“COLLINGWOOD” STRATA IN SOUTH-CENTRAL

ONTARIO – A PETROPHYSICAL

CHEMOSTRATIGRAPHIC APPROACH TO COMPARISON

AND CORRELATION USING GEOPHYSICAL BOREHOLE

LOGS.

by

Christopher C. Rancourt

A thesis submitted in conformity with the requirements for the degree of Master of Science

Department of Geology University of Toronto

© Copyright by Christopher C. Rancourt, 2009

ii

“COLLINGWOOD” STRATA IN SOUTH-CENTRAL ONTARIO – A PETROPHYSICAL

CHEMOSTRATIGRAPHIC APPROACH TO COMPARISON AND CORRELATION USING

GEOPHYSICAL BOREHOLE LOGS.

Christopher C. Rancourt

Department of Geology, University of Toronto, 2009

ABSTRACT

A petrophysical chemostratigraphic comparison and correlation of “Collingwood” strata across

central Ontario was conducted using geophysical borehole log data and core produced by the

Ontario Oil Shale Assessment Project (OSAP). Outcrop sections were also measured, sampled

and described. The resultant geophysical correlation was compared to sections in the Michigan

Peninsula. Microfacies analyses and a biostratigraphic review were also conducted. The dark

organic rich rocks collectively referred to as the “Collingwood Member, Lindsay Formation”, in

Ontario were deposited during the progressive drowning of a mid to late Ordovician carbonate

ramp. Due to variability in ramp palaeotopography, condensation intensity (sedimentation

stress) varied across the region during drowning. This variability resulted in regional differences

in Collingwood section thickness and facies. Less condensed carbonate rich “Collingwood”

sections are associated with palaeotopographic highs such as the Algonquin Arch in Ontario and

grade upwards and outwards (off-arch) from predominantly deep-shelf carbonates (microfacies

type SMF 9, FZ 2 – open sea shelf –deep undatherm below wave base) to more condensed

deeper water shale rich strata (microfacies type SMF 3, FZ1- basin fondotherm below oxygen

level) – that contain abundant graptolites and Triarthrus trilobites.

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ACKNOWLEDGEMENTS

Special thanks and my deepest gratitude go to Andrew Miall for supervising this work and to

Nick Elyes, Ulrich Wortman and Jörg Bollmann for serving as my committee on such short

notice. I dedicate this work to my wife Kasia, daughters Megan and Emily, my Father the late

Andre L. Rancourt and mother Merle J. Rancourt. Special thanks also go to John B. Lawson for

being a friend and mentor in life.

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TABLE OF CONTENTS ABSTRACT .......................................................................................................................................... ii

ACKNOWLEDGEMENTS .................................................................................................................. iii

TABLE OF CONTENTS ..................................................................................................................... iv

1.0 INTRODUCTION ................................................................................................................. 1

2.0 STRATIGRAPHIC REVIEW ................................................................................................ 3

3.0 GEOLOGICAL SETTING .................................................................................................... 5

4.0 LOCALTIES AND DATA COLLECTION .......................................................................... 6

5.0 REGIONAL SUBSURFACE STRATIGRAPHY ................................................................. 6

6.0 MICROFACIES ANALYSIS ................................................................................................ 8

6.1 Lower Mbr. (Lindsay Fm.) Nodular Limestones. SMF 9, Facies Zone 2 .............................. 8

6.2 Collingwood Mbr. (Lindsay Fm.) Marlstone SMF 3, Facies Zone 1 ................................... 10

6.3 Collingwood Mbr. (Lindsay Fm.) Pale Grey and Buff -coloured Carbonate interbeds SMF

9, Facies Zone 2 ................................................................................................................... 12

6.4 Blue Mountain Fm. Shale/calcareous shale .......................................................................... 12

6.5 Microfacies Analysis Results ............................................................................................... 12

7.0 BIOSTRATIGRAHY AND PALAEOBIOLOGY .............................................................. 13

7.1 Trilobites .............................................................................................................................. 13

7.2 Graptolites ............................................................................................................................ 13

7.3 Conodonts ............................................................................................................................. 14

7.4 Chitinozoa ............................................................................................................................ 14

7.5 Biostratigraphy and Palaeobiology Results .......................................................................... 14

8.0 GEOPHYSICAL BOREHOLE LOG CORRELATION ..................................................... 16

8.1 Method .................................................................................................................................. 16

8.2 Geophysical Borehole Log Identified Unit (Petrophysical Chemostratigraphic approach) . 16

8.3 Condensation ........................................................................................................................ 19

8.4 “Collingwood” Strata in Central Ontario and the Michigan Basin ...................................... 23

8.5 Datum, Stratal Condensation and Boundary Contacts ......................................................... 24

9.0 DISCUSSION AND CONCLUSIONS................................................................................ 26

10.0 REFERENCES ..................................................................................................................... 30

FIGURES………………………………………………………………………………..(1 through 24)

