr/Ti value in the Flat Landing Brook relative to that in the Nepisiguit Falls samples. The higher Zr/Ti value explains why the former rocks plot near the top of the rhyodacite–dacite field on a Nb/Y versus Zr/TiO2 diagram (Fig. 12d). The total REE content is higher in the Flat Landing Brook Formation than in the Nepisiguit Falls Formation, with an average ΣREE of 240 ppm. The REE profiles have steeper slopes in the Flat Landing Brook, with average Lan/Smn and Lan/Lun values of 7.9 and 8.0, respectively. The average Eun/Eu* is 0.22 for the Flat Landing Brook samples, identical to that of the uppermost stratigraphic unit in the Nepisiguit Falls Formation.

Basalt Dyke

The chemistry of sample HN-119-0307.3 m, collected from near the base of Unit NF4, is unlike that of other rocks from the Nepisiguit Falls Formation. It is depleted in LREE, has much higher Cr, Ni, and V, and has lower Zr. On a Nb/Y versus Zr/Ti diagram, the sample falls in the subalkaline basalt field (Fig. 12d). The sample is from a sill or dyke that likely fed mafic rocks higher in the Flat Landing Brook Formation or possibly is from the Little River Formation (Tetagouche Group), which stratigraphically overlies the Flat Landing Brook Formation.

EXHALITE CHARACTERISTICS

Upper, Lower, and North Zones

Breccia-matrix sulphides and chalcopyrite-rich stringer mineralization stratigraphically underlie the Upper, Lower, and North zones of the Halfmile Lake deposit (Fig. 3). The breccia-matrix sulphides typically occur at the base of the massive sulphide lens, stratigraphically immediately above the stringer mineralization; they are laterally persistent and account for the bulk of sulphide mineralization. Sulphide minerals represent between 50% and 90% of the rock volume in the breccia zones and are dominated by pyrrhotite with subordinate chalcopyrite, pyrite, and minor sphalerite and galena. Breccia-matrix sulphides are generally of low grade (4–10 wt % Zn+Pb), with a Zn/Pb value of approximately 4 (Adair 1992b). The pyrrhotite content decreases stratigraphically upward as breccia-matrix sulphides grade into pyrite-dominated massive sulphides (Adair 1992b). The massive sulphides initially may

29

have been bedded, but any evidence of such a stratiform origin would have been removed by their ductile response to intense penetrative deformation in the region. The development of pyrrhotite-rich breccia-matrix sulphides (Fig. 13a), coupled with the presence of chalcopyrite–pyrrhotite stringer mineralization (Fig. 13b), is interpreted to reflect replacement of volcaniclastic host rocks immediately above the stringer zone in a vent-proximal environment. Such an interpretation supports the proximal autochthonous classification proposed for the Upper, Lower, and North zones by Jambor (1979).

Deep Zone

The Deep Zone massive sulphide lens lies about 500 m north-northwest of, and 300 m below, the Lower Zone at a vertical depth of approximately 1100 m below surface (Fig. 2, 3). It is a relatively flat-lying body of massive sulphides and minor, poorly developed, spatially associated stringer and disseminated sulphides. The massive sulphide lens at the Deep Zone is dominated by pyrite and contains only very minor fragments of chlorite-altered host rock (Fig. 14a, 14b). This is in contrast with the three other zones of the Halfmile Lake deposit, in which pyrrhotite is the dominant sulphide phase, and chloritic fragments may constitute >50% of some intervals (Fig. 13a; Adair 1992b). The presence of minor stringer sulphide mineralization and coincident chlorite and sericite hydrothermal alteration in the structural hanging wall is consistent with relationships reported from the Upper, Lower, and North zones, and reflects the overturned attitude of the deposit (Adair 1992b). But unlike the three other sulphide zones, the Deep Zone contains Algoma-type, oxide-facies iron formation, as evidenced by core from drillholes HN99-123A (Fig. 2, 3) and HN99-124B, which intersect the zone. The Algoma-type iron formation in both drillholes occurs near the centre of the sulphide zones and is in sharp contact with the massive sulphides (Fig. 15). This relationship is interpreted to reflect an isoclinal, parasitic syncline of a massive sulphide sheet and its infolded, capping oxide-facies iron formation. As stated earlier, the Deep Zone contains an NI 43-101-compliant inferred resource of 4.83 Mt grading 6.37% Zn, 1.6% Pb, 0.15% Cu, and 17.04 g/t Ag (Table 2; Trevali Mining Corporation 2011a). The Pb–Cu–Zn ratios of this zone are similar to those in other zones of the Halfmile Lake deposit. As well, the Ag content is comparable with that of the other zones, with grades of 10 g/t to 25 g/t Ag. The average Ag grade for larger deposits in the BMC is about 90 g/t to 100 g/t (McCutcheon et al. 2003). No detailed geochemical–petrographic examination has yet been published of massive sulphides from the Halfmile Lake Deep Zone. Nonetheless, work is currently underway (by J. Zulu of Trevali Mining Corporation) to examine microscale relationships among the various sulphide mineral phases, as well as their trace-element contents. Such work on the Deep Zone lies beyond the scope of the present study.

Figure 13.

a)

b)

Sulphide mineralization at the Upper

Zone, Halfmile Lake deposit. Pyrrhotite-rich breccia-matrix sulphides (brown) with abundant

chloritic fragments (green) at about 74 m. Chalcopyrite–pyrrhotite stringer mineralization cutting

bleached sedimentary rocks at about 44 m. Core diameters are 4.7 cm.

intersected in Kria Resources Ltd. drillhole HK-10-04

30

a

b

Figure 14.

a)

b)

Sulphide mineralization the Deep Zone, Halfmile Lake

deposit (Fig. 2, 3). Massive sulphide lens with minor chloritic fragments at about 1170 m. Fragments

are interpreted to represent altered enclaves of stratigraphically underlying volcaniclastic material

resulting from subsurface replacement. Pyritic massive sulphide and chloritic volcaniclastic material

at about 1178 m. Core diameters are

intersected in drillhole HN99-123 at

4.7 cm.

31

a

b

Figure 15. Overview of exhalite at the Deep Zone, Halfmile Lake

deposit (Fig. 2, 3); photograph shows the interval between about 1173 m and 1189 m. Massive

sulphides are yellow, oxide-facies iron formation is black, and minor chloritic sedimentary rock is

green. Note the absence of breccia-matrix sulphide textures. Core diameter

intersected in drillhole HN99-123

is 4.7 cm.

32

HYDROTHERMAL ALTERATION

An examination of hydrothermal alteration associated with the Deep Zone using Pearce

element ratio analysis was the subject of a thesis by Mireku (2001) and a subsequent paper

by Mireku and Stanley (2007). Presented below is a brief discussion and reinterpretation of

their results in light of the revised tectonostratigraphic relationships and new major-element

data presented herein.

Mireku and Stanley (2007) suggest that most rocks in the structural hanging wall within 300

m to 400 m of the Deep Zone (i.e., the Patrick Brook Formation, according to the present

study) are more altered. The rocks show lower valu alteration

index and therefore reflect a loss of Ca, Na, and K and a gain of CO relative to Al (Mireku

and Stanley 2007, thei

n in the upward-facing limb of the Halfmile Lake

Anticline, according to the present study) and immediate structural footwall (Nepisiguit

Falls Formation in the downward-facing limb of the anticline) are less altered. Similar

results were realized for the Na/Al alteration index, according to Mireku and Stanley (2007,

their Fig. 12b). However, the low Na, Sr,

and Ca contents in rocks of the Miramichi Group could be a primary feature rather than the

result of hydrothermal alteration.

2

as discussed earlier under Lithogeochemistry,

es for the (2Ca+Na+K–CO )/Al

r Fig. 12a). In contrast, rocks higher in the structural hanging wall

(i.e., the Nepisiguit Falls Formatio

2

33

Values for the K/Al alteration index are marginally higher in the Nepisiguit Falls Formation in both the upward- and downward-facing limbs than they are in the Patrick Brook Formation (see Mireku and Stanley 2007, their Fig. 12c). This is probably because volcanic rocks that erupt in a marine setting commonly undergo mass addition of potassium as a result of interaction with seawater (Hughes 1972). It is likely that the K/Al value in the host sequence reflects detrital K-mica content in the Patrick Brook Formation and slightly higher, seawater- induced K-metasomatism of the volcanic rocks rather than hydrothermal, deposit-related K-metasomatism of the host sequence. The (Fe+Mg–S/2)/Al alteration index is useful in recognizing chloritization. When applied to lithogeochemical analyses of the Halfmile Lake deposit, the index suggests that most rocks in the sequence are weakly chloritized, except for felsic rocks immediately adjacent to the Deep Zone and a few samples situated adjacent to the sulphide veins in the structural hanging wall (Mireku and Stanley 2007, their Fig. 12d). These data also show that felsic volcanic rocks of the Nepisiguit Falls Formation in the upward-facing limb are unaffected by hydrothermal alteration, excluding a few samples at the base of the formation. Similarly, a plot of (Fe–S/2)/Mg, which is used to distinguish Fe-rich chlorite (hydrothermal) from Mg-rich chlorite (seawater-related), indicates that most samples within 400 m of the stratigraphic base of the sulphide lens are dominated by Fe-rich chlorite and therefore are interpreted as hydrothermally altered rocks (Mireku and Stanley 2007, their Fig. 13b). However, these data from Mireku and Stanley (2007) and the data collected during the present study (Appendix 1) show that the Miramichi Group here has a marginally higher Fe2O3

tot content (5–10 wt % range) than the 4 wt % to 8 wt % Fe2O3tot range reported by

Rogers et al. (2003) from elsewhere in the BMC. Therefore, although some of the high iron in the structural hanging wall may be attributable to hydrothermal alteration, it is more likely that the bulk of the iron reflects the primary composition of sedimentary rocks in the Patrick Brook Formation (Miramichi Group). The increase in CaO (Fig. 10a) in the structural footwall (Mireku and Stanley 2007) is probably a result of calcite precipitation from deformation-generated metamorphic fluids migrating along the thrust in the structural footwall, and is unrelated to genesis of the Deep Zone.

DISCUSSION

Previous work by Adair (1992b) and others assigned the entire sequence of sedimentary rocks and felsic volcanic and volcaniclastic rocks in the Halfmile Lake deposit to the Nepisiguit Falls Formation (Tetagouche Group), considering them to represent a continuous, downward-facing homoclinal sequence. However, the relogging of drillhole HN99-119 during the present study indicates that most of the sedimentary rocks previously interpreted as Nepisiguit Falls Formation are actually Patrick Brook Formation. This means that a major anticlinal fold closure—that is, the Halfmile Lake Anticline—exists in the immediate structural hanging wall of the deposit.

34

Northern Limb of the Halfmile Lake Anticline

In the upward-facing, northern limb of the Halfmile Lake Anticline, the Nepisiguit Falls Formation has a conformable upper contact with felsic volcanic rocks of the Flat Landing Brook Formation and a conformable lower contact with clastic sedimentary rocks of the Patrick Brook Formation (Fig. 2, 3). The Nepisiguit Falls Formation has a maximum true stratigraphic thickness of about 540 m and is divided into five eruptive units of dominantly quartz–feldspar crystal tuff. Pumice clasts are recognized locally, as are interlayered volcaniclastic rocks (Fig. 6a, 6c). The relatively minor volume of fine-grained volcaniclastic rock contrasts with the fairly thick accumulation of coarse-grained volcaniclastic material. The abundance of coarse-grained volcaniclastic material, combined with the absence of massive felsic lava flows and related hypabyssal intrusions, suggests that the deposit was formed in a transitional setting between vent-proximal and vent-medial. Such a depositional setting would ‘correspond’ with the primary pyroclastic and resedimented syn-eruptive lithofacies (upper part of Grand Falls Member) in the eastern BMC, as interpreted by Downey (2005).

Previous workers (Adair 1992b; Wilson 1993c; Kempster 2001) proposed bedding-parallel thrust faults in the structural hanging wall but offered no estimate of the actual pre-faulting thickness of the Nepisiguit Falls Formation. Results of the present study are fairly consistent with those of de Roo and van Staal (1991), who interpreted the structural hanging wall to be a conformable, upward-facing sequence of sedimentary rocks of the Patrick Brook Formation overlain by mainly volcanic rocks of the Nepisiguit Falls and Flat Landing Brook formations to the north (Fig. 2, 3). Adair (1992b) shows the contact between the Nepisiguit Falls and Flat Landing Brook formations in the downward-facing, structural footwall as a D1 thrust fault. However, the relatively low apparent strain in the footwall (in mafic volcanic rocks of the Flat Landing Brook Formation to the south) indicates that this contact may be a younger reverse fault related to D2 or D3 folding.

Southern Limb of the Halfmile Lake Anticline

In the downward-facing, southern limb of the Halfmile Lake Anticline, felsic volcanic rocks that stratigraphically overlie the Deep Zone massive sulphide lens are chemically similar in Cs, Sn, Zr/Th, TiO2, Zr, and Zr/TiO2 (Fig. 10a, 10b) to Unit NF1 of the Nepisiguit Falls Formation in the anticline’s northern limb but not to Units NF2 to NF5 (Fig. 4). However, the variation in most geochemical markers is minor, and mass change due to hydrothermal alteration has undoubtedly affected the felsic volcanic rocks adjacent to the Deep Zone. Given these considerations, any unequivocal correlation across the anticlinal hinge is not possible, which then begs the question: where did Units NF2 to NF5 in the structural footwall go?

The massive sulphide zones of the Halfmile Lake deposit are likely part of a single, large sulphide-generating system with all four zones lying on one horizon (Fig. 2, 3). Presently, massive sulphide mineralization is almost continuous between the zones. Yet it is unclear whether such geometry is the result of mineralization originating as a continuous sulphide sheet or is the function of deformation-induced coalescence involving two or more discrete sulphide bodies.

35

Depositional Settings of the Halfmile Lake Deposit

Several factors suggest that the depositional setting of the Deep Zone differed from that of the three other zones at the Halfmile Lake deposit. The Deep Zone contains almost no breccia-matrix sulphides and stringer mineralization.

Both features are abundant at the other zones. The Deep Zone sulphide lens is dominated by pyrite, whereas sulphides at the other zones

are dominated by pyrrhotite. The Deep Zone contains Algoma-type, oxide-facies iron formation infolded within some of

the thicker sulphide intersections. Algoma-type iron formation is absent at the other zones. It is uncertain whether these differences reflect a deposit-scale or a regional-scale variation. The extent of iron formation is generally limited across the western BMC. For instance, Algoma-type iron formation is well developed east of Halfmile Lake at the Heath Steele deposit (Fig. 1) but is absent west of and along strike from Halfmile Lake at the Mount Fronsac North deposit (Fig. 1; Walker and Graves 2006). Variations in the thickness and type of iron formation may reflect differences in water depth within a stratified basin (Goodfellow and Peter 1996). As well, iron formation could have existed in shallower parts of the Halfmile Lake deposit but have been tectonically cut out along the thrust or reverse fault in the structural footwall (Fig. 3). The Upper, Lower, and North zones may have formed mainly via replacement of volcaniclastic horizons in a setting proximal to an eruptive centre. In this scenario, ascending hydrothermal fluids alter and then replace volcaniclastic rocks below the rock–water interface, accounting for the abundance of sulphide stringers below the stratigraphic base of the sulphide lenses, as well as for the large component of intensely chloritized lithic fragments throughout the sulphide lenses (Lydon 1989). Subseafloor emplacement of sulphides implies a thermal insulation at the deposition site, resulting in higher temperatures (>250oC) and thereby favouring chalcopyrite deposition (Lydon 1989). Subseafloor deposition can also lead to decreased interaction with seawater, which is commonly considered to be the dominant source of sulphur in VMS systems. This in turn would imply lower ƒS2 at the site of mineralization and favour the deposition of pyrrhotite over pyrite. Likewise, because subseafloor emplacement of sulphides would preclude direct interaction with the seawater column, a conformable iron-oxide cap such as exists at Brunswick No. 12 and Heath Steele (Fig. 1) would not be generated (Peter and Goodfellow 1996). In contrast, the Deep Zone likely formed by the venting and subsequent downslope ponding of hydrothermal fluids that were generated in topographically higher, more proximal parts of the deposit: that is, the Upper and Lower zones. Subsequent ocean oxygenation would form an oxide-facies cap on stratiform parts of the deposit, whereas those parts of the deposit formed via subseafloor replacement mechanisms would be isolated from seawater and thus would be less likely to have an associated oxide-facies iron formation.

36

Note that the sedimentary rocks immediately below the basal unit of the Nepisiguit Falls Formation in the upward-facing limb have elevated Pb and Cu, and marginally elevated As and Zn relative to the adjacent Nepisiguit Falls felsic volcanic and volcaniclastic rocks. Although no sedimentary exhalative material was recognized at this contact in drillhole HN99-119, the anomalous values could reflect a distal plume fallout associated with formation of the Halfmile Lake deposit.

CONCLUSIONS

The structural footwall of the Halfmile Lake volcanogenic massive sulphide deposit comprises a relatively thin (<200 m thick), downward–facing sequence of felsic volcanic and volcaniclastic rocks of the Nepisiguit Falls Formation (Tetagouche Group), lying on the southern limb of the southerly overturned Halfmile Lake Anticline. The sulphide deposit is hosted by the Nepisiguit Falls Formation just above the conformable contact with sedimentary rocks of the Patrick Brook Formation (Miramichi Group). The higher part of the structural hanging wall at the Halfmile Lake deposit consists of an upward-facing volcanic sequence (Nepisiguit Falls and Flat Landing Brook formations) occupying the northern limb of the anticline (Fig. 2, 3). Within the structural hanging wall, there is no apparent evidence at depth for the tectonic imbrication in the near surface, as had been proposed by earlier workers. The downward-facing southern limb of the Halfmile Lake Anticline may be cut out in the structural footwall by a D2–D3 reverse fault rather than by a D1–D2 thrust fault. On the upward-facing limb of the anticline, the Nepisiguit Falls Formation reaches a maximum true thickness of approximately 540 m and can be divided into five eruptive units, none of which is considered vent-proximal. Given their close spatial association and very similar stratigraphic setting, the four massive sulphide zones that constitute the Halfmile Lake deposit (Upper, Lower, North, and Deep zones) are interpreted to lie on the same horizon. However, the relatively limited extent of diamond drilling between the Deep and Lower zones makes any assertion of continuity between the zones tentative. The Upper, Lower, and North zones lie at or near the base of the Nepisiguit Falls Formation, stratigraphically underlain by the Patrick Brook Formation and overlain by the remainder of the Nepisiguit Falls Formation. All three zones have well-developed stringer mineralization in the structural hanging wall and show evidence (in the form of abundant chlorite-altered fragments) of volcanic rocks having been replaced by massive sulphides. These features, coupled with the pyrrhotite-dominant nature of the massive lenses and the lack of Algoma-type iron formation stratigraphically overlying the sulphides in the structural footwall, suggest a vent-proximal, subseafloor emplacement for shallower zones of the Halfmile Lake deposit. In contrast, the Deep Zone is stratigraphically underlain by about 10 m of felsic tuff and volcaniclastic rocks of the Nepisiguit Falls Formation, in the structural hanging wall. The zone lacks a well-developed stringer zone, and the massive sulphide lens is dominated by

37

pyrite with only rare pyrrhotite. Algoma-type, oxide-facies iron formation is also associated with the Deep Zone. Collectively, these observations suggest that the zone underwent a lower temperature, vent-distal supraseafloor emplacement process such as described by Lydon (1989).

Recognition that the Halfmile Lake deposit sits at or very near the stratigraphic base of the Nepisiguit Falls Formation is significant, as it places the deposit in a stratigraphic setting similar to the one at the former Heath Steele mine (Lentz and Wilson 1997). It also raises the potential for VMS exploration and discovery in areas underlain by the Nepisiguit Falls Formation in the western BMC. Similarly, areas underlain by the Flat Landing Brook Formation to the east and south of the Halfmile Lake deposit may have rocks of the Nepisiguit Falls Formation and associated massive sulphide deposits at depth.

ACKNOWLEDGEMENTS

We wish to acknowledge financial support from Xstrata Zinc Canada for some of the analytical costs associated with this project. We acknowledge Reg Wilson of the Geological Surveys Branch, New Brunswick Department of Natural Resources, for numerous discussions about the geology of the Halfmile Lake area. Digital lithogeochemical data, previously reported in Mireku (2001) and Mireku and Stanley (2007), were kindly provided by Dr. Cliff Stanley of Acadia University, Nova Scotia. We thank Dayle Rusk of Trevali Mining Corporation for providing access to drill core and confidential material, as well as for discussions. This paper has benefitted greatly from critical reviews by Reg Wilson and Les Fyffe of the Geological Surveys Branch.

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Downey, W.S. 2005. The geological setting, petrology and facies analysis of the Nepisiguit Falls Formation, Bathurst Mining Camp: an example of a deep submarine pyroclastic eruptive sequence. Unpublished M.Sc. thesis, University of New Brunswick, Fredericton, New Brunswick, 294 p.

Downey, W.S., McCutcheon, S.R., and Lentz, D.R. 2006. A physical, volcanological, chemostratigraphic and petrogenetic analysis of the Little Falls Member, Tetagouche Group, Bathurst Mining Camp, New Brunswick. Exploration and Mining Geology, 15, p. 77–98.

Fyffe, L.R. 1982. Taconian and Acadian structural trends in central and northern New Brunswick. In Major Structural Zones and Faults of the Northern Appalachians. Edited by P. St-Julien and J. Bèland. Geological Association of Canada, Special Paper 24, p. 117–130.

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Goodfellow W.D., and McCutcheon, S.R. 2003. Geological and genetic attributes of volcanic associated massive sulfide deposits of the Bathurst Mining Camp, northern New Brunswick: a synthesis. In Massive Sulfide Deposits of the Bathurst Mining Camp, New Brunswick, and Northern Maine. Edited by W.D. Goodfellow, S.R. McCutcheon, and J.M. Peter. Economic Geology, Monograph 11, p. 245–302.

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Helmstaedt, H. 1973. Structural geology of the Bathurst–Newcastle district. In Field Guide to Excursions. Edited by N. Rast. New England Intercollegiate Geological Conference, Department of Geology, University of New Brunswick, Fredericton, New Brunswick, p. 34–43.

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McCutcheon, S.R., Luff, W.M., and Boyle, R.W. 2003. The Bathurst Mining Camp, New Brunswick, Canada: history of discovery and evolution of geological models. In Massive Sulfide deposits of the Bathurst Mining Camp, New Brunswick, and Northern Maine. Edited by W.D. Goodfellow, S.R. McCutcheon, and J.M. Peter. Economic Geology, Monograph 11, p. 17–36.

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Mining Camp, and its relationships to coeval rocks in southwestern New Brunswick and adjacent Maine: a synthesis. In Massive Sulfide Deposits of the Bathurst Mining Camp, New Brunswick, and Northern Maine. Edited by W.D. Goodfellow, S.R. McCutcheon, and J.M. Peter. Economic Geology, Monograph 11, p. 37–60.

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Appendix 1: Analytical Data for Samples from Drillhole HN99-119,

Halfmile Lake Deep Zone, Halfmile Lake Deposit, Bathurst Mining Camp

Notes

1. Analyses for the current study were conducted by Activation Laboratories Ltd. in Ancaster, Ontario. Analytical methods and detection limits for the data compiled from Mireku (2001) are described in Mireku (2001) and Mireku and Stanley (2007).

2. All values are in ppm unless otherwise stated. 3. Analytical methods used: FUS–ICP = Metaborate/tetraborate fusion–inductively coupled

plasma emission spectrometry, FUS–MS = Metaborate/tetraborate fusion–mass spectrometry, INAA = Instrumental neutron activation analysis, TD–ICP = Total digestion–inductively coupled plasma mass spectrometry

4. Units analyzed: FLB = Flat Landing Brook Formation (Tetagouche Group), NF1–5 =

eruptive units of the Nepisiguit Falls Formation (Tetagouche Group), OM = Patrick Brook Formation (Miramichi Group), (vc) = volcaniclastic rocks

Sample Number / Data Source red = this study; black = Mireku 2001

HN-119-0050.3

HN-119-0082.8

HN-119-0138.7

HN-119-0175.6

HN-119-0202.2

HN-119-0221

HN-119-0243.6

HN-119-0256.8

HN-119-0285

HN-119-0304.7

HN-119-0307.3

Rock Unit

Analytical

Method Detection

Limit

FLB FLB NF5 NF5 NF5 NF4 NF4 NF4 NF4 NF4 Basalt Dyke

SiO2 wt% FUS-ICP 0.01 71.73 69.6 75.31 74.22 72.3 74.39 77.57 74.24 73.7 75.07 44.91

Al2O3 wt% FUS-ICP 0.01 11.42 12.76 13.03 12.98 13.25 12.5 11.68 12.5 13.23 12.87 19

Fe2O3(Tot) wt% FUS-ICP 0.01 4.99 4.89 2.07 2.18 3.64 2.3 2.67 3.03 2.15 2.22 11.7 MnO wt% FUS-ICP 0.001 0.066 0.096 0.051 0.051 0.041 0.046 0.038 0.044 0.027 0.029 0.159 MgO wt% FUS-ICP 0.01 0.73 2.03 0.57 0.72 0.85 0.78 0.76 1.07 0.84 0.69 10.55 CaO wt% FUS-ICP 0.01 0.7 0.6 0.51 0.46 0.47 0.59 0.25 0.21 0.26 0.22 0.32

Na2O wt% FUS-ICP 0.01 0.67 1.62 3.52 2.63 1.04 1.87 3.36 1.15 2.13 1.64 2.25

K2O wt% FUS-ICP 0.01 6.82 6.18 3.54 4.88 5.78 5.54 2.82 5.99 5.82 6.43 6.8

TiO2 wt% FUS-ICP 0.001 0.347 0.36 0.28 0.287 0.287 0.282 0.257 0.277 0.281 0.271 1.157

P2O5 wt% FUS-ICP 0.01 0.11 0.13 0.12 0.11 0.12 0.13 0.11 0.1 0.12 0.12 0.08

LOI wt% FUS-ICP 0.01 3.23 2.6 1.7 1.78 2.13 1.8 1.18 1.67 1.27 1.13 3.87

Ag FUS-MS 0.5 0.9 0.9 0.5 0.6 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

As INAA 0.1 77.4 24.5 17.3 11.5 13 34.3 2.6 5.6 3.6 6.6 69.8

Au ppb INAA 2 15 18 <2 <2 <2 <2 <2 <2 <2 <2 <2

Ba FUS-ICP 3 815 862 664 877 873 898 562 1358 1236 1508 413

Bi FUS-MS 0.1 1.3 1.7 0.5 0.5 0.7 0.4 0.2 0.2 0.3 0.3 0.3

Cd TD-ICP 0.5 0.7 <0.5 1.2 0.9 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Co INAA 1 5 7 2 3 7 2 3 4 2 3 48

Cr INAA 0.1 12 2.5 2.5 10 11 9 9 14 11 10 360

Cs FUS-MS 0.1 0.9 0.8 1.2 0.8 0.8 0.7 0.6 0.8 0.7 0.7 8

Cu TD-ICP 1 10 6 16 8 28 9 4 4 4 1

Ga FUS-MS 1 16 18 15 16 17 16 13 15 15 14 19

Ge FUS-MS 0.1 1.1 1 0.8 0.9 1 1 1 1.1 1 1 1.5

Hf FUS-MS 0.1 7.1 7.5 5 5.2 5.6 5.2 4.5 4.9 5.5 4.9 1.5

Mo FUS-MS 2 4 28 <2 <2 2 <2 <2 <2 <2 <2 <2

Nb FUS-MS 0.1 14.2 14.8 11.9 13.7 10.9 11.5 10.6 11.4 13.1 11.7 3.8

Ni TD-ICP 1 4 3 5 4 4 4 5 3 3 146

Pb FUS-MS 1 134 91 61 187 28 24 13 15 17 22 9

Rb FUS-MS 1 181 140 111 137 184 155 86 161 147 143 380

S wt% TD-ICP 0.001 2.11 0.834 0.17 0.024 0.073 0.087 0.031 0.027 0.011 0.004

Sb FUS-MS 0.1 4.9 1.6 0.5 0.7 2.2 0.9 0.5 1.4 0.8 1 1.1

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HN-119-0050.3

HN-119-0082.8

HN-119-0138.7

HN-119-0175.6

HN-119-0202.2

HN-119-0221

HN-119-0243.6

HN-119-0256.8

HN-119-0285

HN-119-0304.7

HN-119-0307.3

Rock Unit

Analytical

Method Detection

Limit

FLB FLB NF5 NF5 NF5 NF4 NF4 NF4 NF4 NF4 Basalt Dyke

Sc FUS-ICP 1 7 7 5 6 6 6 4 5 6 5 40

Se INAA 3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3

Sn FUS-MS 1 4 4 7 8 7 6 7 7 6 6 2

Sr FUS-ICP 2 50 66 67 67 50 64 43 46 60 67 33

Ta FUS-MS 0.01 1 1.02 0.87 0.93 0.9 0.87 0.81 0.8 0.93 0.85 0.08

Th FUS-MS 0.1 19 20.9 16.1 16.8 17 16.3 14.6 16 17.1 15.6 0.06

Tl FUS-MS 0.01 1.23 0.88 0.49 0.57 0.73 0.6 0.33 0.6 0.55 0.52 2.19

U FUS-MS 0.01 5.14 5.75 5.16 5.14 5.27 5.04 4.46 4.96 5.05 5.03 0.18

V FUS-ICP 5 26 25 19 20 20 20 18 18 18 18 265

W FUS-MS 0.5 3 1.5 1.7 1.6 2.1 2.6 1 1.9 1.1 0.6 <0.5

Y FUS-MS 0.1 40.3 44.6 39.1 40.5 41.8 40.1 31.1 39.7 41 41 36

Zn TD-ICP 1 71 54 541 320 27 30 32 18 19 90

Zr FUS-MS 1 261 273 174 179 186 184 157 176 194 169 43

La FUS-MS 0.1 47.8 49.1 38.1 37.5 38.3 35.4 31.1 37.9 38.4 36.5 5.16

Ce FUS-MS 0.1 104 107 82 80.5 83 76.1 67.5 81.4 82.3 78.5 11.9

Pr FUS-MS 0.1 10.6 10.9 8.25 8.21 8.47 7.75 6.76 8.19 8.23 7.87 1.4

Nd FUS-MS 0.1 39.4 40.1 30.9 30.7 31 28.8 24.9 30 30.2 28.9 6.46

Sm FUS-MS 0.1 8.17 8.65 6.93 6.81 7.06 6.59 5.42 6.54 6.79 6.54 2.18

Eu FUS-MS 0.001 0.872 0.787 0.663 0.677 0.755 0.697 0.587 0.614 0.728 0.792 0.383

Gd FUS-MS 0.01 7.35 7.93 6.37 6.47 6.62 6.3 5.09 6.2 6.44 6.33 3.44

Tb FUS-MS 0.01 1.2 1.32 1.11 1.13 1.18 1.15 0.91 1.08 1.17 1.13 0.85

Dy FUS-MS 0.01 6.91 7.77 6.78 6.78 7.21 7.08 5.41 6.4 6.92 6.84 6.1

Ho FUS-MS 0.01 1.36 1.52 1.34 1.37 1.41 1.38 1.04 1.26 1.32 1.34 1.33

Er FUS-MS 0.01 3.97 4.47 3.83 3.95 3.96 3.86 2.99 3.63 3.78 3.83 3.98

Tm FUS-MS 0.001 0.6 0.661 0.55 0.584 0.594 0.564 0.445 0.526 0.554 0.556 0.586

Yb FUS-MS 0.01 3.8 4.28 3.49 3.71 3.8 3.66 2.88 3.37 3.55 3.53 3.69

Lu FUS-MS 0.002 0.592 0.667 0.535 0.556 0.577 0.551 0.445 0.533 0.542 0.526 0.551

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HN-119-0308.8

HN-119-0339.5

HN-119-0376

HN-119-0385.6

HN-119-0445

HN-119-0482

HN-119-0517.6

HN-119-0541

HN-119-0554.6

HN-119-0580.6

HN-119-0617

Rock Unit

Analytical

Method Detection

Limit

NF3 NF2 (vc) NF2 (vc) NF2 NF2 NF2 NF2 NF2 (vc) NF1 NF1 NF1

SiO2 wt% FUS-ICP 0.01 74.2 56.17 59.05 74.06 72.3 76.73 75.11 64.99 74.44 74.85 61.86

Al2O3 wt% FUS-ICP 0.01 12.92 17.3 15.13 12.8 13.24 11.53 12 12.94 12.79 12.23 15.38


Na2O wt% FUS-ICP 0.01 0.87 2.13 2.31 2.06 2.29 2.99 2.99 4.01 2.31 1.71 0.07

K2O wt% FUS-ICP 0.01 6.46 3.93 2.99 5.98 6.01 4.5 3.26 1.88 5.38 6.41 4.87

TiO2 wt% FUS-ICP 0.001 0.27 0.86 1.421 0.265 0.283 0.252 0.256 0.624 0.274 0.254 0.909

P2O5 wt% FUS-ICP 0.01 0.11 0.21 0.38 0.11 0.13 0.11 0.07 0.08 0.1 0.1 0.24

LOI wt% FUS-ICP 0.01 1.67 3.69 3.87 1.21 1.17 0.8 1.6 4.02 1.42 1.8 3.57

Ag FUS-MS 0.5 <0.5 1.1 <0.5 <0.5 <0.5 <0.5 <0.5 0.5 <0.5 <0.5 0.6

As INAA 0.1 7.6 14 11.6 3 4.4 4.6 3.1 16.2 4.2 1.5 10

Au ppb INAA 2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

Ba FUS-ICP 3 1581 1085 615 1153 865 1045 707 476 1319 1202 1132

Bi FUS-MS 0.1 0.5 0.3 0.5 0.1 0.1 0.1 0.1 <0.1 <0.1 <0.1 0.2

Cd TD-ICP 0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Co INAA 1 4 19 17 3 2 2 3 12 3 2 13

Cr INAA 0.1 10 10 2.5 15 14 14 13 89 11 10 97

Cs FUS-MS 0.1 1.2 1.3 1.1 1.2 1.3 0.9 1.3 0.9 1.8 2.4 5

Cu TD-ICP 1 3 1 2 8 15 2 2 13 1 2 73

Ga FUS-MS 1 13 23 18 14 15 11 14 16 15 13 22

Ge FUS-MS 0.1 1.1 1.5 1.3 1 1.2 1.2 0.9 1.1 1.1 0.9 1.9

Hf FUS-MS 0.1 5.1 10.5 4.8 5 5 4.5 4.2 5.7 4.8 4.7 5.6

Mo FUS-MS 2 <2 <2 <2 <2 <2 <2 3 <2 <2 <2 <2

Nb FUS-MS 0.1 11.9 23.9 15.6 11 12.2 10.5 12.3 15.7 11.7 12.5 19.9

Ni TD-ICP 1 5 5 5 5 3 4 6 27 4 3 35

Pb FUS-MS 1 21 25 16 16 13 15 7 11 12 11 42

Rb FUS-MS 1 164 114 77 148 161 111 107 49 141 175 189

S wt% TD-ICP 0.001 0.011 0.009 0.004 0.054 0.02 0.005 0.22 0.071 0.021 0.049 0.563

Sb FUS-MS 0.1 1.5 0.8 0.7 0.7 0.5 0.7 1.1 0.6 0.5 0.3 2.4

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HN-119-0308.8

HN-119-0339.5

HN-119-0376

HN-119-0385.6

HN-119-0445

HN-119-0482

HN-119-0517.6

HN-119-0541

HN-119-0554.6

HN-119-0580.6

HN-119-0617

Rock Unit

Analytical

Method Detection

Limit

NF3 NF2 (vc) NF2 (vc) NF2 NF2 NF2 NF2 NF2 (vc) NF1 NF1 NF1

Sc FUS-ICP 1 5 15 30 5 5 5 5 18 5 5 16

Se INAA 3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3

Sn FUS-MS 1 7 6 5 6 6 5 5 4 4 5 5

Sr FUS-ICP 2 64 48 68 62 59 59 35 93 57 52 26

Ta FUS-MS 0.01 0.84 1.4 0.84 0.82 0.85 0.77 0.83 0.98 0.85 0.81 1.11

Th FUS-MS 0.1 15.7 21 7.74 15.7 16 14.4 14.6 11.1 16.1 14.9 11.6

Tl FUS-MS 0.01 0.62 0.39 0.29 0.57 0.59 0.46 0.47 0.2 0.52 0.79 0.56

U FUS-MS 0.01 4.89 5.29 2.17 4.44 4.71 3.65 4.45 3.23 5.08 4.71 3.07

V FUS-ICP 5 18 88 279 18 19 14 17 91 20 20 131

W FUS-MS 0.5 1 3.4 1.6 1.2 1 0.7 1 <0.5 <0.5 <0.5 2.1

Y FUS-MS 0.1 38.3 54.7 31.7 42.3 39.9 39.7 36.8 44.2 39.9 42.2 39.7

Zn TD-ICP 1 18 44 92 23 21 27 20 54 25 17 100

Zr FUS-MS 1 179 422 196 177 185 165 157 217 181 175 237

La FUS-MS 0.1 36.3 67.5 36.3 36.3 36.2 34.1 33.2 48.3 39.3 33.6 48.2

Ce FUS-MS 0.1 79.9 144 74.4 78.7 77.9 73.9 70.9 97.1 83.2 72.7 95.9

Pr FUS-MS 0.1 8.12 14.7 7.64 7.91 7.74 7.4 7.02 9.68 8.22 7.25 9.59

Nd FUS-MS 0.1 29.9 55.4 29.8 29 28.3 27 25.4 36.4 30.5 26.3 35.5

Sm FUS-MS 0.1 6.57 11.2 6.27 6.45 6.24 6.01 5.7 7.71 6.75 6.19 6.9

Eu FUS-MS 0.001 0.812 1.19 1.65 0.741 0.638 0.643 0.573 1.17 0.744 0.69 1.39

Gd FUS-MS 0.01 6.28 10 6.15 6.41 6.02 5.79 5.69 7.39 6.52 6.21 6.21

Tb FUS-MS 0.01 1.11 1.61 0.96 1.14 1.08 1.03 1.02 1.23 1.12 1.12 1

Dy FUS-MS 0.01 6.43 9.36 5.38 6.85 6.4 6.16 5.94 7.01 6.56 6.82 6.01

Ho FUS-MS 0.01 1.29 1.81 1.05 1.36 1.26 1.24 1.14 1.38 1.27 1.31 1.21

Er FUS-MS 0.01 3.55 5.2 3.06 3.89 3.59 3.62 3.25 3.99 3.57 3.65 3.57

Tm FUS-MS 0.001 0.532 0.755 0.461 0.565 0.52 0.524 0.474 0.594 0.514 0.521 0.53

Yb FUS-MS 0.01 3.36 4.9 3.07 3.5 3.26 3.25 3.06 3.91 3.29 3.23 3.42

Lu FUS-MS 0.002 0.517 0.774 0.5 0.532 0.499 0.486 0.475 0.614 0.504 0.491 0.547

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HN-119-0629.5

HN-119-0640

HN-119-0946.4

HN-119-0981

HN-119-1033

HN-119-1066.4

HN-119-1117.6

HN-119-1141

HN-119-1165.8

HN-119-1191.3

HN-119-1195

Rock Unit

Analytical

Method Detection

Limit

NF1 OM OM OM OM OM OM OM OM OM NF1

SiO2 wt% FUS-ICP 0.01 74.5 74.68 69.11 79 63.9 51.7 71.1 61.98 64 62.9 71.78

Al2O3 wt% FUS-ICP 0.01 12.3 10.46 13.64 8.36 16.9 23.8 12 17.51 15.3 16.6 14.39


Na2O wt% FUS-ICP 0.01 3.66 1.03 0.12 0.07 0.14 0.2 0.05 0.15 0.1 0.79 1.08

K2O wt% FUS-ICP 0.01 2.5 2.26 3.4 1.4 3.86 5.73 2.24 4.43 3.72 4.01 3.75

TiO2 wt% FUS-ICP 0.001 0.26 0.726 0.981 0.63 1.03 1.35 0.66 1.031 0.82 1.01 0.316

P2O5 wt% FUS-ICP 0.01 0.11 0.1 0.07 0.07 0.1 0.12 0.07 0.09 0.1 0.2 0.13

LOI wt% FUS-ICP 0.01 1.58 2.58 3.05 1.75 3.75 4.1 2.6 3.48 3.8 2.95 2.62

Ag FUS-MS 0.5 <0.5 0.8 0.9 0.4 0.1 0.3 0.4 0.7 0.2 0.3 <0.5

As INAA 0.1 3.4 26.8 15.6 4 1.5 8 12 19.2 13 46 4.4

Au ppb INAA 2 <2 <2 <2 <2 <2

Ba FUS-ICP 3 985 302 479 222 599 722 357 630 454 443 425

Bi FUS-MS 0.1 <0.1 0.3 <0.1 2.5 2.5 2.5 5 0.1 8 2.5 <0.1

Cd TD-ICP 0.5 <0.5 <0.5 <0.5 0.5 0.5 0.5 0.5 0.5 0.5 <0.5

Co INAA 1 4 14 13 12 13 15 25 8 22 16 3

Cr INAA 0.1 6 53 79 81 58 42 49 97 38 52 10

Cs FUS-MS 0.1 1.7 2.3 3.5 4.1 3.2

Cu TD-ICP 1 2 14 8 8.1 35.3 2.3 19.4 102 31.8 4

Ga FUS-MS 1 15 14 18 23 16

Ge FUS-MS 0.1 1 1.6 1.7 1.6 2.1

Hf FUS-MS 0.1 4.8 7 8.2 6.3 5.2

Mo FUS-MS 2 <2 <2 <2 0.5 0.5 0.5 0.5 <2 0.5 0.5 <2

Nb FUS-MS 0.1 12 15.8 21.1 11 19 22 12 22 17 18 13.1

Ni TD-ICP 1 3 33 36 33 34 40 24 40 27 37 4

Pb FUS-MS 1 5 71 2.5 4 1 1 1 2.5 7 6 7

Rb FUS-MS 1 73 98 144 65 180 234 96 185 164 165 165

S wt% TD-ICP 0.001 0.07 0.025 0.039 0.12 0.33 0.02 0.14 1.63 0.37 0.002

Sb FUS-MS 0.1 0.5 0.6 0.8 2.5 2.5 2.5 2.5 0.9 2.5 2.5 0.7

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HN-119-0629.5

HN-119-0640

HN-119-0946.4

HN-119-0981

HN-119-1033

HN-119-1066.4

HN-119-1117.6

HN-119-1141

HN-119-1165.8

HN-119-1191.3

HN-119-1195

Rock Unit

Analytical

Method Detection

Limit

NF1 OM OM OM OM OM OM OM OM OM NF1

Sc FUS-ICP 1 5 10 13 1.3 1 1.5 1.4 19 0.7 0.8 6

Se INAA 3 <3 <3 <3 <3 <3

Sn FUS-MS 1 5 3 6 5 5 5 5 12 5 5 10

Sr FUS-ICP 2 55 19 15 8 17 24 12 18 14 16 17

Ta FUS-MS 0.01 0.8 0.9 1.17 1.24 0.93

Th FUS-MS 0.1 15.7 9.84 11.9 13.4 17.7

Tl FUS-MS 0.01 0.28 0.32 0.49 0.83 8.56

U FUS-MS 0.01 4.89 2.54 3.54 3.26 5.51

V FUS-ICP 5 20 81 101 21 18 26 18 134 15 17 22

W FUS-MS 0.5 0.6 0.6 2.2 5 5 5 5 6 5 5 1.9

Y FUS-MS 0.1 40.6 31.5 33.5 31 61 72 47 34.9 52 57 46.3

Zn TD-ICP 1 20 101 51 36.4 142 71 65.9 70.3 124 78

Zr FUS-MS 1 182 309 350 264 243 221 193 266 243 233 197

La FUS-MS 0.1 35.7 37.6 40.1 22.9 34.6 49.8 24 57.7 20.5 28.3 42.7

Ce FUS-MS 0.1 76.2 76.3 82.9 116 91.5

Pr FUS-MS 0.1 7.44 7.46 8.26 11.4 8.94

Nd FUS-MS 0.1 27.2 28 31 42.1 32.5

Sm FUS-MS 0.1 5.78 5.43 6.15 8.14 7.21

Eu FUS-MS 0.001 0.735 1.04 1.13 1.65 1.25

Gd FUS-MS 0.01 5.8 4.91 5.58 7.22 7.22

Tb FUS-MS 0.01 1.02 0.79 0.91 1.08 1.23

Dy FUS-MS 0.01 6.08 4.72 5.54 5.96 7.27

Ho FUS-MS 0.01 1.23 0.95 1.1 1.16 1.42

Er FUS-MS 0.01 3.6 2.8 3.21 3.35 4.09

Tm FUS-MS 0.001 0.538 0.417 0.489 0.501 0.603

Yb FUS-MS 0.01 3.51 2.73 3.36 3.34 3.79

Lu FUS-MS 0.002 0.54 0.449 0.548 0.555 0.565

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8


HN-119-1196.6

HN-119-1263.6

HN-119-1270

HN-119-1271.1

HN-119-1286.3

HN-119-1296.5

HN-119-1319.5

HN-119-1332.04

HN-119-1341.5

HN-119-1386.8

HN-119-1403

HN-119-1407.16

Rock Unit

Analytical

Method Detection

Limit

NF1 NF1 (vc) NF1 NF1 (vc) NF1 OM OM OM OM NF1 NF1 NF1

SiO2 wt% FUS-ICP 0.01 78.8 64.5 65.88 63.2 73.8 72.26 65.8 64.6 63.6 64.5 49.03 65.1

Al2O3 wt% FUS-ICP 0.01 11.5 15.2 14.26 16.2 13.7 14.46 13.2 15.8 14.7 14.4 16.66 14.5

Fe2O3(Tot) wt% FUS-ICP 0.01 2.08 8.06 7.56 8.88 2.92 2.7 7.04 7.03 6.61 5.56 10.26 6.08 MnO wt% FUS-ICP 0.001 0.04 0.02 0.279 0.26 0.03 0.035 0.05 0.08 0.1 0.1 0.215 0.07 MgO wt% FUS-ICP 0.01 1.24 0.81 1.98 2.21 1.35 1.69 3.93 2.24 4.59 3.63 9.57 4.28 CaO wt% FUS-ICP 0.01 0.24 0.09 0.27 0.32 0.3 0.28 0.52 0.22 0.29 2.11 1.94 0.51

Na2O wt% FUS-ICP 0.01 0.26 0.09 1.42 0.63 3.47 2.21 4.73 0.67 5.68 3.82 3.73 2.94

K2O wt% FUS-ICP 0.01 3.37 4.76 3.05 3.79 2.35 4.28 0.28 4.38 0.26 2.12 1.14 2.36

TiO2 wt% FUS-ICP 0.001 0.26 0.98 0.874 0.99 0.3 0.302 0.74 0.98 0.77 0.72 1.279 0.72

P2O5 wt% FUS-ICP 0.01 0.09 0.05 0.18 0.21 0.1 0.13 0.21 0.12 0.14 0.14 0.15 0.16

LOI wt% FUS-ICP 0.01 2.25 5.6 2.76 3.1 1.65 2.29 2.2 3.05 2.25 3.05 5.41 2.75

Ag FUS-MS 0.5 0.1 1.1 0.6 0.4 0.1 0.6 0.2 0.1 0.4 0.1 <0.5 0.4

As INAA 0.1 88 113 32.7 67 1.5 6.3 1.5 8 1.5 1.5 5 1.5

Au ppb INAA 2 <2 <2 <2

Ba FUS-ICP 3 342 504 373 478 236 667 34 536 25 467 149 361

Bi FUS-MS 0.1 2.5 2.5 <0.1 2.5 2.5 0.2 2.5 2.5 2.5 2.5 <0.1 2.5

Cd TD-ICP 0.5 0.5 0.5 <0.5 0.5 0.5 <0.5 0.5 0.5 0.5 0.5 <0.5 0.5

Co INAA 1 3 16 15 15 4 3 0.5 13 11 9 27 9

Cr INAA 0.1 37 53 75 43 73 14 40 50 72 57 158 64

Cs FUS-MS 0.1 2.1 3.1 1.9

Cu TD-ICP 1 1.1 35 15 42.8 2 <1 1.3 21.2 1.4 17.4 2 3.3

Ga FUS-MS 1 18 19 18

Ge FUS-MS 0.1 1.5 1.5 1.7

Hf FUS-MS 0.1 5.5 5.4 4.2

Mo FUS-MS 2 0.5 2 <2 0.5 2 <2 0.5 0.5 0.5 0.5 <2 0.5

Nb FUS-MS 0.1 10 17 19.3 20 11 13.8 14 17 14 12 11.1 14

Ni TD-ICP 1 5 52 38 39 26 4 11 31 18 20 20 8

Pb FUS-MS 1 9 403 2.5 23 4 2.5 1 1 1 1 2.5 3

Rb FUS-MS 1 151 197 121 147 97 170 10 170 10 65 39 81

S wt% TD-ICP 0.001 0.02 5.63 0.13 0.32 0.03 <0.001 0.04 0.16 0.005 0.02 0.002 0.05

Sb FUS-MS 0.1 2.5 6 0.5 2.5 2.5 0.5 2.5 2.5 2.5 2.5 <0.2 2.5

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HN-119-1196.6

HN-119-1263.6

HN-119-1270

HN-119-1271.1

HN-119-1286.3

HN-119-1296.5

HN-119-1319.5

HN-119-1332.04

HN-119-1341.5

HN-119-1386.8

HN-119-1403

HN-119-1407.16

Rock Unit

Analytical

Method Detection

Limit

NF1 NF1 (vc) NF1 NF1 (vc) NF1 OM OM OM OM NF1 NF1 NF1

Sc FUS-ICP 1 0.25 0.25 14 1.2 0.25 6 9.2 0.8 9.6 5 42 3.1

Se INAA 3 <3 <3 <3

Sn FUS-MS 1 5 5 5 5 5 8 5 5 5 5 2 5

Sr FUS-ICP 2 11 22 23 21 36 31 49 18 60 93 51 42

Ta FUS-MS 0.01 0.98 0.9 0.54

Th FUS-MS 0.1 11 17.4 4.32

Tl FUS-MS 0.01 0.64 0.55 0.18

U FUS-MS 0.01 2.81 5.42 1.31

V FUS-ICP 5 1 6 125 23 5 23 36 15 74 37 245 26

W FUS-MS 0.5 5 5 2 5 5 1.4 5 5 5 5 <0.5 5

Y FUS-MS 0.1 35 47 27.6 53 45 39.2 50 52 44 43 30.2 49

Zn TD-ICP 1 22.1 516 158 100 13.2 26 17.8 28.9 64 63.1 226 25.8

Zr FUS-MS 1 139 246 233 233 158 212 241 250 239 221 182 244

La FUS-MS 0.1 21.2 28.8 36.3 26.3 26.7 41.3 27.4 33.4 27.7 20 25.3 30.2

Ce FUS-MS 0.1 72.8 87.1 52

Pr FUS-MS 0.1 7.27 8.61 5.31

Nd FUS-MS 0.1 27.1 30.9 21.4

Sm FUS-MS 0.1 5.43 6.77 4.94

Eu FUS-MS 0.001 1.13 0.672 1.26

Gd FUS-MS 0.01 4.85 6.39 5.28

Tb FUS-MS 0.01 0.79 1.07 0.84

Dy FUS-MS 0.01 4.47 6.07 4.97

Ho FUS-MS 0.01 0.89 1.2 0.98

Er FUS-MS 0.01 2.61 3.5 2.87

Tm FUS-MS 0.001 0.402 0.521 0.437

Yb FUS-MS 0.01 2.71 3.36 2.94

Lu FUS-MS 0.002 0.441 0.536 0.477

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Stratigraphic and Structural Relationships in the Western Sackville Subbasin of the Maritimes Basin, Southeastern New Brunswick:

A Petrographic, Petrophysical, and Seismic Analysis

HOLLY J. STEWART Geological Surveys Branch, New Brunswick Department of Natural Resources,

P.O. Box 6000, Fredericton, New Brunswick, CANADA E3B 5H1 ([email protected])

Stewart, H.J. 2011. Stratigraphic and structural relationships in the western Sackville Subbasin of the Maritimes Basin, southeastern New Brunswick: a petrographic, petrophysical, and seismic analysis. In Geological Investigations in New Brunswick for 2010. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Lands, Minerals and Petroleum Division, Mineral Resource Report 2011-2, p. 50–74.

___________________________________________________________________________

The Sackville Subbasin is one of several depocentres in the southeastern New Brunswick segment of the Maritimes Basin in Atlantic Canada. The western part of the subbasin includes Late Devonian to Early Carboniferous sedimentary rocks. Detailed petrographic and petrophysical analyses were conducted of cuttings from three deep exploration wells near Dorchester in the western subbasin. These analyses, combined with reinterpreted seismic survey data from the area, revealed information of relevance to hydrocarbon exploration in the region. The data helped to more precisely define the stratigraphy and, to a lesser extent, the structure of the western Sackville Subbasin. This study demonstrated that the depth to pre-Late Devonian basement rocks was shallower than previously interpreted. It also helped to delineate the distribution and internal stratigraphy of the hydrocarbon-bearing Early Carboniferous Albert Formation (Horton Group) in the report area.

The Albert Formation typically contains three conformable units that, in ascending order, are the Dawson Settlement, Frederick Brook, and Hiram Brook members. All members contain kerogenous sandstone, mudstone, and shale; and regionally, all members have produced economic quantities of oil and gas. Recently, the main unit targeted for conventional gas exploration and development is the Hiram Brook Member, whereas that investigated for unconventional gas exploration is the Frederick Brook Member. The current study identified only the Dawson Settlement and Frederick Brook members in the three deep wells near Dorchester. This observation, combined with the reinterpreted seismic data, indicates that the Hiram Brook Member may have been eroded during a basin inversion event in the area during the Early Carboniferous. Absence of the Hiram Brook Member in these wells has obvious implications for hydrocarbon exploration in the western part of the Sackville Subbasin.

_________________________________________________

Le sous-bassin de Sackville figure parmi quelques-uns des centres de sédimentation de la partie sud-est du Nouveau-Brunswick du bassin des Maritimes, au Canada atlantique. La partie occidentale du sous-bassin comprend des roches sédimentaires dont la formation remonte à la période comprise entre le Dévonien tardif et le

51

Carbonifère précoce. Des analyses pétrographiques et pétrophysiques approfondies ont été réalisées sur des déblais de forage de trois puits d’exploration en profondeur, près de Dorchester, dans le sous-bassin de l’ouest. De concert avec des données de levé sismique réinterprétées, les résultats de ces analyses ont permis d’obtenir de l’information pertinente pour les travaux de prospection d’hydrocarbures dans la région. Ces données ont notamment permis de définir avec plus de précision la stratigraphie et, dans une moindre mesure, la structure de la partie ouest du sous-bassin de Sackville. Elles ont notamment établi que les roches du socle antérieures au Dévonien tardif étaient à une profondeur moindre que ce que l’on avait déduit auparavant. Cette étude a également aidé à délimiter dans le secteur concerné la répartition et la stratigraphie interne de la Formation d’Albert, du Carbonifère précoce (groupe de Horton), qui contient des hydrocarbures.

Pour l’essentiel, la Formation d’Albert contient trois unités concordantes, que voici (en ordre ascendant) : ce sont les membres de Dawson Settlement, du ruisseau Frederick, et du ruisseau Hiram. Tous ces membres renferment du grès, du mudstone et du schiste bitumineux. Au plan régional, tous les membres ont fourni des volumes rentables de pétrole et de gaz. Récemment, le membre du ruisseau Hiram a été le principal secteur visé par des travaux d’exploration et de mise en valeur du gaz classique, tandis que des travaux d’exploration de gaz non classique ont concerné le membre du ruisseau Frederick. L’étude actuelle n’a permis que de détecter la présence des membres de Dawson Settlement et du ruisseau Frederick dans trois puits creusés en profondeur près de Dorchester. Cette observation et l’interprétation des données de levé sismique portent à croire que le membre du ruisseau Hiram peut avoir subi une érosion au cours d’une inversion de bassin survenue dans la région au début du Carbonifère. L’absence du membre du ruisseau Hiram dans ces puits a des incidences manifestes sur les travaux d’exploration de gisements d’hydrocarbures dans la partie occidentale du sous-bassin de Sackville.

_________________________________________________

INTRODUCTION

The hydrocarbon deposits of Late Devonian to Carboniferous rocks in the Maritimes Basin of Atlantic Canada (Fig. 1) were first recognized in the mid-19th century and have since been the subject of numerous government, industry, and academic studies. Recent exploration work confirms what many of these reports concluded: namely, that rocks of the Late Devonian to Early Carboniferous Horton Group of the Maritimes Basin in southeastern New Brunswick—particularly those of the Albert Formation—contain the most economically significant resources of gas (conventional and unconventional) and oil in the province. The Albert Formation consists predominantly of fluvial and lacustrine sedimentary rocks that were deposited within the isolated, Early Mississippian depocentres of the Maritimes Basin. The most easterly of these depocentres, the Sackville Subbasin (Fig. 1, 2), was defined by Martel (1987) and is one of the least studied. The work by Martel (1987) was based mainly on seismic surveys completed by Chevron Canada Resources Ltd. between 1982 and 1985, and on limited surface outcrop and borehole information.

MO

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Figure 2. Simplified geological map of the western Sackville Subbasin, southeastern New Brunswick,

Figure 1 for the

location of this map area.

modified after St. Peter and Johnson (2009) and Webb and Stewart (2011). See

53

At the time of Martel's report, only two deep wells had been drilled in the Sackville Subbasin,

both of them near Dorchester in the western part of the subbasin (Fig. 1, 2). They were Shell

Dorchester 1 drilled by Shell Oil Company in 1949, and Imperial Dorchester 1 drilled by

Imperial Oil Limited in 1960. A third deep well, Columbia/Corridor Coppermine Hill 2

(hereafter, Coppermine Hill 2), was drilled northeast of Dorchester in 2001 by Columbia

Natural Resources Canada Limited (Fig. 2). The three wells were reviewed by St. Peter

(2001) and referred to by St. Peter and Johnson (2009). These authors combined well data

with geological mapping results from the western part of the subbasin and presented a

number of stratigraphic and structural interpretations.

Crystallinebasement

CumberlandGroup

Horton GroupMabou GroupPictou Group

Windsor Group

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Early Carboniferous

Pre-Late Devonian

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Well location with UIN

Lines of section (Fig. 4)

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UIN 716

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Late Carboniferous Late Devonian–

Early Carboniferous

Sackville

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t

Cale

donia

Uplift

UIN 330 Sackville

Nova Scotia

2

114

16

Bay

of F

undy

Sackville

Syncli

ne

Unique Identifier Numbers (UINs) and namesof the deep wells examined for the currentstudy:

UIN 325 – Shell Dorchester 1

UIN 330 – Imperial Dorchester 1

UIN 716 – Columbia/Corridor Coppermine Hill 2

54

The current study examined the three deep wells in detail using petrographic and petrophysical analysis. The analytical results were integrated with seismic data, mainly from a two-line survey conducted in 1996 by Corridor Resources Inc. (Fig. 2). The combined information helped to confirm or, in cases, to re-evaluate some interpretations of Late Devonian to Carboniferous stratigraphy and structure around Dorchester. A clearer understanding of the stratigraphy, coupled with seismic analysis, will lead to a better assessment of the hydrocarbon potential of the Albert Formation in the Sackville Subbasin. Note: the three deep wells of the current study are catalogued in the New Brunswick Department of Natural Resources (NBDNR) borehole database by their Unique Identifier Numbers (UINs), which are shown on Figure 2. Additional information about the wells is available in this online database (NBDNR 2011).