APPENDIX A …………………………………………………………………………...(Plates 1 & 2)

1

1.0 INTRODUCTION

Between 1980 and 1983 the economic potential of Ontario's "oil shales" was investigated

by the Ontario Geological Survey. The study was known as the “Ontario Oil Shale Assessment

Project” OSAP (See Johnson et al., 1983, 1985). In South-central Ontario the Collingwood

Member of the Lindsay Formation, at that time the Craigleith Member of Liberty's (1969)

Whitby Formation were among some of the “oil shales” assessed (see Collingwood distribution

map Figure 1 and historic stratigraphic nomenclature Figure 2). Because these strata were

known from only a scant few geographically isolated outcrops (Figure 3), none of which exposed

complete sections, OSAP’s borehole program promised to provide much needed stratigraphic

data (Russell and Telford, 1983).

Since the publication of OSAP data by Johnson et al., (1983-1985), biostratigraphic,

petrographic, petrochemical, and stratigraphic analyses (including a stratigraphic revision) have

been conducted and published by various authors (See Russell and Telford (1983); Churcher et

al. (1986); Churcher et al. (1991); Hiatt (1985); Hiatt and Nordeng (1985); Wilson and Sengupta

(1985); Snowdon (1984); Macauley et al. (1990); Johnson et al. (1991); Lehman et al. (1995).

Yet despite the new OSAP data, analyses, and stratigraphic revision, our understanding of these

organic-rich strata does not appear to have advanced significantly, as the wide range in post-

OSAP palaeoenvironmental interpretations bear witness. These include normal marine shallow-

shelf, deep-shelf, stratified marine, stranded basin and restricted lagoon interpretations.

The areal distribution of Collingwood strata was estimated by Churcher et al. (1991)

(Figure 1). Pleistocene glacial scouring removed the Collingwood Mbr. north and east of St.

Joseph's Island, Manitoulin Island, Craigleith, and Bowmanville, exposing older parts of the

carbonate shelf and Precambrian Shield (Churcher et al., 1991). Collingwood Mbr. strata were

reported to thin basinward toward the Michigan and Appalachian basins (Churcher et al., 1991;

Johnson et al., 1983; Hiatt, 1985; Hiatt and Nordeng, 1985). According to Russell and Telford

(1983) total organic carbon content (TOC) also decreases basinward. A thin phosphatic bed was

reported to replace Collingwood Mbr. strata basinward (Michigan Basin) of its pinchout

(Churcher et al., 1991). According to Churcher et al. (1991), Collingwood strata have been

identified as outliers in only a few holes in Southwestern Ontario (see Figure 4).

2

The lithologic content of the Collingwood Mbr. and its stratigraphic boundary contacts

were defined in the stratigraphic revision proposed by Russell and Telford, (1983). Russell and

Telford (1983) based their stratigraphic revision and conception of the “Collingwood Mbr.” on

(a) mappable geophysical borehole log signatures and (b) similarities in correlative lithologies

across the region. However, preliminary investigation of these strata and geophysical borehole

logs indicated to the author regional differences in facies, section thickness, and contact

boundary conditions that suggest the lithostratigraphic formation model adopted by Russell and

Telford (1983) is problematic.

Regional differences in facies, section thickness, and contact boundary conditions would

explain much of the variability not only in environmental interpretations but also in pre-OSAP

geologic reports on lithologic content and boundary contacts. “With great understatement” was

the comment Russell and Telford (1983) used to acknowledge Winder’s (1961) declaration that

geologic reports showed inconsistencies.

Geophysical borehole log profiles ( gamma and resistivity) of Collingwood Mbr. strata

have been described as “characteristic” in the Michigan Peninsula by Hiatt and Nordeng (1985);

Wilson and Sengupta (1985), and in Ontario by Russell and Telford (1983); Churcher et al.,

(1991). The purpose of this study was to determine if a petrophysical chemostratigraphic

approach (using geophysical borehole logs) to compare and correlated Collingwood strata in

South-central Ontario would provide a better understanding of these strata. In addition to the

petrophysical chemostratigraphic comparison and correlation a microfacies analysis and review

of the biostratigraphic data was also conducted. The petrophysical chemostratigraphic

comparison and correlation of Collingwood strata in central Ontario was also compared to

reportedly correlative strata in the Michigan Peninsula.

3

2.0 STRATIGRAPHIC REVIEW

A comprehensive review of pre-1983 stratigraphic nomenclature and age attribution for

strata equivalent to the Collingwood was conducted by Liberty (1955; 1969). Another

researcher, Winder (1961), produced a lexicon of Palaeozoic names in Southwestern Ontario, in

which the various stratigraphic nomenclature uses were discussed. Figure 2 summarizes and

compares the historic and current stratigraphic nomenclature use in South-central Ontario. In

addition Figure 2 presents the current stratigraphic nomenclature for Southwestern Ontario and

Eastern Ontario.