REGIONAL GEOLOGY

Maritimes Basin

The Late Devonian to Early Permian Maritimes Basin (Fig. 1, inset 2) is an extensive successor basin that developed during the waning stages of, and following, the Middle Devonian Acadian Orogeny; remnants of the basin occur throughout Atlantic Canada (Roliff 1962; St. Peter and Johnson 2009, and references therein). The basin has a rich sedimentological and structural history that involved subaerial to marine sedimentation over a period of 90 Ma. The Maritimes Basin is structurally complex, due to episodes of basin inversion and faulting that produced several major disconformities, paraconformities, and angular unconformities. In New Brunswick, the basin is subdivided into four major Early Carboniferous subbasins or depocentres (Fig. 1), those being the Moncton, Cocagne, Cumberland, and Sackville subbasins (van de Poll 1995; St. Peter 2006). The subbasins are now delineated by major faults and basement uplifts and may be partially concealed by younger Carboniferous strata and their boundaries (Fig. 1; St. Peter 2000; St. Peter and Johnson 2009).

Stratigraphy of the Sackville Subbasin

The Sackville Subbasin covers an area of about 800 km2 and essentially is defined by its Late Devonian to Early Carboniferous stratigraphy. Paleogeographically, most of the basin-fill clastic sediments that dominate the subbasin succession were derived from the Caledonia, Westmorland, and Hastings uplifts (Fig. 1). The subbasin stratigraphy (Fig. 3) has been described in detail by Martel (1987) and St. Peter and Johnson (2009) as a sequence of various lithologies. In general, the succession begins with the mainly red to grey, proximal alluvial fans and other fluvial and lacustrine rocks of the late Famennian (Late Devonian) to Tournaisian (Early Carboniferous) Horton Group (Fig. 3), which are overlain unconformably or disconformably by grey, coarse-grained deposits of the late Tournaisian Sussex Group. The mainly evaporitic

SACKVILLESUBBASIN

WESTERNSACKVILLESUBBASIN

Salisbury Formation Salisbury Formation

Breau Creek Mbr

Cole Point MbrBossPointFm

Boss Point Formation

Round Hill Formation

Albert FormationAlbertFmMcQuade

Brook Formation

McQuade BrookFormationMemramcook

Formation MemramcookFormation

SP

OR

E Z

ON

E

1

2

3

4

5

Dorchester Cape Mbr

HopewellCape

FormationMaringouinFormation

Lime-KilnBrook Formation

Pugwash MineFm

Pugwash MineFm

Upperton Fm Upperton Fm

Macumber Formation Macumber Formation

GL

OB

AL

STA

GE

SY

ST

EM

SU

BS

YS

TE

M

EU

RO

PE

AN

STA

GE

LA

TE

(Pen

nsylv

an

ian

)

BASHKIRIAN

SERPUKHOVIAN

VISEAN

TOURNAISIAN

FAMENNIAN

DE

VO

NIA

N

LA

TE

NA

MU

RIA

NW

ES

T-

PH

ALIA

N

AG

E(M

a)

GR

OU

P

PICTOU

MA

BO

UW

IND

SO

R

CUMB-ERLAND

311.7±1.1

314.5

318.1±1.3

326.4±1.6

345.3±2.1

359.2±2.5

374.5±2.6

HO

RT

ON

SU

SS

EX

PRE-LATE DEVONIAN

CA

RB

ON

IFE

RO

US

EA

RLY

(Mis

sis

sip

pia

n)

Crystalline basement

Hillsborough Formation

Frederick BrookMember

Dawson SettlementMember

HopewellCape

FormationMaringouinFormation

Lime-KilnBrook Formation

Figure 3. General stratigraphy of the Sackville Subbasin according to St. Peter and Johnson

(2009) and as revised according to Stewart (2011) and the current report.

(St. Peter andJohnson 2009) (Stewart 2011)

55

56

sequence of the Visean Windsor Group rests with angular unconformity on the Sussex Group and records the incursion of the Windsor Sea into the basin. Redbed sedimentary rocks conformably overlying the late Visean to early Serpukhovian (Early Carboniferous) Mabou Group signify the resumption of proximal alluvial and other fluvial deposition in the region. A major regional unconformity separates these four mainly Early Carboniferous groups from the overlying Late Carboniferous Cumberland and Pictou groups (Fig. 3) that, in the report area, have been identified as Bashkirian (St. Peter and Johnson 2009). The predominantly grey to red fluvial sequences of the two youngest groups heralded the onset of more distally derived fluvial sedimentation that blanketed the Sackville and other subbasins in the region and also buried some previously exposed basement uplifts. It is noteworthy that Martel (1987) interprets seismic reflectors below the Horton Group at the base of the succession as a possible interbedded volcanic and clastic sequence of rocks, similar to those mapped in the same stratigraphic position in nearby Nova Scotia. To date, such rocks have not been found either at surface or at depth in New Brunswick.

Structure of the Sackville Subbasin

The subbasin is delineated primarily by major basin-bounding faults that trend northeasterly or north–northwesterly, including the Harvey–Hopewell, Dorchester, Port Elgin, and Wood Creek faults (Fig. 1, 2; St. Peter and Johnson 2009). As discussed by Martel (1987), these faults likely underwent periods of significant, basin-facing, dip-slip movement that allowed the accumulation of thick (>1 km) basin-fill sediments during basin subsidence in the Late Devonian to Early Carboniferous. However, some of the faults undoubtedly also experienced a protracted history of reverse and strike-slip movement during this time, as well as later movements that post-dated deposition of Late Carboniferous cover material within the Sackville Subbasin (see St. Peter and Johnson 2009). The internal structural history of the Sackville Subbasin is quite complex. Unconformities in the Early Carboniferous stratigraphic section attest to at least two main periods of basin inversion caused by compression or transpression, in addition to intrabasinal faulting events with local basement uplifts, Late Carboniferous downwarping, broad folding, and salt diapirism (Martel 1987; St. Peter and Johnson 2009). The first major deformation event occurred before deposition of the Windsor Group; it involved transpression that caused uplifting, folding, and erosion of the upper part of the Sussex Group and underlying rocks. The second, and likely more regional, period of deformation and uplift affecting Carboniferous strata took place after deposition of the Mabou Group but before deposition of the Cumberland Group. This event was due mainly to the reactivation of some basin-bounding faults. The latest folding events to affect the younger strata were also associated with continued reactivation along a number of these faults and were accentuated by episodes of salt diapirism (Martel 1987; St. Peter and Johnson 2009).

57

DETAILED STRATIGRAPHY OF THE SACKVILLE SUBBASIN

The following stratigraphic relationships (see Fig. 3) and unit descriptions are summarized from comprehensive accounts in St. Peter (2001) and St. Peter and Johnson (2009).

Horton Group

The Horton Group in the report area consists of the Memramcook, McQuade, and Albert formations. The oldest unit is the Famennian to Tournaisian Memramcook Formation, which contains red, grey, and green, thick-bedded polymictic conglomerates, as well as trough cross-bedded, coarse- to fine-grained, feldspathic to lithic sandstones. These coarser facies are interstratified with red siltstone and mudstone (Norman 1941; St. Peter and Johnson 2009). The McQuade Formation gradationally overlies, and likely is in part a lateral distal facies of, the Memramcook Formation (St. Peter 2006; St. Peter and Johnson 2009). The McQuade Formation ranges from early Tournaisian Zone 1A to middle Tournaisian Zone 2A and consists of red to grey, medium- to fine-grained fluvial strata. Interbedded reddish brown and grey mudstone, siltstone, and fine- to coarse-grained, laminated and cross-bedded sandstone are the dominant lithotypes. Also present are pebble conglomerates containing intraclasts of mudstone and micritic limestone. The Early Tournaisian Albert Formation (Dawson 1853; Bailey and Ells 1878; Ami 1900; Wright 1922; Norman 1932, 1941; St. Peter 1992) gradationally overlies, and is in part laterally equivalent to, the McQuade Brook Formation. The Albert is divided into three conformable members: Dawson Settlement, Frederick Brook, and Hiram Brook (Greiner 1962). At the base is the Dawson Settlement Member, which consists of grey, variously grain-sized calcareous sandstone with lenses of non-kerogenous dark grey shale and mudstone. Interbeds of green conglomerate and pebbly sandstone, light grey limestone, and brown kerogenous shale are also present. The Frederick Brook Member lies stratigraphically above the Dawson Settlement Member and consists of brown, kerogenous, dolomitic mudstone, and oil shale. Grey, non-kerogenous shale and mudstone, sandstone, conglomerate, limestone, and dolostone are also present. The Hiram Brook Member is the youngest unit of the Albert Formation. It consists predominantly of brown, thin- to medium-bedded, variously grain-sized calcareous sandstone intercalated with grey, non-kerogenous, slightly calcareous mudstone and shale. Interbeds of brown, kerogenous dolomitic shale, conglomerate, and grey limestone have also been noted (St. Peter and Johnson 2009). Rocks of the Hiram Brook Member were recognized in none of the three deep wells examined during this study (Fig. 3).

Sussex Group

The Sussex Group in the Sackville Subbasin is represented solely by the Round Hill Formation. The formation appears in outcrop elsewhere in the Maritimes Basin of southeastern New Brunswick (St. Peter and Johnson 2009) but has not been mapped at surface in this subbasin; instead, it has been identified only in a drillhole (St. Peter 2001).

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The Round Hill Formation contains grey and locally red polymictic conglomerate, fine- to coarse-grained sandstone, minor mudstone, and rare limestone that together represent part of a late Tournaisian alluvial fan (McLeod 1980; St. Peter and Johnson 2009). Rocks of the Round Hill Formation were not observed in well intersections of the current study.

Windsor Group

Regionally, the Windsor Group is characterized by an Early Visean basal conglomeratic unit that unconformably overlies older sequences and that is succeeded by various types of evaporitic successions ranging from Early Visean to Namurian (Dawson 1873; Bell 1944). In the report area, this group comprises, in ascending stratigraphic order, the Hillsborough, Macumber–Gays River, Upperton, Pugwash Mine, and Lime-Kiln Brook formations. The conglomeratic unit, the Hillsborough Formation, consists of dark reddish brown, grey, and commonly sandy conglomerate with minor lithic sandstone, pebbly sandstone, and mudstone (Wright 1922; St. Peter 1992). The Macumber Formation is typically considered the oldest formation in the evaporitic sequence of the Windsor Group, consisting of grey to black, thin-bedded and laminated wackestone to packstone (Weeks 1948). The Gays River Formation, which interfingers with the Macumber, consists of grey to brown algal boundstone and is locally interbedded with minor grey, polymictic pebble conglomerate and calcareous, fine-grained to pebbly lithic sandstone, and limestone breccia mudstone (Boehner 1977). The Upperton Formation overlies the Macumber and Gays River formations. Near surface, gypsum of the Upperton often replaces the primary lithology, which is anhydrite (Anderle et al. 1979; McCutcheon 1981). The Pugwash Mine Formation consists mainly of colourless to white halite that is locally interbedded with minor red or reddish brown and grey shale commonly containing rock salt crystals. Very minor sandstone, anhydrite, dolomite, and selenite stringers are also present in places (Carter and Anderle 1990). The Lime-Kiln Brook Formation (Ryan and Boehner 1994) is divided into three informal members in New Brunswick (St. Peter and Johnson 2009). They contain differing proportions of gypsum, anhydrite, selenite porphyroblasts, wackestone, grainstone, sandstone, conglomerate, and limestone, as well as minor siltstone and mudstone. Typically, they include stromatolites, biomicrites, and oolitic grainstones (St. Peter and Johnson 2009). Parts of the Upperton and Lime-Kiln Brook formations can be laterally continuous with the Pugwash Mine Formation (Fig. 3). When the last-named formation is absent, the Lime-Kiln Brook directly overlies the Upperton.

Mabou Group

In the Sackville Subbasin, the Mabou Group is represented by the Maringouin and Hopewell Cape formations. The late Visean Maringouin Formation is a coarsening-upward sequence of red to grey calcareous, very fine- to fine-grained sandstone with brick red siltstone and mudstone; thicker and more abundant red sandstones are noted near the top of the formation

59

(Norman 1941; Gussow 1953). The Maringouin Formation can in part be laterally equivalent to the Lime-Kiln Brook Formation (Windsor Group) and is also considered a distal lateral equivalent of the lower part of the Hopewell Cape Formation. The Hopewell Cape Formation is a brownish red, poorly sorted, pebble–cobble, polymictic conglomerate with coarse-grained to pebbly lithic and variously grain-sized sandstones. This facies, which is typically a fining-upward sequence, also contains brick red to maroon, very fine- to fine-grained, ripple-laminated and massive sandstone, siltstone, and mudstone. Reduction spheroids and calcrete are common within the finer grained units of the Hopewell Cape Formation. At the top of the formation is the Dorchester Cape Member, which comprises red, very fine- to fine-grained, ripple-laminated sandstone, siltstone, and mudstone. The member differs from lower sections of the formation in that it contains silcrete and more abundant calcrete (van de Poll 1994; St. Peter and Johnson 2009). The Hopewell Cape Formation was not subdivided in the current study.

Cumberland Group

The Cumberland Group is represented in the Sackville Subbasin by the Westphalian Boss Point Formation, which unconformably to disconformably overlies the Mabou Group. The Boss Point is characterized by commonly yellowish weathering, grey, plant-bearing quartzose sandstone; and well-sorted, rounded quartz-pebble conglomerate interbedded with fine-grained sandstone, siltstone, mudstone, and lesser amounts of carbonaceous limestone, shale, and coal (Bell 1914, 1944; Browne 1991; St. Peter and Johnson 2009). Although the Boss Point Formation is divided into members at some localities, it remains undivided for the purposes of the present study.

Pictou Group

The Westphalian to Stephanian Pictou Group was not observed in wells within the report area but does occur on surface in the eastern part of the Sackville Subbasin. The only rocks of the Pictou Group identified in New Brunswick are those of the Salisbury and Richibucto formations. The Salisbury Formation consists of predominantly red, very fine- to fine-grained sandstone, siltstone, and mudstone; and pinkish grey to red, trough cross-bedded sandstone, pebbly sandstone, and conglomerate. The Richibucto Formation contains grey and minor reddish brown, parallel- and trough cross-bedded sandstone, pebbly sandstone, and intraformational conglomerate. Interstratification occurs with red, very fine-grained sandstone, siltstone, mudstone, and minor lacustrine limestone; coalified plant fragments and thin coal seams are common in both formations of the Pictou Group (St. Peter and Johnson 2009).

METHODOLOGY

The Shell Dorchester 1, Imperial Dorchester 1, and Coppermine Hill 2 wells in the vicinity of Dorchester (Fig. 2) are the only deep exploration wells in the study area of the western Sackville Subbasin and thus were chosen for petrographic and petrophysical analysis.

60

Well cuttings for the petrographic examination were selected at 10 ft [3.03 m] intervals for the two older wells (Shell Dorchester 1, Imperial Dorchester 1) and at 3 m intervals for the younger, Coppermine Hill 2 well. Chip samples were observed under a stereoscopic microscope at 10x to 70x magnification to determine lithotype, colour, grain size, constituents, sorting, rounding, cementation, and potential for hydrocarbon content. Late Devonian to Carboniferous lithotypes identified in the study included conglomerate, sandstone, siltstone, anhydrite, halite, limestone, and shale. Pre-Late Devonian lithotypes consisted of granitic and metasedimentary rocks. As with the investigation by Parks (2010) of the Albert Formation in the McCully Field (Fig. 1), the current petrophysical study compared and interpreted the various wireline log signatures that characterize the lithofacies identified by petrographic examination. (Schlumberger Limited (2010) describes the theory behind wireline tool functions.) The integration of petrographic and petrophysical well data is key to creating an accurate strip log of lithofacies in hydrocarbon-bearing rocks of the Maritimes Basin. A reliance solely on wireline data, without an accompanying microscopic examination of well cuttings from the same depth, can lead to false identification of some rock types. Wireline logs were available only for the Shell Dorchester 1 and Coppermine Hill 2 wells. Those for Shell Dorchester 1 consisted of self-potential, sonic, and various resistivity logs; those for Coppermine Hill 2 comprised gamma ray, neutron, density, sonic, and assorted resistivity logs. Abbreviated lithologic descriptions derived from the petrographic analysis were displayed on the strip logs beside wireline data and drilling parameters. After the petrographic and petrophysical analyses were completed, standardized strip logs were generated for all three wells. These detailed strip logs formed the basis for constructing cross-sections between the wells (Fig. 4a, 4b). Appendices 2, 3, and 4 of Stewart (2011) provide the complete strip logs for Shell Dorchester 1, Imperial Dorchester 1, and Coppermine Hill 2, respectively, showing the lithologic, wireline (where available), and drilling data for each well.

PETROGRAPHIC CHARACTERISTICS

The petrographic descriptions of lithofacies in the three wells are presented below according to group, formation, and (for the Albert Formation) member. Descriptions of cuttings from the individual wells represent an average of all observed lithologic characteristics of each formation in that well. All wells were drilled vertically, and all numbered depths in metres represent the ‘measured depth’ or MD (Table 1).

Shell Dorchester 1 (UIN 325)

Horton Group

The Horton Group in this well (Fig. 4a, 4b) is represented by the McQuade Brook Formation, Albert Formation, and probably Memramcook Formation (see Discussion, below). The McQuade Brook Formation was intersected at the base of the well in the 2277 m to 2508 m depth interval. It is dominated by siltstone that varies from light to dark grey, is siliceous, and has calcite veining. Sandstone, the second most abundant lithology, is maroon to grey,

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fine- to medium-grained, micromicaceous, poorly sorted, and well consolidated; and has subangular constituents. This sandstone is noteworthy, being pebbly with schistose clasts. Between the depths of 2277 m and 2343 m, a coarse-grained facies of blue to green conglomerate and sandstone (likely equivalent to the Memramcook Formation) was observed in association with the finer grained, siltstone-dominated sequence. The Dawson Settlement Member of the Albert Formation overlies the McQuade Brook Formation and is present in the 1958 m to 2277 m depth interval. The dominant lithology is dark grey, silty, calcareous, and slightly micaceous shale that contains evidence of plant fragments. Intervals of medium to dark grey, calcareous, and commonly siliceous siltstone occur throughout the section, decreasing in abundance with depth in each interval. Lenses of very fine-grained calcareous sandstone occur throughout the section; the sandstone is white to grey with high concentrations of quartz and muscovite. Also present are white to light grey, microcrystalline dolomitic limestones that reach a maximum concentration at 2035 m, then decrease in abundance with depth. Two types of conglomerate occur in the lowermost section of the Dawson Settlement Formation. One type is blue to green with chlorite, muscovite, granitic clasts, and subangular to angular quartz clasts; it closely resembles the blue to green conglomeritic facies in the underlying Memramcook–McQuade sequence. The other conglomerate has a pink to maroon, fine- to coarse-grained matrix with chlorite, muscovite, and quartz, as well as subangular to angular granitic clasts. Some intervals contain up to 10% grey to green, slightly calcareous siltstone. The Frederick Brook Member lies above the Dawson Settlement Member and was intersected in the 1695 m to 1958 m depth interval. Shale, the dominant lithology, is dark grey, silty, calcareous, and slightly micaceous with evidence of plant fragments. Intervals of medium to dark grey calcareous siltstone decrease in abundance with depth; typically, the siltstone is siliceous. Lenses of minor, very fine-grained, white to grey calcareous sandstone are present throughout the section in association with predominant quartz and muscovite and minor selenite stringers; the sandstone lenses are slightly less extensive than in the underlying Dawson Settlement Member. A 20 m thick interval of white microcrystalline anhydrite was intersected in the 1828 m to 1848 m depth interval.

Windsor Group

The Windsor Group lies above the Horton Group and represents a significant portion of the stratigraphy in this well (Fig. 4a, 4b). The basal Hillsborough Formation was intersected in the 1600 m to 1695 m depth interval. The formation consists mainly of polymictic conglomerate that varies between greyish green and reddish brown with clasts of subangular to subrounded quartz and a variety of igneous lithologies. The conglomerate grades into sandstone toward the base of the section. Minor limestone observed in this section may be the result of cavings.

LATE DEVONIAN–CARBONIFEROUS

Cumberland Group

Boss Point Formation

Hopewell Cape Formation

Maringouin Formation

Windsor Group

Lime-Kiln Brook Formation

Pugwash Mine Formation

Upperton Formation

Macumber–Gays River formations

Hillsborough Formation

Horton Group

Albert Formation (Frederick Brook Member)

Albert Formation (Dawson Settlement Member)

Memramcook–McQuade Brook formations

Crystalline basement

PRE-LATE DEVONIAN

NESW

N S

Mabou Group

Sh

ell D

orc

heste

r 1

2508 m

3420 m

2508 m 2420 m

Approximate contact

Approximate unconformity

a)

b)

Figure 4. a)

b)

Stylized cross-sections between the Shell Dorchester 1 and Coppermine Hill 2 wells, and

the Shell Dorchester 1 and Imperial Dorchester 1 wells. Figure 2 shows the lines of section.

62

Co

pp

erm

ine H

ill 2

Sh

ell D

orc

heste

r 1

Imp

eri

al D

orc

heste

r 1

Fault

(Not to scale)

(Not to scale)

63

Table 1. Tops of Pre-Late Devonian to Carboniferous formations in the western Sackville Subbasin, New Brunswick, as interpreted from a petrographic examination of well cuttings in the Dorchester area. Compare with cross-sections in Figures 4a and 4b.

WellShell

Dorchester 1

Imperial Dorchester 1

Coppermine Hill 2

KB (m) 6.4 24.08 145.3

GRD (m) 4.27 19.51 140

Tops of Formations (m)

GROUP FORMATION / MEMBER MD/ TVD

SS MD/ TVD

SS MD/ TVD

SS

Cumberland Boss Point Formation 0 -24.08 0 -145.3

Hopewell Cape Formation 0 -6.4 536 511.92 177 31.7Mabou

Maringouin Formation 1204 1179.92 1026 929.7

Lime-Kiln Brook Formation 119 112.6 1472 1447.92 1426 1280.7

Pugwash Mine Formation 530 523.6 1576 1551.92 1745 1599.7

Upperton Formation 1539 1532.6 2335 2310.92 2100.5 1955.2

Macumber–Gays River formations 1564 1557.6 2150.5 2005.2

Windsor

Hillsborough Formation 1600 1593.6 2218 2072.7Albert Formation (Frederick Brook Member)

1695 1688.6

Albert Formation (Dawson Settlement Member)

1958 1951.6 Horton

Memramcook–McQuade Brook formations

2277 2270.6 2553 2407.7

— Crystalline basement 2862 2716.7

Total depth of well 2508 2501.6 2420 2395.92 3420 3274.7

Notes: GRD = Ground elevation, KB = Kelly bushing elevation, MD = Measured depth, SS = Sub-sea level, TVD = True vertical depth

The overlying Macumber–Gays River formations were intersected in the 1564 m to 1600 m depth interval. The main lithology is grey, frosted limestone with minor conglomerate near the base that apparently grades into the Hillsborough Formation below. Overlying the Macumber–Gays River formations is a thin bed of Upperton Formation, between 1539 m and 1564 m. The dominant Upperton lithology is anhydrite with minor gypsum, salt, and limestone near the base of the interval. The anhydrite is white to grey and microcrystalline with minor orange staining. The Upperton Formation is overlain by the Pugwash Mine Formation, which was intersected between 530 m and 1539 m. The Pugwash Mine Formation in this well is represented by a thick succession of relatively clean, clear to white salt, except near the top of the section, where the salt is orange. Minor siltstone stringers and selenite crystals are present in some sections. At the top of the Windsor section, the Lime-Kiln Brook Formation was intersected in the 119 m to 530 m depth interval. The formation in this well consists mainly of white to grey microcrystalline anhydrite with stringers of gypsum, selenite, and salt.

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Mabou Group

The Mabou Group in this well (Fig. 4a, 4b) is represented only by the Hopewell Cape Formation, which occurs from the collar to a depth of 119 m. The formation consists of maroon to brown sandstone with poorly sorted, subrounded, poorly consolidated gravel and becomes coarser grained with depth.

Imperial Dorchester 1 (UIN 330)

Late Devonian to Carboniferous rocks older than the upper Windsor Group (i.e., rocks of the Horton and Sussex groups and Windsor rocks older than the Upperton Formation) were not intersected in this well (Table 1).

Windsor Group

The Upperton Formation (Fig. 4b) is present between 2335 m and 2420 m, where it consists of salt, varied proportions of dirty anhydrite, and differing quantities of shale. The salt can be both clear and opaque and typically appears as large crystals. The dirty anhydrites, and what possibly may be gypsum, are white to light grey and in the form of powdered crystals. The shale is grey, calcareous, and fissile, and ranges from hard to soft throughout the entire section. The overlying Pugwash Mine Formation (Fig. 4b) is found in the 1576 m to 2335 m depth interval. Halite, which occurs throughout the interval, is predominantly white to light pink and less commonly light brown. Salt crystals vary from fine- to coarse-grained aggregates, and when the large crystals are clean, they are semitransparent to transparent. The Pugwash Mine Formation in this section contains minor quantities of red to maroon and grey to green shales that are very slightly calcareous, fissile, and vary in hardness. Also present is minor white, powdery anhydrite. The top of the Windsor Group is represented by the Lime-Kiln Brook Formation in the 1472 m to 1576 m depth interval (Fig. 4b). The formation here consists of reddish maroon to brown, clay-coated siltstone, clay, and shale, with minor sandstone stringers. The shale is non-calcareous, micromicaceous, and moderately soft; it ranges from blocky to subfissile. The clay coating is grey, vuggy, and moderately consolidated. The overlying Maringouin Formation (Fig. 4b) was intersected between 1204 m and 1472 m and contains red, brown, and grey siltstone as the dominant lithology. Most of the siltstone is oxidized, blocky, and very slightly calcareous; it contains minor mica, is hard, and has a dirty coating. Minor sandstone and conglomerate lenses appear near the base of the formation. The sandstone is red to brown and les commonly grey, very fine to medium grained with a quartz matrix, slightly calcareous, well sorted, subangular, and well consolidated. Sandstone abundance increases near the base of the formation. The conglomerate is maroon to brown, very slightly calcareous, has biotite in the matrix, is poorly sorted, and is well consolidated. Subangular to angular clasts in the conglomerate are composed of quartz and a variety of igneous fragments.

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The Hopewell Cape Formation (Fig. 4b) overlies the Maringouin Formation at depths of between 536 m and 1204 m and consists of conglomerate and sandstone. The conglomerate is maroon to brown, poorly sorted and well consolidated with subangular clasts of quartz, igneous fragments, and schist in a matrix with extensive biotite. Red to brown sandstone varies from very coarse to fine grained, is highly calcareous, is poorly sorted, and has subangular grains. Minor lenses of maroon to brown siltstone also occur throughout the section; the siltstone is siliceous, blocky, slightly calcareous, and hard.

Cumberland Group

The Imperial Dorchester 1 well was collared in rocks of the Boss Point Formation, which extend down to a depth of 536 m (Fig. 4b). Lithotypes of the formation consist of grey and maroon siltstone; grey, very fine- to coarse-grained grey and maroon sandstone; white to pink polymictic conglomerate; and minor, light to medium grey shale that is blocky and non-calcareous. Despite the lithologic variety, the grain sizes show an overall trend of becoming finer with depth.

Coppermine Hill 2 (UIN 716)

Pre-Late Devonian Rocks

This well intersected rocks of the pre-Late Devonian basement between 3420 m and 2862 m (Fig. 4a). The main basement lithologies comprise alternating sequences of schist, metasedimentary rocks, and weathered to unweathered granitic rocks. The schist appears in discrete zones devoid of other material. It is light to medium grey to green and poorly sorted; has abundant subrounded to elongated, grey to white quartz grains; and contains chlorite, biotite, and muscovite. The maroon to brown metasedimentary rocks are slightly calcareous, pyritiferous, and very hard. They resemble the pyritiferous, hard siltstones of the overlying McQuade Brook Formation (see below) but are much more indurated. The composition of the granitic rocks is somewhat similar to that of the schist, but the brown, grey, and orange quartz minerals are angular instead of subrounded. The granitic intervals also contain minor calcite (possibly vein material) and are pyritized, hard, and shiny.

Horton Group

Rocks of the McQuade Brook Formation (Horton Group) were intersected between 2862 m and 2553 m and overlie crystalline basement (Fig. 4a). The formation consists mainly of dirty, dark grey and brown to dark maroon and brown siltstone that is very calcareous, blocky, and has minor grey clay content. This siltstone-dominated facies is maroon-brown at the base, medium to dark grey in the mid-section, and dark brown in the upper section. The McQuade Brook Formation in this well has high pyrite content and is very hard, suggesting deep burial. The strip log for Coppermine Hill 2 (Stewart 2011, her Appendix 4) shows thin intervals of brown, polymictic conglomerate within the siltstone facies, beginning at 2629 m and

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becoming more common uphole until the interpreted Windsor–Horton boundary is reached at 2553 m. At this depth, the brown conglomerates, which probably represent the Memramcook Formation (see Discussion, below) ‘give way’ to maroon to brown conglomerates of the Hillsborough Group (Windsor Group).

Windsor Group

The Hillsborough Formation represents the base of the Windsor Group in this well and was intersected between 2218 m and 2553 m (Fig. 4a). The main lithology is conglomerate, accompanied by a minor, 20 m section of sandstone and siltstone. The conglomerate is maroon to brown, polymictic with quartz and a variety of igneous clasts, poorly sorted, predominantly subrounded, and slightly calcareous. The sandstone is dark grey, fine grained, has a high percentage of quartz and biotite in the matrix, and is moderately sorted with subangular grains. The pebbly siltstone is maroon to brown, non-calcareous, and blocky. The siltstone section may be thicker than indicated, but a 10 m to 15 m interval of chip samples is missing from above and below the section. The Macumber–Gays River formations were intersected in the 2150.5 m to 2218 m depth interval (Fig. 4a) and consist mainly of dirty anhydrite, limestone, and salt. The anhydrite is white to light grey and has powdered crystals; the limestone is light grey with mud cement. The salt is white to light grey, semitransparent to transparent, and in both powdered and large-crystal form. The Upperton Formation overlies the Macumber–Gays River formations and was intersected at a depth interval of 2100.5 m to 2150.5 m (Fig. 4a). The Upperton Formation is a narrow, dirty section that consists mainly of white to light grey, powdered anhydrite crystals but also contains significant salt and siltstone stringers. The salt is white to light grey, semitransparent to transparent, and in both powdered and large-crystal form. The halite-dominated Pugwash Mine Formation occurs in the 1745 m to 2100.5 m depth interval (Fig. 4a). The salt is light brown to greyish with intermittent stringers of medium to dark grey siltstone and minor white powdery anhydrite. The larger halite crystals in general appear powdery but when cleaned are semitransparent to transparent. The top of the Windsor Group is represented by the Lime-Kiln Brook Formation, which extends from 1745 m to 1426 m (Fig. 4a) and features miniscule white clay throughout the formation. The formation consists of siltstone and sandstone with minor salt and significant limestone in various intervals. The siltstone is maroon to grey, siliceous, veined in places with calcite, micromicaceous with minor pyrite, moderately hard, and blocky to platy. The sandstone is maroon, very fine to fine grained, siliceous, veined with calcite, micromicaceous with biotite, moderately sorted, and subangular to subrounded. Salt occurs as large, white to orange, semitransparent crystals. Light grey, calcite-veined limestone is present in the 1587 m to 1662 m depth interval.

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Mabou Group

The Mabou Group in this well is represented by the Maringouin and Hopewell Cape formations. The Maringouin Formation extends from 1026 m to 1426 m (Fig. 4a) and alternates between siltstone and minor sandstone lenses at the base of the section. The siltstone is maroon to brown and grey, calcareous, micromicaceous, and brittle in places. The sandstone lenses are very fine to fine grained and non-calcareous with constituents that vary from subangular to subrounded. The top of the sequence is dominated by similar sandstone but is mainly fine grained to very coarse grained. A single section of shale occurs between 1158 m and 1170 m; the shale is light to dark grey, blocky, very hard, and at some depths is vitreous, subfissile, and micromicaceous. The Hopewell Cape Formation was observed in the 177 m to 1026 m depth interval (Fig. 4a) and consists predominantly of conglomerate with lesser amounts of interbedded sandstone and siltstone that exhibit properties similar to the sandstone and siltstone in the previous interval. The conglomerate is dark maroon to dark brown and grey, polymictic, calcareous, and poorly sorted with a cement of siltstone and sandstone. All finer grained rocks in this interval are red to brown siltstone.

Cumberland Group

The well was collared in rocks of the Boss Point Formation to a depth of 177 m. The section consists mainly of a mixture of white to brown sandstone and siltstone with minor red to brown mudstone stringers. The sandstone is calcareous, poorly consolidated, and very fine to coarse grained with subrounded and subangular grains. The calcareous siltstone is predominantly red to brown and less commonly grey; it also is hematitic and very soft.

DISCUSSION

This detailed study of petrographic and petrophysical data from the three deep wells in the western Sackville Subbasin has helped to more precisely define the contacts between groups, formations, and members of Late Devonian to Carboniferous rocks in the report area (Table 1). Study results also provide a basis for examining and, in some cases, suggesting revisions to several previous stratigraphic and structural interpretations of rocks in the area.

Pre-Late Devonian Basement

Rocks identified as pre-Late Devonian basement were intersected only in the Coppermine Hill 2 well. They consist of alternating intervals of schist, metasedimentary rocks, and weathered to unweathered granitic rocks. The schists were previously identified by Gemmel and Giles (2001) as sandstones, the metasedimentary rocks as siltstones, and the granitic rocks as conglomerates. Evidence to support the reinterpretation of these rocks is as follows.

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The schist appears to be present in discrete zones devoid of other material, is chloritic, contains micaceous material, and has elongated quartz grains—features that are more typical of schist than of siltstone.

The metasedimentary rocks in this well are highly indurated, unlike most of those

commonly found in Late Devonian to Carboniferous rocks in the region. The material identified herein as granitic rocks contains very weathered angular chips and

lacks sedimentary or metasedimentary clasts. Moreover, no metasedimentary material that could indicate the presence of a matrix is attached to the angular fragments.

The wireline log signatures for the Coppermine Hill 2 well (Stewart 2011, her Appendix 4) show that the gamma ray response gradually decreases with depth and then becomes sporadic at the contact between the reinterpreted pre-Late Devonian crystalline basement and the younger cover rocks. The sonic wireline log remains stable between 200 μsec/m and 220 μsec/m at this contact.

Horton Group

Memramcook–McQuade Brook Formations

The McQuade Brook Formation and likely the Memramcook Formation were intersected at the base of the Horton section in two of the three wells being studied: Shell Dorchester 1 and Coppermine Hill 2. It is difficult to distinguish clearly between the two formations in these wells, but in general terms, the Memramcook Formation is characterized as being a coarser grained, proximal facies, whereas the McQuade Brook Formation is a finer grained, distal facies (St. Peter and Johnson 2009). Palynological analyses by Dolby (2011) of samples from both wells (one from a depth of 8190 ft [2481.8 m] in Shell Dorchester 1 and one from a depth of 2727 m in Coppermine Hill 2) date the rocks as Tournaisian Zone 1C to 1D. This age range supports their identification as either Memramcook Formation or McQuade Brook Formation. The coarse-grained conglomerate and sandstone facies interpreted as Memramcook Formation in the Shell Dorchester 1 well is assumed to grade laterally into the finer grained, siltstone-dominated sequence of the McQuade Brook Formation in the Coppermine Hill 2 well. The thin intervals of brown conglomeratic rock within the uppermost McQuade Brook siltstones in Coppermine Hill 2 may represent interfingerings of Memramcook-equivalent material. Given the relative geographic positions of the two wells (Fig. 2) and the foregoing lithofacies relationships, it would appear that the coarser Memramcook Formation grades into the finer McQuade Brook Formation toward the northeastern (i.e., deeper) part of the Sackville Subbasin. Such a relationship supports the interpretation that the two formations represent proximal and distal temporal equivalents (see St. Peter and Johnson 2009, their p. 38).

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Albert Formation

Results of the present study have helped to more precisely define the distribution and internal stratigraphy of the hydrocarbon-bearing Albert Formation in the western Sackville Subbasin. The Albert Formation was intersected only in the Shell Dorchester 1 well, where it is represented by two of its three members: Dawson Settlement and Frederick Brook. Rocks of the Hiram Brook Member were not observed in any of the wells (Table 1). In the Shell Dorchester 1 well, the McQuade Brook Formation is in gradational contact with the overlying Dawson Settlement Member (Albert Formation). The Dawson Settlement–Frederick Brook contact at 1958 m is marked by an abrupt facies change between the very fine-grained sandstone and limestone of the Dawson Settlement Member and the overlying shales of the Frederick Brook. The sharp facies change is mirrored in the wireline data, in which the 20 ohms (Ω), 30 Ω, and 60 Ω array induction, sonic, and self potential logs all show signatures that veer to the left at the contact (see Stewart 2011, her Appendix 2). The main differences between the two members in this well are that the Dawson Settlement has limestone and abundant quantities of very fine-grained calcareous sandstone, whereas the Frederick Brook lacks limestone, has less abundant very fine-grained sandstone and includes a 20 m interval of anhydrite. A palynological age of Tournaisian Zone 2 was obtained for the well cuttings interpreted here as Frederick Brook Member, but no such confirming age could be obtained for cuttings identified as Dawson Settlement Member (Dolby 2011). The Imperial Dorchester 1 and Coppermine Hill 2 wells contain no units that are laterally equivalent to the Albert Formation at the same depth (Table 1). In Coppermine Hill 2 to the northeast, the top of the McQuade Brook Formation is in sharp contact with the overlying Hillsborough Formation (Windsor Group), and the Albert Formation is entirely absent (Fig. 3, 4a). Thus, the Albert Formation pinches out somewhere between the Shell Dorchester 1 and Coppermine Hill 2 wells (Fig. 4a, 5), which indicates that the stratigraphic section of Albert Formation in the western Sackville Subbasin is thinner than was previously interpreted. However, it is possible that additional intersections of the Albert Formation could be encountered at depth below the Imperial Dorchester 1 well, which ended in rocks of the Windsor Group (Table 1).

Windsor and Mabou Groups

The Windsor Group makes up a significant portion of the stratigraphy in Shell Dorchester 1 and appears to have influenced structural relationships among rocks in the well. In the southern part of the cross-sectioned area (i.e., Imperial Dorchester 1 in Fig. 4b), the Hillsborough and Macumber–Gays River formations were not intersected but are assumed to be present at greater depths. As demonstrated in both cross-sections (Fig. 4a, 4b), the basal formations of the Windsor Group (Hillsborough, Macumber–Gays River, Upperton) have relatively uniform thicknesses across this part of the subbasin. However, the younger formations (Pugwash Mine, Lime-Kiln Brook) show more varied thicknesses.

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In his seminal paper on the Carboniferous stratigraphy and structure of New Brunswick, Gussow (1953) discussed the presence of a salt dome in the Sackville Subbasin. Results of the current study offer further evidence for such a dome involving the salt-dominated Pugwash Mine Formation: evidence includes relative unit thicknesses and the apparent absence of some lithographic formations above the salt units (Fig. 4a, 4b, 5). According to Martel (1987), the thickest part of the salt dome lies to the west in the vicinity of Shell Dorchester 1. The present study supports Martel’s concept of a westward thickening dome (Fig. 2), in that the Pugwash Mine Formation is 1009 m thick in Shell Dorchester 1 and only 365 m thick in Coppermine Hill 2 (Table 1). In Imperial Dorchester 1 to the south (Fig. 4b), the formation has an intermediate thickness of 759 m. Lithologic data (Fig. 4a; Table 1) and the 1996 seismic profile (Fig. 5) suggest that the Maringouin Formation is truncated above the slightly thinned Lime-Kiln Brook Formation between the Coppermine Hill 2 and Shell Dorchester 1 wells. Lithologic data also indicate a similar truncation of the Maringouin Formation above the substantially thinned Lime-Kiln Brook Formation to the south of Shell Dorchester 1 in the direction of Imperial Dorchester 1 (Fig. 4b; Table 1). However, these apparent thinning relationships are more likely due to facies changes between the two formations: as noted by St. Peter and Johnson (2009), the Maringouin can in part be laterally equivalent to the Lime-Kiln Brook. Whatever the Lime-Kiln Brook–Maringouin facies relationship in this part of the western Sackville Subbasin, the seismic profile (Fig. 5) does indicate that a buoyant salt dome pushed up through the overlying strata, causing the stratigraphy to appear anticlinal near Shell Dorchester 1. Under such a scenario, the dome would have affected the subsequent configuration and erosional history of overlying strata in the Mabou and Cumberland groups.

Seismic Survey and Structural Implications

The 1996 seismic profile reveals a fault that caused noticeable reverse displacement of pre-Late Devonian rocks near Shell Dorchester 1 (Fig. 5). Rocks of the Horton Group seem to display only minor movement along this structure, indicating that the apparently significant basement displacement could have resulted from strike-slip movement along irregular basement topography. Martel (1987) interpreted similarly Horton-age and younger faults (e.g., the Dorchester Fault) along a seismic line completed by Chevron Canada Resources Ltd. The 1996 seismic profile also indicates that faulting and folding of the Horton strata took place before deposition of the Windsor Group (see St. Peter and Johnson 2009). It likely was during this interval that the Albert Formation was eroded to varied degrees, which would account for the missing Albert section in the Coppermine Hill 2 well. Importantly, the uppermost unit of the Albert Formation—the Hiram Brook Member, one of the main targets for conventional gas in the region—is absent from all deep wells in the Dorchester area and presumably was eroded completely during basin inversion in the Early Carboniferous. Nonetheless, the lack of Hiram Brook strata does not rule out the potential for conventional gas elsewhere in the basin or for unconventional gas buried at depth below the Hiram Brook Member.

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CONCLUSIONS

A detailed analysis was conducted of petrographic and petrophysical data from three deep wells near Dorchester in the western Sackville Subbasin. The analyses were integrated with data from a 1996 seismic survey carried out between the wells. The study results concerning the stratigraphy and structure of rocks in the western subbasin can be summarized as follows. The contacts between some groups, formations, and members of the Late Devonian to

Carboniferous rocks in the report area were more precisely defined. Rocks mapped as Carboniferous conglomerate by earlier authors were herein identified as

pre-Late Devonian crystalline basement, which indicates that the depth to basement in the report area is shallower than previously interpreted.

The stratigraphic section of Albert Formation in the western Sackville Subbasin can be

subdivided into the Dawson Settlement and Frederick Brook members. The Hiram Brook Member (Albert Formation), a key target for conventional gas in southeastern New Brunswick, is absent from all three deep wells in the report area.

The total thickness of the Albert Formation in the report area is thinner than previously

interpreted, and the formation appears to pinch out to the northeast of Dorchester. The stratigraphic and structural relationships in the report area, as revised on the basis of

the current study, can be interpreted to support Gussow’s (1953) suggestion of a salt dome in the western Sackville Subbasin.

Future work will include petrographic and petrologic analysis of other wells in the western Sackville Subbasin, as well as additional field mapping and seismic interpretation.

ACKNOWLEDGEMENTS

First and foremost, the author thanks Malcolm McLeod for carefully reviewing this paper and providing insight on some of the subject matter. Steven Hinds reviewed the first draft of the paper and aided in seismic interpretation. Craig Parks provided insight on both the petrographic analysis and the geophysical log interpretation. The author also wishes to thank Terry Leonard for preparing most of the figures.

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Martel, A.T. 1987. Seismic stratigraphy and hydrocarbon potential of the strike-slip Sackville sub-basin, New Brunswick. In Sedimentary Basins and Basin-Forming Mechanisms. Edited by C. Beaumont and A.J. Tankard. Canadian Society of Petroleum Geologists, 12, p. 319–334.

McCutcheon, S.R. 1981. Stratigraphy and paleogeography of the Windsor Group in southern New Brunswick. Unpublished M.Sc. thesis, Acadia University, Wolfville, Nova Scotia, 206 p. [also] New Brunswick Department of Natural Resources; Mineral Resources Division, Open File Report 81–31, 210 p.

McLeod, M.J. 1980. Geology and mineral deposits of the Hillsborough area, map area V-22 and V-23 (Parts of 21 H/15E and 21 H/15W). New Brunswick Department of Natural Resources; Mineral Resources Branch, Map Report 79–6, 35 p.

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Surficial Geology Mapping in New Brunswick: Past, Present, and Future

SERGE ALLARD Geological Surveys Branch, New Brunswick Department of Natural Resources,

P.O. Box 6000, Fredericton, New Brunswick, CANADA E3B 5H1 ([email protected])

Allard, S. 2011. Surficial geology mapping in New Brunswick: past, present, and future. In Geological Investigations in New Brunswick for 2010. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Lands, Minerals and Petroleum Division, Mineral Resource Report 2011-2, p. 75–126.

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A comprehensive understanding of surficial geology is integral to the socioeconomic fabric of New Brunswick. It is the responsibility of the Geological Surveys Branch (GSB) to delineate, describe, and analyze the distribution of surficial materials in order to successfully 1) identify and characterize granular aggregate resources (sand, gravel, clay, and till) for use in infrastructure construction projects, 2) provide useful data to the mineral exploration community, 3) offer pertinent baseline geological information to agencies involved in forestry, agriculture, groundwater resources, and land-use planning, and 4) help to identify landforms and sediment characteristics that present hazards to public health and safety. Extensive surficial geology data have been collected by the GSB as a result of till geochemistry investigations, granular aggregate mapping projects, and other surficial mapping projects that span the past five decades. However, only modest advances have been made in synthesizing maps that are comprehensive and easily accessible by clients. This is due partly to the fact that the existing data sets did not provide the level of detail needed to produce such maps. Older detailed maps are available for some areas, but in many cases they are outdated, difficult for clients to access, and unavailable in a digital georeferenced format. Since 2009, new mapping endeavours in areas of poor coverage, combined with advanced technological capabilities in the fields of remote sensing and GIS, have enabled GSB staff to ‘bridge the gap’ and to produce detailed, up-to-date surficial geology maps for southwestern New Brunswick. These maps reflect a newly devised, consistent approach to field mapping and map production. The GSB has recently emphasized the compilation and publication of standardized digital maps for bedrock geology. Likewise, the current initiative to produce consistent surficial geology maps for southwestern New Brunswick represents the first, pilot step toward creating a standardized set of surficial geology maps for the entire province. Such maps will significantly improve our understanding of surficial geology in New Brunswick.

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Une bonne compréhension de la géologie superficielle fait partie intégrante du tissu socioéconomique du Nouveau-Brunswick. La Direction des études géologiques (DEG) a pour mandat de définir, de décrire et d’analyser la répartition des matériaux de surface

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et, ce faisant, de réussir 1) à définir et à caractériser les ressources en agrégats granulaires (comme le sable, le gravier, l’argile et le till) destinées aux projets de construction d’infrastructures; 2) à offrir des données utiles pour les prospecteurs miniers; 3) à offrir des données géologiques de base pertinentes pour les organismes qui oeuvrent à l’aménagement du territoire, à la gestion des ressources d’eau souterraine, à l’exploitation de la ressource forestière et à l’agriculture; et 4) à aider à identifier les configurations de terrain et les caractéristiques sédimentaires susceptibles de porter atteinte à la santé et à la sécurité publiques. La Direction des études géologiques a recueilli un vaste corpus de données sur la géologie superficielle dans le cadre d’études sur la composition géochimique du till, de projets de cartographie des agrégats granulaires, et d’autres projets de cartographie des matériaux de surface réalisés au cours des trente dernières années. Très peu de percées ont toutefois été réalisées en ce qui a trait à la synthétisation de cartes globales et que peuvent consulter facilement les clients. Cela s’explique en partie par le fait que les ensembles de données existantes n’offrent pas le degré de précision voulu pour produire des cartes aussi détaillées. Il y a certes des cartes détaillées pour certaines régions, mais dans de nombreux cas, il s’agit de cartes désuètes, de consultation difficile pour les clients, et qui n’existent pas dans un format de données numériques à référence spatiale. Depuis 2009, de nouveaux projets de cartographie dans les secteurs mal représentés et les nouveaux développements technologiques dans les domaines de la télédétection et des SIG ont permis à la DEG de « combler les lacunes » et de produire des cartes à jour et plus détaillées. En outre, les nouvelles cartes de géologie superficielle produites rendent compte d’une approche innovatrice et plus cohérente en termes de levé sur le terrain et de production de cartes. La DEG a récemment axé ses efforts sur la compilation et la publication de cartes numériques uniformes de la géologie du substrat rocheux. De même, le programme actuel de production de cartes de géologie superficielle uniformes du sud-ouest du Nouveau-Brunswick est une première initiative pilote visant la création d’une série de cartes de géologie superficielle uniformes pour l’ensemble de la province. Ces cartes amélioreront dans une très large mesure notre compréhension de la géologie superficielle du Nouveau-Brunswick.

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INTRODUCTION

Surficial geology refers to the study of unconsolidated or poorly consolidated rock materials found at the earth’s surface. At a basic level, these loosely consolidated sediments are the result of erosion and weathering of bedrock. Over time, solid rock is broken down into successively smaller fragments to form loose accumulations of sand, silt, clay, and gravel or other distinct accumulations of sediments that contain a variety of size fractions. In New Brunswick, these surficial deposits can vary in thickness from a few centimetres to likely more than 100 m: thicknesses exceeding 80 m have been documented by Lamothe

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(1990). Such sediments are the parent material (C-horizon) of the soil that occurs between the zone of biologically modified soil (A- and B- horizons) and the underlying rock. (Note that ‘soil’ is used hereafter in the restricted context, meaning biological soil—that is, the A- and B- horizons only.) When mapping surficial geology, a geologist first makes observations about the surficial materials at a network of points throughout the chosen map area. The observation points may be auger holes, roadcuts, gravel pits, streamcuts, or any other location where surficial sediments are exposed. After examining these data in conjunction with water well and borehole data, other published information, and various digital elevation data and aerial photographs, the geologist can interpret the distribution of surficial materials and produce a surficial geology map. More than 90% of New Brunswick is covered by unconsolidated materials that formed as the result of Pleistocene glaciation. The remaining 10% comprises bare rock, residuum, and deposits of Holocene origin (e.g., alluvium, colluvium, and organic deposits). During the most recent (Wisconsinan) ice age, large glaciers up to 2 km thick formed and coalesced over New Brunswick. The erosive action of these glaciers had a locally profound effect on shaping the landscape. Flowing glaciers scoured bedrock, and the erosion products, along with pre-existing unconsolidated surficial deposits, were deposited and redeposited by actions of the glacial system. Through advance and subsequent melting of debris-laden ice, various surficial deposits were formed. Reworking of these deposits and the emergence of new deposits took place during the Holocene as a result of fluvial, colluvial, and other currently active geological processes. Surficial materials and the overlying soils represent the zone in which humans interact with the landscape. It thus makes sense that, over time, people developed a keen interest in understanding the physical attributes of surficial deposits as well as the processes and conditions that led to their formation. The effects of New Brunswick’s diverse surficial geology are far-reaching, initially having influenced where habitation occurred. Today, agriculture, forestry, mining and mineral exploration, construction, and land-use planning all rely on an understanding of surficial materials. The Geological Surveys Branch (GSB) of the New Brunswick Department of Natural Resources (NBDNR) has the responsibility to delineate, describe, and analyze surficial materials in order to generate client-oriented maps and reports that 1) help to locate construction aggregate resources (sand, gravel, clay, and till), 2) assist the mineral exploration community, 3) provide useful baseline geological information to agencies involved with forestry, agriculture, groundwater resources, and land-use planning, and 4) help to identify landforms and sediment characteristics that present hazards to public health and safety. In 2009 the GSB launched a project to produce new, up-to-date, 1:50 000 scale surficial geology maps for the area in southwestern New Brunswick covered by map quadrant 21 G of

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Canada’s National Topographic System (NTS) (Fig. 1). From 2009 to the present, fieldwork was conducted in six of the fourteen 1:50 000 NTS map sheets of 21 G. As well, maps were published for four sheets of 21 G (Fig. 1) using a new methodology designed to create consistent, standardized maps of surficial geology for the area. The new 21 G maps represent the first, pilot series of what will become a set of comprehensive, standardized surficial geology maps for the entire province. How these maps were produced—including detailed descriptions of the new methodology and the revised map units—is the subject of the present report.

PREVIOUS WORK

Surficial mapping and the interpretation of glacial history in New Brunswick were first conducted in the mid-1800s by Robb (1851), Hind (1865), and Matthew (1872, 1879). Through the course of their investigations and by mapping glacial striae, they adopted the notion that glaciation in the area comprised a massive glacier flowing in a south-southeasterly direction. They recognized that the glacier had a profound effect on the New Brunswick landscape and that the unconsolidated sediments mantling the surface of the province were formed by processes related to glacial advance and retreat. The astute surficial geology observations made by Chalmers (1884, 1885, 1890, 1902) led him to conceptualize the ‘Appalachian system of glaciers,’ in which numerous local ice masses interacted to form the complex erosional record that characterizes many parts of New Brunswick. The Appalachian Glacier Complex model is still relevant today and has been adapted and improved upon to explain glacial phenomena observed across the Maritimes (Seaman 2004, 2009; Stea 2004). Following the Second World War, major infrastructure projects were in effect across Canada. These activities, brought on by a thriving economy, required the use of surficial geology information to locate suitable sand and gravel resources, assess groundwater potential, provide information on foundation conditions for construction, and conduct agricultural surveys (Fulton 1993). By the mid-1950s, it was generally recognized that surficial geology data were beneficial to agriculture, forestry, and land-use planning in New Brunswick. H.A. Lee with the Geological Survey of Canada (GSC) completed a lengthy mapping program of the upper and middle Saint John River valley (Fig. 2), becoming among the first to systematically describe and delineate surficial sediments and to produce surficial geology maps (1:63 360 scale or 1 inch to 1 mile) for the province (Lee 1955a, 1955b, 1956, 1957, 1959a, 1959b, 1962). He was preceded by Wicklund and Langmaid (1953) with the Canada Department of Agriculture, who conducted regional soil surveys that provided some information on glacial sediments and their relevance to the physical attributes of overlying soils. From the late 1960s to the early 1980s, the GSC conducted reconnaissance-scale mapping in New Brunswick as part of its larger mandate to map extensive areas of Canada. The motivation to examine New Brunswick was influenced in part by the 1950s discoveries of substantial base metal deposits in the Bathurst Mining Camp (Fig. 1) and the recognition that

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maps (in yellow), and areas mapped during the recent (2009 to present) fieldwork program.

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Figure 2. Index to surficial geology maps produced for New Brunswick between 1955 and 2011 by

the Geological Survey of Canada

(GSC).

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Maps by the NewBrunswick

Department ofNatural Resources

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surficial maps and related data sets were important tools for mineral exploration. Gadd (1973) mapped southwestern New Brunswick, and Gauthier (1982) mapped northern New Brunswick at scales of 1:200 000 and 1:100 000, respectively. Rampton and Paradis (1981a–c), working under provincial auspices, mapped central and southern New Brunswick at a scale of 1:250 000 (Fig. 2). Surficial mapping by the GSC culminated in the production of a provincial, 1:500 000 scale map (Rampton 1984a, modified as 1984b) and a comprehensive report (Rampton et al. 1984) describing the Quaternary history of New Brunswick. Although some glacial theories in the report have since been disproven, it is the most recently available, relevant synthesis of Quaternary geology for the province as a whole. Newer works by Seaman (2004, 2006, 2009) and Seaman and McCoy (2008) provide a more up-to-date account of the complex glacial history and Quaternary stratigraphy in west-central New Brunswick.

Granular Aggregate Inventory Program (GAIP)

By the early 1970s, the availability of suitable granular aggregate materials for infrastructure construction projects (highways, hydroelectric dams, and bridges) had become a concern in New Brunswick. In anticipation of policy changes (enacted on April 1, 1975) that would ban aggregate extraction from provincial beaches, the NBDNR initiated the New Brunswick Granular Aggregate Inventory Program (GAIP). The program involved the systematic mapping of surficial units considered to be important as granular aggregate resources, those being glaciofluvial deposits, alluvial deposits, and select ablation till deposits. Fieldwork began in 1974 to outline alternative sources of concrete sand in the Moncton area, which would be significantly affected when provincial beaches were closed for aggregate extraction. The inventory project was later extended to the Saint John area, the Bathurst–Campbellton area, the Saint John River valley between Edmundston and Fredericton (Fig. 1), and subsequently to the remainder of the province. The field mapping and sampling components of the inventory were completed in 1986. Mapping was based on the federal 1:50 000 scale NTS maps for the province (Fig. 1, 3a). The associated reports (Fig. 3b), which commonly dealt with two or more map areas, presented 1) a brief description of the bedrock and surficial geology of the study area, 2) a description of the types and general characteristics of granular aggregate deposits present, 3) appendices containing section descriptions and the results of mechanical grain-size and lithologic analyses, and 4) estimated recoverable reserve volumes for specific deposits. Reports and maps were produced for each map area as part of the GAIP, yet only a small percentage of the actual field observations were published. For a single 1:50 000 scale NTS map sheet, it was not unusual for a geologist to capture field notes at more than 200 observation sites but to report on only a few tens of sites. At the time, no foreseeable reason appeared to exist to include observations that had no bearing on the perceived economic potential of surficial deposits in the granular aggregate reports. Thankfully, the geologists

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conducting the mapping surveys had the foresight to meticulously record these observations in their notebooks or on their field maps and aerial photographs. Maps and reports resulting from the GAIP are still relevant today and continue being used by industry to locate granular aggregate materials and to facilitate land-use planning. In fact, historically they are some of the most requested items produced by the NBDNR. In response to this interest and in order to increase client accessibility, the GSB staff has created an online, interactive granular aggregate database (NBDNR 2011a) that contains all site data from approximately 2500 sample sites and provides easy access to the scanned maps and reports. This database is one of the most frequently accessed online databases of the GSB website. Following the era of GSC-led and GAIP surficial mapping projects during the early 1950s to 1980s, no systematic surficial mapping took place in New Brunswick. The provincial government occasionally conducted projects of limited scope, such as surficial mapping around municipalities (e.g., Seaman 1985). As well, a few surficial geology-related graduate theses were completed (e.g., Balzer 1992). However, these projects generally lacked any consistency of approach or map presentation style.

Till Geochemistry Surveys

The early 1970s brought the realization that many principles of surficial geology could help with locating orebodies in glaciated terrains. Examining the lithologic content and geochemistry of glacial sediments, coupled with delineating the provenance of these sediments, could lead to the discovery of orebodies (Shilts 1975). Surveys involving the geochemical analysis of glacial till (hereafter referred to as till geochemistry surveys) proved to be a good reconnaissance-scale method of assessing the mineral potential of a region. A solid understanding of surficial geology principles is fundamental to any till geochemistry survey, not only for successfully identifying the preferred sample medium (basal till in most cases), but also for understanding how glacial stratigraphy, depositional history, and post-glacial alteration can effect the survey results (Shilts 1975). By the mid-1970s, Canada and some Scandinavian countries had successfully used till geochemistry as a mineral exploration technique. The first New Brunswick forays into till geochemistry were conducted by exploration companies around Mount Pleasant (Fig. 4) in southwestern New Brunswick (Szabo et al. 1975) and at Sisson Brook (Fig. 4) in west-central New Brunswick (Snow and Coker 1987). In the early 1980s, following the success of the industry projects, the NBDNR conducted and contracted numerous till geochemistry sampling projects at select locations throughout the province (Pronk 1984a, 1984b; Thomas et al. 1987). By 1986 the NBDNR had embarked on a full-scale, methodical till geochemistry sampling program. Sampling initially was conducted in northern New Brunswick in the vicinity of the Bathurst Mining Camp (Fig. 1) but later was expanded to cover some of the Miramichi

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Bathurst

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Highlands, Caledonian Highlands, and St. Croix Highlands (Fig. 4), all areas considered to

have significant mineral potential. In the pursuit of provincial coverage, more recent surveys

have been undertaken in the New Brunswick Lowlands, Chaleur Uplands, and Edmundston

Highlands (Fig. 4), albeit at a reduced sample density (Fig. 5). The till geochemistry program

is ongoing and has proven highly effective in delineating mineral occurrences and stimulating

mineral exploration throughout New Brunswick. To date, the till geochemistry data set

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The scope of the NBDNR till geochemistry program did not include comprehensive surficial mapping and the production of surficial geology maps; however, the work yielded a wealth of surficial data. At each sample site station, geologists recorded information about the site physiography and the physical attributes of the sample media (lodgement tills in most cases). They also took field notes at sites where samples were not collected, recording descriptions of glacial landforms, sediment characteristics, sediment thickness, and stratigraphy.

CURRENT INITIATIVE: NEW MAPPING METHODOLOGY

Background

As a result of the foregoing till geochemistry program, granular aggregate mapping, and related investigations since the mid-1950s, large amounts of surficial geology data have been compiled by the GSB staff. Yet until recently, only modest advances had been made in synthesizing comprehensive surficial geology maps. This was due in part to the fact that the data sets acquired during the earlier surveys had an insufficient level of detail to produce such maps. Detailed older maps are available for some areas (Fig. 2), but in many cases they are largely the result of aerial photograph interpretation with very little ground-truthing, are difficult for clients to access, and are unavailable in a digital geo-referenced format. However, thanks to recent mapping in areas of poor coverage and to advanced technological capabilities in the fields of remote sensing and GIS, the GSB staff can now ‘bridge the gap’ and produce digital, comprehensive surficial geology maps that answer the need for up-to-date, relevant, and consistent surficial geology information in New Brunswick. For a variety of reasons, the earlier surficial maps by the GSB did not adhere to a common methodology of production. (The GAIP maps are consistent in legend and presentation but are not considered comprehensive surficial geology maps.) However, in 2009 the GSB staff launched a multiyear mapping program to produce 1:50 000 scale digital surficial maps for southwestern New Brunswick (NTS 21 G; Fig. 1). GSB geologists used the new program as an opportunity to design and implement a standardized mapping system that would ensure map consistency. Since then, surficial geology maps published under the new system are consistent in terms of how units are defined, described and classified; symbology; map presentation (i.e., colours and fonts, etc.); and overall layout. As well, all maps are edge-matched so that geological boundaries and features cross map boundaries without discrepancy. The GSB has recently emphasized the compilation and publication of standardized digital maps of New Brunswick’s bedrock geology as part of its mandate to promote mineral exploration and development. Likewise, the current initiative to produce consistent, up-to-date surficial geology maps of southwestern New Brunswick is the first step toward providing a standardized set of such maps covering the entire province for use by the forestry, agriculture, mining, construction, and land-use planning sectors. Such maps will significantly improve our understanding of surficial geology in New Brunswick.

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As part of the pilot project to publish standardized surficial maps for NST 21 G, the GSB staff has conducted the following activities between 2009 and the present: 1. developed a new surficial geology map legend, deposit classification system, and map

presentation style to be used in producing all new surficial geology maps in New Brunswick;

2. complied and digitized all existing surficial geology data for southwestern New Brunswick (21 G);

3. conducted fieldwork in the Musquash, St. George, St. Stephen, Rollingdam, McDougall Lake, and Fredericton Junction map areas of 21 G (Fig. 1);

4. conducted imagery interpretation of the St. George, McDougall Lake, Fredericton Junction, and McAdam map areas (Fig. 1); and

5. published 1:50 000 scale surficial geology maps for the St. George, McDougall Lake, Fredericton Junction, and McAdam map areas (Allard 2011 a–d).

1. New Map Legend, Classification System, and Presentation

Legend

In 2009, in consultation with GSB staff and with advice from GSC staff, the author undertook the task of developing a new surficial geology legend that would apply to all of New Brunswick and could be used for each surficial map produced by the GSB. The standardized New Brunswick Surficial Geology Legend (Table 1) closely resembles the one recently implemented by GSC Québec (Yves Michaud, pers. comm. 2010), with only minor variations in nomenclature and format. In some cases, these differences are warranted by the nature of geological data available in New Brunswick. For example, the mapping and classification of wetlands in New Brunswick by the NBDNR is more rigorous and comprehensive than what takes place during a typical surficial mapping program. The availability of detailed wetland data makes it possible not only to display deposits containing significant accumulations of organic material, but also to plot accurate boundaries for discrete wetlands in a map area. Distribution of wetlands and their proximity to other map units can have significant implications for such activities as forestry, agriculture, and land-use planning. Map units are classified first on the basis of their age, then by depositional environment, and finally by facies and/or geomorphology. From oldest to youngest, the 12 map units comprise residuum, till deposits, glaciofluvial deposits, glaciomarine deposits, glaciolacustrine deposits, marine deposits, lacustrine deposits, eolian deposits, alluvial deposits, organic deposits, colluvial deposits, and anthropogenic materials. Note that, in some cases, multiple types are deposited contemporaneously. Areas where bedrock appears in outcrop at the surface are also shown on the maps. The 12 map units are further subdivided and classified to give a total of 47 possible legend units, including the one for bedrock. Table 1 and Deposit Types (see below) provide summary and detailed descriptions, respectively, for each of the 47 units.

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In addition to containing a standardized Surficial Geology Legend, each map includes a diagram of the Quaternary Stratigraphic Column for New Brunswick (Fig. 6), which subdivides the Middle to Late Pleistocene into glacial phases that affected Atlantic Canada (Stea et al., in press). Where applicable, the map units are assigned to their interpreted glacial phase or interphase of origin. Material thickness must exceed 1 m to qualify as a map unit, with three exceptions, which are described below: Till Veneer (Tv), Glaciomarine Veneer (GMv), and Organic Veneer (Ov). Till Veneer: Because the dominant landform assemblage in many areas of New Brunswick

is a veneer of till over bedrock, it was deemed important to distinguish between areas of thin till cover and those of bare bedrock at surface. In a strict (>1 m) mapping approach, areas covered with till veneer would fall under the Bedrock (R) unit. Yet even thin till veneer presents more opportunities for drift prospecting than do areas of bare rock. Identifying areas of bare rock also has value to the forestry and mineral exploration sectors.

Glaciomarine Veneer: Like till veneer, glaciomarine veneer occurs consistently across New

Brunswick (in this case, along most coastal areas) and thus is denoted as such on the maps. Polygons marked ‘GMv’ can indicate the extent of marine inundation during the Late Wisconsinan.

Organic Veneer: The symbol ‘Ov’ is used to describe wetlands that lack significant organic

accumulation. The generic term ‘wetlands’ had been considered to distinguish these areas, but because they contain some degree of organic accumulation (veneer), a map unit to specifically denote organic veneer was deemed more appropriate for a surficial geology map.

All deposit types in the Surficial Geology Legend have a veneer subunit (Table 1), but the subunits are used only in section descriptions, on cross-section diagrams, or in exceptional situations (aside from the aforementioned Tv, GMv, and Ov units). If a unique assemblage of sediments has significant stratigraphic implications, it may be important to note all sediments in the sequence, veneer and otherwise. For example, if Unit Tl overlies a veneer of glaciofluvial sediments (GFv) that overlie bedrock (R), and if the sediment package is laterally continuous across a distance that warrants a map unit, then the unit label will refer to the vertically layered package as, in this case, Tl/GFv/R. In the context of New Brunswick Quaternary stratigraphy, the occurrence of basal till overlying anything other than bedrock or weathered bedrock is unusual. Where a typical sequence of sediments is encountered (i.e., GFv/Tl), the corresponding map unit will not refer to the overlying veneer material (in this case, GFv), as it does not exceed 1 m in thickness. To consistently map all surficial sediments that are less than 1 m thick would be impractical. On maps covering landscape features (e.g., river valleys) that contain significant accumulations of superimposed surficial deposits and have sufficient borehole data, a cross-section diagram may be included.

Figure 6. Quaternary stratigraphic column for New Brunswick, modified after Seaman (2009). The

inferred ages of deposit types for the McDougall Lake map area (Fig. 1) are used here to demonstrate

how the column is portrayed on the new surficial geology maps. This chart does not show the base of

the Pleistocene (= base of the Quaternary), which is placed at 2.588 Ma (Gibbard and Head 2009). The

pre-Pleistocene deposits are, by definition, also pre-Quaternary.

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14C Age Glacial GlacierEpoch Stage

(ka) Phase Source

10

Collins PondGaspereauIce Centre

11

13

ChignectoFundy

HighlandsIce Divide

15

ScotianCentral

Maine IceCentre

18

EscuminacEscuminacIce Centre

22

La

te

30 Inactiveice cover

40

Mid

dle

55

Wis

co

ns

ina

n

Ea

rly

CaledoniaLaurentide

Ice Sheet

75

Deglaciated

Sa

ng

am

on

ian

130

PL

EIS

TO

CE

NE

Illi

no

ian

200

Northumberland

WhiteMountains–

MeganticHills IceDivide

H, A, Ob

Of, Ov

T , Td,

Tv, Tm

l

GM Gl, Fx,

GFo, GFt, Tm

W

QU

AT

ER

NA

RY

HO

LO

CE

NE

PeriodDepositional

Events

Reworking

of T , Td,

Tv, and Tm

l

90

Table 1. New Surficial Geology Legend for New Brunswick, coloured according to the three-pigment RGB system (cont’d on p. 91–93).

HOLOCENE Anthropogenic Materials

H 128,0,0 Anthropogenic Human-made or human-altered geological materials (i.e., landfills, fill, mine tailings)

Colluvial Deposits: materials that reached their present position as a result of gravity-induced movement

Cs 230,230,128 Scree Accumulations of angular boulders, cobbles, and gravel along the base of cliffs; form fans or aprons

C 230,204,0 Colluvium Unsorted, crudely stratified complex of reworked glacial deposits, fractured bedrock and slope wash; generally mantle steep valley walls and floors

Cv 246,217,0 Veneer

Organic Deposits: peat and muck; formed by the accumulation of plant material in various stages of decomposition

Of 112,112,112 Fen Accumulations of organic material derived from sedges and decaying woody debris in eutrophic, mineral-rich wetlands; generally occur as flat, wet plains occupying natural depressions

Ob 0,0,0 Bog Peat-covered wetlands in which vegetation shows the effects of a high water table and a general lack of nutrients; characterized by raised mounds or plateaus and acidic waters

Ov 159,159,159 Veneer

Alluvial Deposits: sediments deposited by modern rivers and streams

Ap 255,255,100 Plain Sorted sand, gravelly sand, gravel, silt, and organic debris; form an active floodplain close to river level with meander channels and scroll marks; prone to seasonal flooding

At 255,230,128 Terrace Sorted sand, gravelly sand, gravel, silt, and organic debris; form inactive terraces above the modern floodplain

Af 215,193,0 Fan Poorly sorted sand, gravel, silt, and organic debris; occur where a stream issues from a narrow valley onto a plain or flat valley floor

A 255,255,0 Undifferentiated

Av 250,240,119 Veneer

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Eolian Deposits: wind-deposited sediments; well sorted and stratified to massive

Ed 215,132,35 Dune Stratified fine to medium sand, forming parabolic dunes or ridges

El 230,178,70 Loess Veneer of massive wind-blown silt and fine sand

Lacustrine Deposits: sediments deposited in and adjacent to lakes; exposed by recent fluctuations in lake levels

Ld 230,76,255 Delta Sand, sandy gravel, gravel, and cobble gravel; stratified and well sorted; form where a stream enters a lake; planar surface, commonly marked by abandoned channels

Ll 255,178,255 Littoral Sand, silty sand, sandy gravel, gravel, and cobble gravel; normally graded; form beach ridges and terraces

Lb 255,91,255 Basin Silt, clay, and fine sand; generally laminated

L 230,128,204 Undifferentiated

Lv 234,146,211 Veneer

Marine Deposits: sediments deposited in the modern marine environment

Mi 204,230,255 Intertidal Clayey silt and silty clay; form coastal plains; exposed between the extreme high-tide and extreme low-tide marks

Md 102,178,255 Delta Sand, sandy gravel, gravel, and cobble gravel; stratified and well sorted; occur where streams flow into the sea; form planar surfaces, commonly marked by abandoned channels

Ml 102,178,204 Littoral Sand, silty sand, sandy gravel, gravel, and cobble gravel; form beaches, bars, and spits

M 153,230,255 Undifferentiated

Mv 175,236,255 Veneer

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PLEISTOCENE

Glaciolacustrine Deposits: sediments deposited in ice-dammed lakes in valleys and other low-lying areas along the margins of decaying ice centres

GLd 153,76,230 Delta Sand, sandy gravel, gravel, and cobble gravel; stratified and well sorted; occur where meltwater streams flowed into proglacial lakes; form planar surfaces marked by abandoned channels

GLl 204,178,255 Littoral Sand, silty sand, sandy gravel, and gravel; normally graded; deposited (or reworked) sediments along the shore and within proglacial lakes; commonly form beach ridges and terraces

GLb 204,153,255 Basin Silt, clay, and fine sand; generally laminated, commonly in the form of rhythmites

GL 178,153,204 Undifferentiated

GLv 194,173,215 Veneer

Glaciomarine Deposits: sediments deposited in the marine environment during the Late Wisconsinan episode of marine submergence and subsequent emergence

GMd 153,153,255 Delta Sand, sandy gravel, gravel, and cobble gravel; stratified and well sorted; occur where meltwater streams flowed into the sea; form planar surfaces, commonly marked by abandoned channels

GMl 149,221,255 Littoral Sand, silty sand, sandy gravel, gravel, and cobble gravel; normally graded; occur in areas that were inundated by shallow seas during the Late Wisconsinan; often form beach ridges and terraces

GMb 26,215,255 Basin Clayey silt and silty clay, generally massive; deposited by settling during Late Wisconsinan marine submergence

GM 153,204,230 Undifferentiated

GMv 178,217,236 Veneer

Glaciofluvial Deposits: stratified sediments deposited by glacial meltwater in contact with or in proximity to glaciers

GFo 240,120,0 Outwash Plain Sand, sandy gravel, and cobbles; form plains and fans with flat to undulating surfaces marked by shallow sinuous meltwater channels

GFt 176,88,0 Outwash Terrace

Sand and gravel, generally stratified; occur as flat terraces perched above alluvial terraces and generally associated with large meltwater channels

GFx 255,0,0 Ice-Contact

Stratified Drift

Sand, gravel, cobbles, boulders (minor silt); form eskers, kames, kame terraces, and other moraine features; hummocky surface, locally punctuated by kettles and marked by abrupt slopes

GF 128,64,0 Undifferentiated

GFv 204,102,0 Veneer

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Till Deposits: sediments deposited by the action of advancing or decaying glaciers

Tm 163,240,0 Melt-Out Diamicton; deposited during the melting of debris-laden ice; stoney; loose; form hummocky topography

Tl 38,178,102 Lodgement Diamicton; deposited by the glacier sole sliding over the bed (substrate); overconsolidated; form undulating or streamlined topography

Td 0,88,0 Deformation Diamict products of subglacial shear; stoney; loose; consist predominantly of local material with local occurrences of glacially sheared bedrock (glacitectonite)

T 0,119,0 Undifferentiated

Tv 227,168,171 Veneer

PRE-PLEISTOCENE Residuum: mechanically or chemically weathered bedrock

W 128,128,0 Residuum Disaggregated (rotten) bedrock; varied degrees of mineral alteration; thickness can be locally highly varied; outcrops of competent bedrock and minor deposits of till or colluvium common

Wv 168,164,0 Veneer

Bedrock: areas of bedrock that appear in outcrop at surface; often glacially polished and showing evidence of glacial flow orientation

R 255,0,255 Bedrock Continuous bedrock outcrop; isolated deposits of colluvium or till common

Classification System

Early in the map design process, the possibility was discussed of using a strictly lithostratigraphic approach to mapping tills, similar to what was done in Nova Scotia (Ralph Stea, pers. comm. 2009). The value of such an approach was recognized, especially in that mapping till units on the basis of lithologic provenance could benefit the mineral exploration community. However, the facies classification system for mapping tills was finally selected as more appropriate for New Brunswick, given the province’s complex glacial history involving multiple ice-flow events and heavily reworked till. Unlike elsewhere in Canada, including Nova Scotia, New Brunswick generally lacks a stratigraphic record of multiple, regionally extensive till sheets (Seaman 2004). Rather, the

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province is typically, but not always (Lamothe 1992; Seaman and McCoy 2008; Seaman 2009), characterized by an apparent till sheet that blankets bedrock, featuring little to no stratigraphic variation. The lodgement till unit initially was deposited by a single ice-flow event but later came to reflect multiple ice-flow phases, having been repeatedly reworked and deformed (‘hybridized’) during its depositional history (see Allard and Pronk 2003; Seaman 2004). Most events caused only minor reworking, but others had significant effects. Despite recent advances in the knowledge of New Brunswick’s glacial history, the subject remains poorly understood. Seaman (2004, 2006, 2009) and Seaman and McCoy (2008) have made significant strides in delineating the till stratigraphy and interpreting the glacial history of west-central New Brunswick. However, much work remains in deciphering till stratigraphy across the province. For example, little is known about the preservation of pre-Wisconsinan tills and their distinguishing criteria, or about the full impact of the Younger Dryas stadial in New Brunswick. In most cases, it is possible to discern lateral variation in till units with respect to colour, texture, and lithology. But until the province’s glacial history and Pleistocene stratigraphy is more clearly defined, a purely lithostratigraphic approach to classifying tills cannot be implemented with confidence. That said (and as mentioned above), if boreholes in a map area indicate distinct buried till units or other unusual assemblages of surficial units implying a significant age discrepancy with what is recorded at surface, that information will be displayed on the map in a cross-section, and appropriate notes will be included in the legend. Such data will be valuable in the future if the GSB chooses to adopt a lithostratigraphic approach to till classification.

Map Presentation

Legend unit colours (Table 1) are similar to those used by the GSC and follow the basic colour scheme informally recognized as standard by the Canadian surficial geology community. Each legend unit is assigned a unique, three-pigment RGB colour. Where the surficial cover forms a pattern that is either too complex (too many lateral units) or is at too small a scale to justify a discrete legend unit, the polygon is coloured according to the dominant deposit type and labelled as a compound unit in descending order of cover, using a dot between units (e.g., Tm.GFx). Where a compound legend unit lies adjacent to a distinct unit that happens to be the same as the dominant component of the compound unit (e.g., Tm.GFx directly adjacent to Tm), the compound unit is coloured a slightly lighter shade. This is done from a cartographic perspective to ensure optimum map readability. Where distinct units are superimposed vertically in the field, the corresponding unit label indicates vertical stratigraphy by inserting a slash between units (e.g., A/GLb), and the map polygon is coloured according to the uppermost unit.

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Symbology on the maps is similar to that used by the GSC. Geological features delineated by lines include, but are not limited to, geological contacts, eskers, moraines, and abandoned fluvial channels (Fig. 7). It is important to note that, in the context of New Brunswick surficial geology, ‘moraine’ is used as a geomorphological term to describe an accumulation of glacial debris forming a ridge, not as a term to define composition or origin of a particular deposit. In other jurisdictions, chiefly within Europe, ‘moraine’ is a generic term for deposits of glacial origin. For example, ‘ground moraine’ is sometimes used in place of ‘till.’ (Such inconsistent and even conflicting usage of glacial terms is common in the discipline; attempts to standardize surficial geology terminology (e.g., Brodzikowski and van Loon 1987) have for the most part been unsuccessful.) Topographic contour lines are included on the maps and were obtained from the Natural Resources Canada (NRC) NTS database of 1:50 000 scale maps (NRC 2011). The maps also include a Digital Elevation Model (DEM) in the background to give viewers a greater sense of topography. DEMs (see Image Interpretation, below) are especially useful for those less familiar with interpreting topographic contour lines. Legend units are set to 50% transparency to allow subtle viewing of the background DEM. The digital elevation data used to create the background DEM were obtained from the Canadian Digital Elevation Data (CDED) website (GeoBase 2011). The source data for CDED at the 1:50 000 scale is extracted from hypsographic and hydrographic elements of the National Topographic Database and from data provided by Service New Brunswick. The DEM was created as a black-and-white, shaded relief image using the Lambertian Reflection Method with a 4x z-scale factor (vertical exaggeration) and a northwest light position (illumination towards 135° from an angle of 45° above the horizontal).

2. Compilation of Existing Data

Before any fieldwork was conducted, a project was initiated to inventory and compile all existing surficial geology data into consistent digital formats. As outlined above, southwestern New Brunswick (NTS 21 G) was chosen as the pilot area for the compilation. Three types of data were of interest: 1) point data (text materials) that described surficial features at point locations for which coordinate data were available, 2) line and symbol data that denoted surficial features (i.e., geological contacts, striae, drumlins, abandoned fluvial channels, moraine ridges, and so on), and 3) lithologic logs for water wells and other boreholes in the map area. Significant sources of previously unpublished point data consisted of 1) field observations collected as part of the till geochemistry surveys but not included in the related reports, 2) field notebooks used by geologists during the Granular Aggregate Inventory Program, 3) notes written on aerial photographs by field geologists during the GAIP and subsequent mapping projects, including the till geochemistry surveys, and 4) notes written on field maps during the GAIP. These data, representing about 6500 stations (Fig. 8), were combined with material from published sources and compiled into a spreadsheet informally referred to as the New Brunswick Surficial Geology Database.

Observation site

Geological contact (interpreted)

EOLIAN LANDFORMS

Undifferentiated eolian ridge

Dune

ALLUVIAL LANDFORMS

Alluvial fan

Alluvial levee

Alluvial terrace

LACUSTRINE/MARINE LANDFORMS

Lacustrine terrace

Marine terrace

Delta (small)

Beach ridge

Fossil site

Glaciomarine limit

Glaciolacustrine limit

GLACIOFLUVIAL LANDFORMS

Boulder field

Granular aggregate sample site

Till geochemistry sample site Limits of abandoned fluvial channel

Kame delta (small)

Kame

Limits of kettle (large)

Kettle (small)

Kame terrace

Esker (direction known)

Esker (direction unknown)

GLACIAL LANDFORMS

Moraine ridge

De Geer moraine

Rogen moraine

Fluting

Drumlin

Glacial striae (direction known)

Glacial striae (direction unknown)

BEDROCK FEATURES

Tor

Bedrock outcrop

Abandoned fluvial channel (small)

Area of numerous bedrock outcrops

Weathered bedrock

Figure 7. Abridged version of the new symbology legend for surficial geology maps of New Brunswick.

Note that some symbols may be changed or added in the final version.

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Previously unpublished surficial geology line and symbol data for southwestern New Brunswick were obtained from old aerial photographs (mainly those used by GAIP mappers) and from preliminary maps or field maps used by staff working on the granular aggregate and till geochemistry programs. These features and all those from previously published sources were integrated into a common GIS project environment. Lithologic logs for water wells were obtained from the New Brunswick Department of Environment. Data related to other boreholes were extracted from university graduate theses and additional research literature. These data were compiled into an electronic database and in the future will be integrated with the GIS for ease of viewing and interpretation.

3. Field Mapping

Another key step in producing up-to-date, detailed surficial maps for southwestern New Brunswick was to identify and target areas in NTS 21 G that required additional field mapping, due to their inadequate coverage of observation sites. To date, fieldwork has been conducted in the Musquash, St. George, St. Stephen, Rollingdam, McDougall Lake, and Fredericton Junction map areas (Fig. 1). A total of some 3000 new observations of the surficial geology were made at various point locations in these areas. Observations typically took place at roadcuts and pits and, to a lesser extent, at auger holes, natural exposures, stream banks, and coastal sections. These data were integrated with the pre-existing point data in the New Brunswick Surficial Geology Database.

4. Image Interpretation

Following fieldwork, and during the map production phase using GIS, various types of airborne imagery were interpreted to detect patterns and features of significance to the surficial geology of an area. Three types of imagery were used: 1) Digital Elevation Models (DEMs) created from Shuttle Radar Topography Mission (SRTM) data (NASA Jet Propulsion Laboratory 2011), 2) DEMs created from unfiltered data extracted from the New Brunswick Digital Topographic Data Base (DTDB) (Service New Brunswick 2011), and 3) digital aerial photographs collected by the NBDNR. These three forms of imagery have proven invaluable in helping to distinguish unit boundaries and to identify and map erosional and depositional glacial landforms. The SRTM DEMs are limited in terms of mapping small-scale landscape features, but they produce a more natural, less ‘noisy’ approximation of the terrain surface than do the higher resolution DTDB images. The SRTM imagery (Fig. 9) has an x–y resolution of 3 arc-seconds (30 m) and is best suited for discerning large-scale linear glacial features such as drumlins, fluting and, to a lesser extent, features such as eskers and end moraines. In fact, the SRTM imagery should be considered superior for mapping large-scale and even megascale glacial lineations. The ability to change the illumination orientation of the 3-D surface DEM makes this imagery highly effective not only for ascertaining the dominant orientation of fluting, but also for identifying palimpsest landforms. The SRTM imagery is also useful in separating

Drumlins and megaflutes mapped using images from theDigital Elevation Models (DEMs). The images

can be illuminated from various angles to enhance the appearance ofglacial features.

Eskers mapped using SRTM and aerial photography imagery.

Shuttle RadarTopography Mission (SRTM)

0 10 km

Maparea

Figure 9. Extract of the Shuttle Radar Topography Mission Digital Elevation Model for southwestern

New Brunswick, demonstrating how the model can be used to delineate drumlins, flutings, and

eskers in the landscape surrounding Oromocto Lake.

Lake

Oro

mo

cto

99

areas with intense glacial fluting (which generally indicates lodgement till) from areas with a

more irregular if not hummocky surface expression (which can indicate melt-out till).

The DTDB ground data has an x–y resolution of 1 m and, in comparison with SRTM imagery,

produces a DEM with much more high-frequency signal (‘noise’). Although DTDB imagery is

somewhat useful in mapping large-scale glacial flow lineations, it is less effective than SRTM

imagery for this purpose. On the other hand, DTDB imagery (Fig. 10) is very advantageous

in helping to map the extent of glaciofluvial deposits (eskers in particular), moraine

features, hummocky melt-out till deposits and, to some degree, alluvial deposits.

Digdeguash

RIv

er

Maine,USA

Esker (direction known)

Figure 10. Extract of the Service New Brunswick DTDB Digital Elevation Model for the McDougall Lake

map area (Fig. 1), demonstrating how the model can be used to delineate eskers in the landscape.

Figure 4 shows the location of McDougall Lake in southwestern New Brunswick.

100

LittleLong

Lake

McD

ouga

ll

Magaguadavic

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Outlet

1 km0

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101

Standard aerial photographs were also used in the mapping process. Stereoscopic viewing of high-resolution aerial photographs is excellent for determining unit boundaries, particularly of organic deposits, alluvial deposits, and glaciofluvial deposits. Aerial photographs are used 1) where SRTM and DTDB images are not effective for delineating complex geology, 2) to map smaller scale glacial features such as abandoned fluvial channels or small moraine ridges and kames, and 3) to identify all areas of bedrock outcrop at surface.

Summary

Between 2009 and the present, four new surficial geology maps (Fig. 1) were compiled according to the new methodology and by integrating multiple data sources, as detailed above. The maps are available in two publication formats: Adobe PDF (Fig. 11) and ESRI Shapefile (SHP). They can be downloaded as electronic files without charge from the NBDNR website (NBDNR 2011b) or purchased as paper maps from the NBDNR by emailing a request to [email protected] or by telephoning (506) 453-3837.

DEPOSIT TYPES

The following section describes the deposit types that are relevant to mapping the surficial geology of New Brunswick. Most of the examples provided here are from the pilot area of NTS 21 G in southwestern New Brunswick (Fig. 1). However, some deposit types do not occur as mappable units in NTS 21 G and so are exemplified by sites located elsewhere in the province. Details of the 47 legend units described below (and summarized in Table 1) may undergo minor alterations as mapping progresses across the remainder of the province.

Pre-Pleistocene

Bedrock

The Bedrock (R) map unit denotes areas where bedrock appears in outcrop at the surface. Thin deposits of unconsolidated materials overlying the bedrock are common. Typically, they comprise till veneer in upland areas; colluvium on slopes; and a variety of materials including organic, glaciomarine, and till veneer deposits in lowland areas. Substantial outcroppings of continuous bedrock are most common in upland areas and coastal regions but can occur in any area affected by intense glacial scouring, mass-wasting processes, or (as is the case in coastal regions affected by Late Wisconsinan marine submergence) wave-washing. Along the Bay of Fundy in southwestern New Brunswick, wave-washing has completely removed the glacial sediments from many hilltops and ridges. Isolated occurrences of bedrock outcrop are commonly encountered in areas of thick surficial deposits (i.e., Unit Td) as the result of undulating bedrock topography in the subsurface. Pleistocene glaciation had a profound effect on shaping the landscape of New Brunswick. Significant glacial scouring resulted in megascale fluting of bedrock surfaces, creating

Figure 11. Quadrangle extracted from one of the new 1:50 000 scale surficial geology maps produced

for NTS 21 G in southwestern New Brunswick using the new methodology. This quadrangle is from the

St. George map sheet (Fig. 1), published as Allard (2011a).

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streamlined hills and ridges with an orientation that generally parallels the dominant direction

of glacial flow in any given region. These megalineations, which can be tens of kilometres

long, are not always easily discerned on aerial photographs but can be clearly delineated by

using high-altitude SRTM imagery. They are typical of the McAdam and Rollingdam map

areas of southwestern New Brunswick (Fig. 1).

Large-scale, glacially streamlined bedrock landforms such as rock drumlins, roches

moutonnées, and whalebacks occur at various localities throughout the report area where

Tm

Tv

GFx

Tv

Tv

Tv

R

R

R

GMl

A

A

A

A A

GFx

Tl

Ob

GMl

GFx

Ov0 2 km

LakeUtopia

MillLake

Figure 12. Glacially polished bedrock displaying whalebacks, striae, and grooves with anorientation of approximately 170° in a pit just north of Prince of Wales (Fig. 4).

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bedrock is sufficiently competent to allow for their formation and preservation. Excellent

examples can be found near Saint John, St. Stephen, and St. Andrews (Fig. 4), where the

surficial cover is thin and bedrock outcrop is prevalent (Fig. 12). Freshly exposed bedrock

surfaces are commonly glacially polished. Glacial striae, grooves, crag-and-tail features, rat

tails, chatter marks, and other small-scale erosional features are typical on these surfaces. It

is not unusual to document multiple striae orientations at a single bedrock outcrop in

southwestern New Brunswick; they record the various Wisconsinan ice-flow phases that

affected the region (Seaman 1991). Most glacially streamlined and erosional landforms in the

report area are the result of the Caledonia Glacial Phase and, to a lesser extent, the

Escuminac and Scotian glacial phases (Fig. 6; Stea et al., in press).

Where naturally exposed, the bedrock surface is typically weathered and fractured due to

mechanical weathering and minor chemical alteration throughout the Holocene. However, as

Rampton et al. (1984) observed, it can be difficult to distinguish fragmented and weathered

bedrock from locally derived till deposits. The thickness of Holocene-derived weathering and

disintegration material in southwestern New Brunswick ranges from less than 0.5 m to about

1 m. Accumulations of residuum that are less than 1 m thick (generally Holocene-derived) are

mapped as Bedrock (R). However, for the purpose of describing stratigraphic sections,

may be used. This latter symbol is restricted to describing such

sections and is not a distinct map unit.

Residual Veneer (Wv)

104

It is important to note that Holocene-derived ‘residuum’ can exceed 1 m in thickness, especially in the northeastern part of the report area (Fig. 1), where bedrock is Carboniferous and less competent. However, most of the thick residual material in the province has a longer, more complicated weathering history and is interpreted to have formed during earlier (pre-Holocene) periods of weathering and subsequent preservation during the Pleistocene. This older residuum is described below.

Residuum

The glacial episodes affecting southwestern New Brunswick were intensely erosive, as evidenced by bedrock scouring and streamlined landforms. Nonetheless—and unexpectedly, given the scale of glacial disturbance throughout the Pleistocene—several isolated but significant pockets of pre-Holocene residuum remain in the province. These accumulations of mechanically and, less commonly, chemically weathered bedrock typically exceed 1 m thick and occasionally reach more than 10 m thick in the report area. They are denoted by the Residuum (W) map unit. The last half century has seen considerable debate concerning the formational age of residuum in New Brunswick. Many authors suggested a pre-Pleistocene origin (e.g., Lee 1962; Anderson 1968; Wang et al. 1981). However, recent work on the paleomagnetic signatures of gossans in northern New Brunswick (Symons et al. 1996) indicates a period of weathering that spans 1.05 Ma to 2.3 ± 0.3 Ma, which correlates to the Early Pleistocene (Fig. 6). From this, Seaman (2009) has deduced that the episodes of significant bedrock weathering in New Brunswick, including gossanization, took place in the Pleistocene, particularly during the Sangamonian interglacial (Fig. 6), as well as in other interglacial or instadial phases. It is assumed that, prior to Pleistocene glaciation, a residuum blanket that possibly was tens of metres thick (and comparable with modern residual profiles in tropical regions) overlay much of southwestern New Brunswick. The residuum preserved today is therefore considered to comprise 1) remnants of this once-extensive, pre-Pleistocene blanket, and 2) residuum from bedrock material weathered during the Pleistocene. Throughout the Pleistocene, most of the combined residuum was eroded by glaciers and incorporated in the resulting glacial sediments. The formerly contiguous residuum blanket is evidenced by its preservation as pockets of thick residuum and also by the presence of surface corestones. Corestones plucked from weathered granitic profiles in west-central New Brunswick (e.g., areas underlain by the Pokiok Batholith) during Pleistocene glacial intervals are widespread in the report area (Fig. 13). Residuum, derived chiefly from weathered granite, has been documented at some two dozen sites in southwestern New Brunswick. A spectacular example occurs about 10 km northwest of McAdam (Fig. 4), where recent excavations have revealed an approximately 10 m section of weathered porphyritic biotite granite residuum (Fig. 14) overlain by about 0.5 m of relatively unweathered basal till. The residuum material is generally considered to be in-situ. However, the weathered granite near surface contains bands of intensely weathered granite mixed with brown clay, and injected clay occurs within fractures to a depth of 8 m; both features are

Figure 14 (to left). An exposure of

weathered granitic residuum (Unit

W) in a pit on the northern flank of

Mount Henry, about 10 km

northwest of McAdam (Fig. 4). The

visible pit face is about 10 m high.

105

Figure 13 (above). Corestones,

plucked from weathered granitic

profiles and deposited down-ice

litter the

landscape in many parts of

southwestern New Brunswick.

This boulder is greater than 4 m

long (a-axis) and was observed

just south of McDougall Lake

(Fig. 4).

during the Pleistocene,

106

interpreted as evidence of minor glacial deformation. The granite is disaggregated to a considerable depth but displays no evidence of significant chemical alteration. Feldspar crystals remain intact, and accumulations of kaolin or other chemical weathering byproducts were not observed. Other significant accumulations of residuum are fairly uncommon in southwestern New Brunswick, but where they do occur, their areal distribution may be more than fortuitous. Initial impressions are that the residual materials appear to share a similar ‘protected’ position in the landscape along the northern flanks of substantial hills or ridges with relatively flat to undulating surfaces extending northward. Such a sheltered geographic setting could have supported localized, subglacial conditions that facilitated the preservation of residuum pockets. However, this concept requires more investigation before a theory can be proposed.

Pleistocene

Till Deposits

Till is a primary glacigenic sediment, formed directly by means of advancing or melting glaciers, and is the most common surficial material in southwestern New Brunswick. Deposits of till are subdivided in terms of facies and geomorphology into three end members: Lodgement (Tl), Deformation (Td), and Melt-Out (Tm) till. Lodgement (Tl) till is sediment deposited by the glacier sole sliding over the bed (substrate), having been liberated and plastered onto the bed by means of pressure-melting (Dreimanis 1989; Evans et al. 2006). Lodgement tills (Fig. 15) are typically diamictons with a bimodal grain-size distribution featuring a high percentage of silt with lesser sand and clay, and a high percentage of gravel with lesser cobbles and boulders. Bedrock that underlies lodgement till is commonly polished and characterized by indicators of glacial flow such as striae and grooves. Colour and texture are derived from the parent bedrock source(s). Lodgement tills are commonly overconsolidated and can appear massive to layered. Layering is due to the presence of numerous subhorizontal joints that give lodgement till its characteristic blocky or fissile structure. Elongated, bullet-shaped clasts are widespread and can be preferentially aligned with their long axis (a-axis) oriented parallel to glacial flow. Lodgement till blankets are common in southwestern New Brunswick, where they form undulating to streamlined topography that locally obscures the underlying bedrock terrain. Thickness is generally between 1 m and 5 m; however, considerably thicker accumulations have been documented in drumlins. Thicknesses exceeding 20 m have been recorded in geotechnical and water wells within a drumlin field that occurs southeast of Fredericton and extends toward the Oromocto River valley (Fig. 4). Significant thicknesses are also expected in a drumlin field in the Rollingdam and St. Stephen map areas (Fig. 1), as recent pit excavations in basal till near St. Stephen have revealed a 10 m thick section of lodgement till.

Figure 15. A roadcut exposure of lodgement till (Unit T ) overlying bedrock, about 15 km north of St.

Andrews (Fig. 4). The exposure is 3 m high.

l

Bedrock

Lodgement till

107

Deformation (Td) till and glacitectonite both result from the subglacial shearing of bedrock

and pre-existing surficial materials.

eformation till’

refers to diamict products of subglacial shear, where no evidence remains of the parent

material structure. Glacitectonite is defined as “rock or sediment that has been deformed

by subglacial shearing but retains some of the structural characteristics of the parent

material, which may consist of igneous, metamorphic or sedimentary rocks, or unlithified

sediments.…” (Benn and Evans 1998, p. 387). Occurrences of glacitectonite are frequently

encountered in areas characterized by a blanket of deformation till. In fact, while mapping in

such an area, it is common to find deformation till at one exposure, glacitectonite at the next,

and so on.

A remarkable example of glacitectonite with evidence of glacial rafting occurs about 17 km

north of St. Andrews, on the northern flank of Blueberry Mountain. A 5 m to 6 m high rockcut

measuring about 100 m long exposes glacially sheared and deformed dioritic and gabbroic

rocks of the Late Silurian Bocabec Gabbro (Fig. 16). At one locale along the exposure, the

base of the section is characterized by weathered, jointed dark grey gabbro, in which the

joints are infilled with silt, clay, and sand as a result of till injection (Fig. 17). A raft of

The transition from deformation till to glacitectonite is

gradational and reflects the degree of subglacial shearing. The term ‘d

Figure 16 (above).

Exposure of glaci-

tectonite (Unit Td) in

a rockcut at Blue-

b e r r y M o u n t a i n ,

about 17 km north of

St. Andrews (Fig. 4).

The exposure is 5 m

high.

Jointed darkgrey gabbro

Raft of lightgrey diorite

Shear zone

108

Figure 17 (to left).

Till injection features

in the jointed dark

grey gabbro shown

above in Figure 16.

Weathering rinds on

the exterior of the

gabbro blocks mark

the development of

c o r e s t o n e s a n d

glacial plucking by

means of till injection.

Figure 18. Shear zone between the jointed dark grey gabbro and overlying raft of light grey diorite in

Figure 16. Note the sheared gabbro fragments. Hammer handle is 46 cm long.

109

Shear zone

massive light grey diorite overlies the dark grey gabbro, separated by a shear zone (<0.5 m

thick) that comprises disaggregated and sheared gabbro corestones and till-injected sand,

silt, and cla

glacial ice. The

sediments can originate from either the supraglacial, englacial, or subglacial zones of the

y (Fig. 18). The diorite also shows evidence of till injection in joints and fractures.

The till injection episode may have pre-dated the rafting episode, as numerous glacial phases

did affect the region. However, it is also possible that the till injection and deformation took

place contemporaneously. More work will be required at this site to fully understand its

implications to the regional glacial history.

Deformation till deposits in southwestern New Brunswick typically consist of locally derived

angular clasts set in a matrix of coarse sand. These tills are generally very representative of

the underlying bedrock and display little evidence of dispersion; they are informally referred

to as ‘local stony tills’ by geologists with the GSB. Deformation till appears to be most common

in, although is not limited to, upland areas. A widespread area of deformation till occurs in the

southeastern corner of the McDougall Lake map area (Fig. 1), underlain by rocks of the Late

Devonian Mount Douglas Phase of the Saint George Plutonic Suite (Fig. 19).

till (Fig. 20) is deposited during the melting of debris-ladenMelt-Out (Tm)

Figure 19. Exposure of deformation till (Unit Td) in the southeastern corner of the McDougall Lake map

area (Fig. 1). Hammer handle is 85 cm long.

glacier and typically occur as a massive diamicton. Although melt-out tills derive their

properties (texture, consistency) primarily from the ice source, the deposits are commonly

modified by post-depositional processes, with meltwater remobilization and mass wasting

playing important roles.

Melt-out till, especially when derived from the subglacial load, can closely resemble

lodgement till. However, the former deposit type is less compact and commonly contains a

higher stone content with abundant cobbles and boulders. Grain-size analysis of till samples

from southwestern New Brunswick (Pronk et al. 2004) shows that melt-out till samples

average 5% less clay and 5% to 10% less silt than lodgement till samples from the same

region. Clast roundness in melt-out till is on a par with that of lodgement till; however, melt-out

till lacks the elongated, bullet-shaped clasts and striated clasts typical of lodgement till. Melt-

out till deposits in southwestern New Brunswick are composed predominantly of locally

derived materials, indicating a provenance similar to that of lodgement till.

Melt-out till deposits typically occur in valleys and other low-lying areas and form hummocky

topography that obscures the underlying bedrock topography. Moraine ridges are common

and either are aligned transverse to the dominant direction of glacial flow (ribbed moraine) or

110

111

Figure 20. Melt-out till (Unit Tm) landforms and surface boulders in a clearcut just south of McDougall

Lake (Fig. 4).

display irregular configurations with no preferred alignment (Fig. 20). Significant blankets of

melt-out till occur in some low-lying regions of southwestern New Brunswick, where adjacent

highland topography resulted in the progressive thinning and eventual fragmentation of

regional glaciers into isolated, decaying ice masses.

The thickness of melt-out till deposits is highly varied across the landscape and can

change dramatically over short distances within a deposit. Deposits are generally thicker

than 5 m and can reach 10 m thick or more in moraine features. Melt-out till generally thins

upslope and transitions into patchy veneer or accumulations of surface boulders (Seaman

2009).

The map unit indicates undivided deposits of lodgement till, glacitectonite and deformation

till, and melt-out till. denotes areas where till is less than 1 m thick but is

included as a map unit, because it is the dominant landform in many areas of southwestern

New Brunswick (see p. 88). However, subdividing till veneer into respective end members is

impractical. With some exceptions, thin till deposits are commonly extensively weathered

(oxidized) and have been so modified by Holocene processes, such as freeze-thaw cycles,

that categorization is difficult.

T

(Tv)Till Veneer

112

A Further Note on Till Deposits

Minor occurrences of other till types can be expected within any given till map unit. In fact, the properties of subglacial tills in southwestern New Brunswick in many cases reveal a complex depositional history that involves multiple cycles of deformation. The blanket of till across the region typically gives the appearance of a homogenous diamicton. However, the homogeneity is more likely the result of multiple glacial-flow events that incorporated and deformed the pre-existing till layer through subglacial shearing, lodgement, or melt-out processes. In southwestern New Brunswick, these processes have formed a hybrid till (Stea and Finck 2001; Allard and Pronk 2003; Seaman 2004) that displays properties inherited from the Caledonia, Escuminac, and Scotian glacial phases (Fig. 6). Given this complex glacial narrative, it is difficult to separate all till deposits in the field into the three end members described above. When mapping tills, one must consider the ‘big picture’ and avoid the temptation to assign each observed exposure to a specific end member. Instead, it is more appropriate to consider, not just the texture, consistency, and lithology of the till, but also the geomorphology of the landscape as indicated by the presence or absence of landforms such as drumlins, Rogen moraine, melt-out till ridges, and so on. The following generalizations concerning till deposition can be made on the basis of current mapping work in the report area. Lodgement till deposits generally occur as continuous blankets and commonly are

associated with streamlined landforms such as drumlins and flutings. Upland areas are characterized by thin lodgement till that locally thickens over bedrock

hollows with localized deposits of glacitectonite and deformation till. Melt-out till deposits are common in valleys and other low-lying areas. Tills in southwestern New Brunswick are technically hybrid tills with properties inherited

from multiple episodes of deformation and reworking. The degree of reworking can range from very minor to intense, but generally it is possible to determine the parent facies.

Glaciofluvial Deposits

Glaciofluvial deposits consist of sediments that settle out of flowing water sourced from melting glaciers. Deposits of glaciofluvial origin occur throughout the report area and typically are closely associated with modern river valleys and streams. They provide evidence of the vast drainage system that occupied southwestern New Brunswick during deglaciation. Glaciofluvial sediments are divided on the basis of facies and geomorphology into Ice-Contact Stratified Drift (GFx), Outwash Terrace (GFt), and Outwash Plain (GFo) deposits.

Figure 21. Pit exposure of glaciofluvial ice-contact stratified drift sediments (Unit GFx) in an

esker segment in the Digdeguash River valley, south of Rollingdam (Fig. 4).

113

Glaciofluvial Ice-Contact Stratified Drift

Glaciofluvial Outwash Terrace Glaciofluvial Outwash Plain

(GFx)

(GFt) (GFo)

sediments are deposited via meltwater

channels flowing on, in, or adjacent to glacial ice. As the ice melts, deposits are laid onto the

substrate. Ice-contact deposits by nature have highly varied characteristics but generally

consist of crudely stratified sand, gravel, and cobbles with differing amounts of boulders and,

to a lesser extent, silt (Fig. 21). Ice-dropped boulders emplaced within finer sediment are a

common feature of ice-contact deposits. Geomorphologically, these deposits occur as

eskers, kames, kame terraces, kame deltas (commonly kettled), and end moraines.

and deposits, known

collectively as proglacial outwash deposits, are formed by meltwater streams sourced from

glaciers. Many of these streams occupied present-day major river valleys in the province,

while others coursed through valleys and channels that are now abandoned.

Outwash terrace deposits in valleys commonly occur as flat terraces perched above the

alluvial terraces and comprise stratified sand and gravel. Outwash plains and fans form in

areas where braided meltwater streams flow over broad flat terrain or where a meltwater

stream issues from a narrow valley onto flat terrain. These deposits have flat to undulating

surfaces commonly marked by shallow sinuous meltwater channels. Proglacial outwash

sediments are typically well sorted but can vary significantly in composition from planar- or

cross-bedded sand to massive, coarse-grained gravel sheets with abundant cobbles (Fig. 22).

xx

Figure 22. Exposure of glaciofluvial outwash terrace sediments (Unit GFt) in the Nerepis River valley

at Blagdon (Fig. 4). Hammer handle is 46 cm long.

The map unit indicates undifferentiated deposit(s) of glaciofluvial material.

is used to denote accumulations that are less than 1 m thick and is restricted to

describing stratigraphic sections.

GF

(GFv)

Glaciofluvial

Veneer

Glaciofluvial deposits can be excellent sources of construction aggregate material. In some

instances, they have undergone extensive meltwater transport prior to deposition, which

results in the removal of fines and unsound clasts. Deposits that contain a high proportion of

hard, resistant clasts or well-sorted, clean sand have been used for quality aggregate

throughout New Brunswick (Fig. 23).

Glaciomarine sediments were deposited in the marine environment during the Late

Wisconsinan episode of marine submergence and subsequently were exposed subaerially as

a result of isostatic rebound of the crust following deglaciation. Deposits are regularly

encountered along the Bay of Fundy coastline and inland to an elevation of about 70 m above

sea level. Glaciomarine sediments are divided on the basis of facies and geomorphology into

Basin (GMb), Littoral (GM ), and Delta (GMd) deposits.

Glaciomarine Deposits

l

114

Figure 23. Commercial sand and gravel operation in an esker deposit (Unit

GFx) about 20 km south of Nackawic (Fig. 4).

115

Glaciomarine Basin (GMb) deposits in southwestern New Brunswick generally comprise very

dense, massive, reddish brown to yellowish brown clayey silt and silty clay. At several

locations they are fossiliferous (Fig. 24, 25). Exposed thicknesses of up to 5 m have been

documented in some areas along the coast.

Glaciomarine Littoral

Glaciomarine Delta

(GM )

(GMd)

l deposits occur in areas that were inundated by shallow seawater

during the Late Wisconsinan; they take the form of beach ridges and terraces. Glaciomarine

beach deposits (raised beaches) are present in coastal regions of southwestern New

Brunswick and, where elevation is low, can appear inland for considerable distances. These

deposits indicate the high-water mark of Late Wisconsinan sea levels. They typically consist

of well-sorted, medium- to coarse-grained sand, gravel, cobbles and, to a lesser extent, silt.

Clasts can have the typical flattened ‘pancake’ appearance common to beach gravels.

Glaciomarine beach deposits are sometimes used as a source of granular aggregate. Those

deposits assumed to have been reworked from glaciofluvial outwash or ice-contact stratified

drift are generally of good commercial quality. However, most of these deposits occur in

ecologically sensitive coastal areas, which limits their exploitability.

deposits in New Brunswick are of the Gilbert variety (Gilbert 1890)

with a well-defined topset, foreset, and bottomset configuration. Topsets comprise horizontally

stratified outwash gravel, cobbles, and sand deposited by meltwater streams flowing on the

delta surface. Foresets consist of dipping beds of sand and fine gravel that were deposited in the

subaqueous environment at the distal margin of the delta. Bottomsets contain silt and clay. The

deltas form planar surfaces that are commonly marked by abandoned fluvial channels.

Figure 24. Massive, reddish brown, fossiliferous glaciomarine basin sediments

(Unit GMb) at Saints Rest Beach (Fig. 4), west Saint John. Knife is 22 cm long.

116

Figure 25. Shell of collected in 2006 by the author and Allen

Seaman (also of the GSB) at Saints Rest Beach (Fig. 4).

Mya arenaria

The shell fragments

have a date ( of 12,330 B.P., which is equivalent to

approximately 14,300 calibrated calendar years.

C sample BGS-2716)14

0 1 cm

117

The map unit GM indicates undifferentiated deposit(s) of glaciomarine material. Glaciomarine Veneer (GMv) is a map unit used to denote accumulations of GMl (and, in rare instances, GMb) that are less than 1 m thick (see p. 88). Wave-washed surfaces are commonly encountered along the coast and at significant distances inland in some regions. Wave-washing along hillsides and in areas of hummocky bedrock topography along the coast results in a veneer of oxidized sand, silt, and gravel at surface. The presence of this material, which can be fossiliferous, demarks the extent of Late Wisconsinan marine inundation in some areas. Glaciomarine delta deposits in the report area (Fig. 26) contain significant resources of construction aggregate material (Allard 2007). Glaciomarine deltas east of St. George (Fig. 4) represent the largest contiguous accumulations of sand and gravel in the province, as exemplified by the Pocologan Delta, which is more than 50 m thick (Allard et al. 2010) and spans an area of 40 km2.

Glaciolacustrine Deposits

Glaciolacustrine sediments are deposited in ice-dammed lakes within valleys and other low-lying areas along the margins of decaying ice centres. They are divided on the basis of facies and geomorphology into Basin (GLb), Littoral (GLl), and Delta (GLd) deposits. Glaciolacustrine Basin (GLb) deposits consist of silt, clay, and fine sand, with occasional quantities of coarser material (dropstones). These deposits are generally laminated, commonly in the form of rhythmites (Fig. 27). In the report area, glaciolacustrine basin deposits are commonly encountered in and around the Saint John, Oromocto, and Nerepis river valleys (Fig. 4), where Glacial Lake Acadia was situated following deglaciation of the region. The origin of glaciolacustrine basin sediments in the report area has been the subject of considerable debate in the past. Some workers (e.g., Kiewiet de Jonge 1951; Lee 1957; Seaman 1982) assigned a glaciolacustrine, glaciomarine, or estuarian origin to deposits in the middle and lower Saint John River drainage basins. Rampton et al. (1984) mapped the same sediments as ‘undifferentiated marine and lacustrine’ deposits. However, recent studies of paleosalinity and depositional models by Daigle (2005), Giudice (2005), and Dickinson (2008) indicate that these deposits consist, in descending order, of lacustrine, glaciolacustrine, estuarine, and marine sediments. Glaciolacustrine Littoral (GLl) deposits consist of sand, silty sand, sandy gravel, and gravel; they normally are graded and sometimes form beach ridges and terraces. Glaciolacustrine Delta (GMd) deposits are found in areas of New Brunswick where glacial meltwater was discharged into short-lived glacial lakes that existed near the end of the last glacial period (Late Wisconsinan). Although examples of such deposits have not yet been identified in southwestern New Brunswick, those elsewhere in the province are of the Gilbert variety. They consist of stratified and well-sorted sand, sandy gravel, and gravel that form planar terrain surfaces, commonly marked by abandoned fluvial channels.

Figure 26 (to left). Glaciomarine

delta sediments (Unit GMd),

exposed at a pit in the Pennfield

Delta situated east of St. George

(Fig. 4). The visible pit face is

about 10 m high.

118

Figure 27 (below). Laminated

glaciolacustrine basin

(Unit GLb) in the Nerepis River

valley just north of Welsford

(Fig. 4). The layers of clayey silt

are intercalated with layers of fine

sand, likely indicating seasonal

varves. Coin diameter is 2.4 cm.

sediments

Figure 28. Marine intertidal (Unit Mi) along the Bay of Fundy coast near Lorneville (Fig. 4),

5 km west of Saint John.

sediments

119

The map unit indicates undivided deposit(s) of glaciolacustrine material.

is used to denote accumulations that are less than 1 m thick and is restricted to

describing stratigraphic sections.

Marine sediments are deposited in the modern marine environment. For the surficial map

legend, they are divided on the basis of facies and geomorphology into Littoral (M ), Delta

(Md), and Intertidal (Mi) deposits.

deposits consist of silty sand, sandy gravel, and gravel that form beaches,

bars, and spits of various thicknesses. deposits contain stratified and well-

sorted sand, sandy gravel, and gravel. They occur where streams flow into the sea and form

planar terrain surfaces that typically are marked by abandoned channels.

deposits consist of clayey silt and silty clay, which form coastal plains that are exposed

between the marks of extreme high tide and extreme low ti 28). Sedimentation takes

place in sheltered tidal water, particularly in estuaries with large sediment loads.

GL

(GLv)

(M )

(Md)

(Mi)

Glaciolacustrine

Veneer

Marine Littoral

Marine Delta

Marine Intertidal

Holocene

Marine Deposits

l

l

de (Fig.

120

The map unit M indicates undifferentiated deposit(s) of marine material. Marine Veneer (Mv) denotes accumulations that are less than 1 m thick and is restricted to describing stratigraphic sections.

Lacustrine Deposits

Lacustrine deposits comprise sediments that are deposited in and adjacent to lakes and are subsequently exposed by fluctuations in lake levels. They are divided on the basis of facies and geomorphology into Basin (Lb), Littoral (Ll), and Delta (Ld) deposits. Lacustrine Basin (Lb) deposits consist of laminated silt, clay, and fine sand; they typically occur as rhythmites. Lacustrine Littoral (Ll) deposits comprise sand, silty sand, sandy gravel and gravel that form beaches, bars, and spits. Lacustrine Delta (Ld) deposits appear as stratified and well-sorted sand, sandy gravel, and gravel and are situated where a stream enters a lake, forming planar terrain surfaces. The map unit L indicates undifferentiated deposit(s) of lacustrine material. Lacustrine Veneer (Lv) denotes accumulations that are less than 1 m thick and is used only to describe stratigraphic sections.

Eolian Deposits

Eolian deposits consist of wind-deposited sediments reworked from marine, glaciofluvial, or glaciomarine sediments and are divided on the basis of geomorphology into Dune (Ed) and Loess (El) deposits. Dune (Ed) deposits typically consist of stratified, fine to medium sand and can form parabolic dunes or ridges. Stabilized and vegetated dunes are present to the west of Oromocto (Fig. 4) at the eastern end of Fredericton International Airport. Eolian Loess (El) occurs as a veneer of massive wind-blown silt and sand and is commonly observed on the surface of glaciofluvial outwash deposits (albeit in weathered form) in the report area. The symbol ‘El’ is not a map unit but is used instead to describe stratigraphic sections.

Alluvial Deposits

Alluvial deposits comprise sediments deposited by modern rivers and streams. Particle size of these deposits depends on various factors, but stream gradient plays an important role. Coarse alluvium intercalated with colluvium (see Colluvium, below) is typically encountered along streams in upland areas, whereas finer alluvium generally occurs in low-lying, flat areas. Alluvial sediments are divided on the basis of facies and geomorphology into Fan (Af), Terrace (At), and Plain (Ap) deposits. Alluvial Fan (Af) deposits consist of poorly sorted sand, gravel, silt, and organic debris that occur where a stream issues from a narrow valley onto a plain or flat valley floor. Alluvial Terrace (At) deposits comprise sorted sand, gravelly sand, gravel, silt, and organic debris; they form inactive terraces above the modern floodplain (Fig. 29). Alluvial Plain (Ap) deposits consist of sorted sand, gravelly sand, gravel, silt, and organic debris. These deposits form

Figure 29. An alluvial terrace deposit (Unit At) along the Oromocto River at Blissville (Fig. 4).

Terrace is about 6 m high.

121

active floodplains close to river level with meander channels and scroll marks, and the plains

are prone to seasonal flooding. The map unit indicates undifferentiated deposit(s) of alluvial

material. is used to denote accumulations that are less than 1 m thick and

is restricted to describing stratigraphic sections.

Alluvial deposits are sometimes used as aggregate sources. However, their proximity to

watercourses and typical association with high water tables often impede any development of

large-scale aggregate operations.

Organic deposits are composed primarily of peat and muck formed by the accumulation of

plant material in various stages of decomposition. They occur consistently in poorly drained

topographic depressions, commonly in close association with waterbodies. The legend for

the surficial geology maps contains three types of organic deposits: Bog (Ob), Fen (Of), and

Organic Veneer (Ov).

represents peat-covered wetlands in which the vegetation shows the

effects of a high water table and a general lack of nutrients. Bogs are characterized by raised

A

(Av)

(Ob)

Alluvial Veneer

Organic Bog

Organic Deposits

122

mounds or plateaus and acidic water. The bog surface is typically covered by sphagnum mosses and ericaceous shrubs. Peat accumulation is generally greater than 2 m in southwestern New Brunswick. Organic Fen (Of) indicates eutrophic, mineral-rich wetlands with accumulations of organic material derived from sedges and decaying woody debris. Fens occur as flat, wet plains occupying natural depressions. They commonly are covered by sedges, grasses, and shrubs, and tend to be sparsely treed. Organic Veneer (Ov) is a map unit used to denote wetlands with minor (<1 m) organic accumulation (see p. 88). Such wetlands take the form of either 1) forested areas where the water table is at surface and soil conditions are water-saturated, or where standing water is present, 2) coastal salt marshes, or 3) wetlands dominated by seasonal standing water. In New Brunswick, the mapping of wetlands is conducted by the Forest Management Branch of the NBDNR. The data are subsequently modified by the Geological Surveys Branch for incorporation into the surficial geology maps.

Colluvial Deposits

Colluvial deposits consist of materials that have reached their present position as a result of gravity-induced movement. Colluvium (C) signifies the unsorted, crudely stratified mélange of reworked glacial deposits, fractured bedrock, and slope wash that generally mantles the floors and walls of steep valleys. Scree (Cs) denotes angular boulders, cobbles, and gravel that accumulate along the base of cliffs, forming fans or aprons. Colluvial Veneer (Cv) is used to represent accumulations that are less than 1 m thick and is restricted to describing stratigraphic sections.

Anthropogenic Materials

The Anthropogenic (H) symbol is used to denote human-made or human-altered geological materials. These materials include, but are not limited to, landfills and mine tailings.

CONCLUSIONS

Field mapping and the production of digital 1:50 000 map plates for NTS 21 G in southwestern New Brunswick will be completed within the next two to four years. Now that a methodological framework has been established for surficial geology mapping in the province, geologists working on surficial geology projects will have at their disposal a set of criteria with which to systematically collect field data and produce maps. Enhanced GIS capabilities and the use of SRTM and CDED imagery have enabled surficial mapping and map production to become more effective and efficient. As other ultra-high resolution Light Detection and Ranging (LiDAR) imagery becomes available, further efficiencies and quality improvements will be realized. A new web-based delivery system of surficial geology maps is also being considered for the future that would enable clients to instantly access geochemical, lithologic, and grain-size data as well as field notes.

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ACKNOWLEDGEMENTS

Aaron Power, Rex Boldon (GSB), Pam Dickinson (GSB), and Jenna Raymond provided field assistance. Les Fyffe (GSB) helped to interpret the geology at the Blueberry Mountain glacitectonite site. Allen Seaman (GSB), Toon Pronk (GSB), Mike Parkhill (GSB), Ralph Stea (Stea Surficial Geology Services), and Yves Michaud (GSC) provided advice. Paul Rennick, manager of the Digital Geoscience Section (GSB), provided considerable technical support. Special thanks to Allen Seaman and Paul Rennick. This paper was critically reviewed by Allen Seaman.

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Trace-Element Values in Bedrock from the Burtts Corner Formation in the Vicinity of the Fredericksburg Basal Till Sb Anomaly, and from Adjacent Formations in the Napadogan Map Area, West-Central New Brunswick

ALLEN A. SEAMAN

Geological Surveys Branch, New Brunswick Department of Natural Resources, P.O. Box 6000, Fredericton, New Brunswick, CANADA E3B 5H1 ([email protected])

Seaman, A.A. 2011. Trace-element values in bedrock from the Burtts Corner Formation in the vicinity of the Fredericksburg basal till Sb anomaly, and from adjacent formations in the Napadogan map area, west-central New Brunswick. In Geological Investigations in New Brunswick for 2010. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Lands, Minerals and Petroleum Division, Mineral Resource Report 2011-2, p. 127–146. _____________________________________________________________________________________________

Trace-element values for basal till samples from the Burtts Corner and Napadogan map areas in west-central New Brunswick were plotted on a bedrock base map for the two map sheets. The plots indicated a possible correlation between high Sb values and areas underlain by bedrock of the Ordovician Push and Be Damned Formation (Tetagouche Group) and the Silurian Burtts Corner Formation (Kingsclear Group). Similarly, the plots indicated elevated Ni values over the Cross Creek and Hayes Brook formations, both of the Kingsclear Group. To confirm these apparent correlations, 10 bedrock samples were collected from the Burtts Corner Formation in the vicinity of the Fredericksburg basal till Sb anomaly, which straddles the two map sheets; and 12 bedrock samples were gathered from various formations (including the Burtts Corner) that crop out along a transect crossing the Napadogan map sheet. Rocks in the second suite range in age from Cambro–Ordovician to Early Carboniferous.

Trace-element analyses of the 22 bedrock samples indicate that high Sb values are not restricted to either the Burtts Corner or the Push and Be Damned formations. Only three samples show Sb values that are anomalous to extremely anomalous when compared with regional background values of the till geochemistry: two of siltstone from the Burtts Corner Formation and one of red manganiferous siltstone from the Ordovician Hayden Lake Formation (Tetagouche Group). These results imply that an as yet undiscovered source of Sb mineralization exists in the area. The study results provide no clear source for the belt of anomalous Ni values in till that overlies the mapped area of the Cross Creek and Hayes Brook formations. Ni is anomalous in the bedrock sample from the former formation but is merely above average in the sample from the latter. However, Ni is very anomalous in a sample of matrix material from a previously unidentified outlier of conglomerate from the Early Carboniferous Shin Formation (Mabou Group) that unconformably overlies the Hayes Brook Formation. Ni was also anomalous in samples from the Burtts Corner, Push and Be Damned, and Hayden Lake formations.

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Des valeurs d’élément trace dans des échantillons du till de fond provenant des secteurs de feuilles de carte de Burtts Corner et de Napadogan, dans le centre ouest du Nouveau-Brunswick, ont été répertoriées sur une carte de base du substratum associée à ces deux feuilles de carte. Les valeurs relevées indiqueraient une corrélation possible entre une teneur élevée de Sb et les secteurs qui reposent sur le substratum de la Formation de Push and Be Damned de l’Ordovicien (groupe de Tetagouche) et de la Formation de Burtts Corner, du Silurien (groupe de Kingsclear). Par ailleurs, les relèvements suggèrent des teneurs de Ni élevées dans les Formations de la crique Cross et du ruisseau Hayes, toutes deux étant rattachées au groupe de Kingsclear. Pour confirmer ces corrélations apparentes, dix échantillons du substratum ont été recueillis dans la Formation de Burtts Corner, dans le secteur de l’anomalie de Sb du till de fond de Fredericksburg, lequel chevauche les secteurs des deux feuilles de carte. Douze échantillons de substratum ont également été recueillis dans diverses formations (dont celle de Burtts Corner) qui affleurent le long d’un axe transversal qui traverse le secteur de feuille de carte de Napadogan. L’âge des roches de la deuxième série varie entre le Cambro-Ordovicien et le début du Carbonifère.

Des analyses d’élément trace dans des vingt-deux échantillons de substratum indiquent que les teneurs élevées en Sb ne sont pas confinées aux Formations de Burtts Corner ou de Push and Be Damned. Seuls trois échantillons indiquent des teneurs de Sb anormales à extrêmement anormales, comparativement aux teneurs régionales caractéristiques de la géochimie du till : soit deux échantillons de siltite de la Formation de Burtts Corner et un échantillon de siltite manganésifère rouge de la Formation du lac Hayden de l’Ordovicien (groupe de Tetagouche). Ces résultats laissent entendre que l’origine de la minéralisation de Sb dans la région reste à élucider.

Les résultats d’étude ne donnent aucune indication claire d’une ceinture de valeurs anormales en Ni dans le till qui recouvre le secteur cartographié des Formations de la crique Cross et du ruisseau Hayes. Une teneur anormale de Ni est observée dans l’échantillon de substratum prélevé dans la première formation, mais elle est tout juste au-dessus de la moyenne dans l’échantillon de la deuxième formation. Toutefois, il y a une teneur de Ni très anormale dans un échantillon de matériau de gangue prélevé dans un îlot auparavant non identifié de conglomérat de la Formation de Shin du début du Carbonifère (groupe de Mabou), qui repose en discordance sur la Formation du ruisseau Hayes. Des teneurs anormales de Ni ont aussi été obtenues dans les échantillons recueillis des Formations de Burtts Corner, de Push and Be Damned et du lac Hayden.

_________________________________________________

INTRODUCTION

The Burtts Corner (National Topographic System (NTS) 21 J/02) and Napadogan (NTS 21 J/07) map areas in west-central New Brunswick (Fig. 1) are underlain by a variety of rocks of the Cambro–Ordovician Miramichi Group, Ordovician Tetagouche Group, Silurian Kingsclear Group, and Carboniferous Mabou Group (Smith and Fyffe 2006a, 2006b). The New Brunswick Bedrock Lexicon (New Brunswick Department of Natural Resources (NBDNR) 2011a) provides detailed descriptions of lithologic units within these groups.

Stanley

Nashw

aak

Riv

er

Taymouth

PenniacMactaquacBasin

Reportarea(area ofFig. 1)

NewBrunswick

CARBONIFEROUS

Pictou Group

Minto Formation

Mabou Group

Shin Formation

Royal Road Basalt

DEVONIAN

Granitic rocks

SILURIAN

Taxis River Formation

Burtts Corner Formation

Cross Creek Formation

Hayes Brook Formation

ORDOVICIAN

Tetagouche Group

Push and Be DamnedFormation

Hayden Lake Formation

CAMBRO–ORDOVICIAN

Miramichi Group

Knights Brook Formation

0 10 km

8

Fredericton

Figure 1. Bedrock geology of the Burtts Corner (NTS 21 J/02) and Napadogan (NTS 21 J/07) map

areas. The geological data are from NBDNR (2008).

129

Kingsclear Group

C

B

A

A

B

C

Hayesville

Burtts Corner

Napadogan

Map Sheet Namesand Numbers

Maine,USA

Highway

Geological contact

Fault

Fredericksburg

21 J/07

21 J/02

Napadogan

107

21 J/10

J/07

21 J/02

21

130

Geochemical analyses of basal till samples (collected between 2002 and 2009) from the Burtts Corner and Napadogan map areas indicated a possible correlation between elevated elemental concentrations in the till and those in specific bedrock units. In particular, above average to anomalous values for Sb appeared to be characteristic of till overlying parts of the Push and Be Damned Formation (Tetagouche Group) and the Burtts Corner Formation (Kingsclear Group) (Fig. 1, 2). Similarly, above average to anomalous values for Ni appeared to be characteristic of basal till overlying parts of the Hayes Brook and Cross Creek formations, both of the Kingsclear Group (Fig. 3). To test the validity of the apparent correlations implied by these geochemical results, two suites of bedrock samples were collected in the summer of 2010 for analysis using the same analytical package as was used for the till samples. Suite 1 (Table 1) comprised wacke, siltstone, and mudstone from the mapped limits of the Burtts Corner Formation in the area of the Fredericksburg basal till Sb anomaly (Fig. 2), which has been reported on by Seaman (2008). Suite 2 consisted of sedimentary and metasedimentary samples from a transect across the central part of the Napadogan map area. These latter samples were collected from bedrock units depicted on Smith and Fyffe (2006b) and ranged from Cambro–Ordovician to Early Carboniferous (Table 1). Appendix 1 (p. 141–146) presents the geochemical data for bedrock samples from both suites. Table 1. Bedrock samples collected for analysis from the report area in west-central New Brunswick. Figure 1 shows the ages of, and relationships among, the groups and formations.

Suite No.

Map Area

Group Formation Map Code

in Appendix 1 No. of

Samples

1 Burtts Corner and Napadogan

Kingsclear Burtts Corner SBU 10

Napadogan Mabou Shin CSN 1

Napadogan Burtts Corner SBU 3

Napadogan Cross Creek SCR 1

Napadogan

Kingsclear

Hayes Brook SHAB 1

Napadogan Push and Be Damned OPBD 2

Napadogan Tetagouche

Hayden Lake OHL 2

2

Napadogan Miramichi Knights Brook ЄOKB 2

Total Number of Samples 22

SAMPLE COLLECTION AND ANALYSIS

Bulk samples were collected from roadside bedrock outcrops using a mini-sledge hammer and a cold chisel. In the Fredericton laboratory of the NBDNR, a rock saw was used to cut

131

surface weathering off the samples. Approximately 300 g of rock for each sample was shipped to Activation Laboratories Ltd. (Actlabs) in Ancaster, Ontario. One sample, a conglomerate of the Shin Formation, was too friable to cut with the saw, and only matrix material from that sample was sent for analysis. At Actlabs, the samples were crushed to <1.7 mm using mild steel plates, and a split was removed for pulverization to 95% <105 μm (Actlabs 2010). Approximately 20 g to 30 g of the resulting rock pulp was analyzed using the near-total metals Au+53 element analytical package (Code 1H2) with add-on Hg analysis using the Flow Injection Mercury System (FIMS, Code 1G). The Au+53 package now gives data for Au plus 54 other elements, and values are obtained using the following analytical methods. Instrumental Neutron Activation Analysis (INAA) for Au plus 27 elements (As, Ba, Br, Ce,

Co, Cr, Cs, Eu, Fe, Hf, Hg, Ir, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Ta, Tb, Th, U, W, and Yb); ‘Total’ Digestion–Inductively Coupled Plasma–Optical Emission Spectrometry (TD–ICP–

OES) for 19 elements (Ag, Al, Be, Ca, Cd, Cu, K, Mg, Mn, Mo, Ni, P, Pb, S, Sr, Ti, V, Y, and Zn); and

TD–ICP–Mass Spectrometry (TD–ICP–MS) for eight elements (Bi, Ge, In, Li, Re, Sn, Te,

and Tl). The ‘total’ digestion methods obtain near-total metal values by dissolving a 0.25 g split of the pulverized sample in a four-acid (hydrochloric, nitric, perchloric, and hydrofluoric) solution prior to analysis (Actlabs 2010). Actlabs (2010) indicates that only partial extraction is obtained for Al, Sn, and Y; and that S values are for sulphides only.

RESULTS

Data

The geochemical results for the analyses of 22 bedrock samples in the report area are listed in Appendix 1 in stratigraphic order from youngest (Carboniferous) to oldest (Cambro–Ordovician). Average and standard deviation values are included for the 13 samples from the Burtts Corner Formation. Elevated values are indicated by a colour code. Note that values below the detection limit were arbitrarily assigned a value equal to half of that limit for calculation purposes. Data on regional background values for trace elements in New Brunswick bedrock are not available. For this reason, the determination of what constitutes an elevated value was based on regional background values obtained from analyses of basal till samples from southern and central New Brunswick, using comparable near-total analytical techniques (Table 2). When these basal till average values were compared with published global average, median, or range values for Earth’s continental crust, soils, and rock types common to those in west-

Table 2. Average regional background values for basal till in southern and central New Brunswick, compared with the published average, median, or range values for Earth’s crust, soil, and rock types that are common to those in west-central New Brunswick. Values in green are from Mason (1966); in yellow are from Krauskopf (1967), in pink are from Rose et al. (1979), and in blue are from WebElements (2011). Notes: 1. bT = basal till; values shown below represent the reduced mean value for 3641 basal till samples from southern and central New

Brunswick, with extreme high and low values trimmed. Appendix D in Seaman (2008) describes how the regional background values for till were determined.

2. Asterisk * = values that represent only partial extraction, avg = average, Sst = sandstone

bT Crust Continental Crust Granite Mafic Shale Sst Soil

(G-1) avg or (W-1) avg or avg or avg or avg, median, Elements and Units avg avg avg avg avg avg avg median avg avg median avg median median or range

Ag ppm <0.3 0.05 0.07 0.07 0.08 0.04 0.04 0.037 0.06 0.1 0.1 0.1 0.19 0.25 0.1 - 1

Al % 6.94* 8.1 8.13 8.2 8.2 7.43 7.7 7.86 8.8 8.0

As ppm 14.3 2 1.8 1.8 2.1 0.8 1.5 2.1 2.2 2 1.5 6.6 12 1.2 7.5

Au ppb <2 3 4 <50 3.1 2 <50 2.3 5 <50 3.2 <50 4 5 2

Ba ppm 429 580 425 425 340 1220 600 840 180 250 330 580 550 170 300

Be ppm 2 2 2.8 2.8 1.9 3 5 3 0.8 0.5 1 3 3 0.x 0.5-4

Bi ppm 0.4 0.1 0.2 0.17 0.025 0.1 0.18 0.3 0.2 0.15 0.05 0.01 1.0 0.3 0.8

Br ppm 7.3 1.8 2.5 2.5 3 0.5 1.3 0.5 3.6 6

Ca % 0.28 3.3 3.63 4.1 5 0.99 1.6 7.83 6.7 2.5

Cd ppm <0.3 0.1 0.2 0.2 0.15 0.06 0.2 0.1 0.3 0.2 0.2 0.3 0.3 0.0x 0.1-0.5

Ce ppm 87 81 60 67 60 230 87 57 30 48 66 50 76 15

Co ppm 14 25 25 25 30 2.4 1 1 50 48 48 20 19 0.33 10

Cr ppm 90 100 100 100 140 22 4 4.1 120 200 170 100 90 35 43

Cs ppm 5 3 3 3 1.9 1.5 5 1.1 1 5

Cu ppm 25 50 55 55 68 13 10 12 110 100 72 57 42 10 15

Eu ppm 1.4 1.2 1.2 1.8 1.0 1.5 1.1 0.8 1

Fe % 3.81 4.65 5.00 5.6 6.3 1.37 2.7 1.42 7.76 8.6 8.65 4.7 4.7 0.98 2.1

Ge ppm 0.5 2 1.5 1.5 1.4 1.0 1.5 1.6 1.5 2

Hf ppm 10 3 3 3 3.3 5.2 4 1.5 2 6

Hg ppb 35 20 80 80 67 200 80 40 200 80 10 400 20 - 40 30 56

In ppm <0.2 0.1 0.1 0.1 0.16 0.03 0.1 0.08 0.1 0.05

K % 1.93 2.5 2.59 2.1 1.5 4.51 3.3 4.2 0.53 0.83 0.83 2.3 2.66 1.07 1.1

La ppm 41.4 25 30 25 34 120 40 55 30 10 17 40 39 7 33

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bT Crust Continental Crust Granite Mafic Shale Sst Soil

(G-1) avg or (W-1) avg or avg or avg or avg, median, Elements and Units avg avg avg avg avg avg avg median avg avg median avg median median or range

Li ppm 44.3 30 20 20 17 24 30 40 12 10 17 60 66 15 22

Lu ppm 0.63 0.5 0.8 0.56 0.1 1.1 0.3 0.6 0.7

Mg % 0.99 1.7 2.09 2.3 2.9 0.24 0.16 3.99 4.5 1.34

Mn ppm 694 1000 950 950 1100 230 400 390 1320 1500 1500 850 850 x0 320

Mo ppm 1 1.5 1.5 1.5 1.1 7 2 1.3 0.05 1 1.5 2 2.6 0.2 2.5

Na % 1.10 2.5 2.83 2.4 2.3 2.46 2.8 1.54 1.9 0.66

Nd ppm 30 28 28 33 55 35 15 20 23

Ni ppm 43 75 75 75 90 2 0.5 4.5 78 150 130 95 68 2 17

P % 0.046 0.09 0.105 0.105 0.1 0.039 0.07 0.06 0.065 0.14 0.11 0.077 0.07 0.017 0.03

Pb ppm 21 10 13 12.5 10 49 20 18 8 5 4 20 25 10 17

Rb ppm 96 150 90 90 60 220 150 276 22 30 32 140 143 40 35

Re ppm 0.003 0.0006 0.001 <0.05 0.0026 0.0006 <0.05 0.0006 0.0004 <0.05 0.0006 <0.05 0.0005 0.0003 0.0005

S % 0.01* 0.03 0.026 0.026 0.042 0.0175 0.027 0.03 0.0135 0.025 0.03 0.022 0.24 0.024 0.01-0.2

Sb ppm 1.1 0.1 0.2 0.2 0.2 0.4 0.2 0.2 1.1 0.2 0.1 1.5 1 - 2 1.0 2

Sc ppm 13.6 13 22 22 26 3 5 34 38 10

Se ppm 0.4 0.1 0.05 0.05 0.05 0.05 0.14 0.05 0.13 0.6 0.6 0.05 0.31

Sm ppm 6.1 6.0 7.3 6 11 9.4 5 5.3 6.5

Sn ppm 1* 2 2 2 2.2 4 3 3.0 3 1 1.5 6 6 0.6 10

Sr ppm 73 300 375 375 360 250 285 100 180 465 465 450 300 20 67

Ta ppm 1.0 2 2 1.7 1.6 3.5 0.7 0.48 3.5

Tb ppm 0.7 0.9 1.1 0.94 1.1 1.5 0.6 0.8 0.9

Te ppm 0.1 0.002 0.01 <0.05 0.001 <0.05 <0.05 <0.05 0.001-0.01

Th ppm 12.6 10 7.2 9.6 6 52 17 20 2.4 2.2 2.7 11 12 5.5 13

Ti % 0.48 0.44 0.44 0.57 0.66 0.15 0.23 0.64 0.90 0.45

Tl ppm 0.6 0.45 0.5 0.45 0.53 1.3 0.75 0.13 0.1 1

U ppm 3.4 2.5 1.8 2.7 1.8 3.7 4.8 3.9 0.52 0.6 0.53 3.2 3.7 1.7 1

V ppm 88 150 135 135 190 16 20 44 240 250 250 130 130 20 57

W ppm <1 1 1.5 1.5 1.1 0.4 2 1.5 0.45 1 1.0 2 1.8 1.6 1

Y ppm 23* 33 33 29 13 40 41 25 25 25 30 35 10 27

Yb ppm 4.0 3.4 3 2.8 1 3.8 3 2.1 3

Zn ppm 75 80 70 70 79 45 40 51 82 100 94 80 100 40 36

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133

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134

central New Brunswick (Table 2), the till values generally fell within the range of the bedrock values. Therefore, in the absence of a data set for regional bedrock trace-element geochemistry, the data set for basal till is considered to be a reasonable proxy. Appendix 1 indicates four levels of statistically defined elevated values (see p. 141), based on the calculated mean (X) and standard deviation (SD). The appendix also includes sample site coordinates, sample lithology, and miscellaneous comments.

Samples from the Burtts Corner Formation

The analytical results for Sb in the 13 bedrock samples from the Burtts Corner Formation (Table 1; Appendix 1) clearly indicate that high Sb content is not a ubiquitous characteristic of the formation; the Sb values range from non-detectable (<0.1 ppm) for two samples to a maximum of 9.8 ppm for sample AS100048 (Appendix 1). The latter value is of similar magnitude to values obtained for several basal till samples in the Fredericksburg Sb anomaly (Fig. 2) but is only two-thirds of the maximum till value in that anomaly (Seaman 2008). However, an even higher maximum value of 30.6 ppm Sb has been obtained for till from a site overlying the Burtts Corner Formation farther to the north-northeast, in the area to the west of bedrock sample AS100063 (63 on Fig. 2). The highest Sb values in bedrock from the Burtts Corner Formation were obtained from two siltstone samples that were collected in quarries: one (AS100048) beside Crow Hill Road and the other (AS100053) just south of North Tay Road. This could indicate that the remaining bedrock samples, which are from surface outcrops, had undergone surficial leaching. However, the two quarry samples also differ in lithology from most of the other Burtts Corner samples, being siltstone rather than wacke (Appendix 1). A third sample from the Burtts Corner Formation is also fine grained: a mudstone from site AS100050, situated near the anomalous basal till site ND-HK13 of Seaman (2008). Together, the values obtained for these three fine-grained samples are moderately to significantly higher than those obtained for most of the wacke samples for numerous elements (Appendix 1). The elements include some that are typical of mineralizing systems in the region, such as As, Be, Bi, Fe, Hg, Sn, and Ti (Malcolm McLeod, pers. comm. 2011). The three samples are also moderately to significantly lower than the wacke samples in Ca, Mg, and Mn. Elements such as Sn and Ti are not susceptible to significant leaching in the surficial environment, whereas Ca, Mg, and Mn are. Therefore, the higher metal values in the three samples most likely reflect differences in lithology rather than in surface exposure. Of the three fine-grained samples cited above, only AS100048 from the Crow Hill Road quarry stands out as extremely anomalous in comparison with background basal till values for southern and central New Brunswick (see Seaman 2008). Specifically—and bearing in mind that the correlation between anomalous values for tills and bedrock samples in this region is only assumed—AS100048 is extremely anomalous in Co, Hg, Mo, S, Sb, and Se; very anomalous in Ag, As, Cu, Pb, Re, Sr, and U; and anomalous in Fe (a hematite vein is visible

Figure 2. Location of analyzed bedrock samples with respect to Sb distribution in basal till within the

Burtts Corner and Napadogan map areas (Fig. 1); compare Thewith the bedrock geology map (Fig. 1).

dotted white line indicates the approximate boundary of the Fredericksburg basal till Sb anomaly.

135

46

47

48

49

50

55

62

6357

58

56

60

61

66

45

51

52

53 54

64

65

59

660000 670000 680000 690000

UTM Eastings (NAD27)

5100000

5120000

5140000

Percentiles

<0.1 ppm

0.8 ppm

1.0 ppm

1.5 ppm

2.4 ppm

3.3 ppm

5.0 ppm

7.0 ppm

100 ppm

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

98

99

100

UT

M N

ort

hin

gs (

NA

D2

7)

0 10 km

in part of the sample), Ni, P, Sc, Sm, V, and Zn. By the same standard, AS100050 is

anomalous only in Rb; and AS100053 is extremely anomalous in S and anomalous in Au, Ba,

Hg, Rb, Re, and Sb.

Eight of the 10 wacke samples exhibit Ca values that are extremely anomalous in comparison

with the regional basal till values, and Sr values that are anomalous to very anomalous. The

much lower Ca and Sr values in sample AS100049, which lies just to the west of peak values

Bedrocksample site

Fault

Geologicalcontact

136

in the Fredericksburg basal till Sb anomaly, may reflect a sample leached by mineralizing solutions. A similar process may be indicated for sample AS100063, which has much lower Ca and Sr values; extremely anomalous values for Ni, Cr, and Mg; and a very anomalous value for Co. However, the presence of these elements in bedrock at this site is not readily apparent on the till geochemistry plots. The bedrock sample site (63 on Fig. 2) lies within a depression at less than the 25th percentile level for Mg, and at the eastern edge of depressions of similar magnitude for Co and Ni (the Ni depression is depicted on Fig. 3).

Samples with Elevated Nickel Values

Anomalous Ni values (from unpublished data) were obtained for 13 basal till samples collected in 2006 and 2009 from sites overlying the mapped area of the Cross Creek and Hayes Brook formations in the report area (Fig. 1). These values generate a discontinuous belt of values at the 98th percentile level near the eastern margins of the two formations (compare Fig. 1 and Fig. 3). A similarly high Ni value was obtained for a sample of fine-grained quartzite with quartz veins (AS100064) from the Cross Creek Formation. In contrast, the sample of wacke from the Hayes Brook Formation (AS100065) contained only an above-average but background level of Ni. However, a previously unidentified outlier of conglomerate of the Early Carboniferous Shin Formation (Fig. 4) was found within the mapped limits of the Hayes Brook Formation, unconformably overlying the latter. Material collected from the outlier (AS100066: the matrix sample) was very anomalous in Ni. Anomalous Ni values are not restricted to the Shin and Cross Creek formations. As noted above, an extreme Ni anomaly occurs in sample AS100063 from the Burtts Corner Formation in the central part of the Napadogan map area. Ni was also anomalous in two other samples from this formation (AS100048, AS100049) from the area west of the Fredericksburg basal till anomaly (Fig. 2, 3). In addition, anomalous Ni values were obtained for the lithic sandstone sample from the Push and Be Damned Formation (AS100057) and for the red manganiferous siltstone (RMS) sample from the Hayden Lake Formation (AS100056).

Other Anomalies

All bedrock samples collected during this project contain anomalous concentrations of at least one element—and in some cases several elements—as defined by background geochemical values of the regional till geochemical data set (Table 2; Appendix 1). In many instances, the anomalous values can be correlated with obvious attributes of the samples collected. For example, high S values in several samples from the Burtts Corner Formation and one sample from the Knights Brook Formation reflect the presence of pyrite. The RMS sample from the Hayden Lake Formation, located near the Napadogan RMS occurrence (Unique Reference Number 1140 in NBDNR 2011b), is the most anomalous of all the collected samples. It is extremely anomalous in Ba, Co, Mn, and Sb; very anomalous in Fe and Te; and anomalous in As, K, Ni, P, Pb, and Rb.

46

47

48

49

50

55

62

6357

58

56

60

61

66

45

51

5253

54

64

65

59

660000 670000 680000 690000

5100000

5120000

5140000

UT

M N

ort

hin

gs (

NA

D2

7)

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

98

99

100

Percentiles

6 ppm

34 ppm

43 ppm

54 ppm

65 ppm

75 ppm

87 ppm

104 ppm

195 ppm

Figure 3. Location of analyzed bedrock samples with respect to Ni distribution in basal till of the Burtts

Corner and Napadogan map areas (Fig. 1 ); compare with the bedrock geology map (Fig. 1).

137

DISCUSSION

Antimony (Sb)

The results presented above clearly indicate that elevated Sb values are not a ubiquitous

characteristic of either the Burtts Corner Formation or the Push and Be Damned Formation.

Only the two Burtts Corner siltstone samples contained anomalous concentrations of Sb;

concentrations in the two Push and Be Damned bedrock samples were merely above

average. One sample from the Knights Brook Formation contained a threshold anomalous

concentration of Sb, and the RMS sample from the Hayden Lake Formation was extremely

anomalous in Sb. Thus, varied degrees of elevated Sb concentration appear to be associated

with all four formations.

UTM Eastings (NAD27)0 10 km

Bedrocksample site

Fault

Geologicalcontact

Figure 4. Redbed conglomerate in a newly discovered outlier of the Early Carboniferous Shin

Formation (Mabou Group), erlying the Silurian Hayes Brook Formation at site

AS100066 (marked as 66 on Fig. 3). Hammer handle is 30 c

unconformably ov

m long.

138

In addition, the highest Sb value in samples of the Burtts Corner Formation was less than one-

third of the maximum observed in the basal till (9.8 ppm in bedrock versus 30.6 ppm in till).

Even the extremely anomalous value for the RMS sample (22.7 ppm) is only three-quarters

that of the till maximum. The evidence of these analyses, combined with the above average to

extremely anomalous values in the different bedrock units, implies that additional Sb

contributions from more highly mineralized and localized bedrock sources remain to be

discovered.

The anticipated correlation between the Cross Creek Formation and anomalous Ni values

in the basal till appears to hold true. The Cross Creek sample site (AS100064) lies just

north of an area of elevated Ni at the 99 percentile level (= very anomalous) in the till

geochemistry data (Fig. 3).

However, study results do not confirm the expected correlation between the Hayes Brook

Formation and elevated Ni values. The Ni value for the Hayes Brook sample (AS100065) is

comparable only to the 90 percentile level in the till data (the 98 percentile level is

Nickel (Ni)

th

th th

139

considered anomalous). Notably, this sample site lies in a gap in the anomalous Ni belt on the till geochemistry plot (Fig. 3). The anomalous area south-southwest of the gap is located just south of site AS100066; the matrix of the conglomerate sample (Shin Formation) from this site exhibits a very anomalous concentration of Ni. This high concentration in the matrix is unexpected, as Figure 3 clearly indicates that high Ni values are not typical of till overlying or adjacent to the Shin Formation. Therefore, the Ni concentration in the matrix material probably reflects a local rather than a regional source, one that likely originated during deposition in the Early Carboniferous. The available data offer no clear explanation for the belt of anomalous Ni overlying the Cross Creek and Hayes Brook formations. The following are among the several possibilities. The original hypothesis that the elevated Ni values reflect Ni in the Cross Creek and Hayes

Brook formations could be correct. Sample AS100065 simply may not represent the typical geochemistry of the Hayes Brook Formation.

The anomalous Ni belt could be due solely to the presence of the Cross Creek Formation.

More detailed geological maps of the region (Smith and Fyffe 2006b) show that the formation outcrops as narrow bands to both the west (~0.5 km wide) and the east (~2 km wide) of the Hayes Brook Formation in the northern part of the Napadogan map area. The anomalous Ni in the till (and in the sample of Shin Formation) could be the result of dispersal from one of these segments of the Cross Creek Formation.

The Shin Formation in the Napadogan map area could be enriched in Ni, unlike that part of

the formation to the south in the Burtts Corner map area. If so, two possible explanations exist for the belt of anomalous basal till. First, the till could have been dispersed northwestward from the band of Shin Formation that outcrops along the eastern margin of the Cross Creek Formation. Evidence for northwestward dispersal has been noted previously for the Hayesville map area (Fig. 1) to the north (Seaman 2006). Second, additional outliers of the Shin Formation could unconformably overlie the Hayes Brook Formation in areas that happen to be situated within gaps in the observed distribution of bedrock outcrops.

The belt of anomalous till could reflect glacial dispersal from point sources within the

mapped area of the two Silurian formations. The dispersal could have been either southwestward during the Escuminac Phase of the Late Wisconsinan glaciation (Seaman 2009), northeastward during the subsequent Scotian and Chignecto phases, or, potentially, southwestward in some parts of the area and northeastward in others.

Finally, the observed distribution of Ni in the basal till could derive from some combination

of the foregoing possibilities. Obviously, further bedrock investigations in this district of west-central New Brunswick will be required to determine which, if any, of the above explanations is correct.

140

CONCLUSIONS

The working premise that the Burtts Corner Formation and the Push and Be Damned Formation were the source of elevated Sb basal till values in the Burtts Corner and Napadogan map areas is only partially correct. Although elevated Sb values were present in some bedrock samples from these formations, such values were far from ubiquitous. Moreover, elevated values were also obtained for samples from the Knights Brook and Hayden Lake formations. It therefore is likely that some units within all four formations contributed to the observed elevated Sb values. However, the Sb values in some basal till samples are significantly higher than those in the bedrock samples, indicating the probability that another, as yet undiscovered, source of Sb mineralization exists in the area. The source of the elevated Ni over the mapped extent of the Cross Creek and Hayes Brook formations is unclear. Additional bedrock mapping and geochemical analyses will be required to identify the source(s).

ACKNOWLEDGEMENTS

Field assistance was provided by Aaron Bustard. Terry Leonard prepared Figure 1, and Serge Allard provided the bedrock base used to generate Figures 2 and 3. This report was significantly improved by the constructive criticisms of Malcolm McLeod, Geological Surveys Branch, NBDNR.

REFERENCES

Actlabs 2010. 2010 Canadian schedule of services and fees. Activation Laboratories Ltd., Ancaster, Ontario, 32 p.

Krauskopf, K.B. 1967. Introduction to Geochemistry. McGraw-Hill Inc., New York, 721 p. Mason, B. 1966. Principles of Geochemistry, 3rd edition. John Wiley & Sons, Inc., New York, 329 p. New Brunswick Department of Natural Resources (NBDNR). 2008. Bedrock geology of New Brunswick.

New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Map NR-1 (revised December 2008).

New Brunswick Department of Natural Resources (NBDNR). 2011a. New Brunswick Bedrock Lexicon. http://dnr-mrn.gnb.ca/Lexicon/Lexicon/Lexicon_Search.aspx?lang=e [accessed July 2011].

New Brunswick Department of Natural Resources (NBDNR). 2011b. New Brunswick Mineral Occurrence Database. http://dnre-mrne.gnb.ca/MineralOccurrence [accessed July 2011].

Rose, A.W., Hawkes, H.E., and Webb, J.S. 1979. Geochemistry in Mineral Exploration, 2nd edition. Academic Press, London, 657 p.

Seaman, A.A. 2006. A new interpretation of the late glacial history of central New Brunswick: the Gaspereau Ice Centre as a Younger Dryas ice cap. In Geological Investigations in New Brunswick for 2005. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Mineral Resource Report 2006-3, p. 1–36.

Seaman, A.A. 2008. Till geochemistry of the Fredericksburg–South Tay River area, parts of the Burtts Corner and Napadogan map areas (NTS 21 J/02 and 21 J/07), York County, west-central New Brunswick. New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Open File (CD-ROM) 2008-6, 55 p.

141

Seaman, A.A. 2009. The Appalachian Glacier Complex, and the Middle to Late Pleistocene history of west-central New Brunswick, Canada. In Geological Investigations in New Brunswick for 2008. Edited by G.L. Martin. New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Mineral Resource Report 2009-2, p. 66–140.

Smith, E.A., and Fyffe, L.R. (compilers). 2006a. Bedrock geology of the Burtts Corner area (NTS 21 J/02), York County, New Brunswick. New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Plate 2006-3 (revised September 2009).

Smith, E.A., and Fyffe, L.R. (compilers). 2006b. Bedrock geology of the Napadogan area (NTS 21 J/07), York County, New Brunswick. New Brunswick Department of Natural Resources; Minerals, Policy and Planning Division, Plate 2006-8 (revised September 2009).

WebElements. 2011. Abundance in Earth’s Crust. http://www.webelements.com/periodicity/abundance _crust/ [accessed March 2011].

_________________________________________________

Appendix 1: Near-Total Extraction Trace-Element Data for

Bedrock Samples from the Burtts Corner and Napadogan Map Areas Appendix 1 (p. 142–146) presents the near-total extraction trace-element data for Au plus 54 elements from rocks collected in the Burtts Corner and Napadogan map areas. Colour shading indicates anomalous values (mean plus 4 to 7.9 standard deviations) to extremely anomalous values (mean plus 16+ standard deviations), as judged by the standard of basal till background values for central and southern New Brunswick (see Table 2). For details regarding the calculation of these background values, see Appendix D of Seaman (2008). Notes

1. Asterisk * denotes elements for which the values represent only partial extraction. 2. Map code symbols representing the names of bedrock units are shown in Table 1. 3. Threshold anomalous X + 2 SD to <4 SD (X = calculated mean; SD = standard deviation) Anomalous X + 4 SD to <8 SD Very anomalous X + 8 SD to <16 SD Extremely anomalous X + ≥16 SD 5. Lithologic abbreviations used:

f. = fine-grained, m. = medium-grained, c. = coarse-grained, hem = hematite, mdst = mudstone, metased = metasedimentary rock, polymict cgl = polymictic conglomerate, py = pyrite, qtz = quartz, qtzite = quartzite, RMS = red manganiferous siltstone, slst = siltstone

6. Analytical method abbreviations used:

FIMS Flow Injection Mercury System ICP–MS ‘Total’ Digestion (TD)–Inductively Coupled Plasma– Mass Spectrometry ICP–OES ‘Total’ Digestion–Inductively Coupled Plasma–Optical Emission Spectrometry INAA Instrumental Neutron Activation Analysis MULT Indicates elements that were analyzed by two different methods:

for Se: MULT denotes INAA and TD–ICP–MS

for Ag, Ni, Zn: MULT denotes INAA and TD–ICP–OES

Mean +

2S

DA

gA

l*A

sA

uB

aB

eB

iB

r

Mean +

4S

Dppm

%ppm

ppb

ppm

ppm

ppm

ppm

Mean +

8S

D0.3

0.0

10.5

250

10.1

0.5

Mean +

16S

DM

ULT

ICP

-OE

SIN

AA

INA

AIN

AA

ICP

-OE

SIC

P-M

SIN

AA

Sam

ple

Bd

rkE

asti

ng

No

rth

ing

Bed

rock

Co

mm

en

ts

Sit

e N

o.

Un

it(N

AD

27)

(NA

D27)

Lit

ho

log

y

AS

100066

CS

N683660

5142940

poly

mic

t cgl

matr

ix o

nly

<0.3

8.5

08.8

<2

530

20.2

<0.5

AS

100045

SB

U656575

5114200

f. w

acke

qtz

vein

ing

<0.3

5.3

8<

0.5

4<

50

1<

0.1

<0.5

AS

100046

SB

U656790

5114030

f. w

acke

<0.3

6.1

625.1

<2

340

2<

0.1

<0.5

AS

100047

SB

U660215

5116510

m. w

acke

<0.3

5.1

73.4

<2

230

10.1

<0.5

AS

100048

SB

U658505

5120445

sls

tspotted; hem

2.2

8.5

578.3

<2

670

30.5

<0.5

AS

100049

SB

U662355

5125330

f. w

acke

<0.3

7.4

35.3

<2

350

20.1

<0.5

AS

100050

SB

U669075

5127160

mdst

sla

ty0.3

5.5

824.6

<2

790

30.4

<0.5

AS

100051

SB

U667900

5128775

m. w

acke

lithic

<0.3

5.1

47.2

<2

<50

10.1

<0.5

AS

100052

SB

U663040

5120005

f. w

acke

0.3

5.3

43.4

<2

130

10.1

<0.5

AS

100053

SB

U665340

5120800

sls

tsla

ty; py

<0.3

9.4

824.5

71050

40.5

<0.5

AS

100053dupl

SB

U665340

5120800

sls

tsla

ty; py

<0.3

10.1

04

0.5

AS

100054

SB

U668560

5121345

m. w

acke

qtz

vein

ing

<0.3

5.8

55.2

4<

50

20.1

<0.5

AS

100055

SB

U667430

5135110

f. w

acke

qtz

vein

ing; py

<0.3

6.0

15.9

<2

230

20.1

<0.5

AS

100062

SB

U664640

5137345

f. w

acke

py

<0.3

5.9

15.7

5390

20.1

<0.5

AS

100063

SB

U670855

5139515

c. w

acke

lithic

<0.3

5.0

13.0

<2

<50

<1

<0.1

<0.5

Avera

ge

SB

U0.3

6.2

614.8

2329.2

20.2

<0.5

SD

SB

U0.6

1.4

621.1

2.0

5326.8

10.2

AS

100064

SC

R678905

5136135

f. q

tzite

~10%

qtz

vein

s<

0.3

5.4

33.1

<2

330

<1

0.1

<0.5

AS

100065

SH

AB

686115

5144610

m. w

acke

fractu

red

<0.3

8.2

911.6

<2

380

10.1

<0.5

AS

100057

OP

BD

660385

5139545

c. lit

hic

sst

qtz

vein

<0.3

7.7

114.5

<2

<50

20.1

<0.5

AS

100058

OP

BD

659115

5142540

sls

t~

50%

qtz

vein

s<

0.3

9.4

827.7

<2

<50

30.2

<0.5

AS

100056

OH

L661880

5138450

RM

S~

25%

qtz

vein

s<

0.3

6.3

655.4

<2

2530

41.2

<0.5

AS

100059

OH

L658720

5143145

sls

t<

0.3

4.0

132.3

<2

910

20.1

<0.5

AS

100060

ЄO

KB

655825

5144340

m. m

eta

sed

spotted; qtz

; py

<0.3

8.2

99.0

<2

640

30.4

<0.5

AS

100061

ЄO

KB

664515

5140875

sls

tsla

ty0.3

10.3

015.0

<2

940

50.5

<0.5

Ele

men

t

Un

it S

ym

bo

l

Dete

cti

on

Lim

it

An

aly

tical M

eth

od

→ → → →

142

Mean +

2S

D

Mean +

4S

D

Mean +

8S

D

Mean +

16S

D

Sam

ple

Bd

rkE

asti

ng

No

rth

ing

Sit

e N

o.

Un

it(N

AD

27)

(NA

D27)

AS

100066

CS

N683660

5142940

AS

100045

SB

U656575

5114200

AS

100046

SB

U656790

5114030

AS

100047

SB

U660215

5116510

AS

100048

SB

U658505

5120445

AS

100049

SB

U662355

5125330

AS

100050

SB

U669075

5127160

AS

100051

SB

U667900

5128775

AS

100052

SB

U663040

5120005

AS

100053

SB

U665340

5120800

AS

100053dupl

SB

U665340

5120800

AS

100054

SB

U668560

5121345

AS

100055

SB

U667430

5135110

AS

100062

SB

U664640

5137345

AS

100063

SB

U670855

5139515

Avera

ge

SB

U

SD

SB

U

AS

100064

SC

R678905

5136135

AS

100065

SH

AB

686115

5144610

AS

100057

OP

BD

660385

5139545

AS

100058

OP

BD

659115

5142540

AS

100056

OH

L661880

5138450

AS

100059

OH

L658720

5143145

AS

100060

ЄO

KB

655825

5144340

AS

100061

ЄO

KB

664515

5140875

Ele

men

t

Un

it S

ym

bo

l

Dete

cti

on

Lim

it

An

aly

tical M

eth

od

Ca

Cd

Ce

Co

Cr

Cs

Cu

Eu

Fe

Ge

Hf

Hg

Hg

In

%ppm

ppm

ppm

ppm

ppm

ppm

ppm

%ppm

ppm

ppb

ppm

ppm

0.0

10.3

31

21

10.2

0.0

10.1

15

10.2

ICP

-OE

SIC

P-O

ES

INA

AIN

AA

INA

AIN

AA

ICP

-OE

SIN

AA

INA

AIC

P-M

SIN

AA

FIM

SIN

AA

ICP

-MS

1.1

5<

0.3

82

27

277

340

0.9

5.8

20.5

6<

5<

1<

0.2

3.1

30.3

43

9109

214

1.0

2.7

20.2

4<

5<

1<

0.2

2.9

9<

0.3

45

11

108

225

1.0

3.3

70.4

6<

5<

1<

0.2

8.0

4<

0.3

42

12

125

331

1.0

2.9

40.3

4<

5<

1<

0.2

0.4

90.4

84

90

156

7130

2.2

8.2

20.5

4629

<1

<0.2

0.3

5<

0.3

64

19

127

637

1.5

5.1

00.7

6<

5<

1<

0.2

0.0

2<

0.3

75

<1

106

11

26

1.2

4.1

90.7

467

<1

<0.2

7.1

9<

0.3

47

13

116

319

1.0

3.3

60.3

410

<1

<0.2

9.4

40.3

45

13

110

338

1.1

3.2

80.2

36

<1

<0.2

0.0

2<

0.3

79

7101

10

51

1.3

4.4

30.8

4122

<1

<0.2

0.0

3<

0.3

50

1.1

<0.2

6.4

60.3

42

12

107

318

0.9

2.9

90.3

37

<1

<0.2

9.3

00.4

43

11

87

221

0.9

3.4

10.4

314

<1

<0.2

3.3

3<

0.3

87

14

150

321

1.6

3.1

00.2

9<

5<

1<

0.2

0.2

40.3

54

61

2310

324

0.8

6.4

10.2

6<

5<

1<

0.2

3.9

2<

0.3

57.7

21

285.5

435

1.2

4.1

20.4

4.6

267

<1

<0.2

3.6

917.6

25.3

608.6

330

0.4

1.6

10.2

1.7

1173

5.6

70.3

75

18

300

<1

114

1.2

3.0

10.2

620

<1

<0.2

1.0

4<

0.3

49

22

127

251

1.0

5.4

10.5

66

<1

<0.2

0.8

70.3

42

28

222

662

1.3

6.4

00.3

421

<1

<0.2

0.1

20.3

109

39

208

663

1.7

7.8

10.4

77

<1

<0.2

0.3

3<

0.3

120

182

46

14

31

1.8

11.2

00.3

4<

5<

1<

0.2

9.2

00.6

106

981

85

1.7

3.6

20.3

7<

5<

1<

0.2

0.0

6<

0.3

110

10

116

367

2.1

6.9

50.2

3<

5<

1<

0.2

0.1

2<

0.3

139

20

127

854

2.3

5.4

60.3

78

<1

<0.2

143

Mean +

2S

D

Mean +

4S

D

Mean +

8S

D

Mean +

16S

D

Sam

ple

Bd

rkE

asti

ng

No

rth

ing

Sit

e N

o.

Un

it(N

AD

27)

(NA

D27)

AS

100066

CS

N683660

5142940

AS

100045

SB

U656575

5114200

AS

100046

SB

U656790

5114030

AS

100047

SB

U660215

5116510

AS

100048

SB

U658505

5120445

AS

100049

SB

U662355

5125330

AS

100050

SB

U669075

5127160

AS

100051

SB

U667900

5128775

AS

100052

SB

U663040

5120005

AS

100053

SB

U665340

5120800

AS

100053dupl

SB

U665340

5120800

AS

100054

SB

U668560

5121345

AS

100055

SB

U667430

5135110

AS

100062

SB

U664640

5137345

AS

100063

SB

U670855

5139515

Avera

ge

SB

U

SD

SB

U

AS

100064

SC

R678905

5136135

AS

100065

SH

AB

686115

5144610

AS

100057

OP

BD

660385

5139545

AS

100058

OP

BD

659115

5142540

AS

100056

OH

L661880

5138450

AS

100059

OH

L658720

5143145

AS

100060

ЄO

KB

655825

5144340

AS

100061

ЄO

KB

664515

5140875

Ele

men

t

Un

it S

ym

bo

l

Dete

cti

on

Lim

it

An

aly

tical M

eth

od

IrK

La

Li

Lu

Mg

Mn

Mo

Na

Nd

Ni

PP

b

ppb

%ppm

ppm

ppm

%ppm

ppm

%ppm

ppm

%ppm

50.0

10.5

0.5

0.0

50.0

11

10.0

15

10.0

01

3

INA

AIC

P-O

ES

INA

AIC

P/M

SIN

AA

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIN

AA

INA

AM

ULT

ICP

-OE

SIC

P-O

ES

<5

2.3

227.7

56.3

0.4

03.0

01050

<1

1.0

652

172

0.0

45

12

<5

1.0

526.6

38.8

0.3

81.3

2418

<1

2.2

813

44

0.0

48

3

<5

1.6

228.7

47.1

0.4

81.8

3439

<1

1.9

915

53

0.0

54

7

<5

1.1

227.7

38.4

0.4

31.7

9680

<1

1.0

214

43

0.0

47

8

<5

2.8

049.1

47.2

0.6

50.8

0211

13

0.4

831

91

0.1

25

92

<5

1.7

735.8

66.2

0.5

71.7

7217

<1

0.0

825

123

0.1

25

<3

<5

2.5

948.6

36.5

0.6

10.6

5143

<1

0.1

822

22

0.0

23

10

<5

1.3

527.4

33.3

0.4

31.8

6693

<1

1.5

2<

551

0.0

63

7

<5

1.1

726.7

44.9

0.4

21.9

0933

<1

0.0

715

50

0.0

55

5

<5

3.4

951.3

70.5

0.6

10.9

2197

<1

0.4

231

22

0.0

21

17

3.6

567.2

0.9

5197

<1

22

0.0

20

20

<5

1.3

925.1

52.9

0.3

71.9

9607

<1

1.3

920

54

0.0

52

14

<5

1.4

123.1

48.0

0.3

52.5

3812

<1

0.0

514

58

0.0

57

8

<5

1.8

937.0

31.1

0.6

51.6

3551

<1

1.6

258

60

0.0

52

11

<5

0.0

315.0

58.0

0.3

812.1

0776

<1

0.2

915

1040

0.0

31

<3

<5

1.6

732.5

47.0

0.4

92.3

9514

10.8

821.2

132

0.0

58

14

0.9

011.2

11.9

0.1

12.9

6264

30.8

013.5

274

0.0

33

24

<5

0.6

928.9

35.7

0.4

01.5

61880

<1

2.1

438

123

0.0

33

6

<5

1.2

919.6

81.4

0.4

72.4

92120

<1

2.6

332

65

0.0

56

11

<5

1.9

423.3

56.9

0.5

52.1

9818

<1

1.3

518

96

0.0

72

5

<5

3.7

045.0

73.2

0.7

52.3

01350

<1

0.1

362

82

0.0

58

<3

<5

3.5

755.8

30.2

0.9

10.7

825000

20.6

226

124

0.1

50

68

<5

2.4

141.6

41.3

0.7

41.9

61470

20.2

866

39

0.0

83

8

<5

2.5

647.4

63.4

0.6

61.6

7455

40.6

568

28

0.0

37

6

<5

3.1

458.9

56.9

0.7

71.3

1437

<1

0.9

195

56

0.0

47

6

144

Mean +

2S

D

Mean +

4S

D

Mean +

8S

D

Mean +

16S

D

Sam

ple

Bd

rkE

asti

ng

No

rth

ing

Sit

e N

o.

Un

it(N

AD

27)

(NA

D27)

AS

100066

CS

N683660

5142940

AS

100045

SB

U656575

5114200

AS

100046

SB

U656790

5114030

AS

100047

SB

U660215

5116510

AS

100048

SB

U658505

5120445

AS

100049

SB

U662355

5125330

AS

100050

SB

U669075

5127160

AS

100051

SB

U667900

5128775

AS

100052

SB

U663040

5120005

AS

100053

SB

U665340

5120800

AS

100053dupl

SB

U665340

5120800

AS

100054

SB

U668560

5121345

AS

100055

SB

U667430

5135110

AS

100062

SB

U664640

5137345

AS

100063

SB

U670855

5139515

Avera

ge

SB

U

SD

SB

U

AS

100064

SC

R678905

5136135

AS

100065

SH

AB

686115

5144610

AS

100057

OP

BD

660385

5139545

AS

100058

OP

BD

659115

5142540

AS

100056

OH

L661880

5138450

AS

100059

OH

L658720

5143145

AS

100060

ЄO

KB

655825

5144340

AS

100061

ЄO

KB

664515

5140875

Ele

men

t

Un

it S

ym

bo

l

Dete

cti

on

Lim

it

An

aly

tical M

eth

od

Rb

Re

S*

Sb

Sc

Se

Sm

Sn

*S

rTa

Tb

Te

Th

ppm

ppm

%ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

15

0.0

01

0.0

10.1

0.1

0.1

0.1

11

0.5

0.5

0.1

0.2

INA

AIC

P-M

SIC

P-O

ES

INA

AIN

AA

MU

LT

INA

AIC

P-M

SIC

P-O

ES

INA

AIN

AA

ICP

-MS

INA

A

92

0.0

01

<0.0

10.7

23.1

<0.1

4.2

<1

120

<0.5

<0.5

0.1

9.6

<15

0.0

03

<0.0

1<

0.1

10.3

<0.1

4.6

<1

174

0.9

<0.5

0.1

6.3

<15

0.0

07

0.0

21.4

12.5

<0.1

4.9

<1

185

<0.5

<0.5

0.2

6.5

57

0.0

05

<0.0

10.9

11.1

<0.1

5.1

1213

<0.5

<0.5

0.1

6.4

158

0.0

31

2.8

99.8

23.5

16.5

11.6

3239

0.8

1.0

0.4

10.0

90

0.0

04

<0.0

1<

0.1

13.2

<0.1

8.3

134

<0.5

1.1

0.1

8.1

228

0.0

06

0.0

21.2

20.7

<0.1

7.9

422

2.1

<0.5

0.2

14.9

69

0.0

02

0.0

60.3

12.2

<0.1

5.3

1216

<0.5

<0.5

0.2

7.0

50

0.0

02

<0.0

10.4

11.7

4.4

5.1

<1

184

<0.5

<0.5

0.2

6.2

215

0.0

18

0.6

34.4

19.4

<0.1

7.8

5131

<0.5

1.2

0.2

14.0

0.0

16

0.6

44

134

0.2

64

0.0

11

0.0

20.4

11.1

<0.1

4.5

<1

181

<0.5

<0.5

0.1

6.3

46

0.0

02

0.0

81.4

10.7

<0.1

4.8

<1

244

<0.5

0.7

0.2

5.7

<15

<0.0

01

0.2

21.8

11.6

<0.1

5.4

2174

<0.5

0.9

<0.1

9.2

<15

<0.0

01

<0.0

10.3

18.5

<0.1

3.7

219

<0.5

<0.5

<0.1

4.3

77

0.0

07

0.3

11.7

14.3

1.7

6.1

2155

0.5

0.5

0.2

8.1

76

0.0

09

0.8

02.7

4.5

4.6

2.2

180

0.5

0.4

0.1

3.2

<15

0.0

01

0.0

20.2

11.1

<0.1

4.9

<1

235

<0.5

<0.5

0.2

6.4

47

<0.0

01

0.0

90.7

21.9

<0.1

4.0

1166

<0.5

<0.5

0.1

7.5

<15

0.0

05

<0.0

11.9

23.8

<0.1

5.9

<1

84

<0.5

1.0

0.2

6.5

208

0.0

05

<0.0

12.1

34.7

<0.1

7.6

<1

26

1.7

<0.5

0.1

10.3

205

0.0

05

<0.0

122.7

15.4

<0.1

10.1

399

<0.5

1.4

0.9

13.2

116

0.0

05

<0.0

11.2

12.7

<0.1

6.8

2155

<0.5

1.0

0.3

10.5

113

0.0

04

0.9

40.8

19.6

<0.1

6.8

441

<0.5

<0.5

0.3

13.9

208

0.0

06

<0.0

12.7

23.1

<0.1

8.8

<1

51

<0.5

<0.5

0.1

17.3

145

Mean +

2S

D

Mean +

4S

D

Mean +

8S

D

Mean +

16S

D

Sam

ple

Bd

rkE

asti

ng

No

rth

ing

Sit

e N

o.

Un

it(N

AD

27)

(NA

D27)

AS

100066

CS

N683660

5142940

AS

100045

SB

U656575

5114200

AS

100046

SB

U656790

5114030

AS

100047

SB

U660215

5116510

AS

100048

SB

U658505

5120445

AS

100049

SB

U662355

5125330

AS

100050

SB

U669075

5127160

AS

100051

SB

U667900

5128775

AS

100052

SB

U663040

5120005

AS

100053

SB

U665340

5120800

AS

100053dupl

SB

U665340

5120800

AS

100054

SB

U668560

5121345

AS

100055

SB

U667430

5135110

AS

100062

SB

U664640

5137345

AS

100063

SB

U670855

5139515

Avera

ge

SB

U

SD

SB

U

AS

100064

SC

R678905

5136135

AS

100065

SH

AB

686115

5144610

AS

100057

OP

BD

660385

5139545

AS

100058

OP

BD

659115

5142540

AS

100056

OH

L661880

5138450

AS

100059

OH

L658720

5143145

AS

100060

ЄO

KB

655825

5144340

AS

100061

ЄO

KB

664515

5140875

Ele

men

t

Un

it S

ym

bo

l

Dete

cti

on

Lim

it

An

aly

tical M

eth

od

Ti

Tl

UV

WY

*Y

bZ

nM

ass

Su

bm

itte

dL

ab

%ppm

ppm

ppm

ppm

ppm

ppm

ppm

gS

am

ple

Rep

ort

0.0

10.1

0.5

21

10.2

1W

eig

ht

No

.

ICP

-OE

SIC

P-M

SIN

AA

ICP

-OE

SIN

AA

ICP

-OE

SIN

AA

MU

LT

INA

Ag

0.1

70.5

3.3

64

<1

18

2.9

93

26.7

305.1

A10-8

658

0.1

10.3

2.6

25

313

2.3

43

27.2

309.6

A10-8

658

0.1

10.4

3.2

36

<1

14

2.2

54

27.6

306.8

A10-8

658

0.1

10.3

1.4

26

315

2.2

48

26.6

324.9

A10-8

658

0.7

61.0

19.0

213

<1

26

3.4

137

25.0

304.4

A10-8

658

0.3

10.4

2.6

83

<1

26

3.2

123

25.0

326.7

A10-8

658

0.6

01.4

3.1

165

<1

63.0

64

19.7

300.9

A10-8

658

0.3

50.4

2.9

77

<1

16

2.2

51

26.3

296.9

A10-8

658

0.2

50.3

2.4

56

<1

17

2.1

53

25.6

316.7

A10-8

658

0.5

01.2

4.5

117

<1

19

3.7

88

20.2

308.4

A10-8

658

0.5

51.2

122

22

87

A10-8

658

0.1

00.4

2.2

29

<1

17

2.0

54

28.0

319.8

A10-8

658

0.2

10.4

2.1

52

<1

17

2.2

69

24.7

300.0

A10-8

658

0.2

60.4

3.5

54

<1

20

3.5

54

26.0

308.2

A10-8

658

0.2

9<

0.1

<0.5

113

<1

13

1.8

63

23.0

304.8

A10-8

658

0.3

10.5

3.8

81

<1

17

2.6

69

0.2

10.4

4.7

58

50.7

29

0.0

80.2

<0.5

15

<1

20

2.5

57

29.4

322.6

A10-8

658

0.3

40.3

3.3

126

<1

20

3.0

90

27.2

301.0

A10-8

658

0.3

00.4

3.2

96

<1

28

3.2

93

25.2

309.9

A10-8

658

0.2

90.8

2.8

91

<1

13

4.7

108

26.9

303.6

A10-8

658

0.4

01.1

<0.5

78

<1

40

5.1

73

28.7

306.8

A10-8

658

0.3

91.5

3.6

85

<1

18

3.9

62

24.0

309.1

A10-8

658

0.6

10.8

4.9

148

<1

18

4.9

85

26.8

334.6

A10-8

658

0.1

81.1

3.2

82

<1

24

4.9

108

23.4

303.2

A10-8

658

146

Mineral Resource Report 2011-2

Price $25.00

ISBN 978-1-55471-042-3ISSN 0548-4014

new brunswick 2010 (mrr_2011-2)

Documents