In 1983, Russell and Telford used OSAP data to propose a stratigraphic reassignment of

Liberty’s (1969) Craigleith Mbr. of the Whitby Fm. (see Figure 2). The Craigleith Mbr. was re-

named the Collingwood Mbr. and re-assigned to the Lindsay Fm. The name “Collingwood”

(first used by P.E. Raymond in 1912) has historically been in use variably as an age and/or

lithologic assignment. Historic descriptions of lithologic content and contact definitions will in

part be discussed in later sections of this study.

At present Collingwood strata are interpreted to be early Upper Ordovician in age

(biostratigraphic age: Maysvillian). In South-central Ontario Collingwood strata are included as

the upper most strata of the combined Simcoe and Basal Groups (equivalent to the Trenton-

Black River Group of Southwestern Ontario and the Michigan Peninsula). In Ontario the upper

Collingwood contact boundary represents the upper boundary of Depositional Sequence 2.

According to Johnston et al. (1991), Depositional Sequence 2 is comprised of primarily craton

derived clastic rocks succeeded by shallow water carbonates and is roughly equivalent to the

Sauk-Tippecanoe sequence of Sloss (1963, 1988)(Johnston et al., 1991) Figure 2. Note however,

that this “sequence boundary” was largely based on the break between predominately carbonate

vs. clastic deposition and does not represent an erosional unconformity in the sense of Mitchum

et al. (1977) (Melchin et al., 1994).

Collingwood strata are reported to be equivalent to the Boas River Fm. (Hudson Bay and

Moose River basins) and the Eastview Mbr. of the Lindsay Fm. (Eastern Ontario) (see Johnston

et al. (1991). However, it was beyond the scope of this study to review those strata. The Boas

River Fm. and the Eastview Mbr. (Lindsay Fm) are separated from Collingwood strata in South-

central Ontario by large distances over which equivalent strata have been removed during

4

Pleistocene glaciation. Therefore, a petrophysical chemostratigraphic comparison of these strata

would require much speculation. To date the relatedness of these strata is based on similar

lithologic and biostratigraphic data.

5

3.0 GEOLOGICAL SETTING

During the Middle Ordovician, closure of the Iapetus Ocean resulted in a series of

collision events at the eastern margin of Laurentia (North America). The subduction of Iapetus

crust and collision with an island arc (Rowley and Kidd, 1981; Cisne et al., 1982; Hay and Cisne,

1988) and or microcontinent/s (Delano et al., 1990) produced the Taconic orogen. Lithospheric

downwarping associated with cratonward loading of thrust blocks (taconic allochthon) produced

a peripheral foreland basin (the Western Taconic Foreland) (Rowley and Kidd, 1981; Quinlin

and Beaumont, 1984; Lash 1988; Bradley and Kidd, 1991). The eastern portion of a shallow

marine carbonate platform now drowned and faulted formed the floor of the basin. Movement

along high-angled faults with strike parallel to the basin axis (north-northeast-south-southwest)

produced grabens and half grabens on the deeper eastern portion of the basin (Cisne et al., 1982;

Bradley and Kidd, 1991). Siliciclastic deposition in the basin migrated with time to the

northwest encroaching on the Trenton carbonate platform/ramp (Rowley and Kidd, 1981;

Bradley and Kusky, 1986; Lehman et al., 1995). The upper Collingwood Mbr. boundary (base

of Blue Mountain Fm.) is thought to represent the first arrival in Ontario of the migrating

siliciclastics (see Johnson et al., 1991).

Today the Michigan and Appalachian basins separated by the Central and Western St.

Lawrence platforms dominate the subsurface (see Figure 5). The Algonquin Arch runs centrally

through the Western St. Lawrence platform producing the only significant topographic relief on

the platform. Similarly the Frontenac Arch (Johnson et al., 1991) interrupts the Western and

Central St. Lawrence platforms. The Laurentian Arch continues northeastward from the

Algonquin Arch.

At the northernmost outcrop (Manitoulin Island), Figure 3, a localized Precambrian

metaquartzite mound is unconformably overlain by Lower Mbr. and Collingwood Mbr. strata

(Johnson and Jia-yu, 1989) (Goldman and Bergstrom, 1997). The development of a short-lived

metaquartzite boulder beach in that area is interpreted to indicate a rapid transgression across the

Precambrian metaquartzite mound (Johnson and Jia-yu, 1989. The Collingwood Mbr. has not

been recognized south of Lake Ontario (Lehman et al., 1995)

6

4.0 LOCALTIES AND DATA COLLECTION

Collingwood Mbr. strata, as defined by Russell and Telford (1983), outcrop in 3 laterally

isolated areas in South-central Ontario (Fig. 3). At each of the three outcrop localities the lower

boundary can reportedly be observed. The upper boundary has not been recognized in outcrop.

Therefore, to examine the Collingwood Mbr. and both boundaries at any given geographic point

requires subsurface data (geophysical borehole-logs and/or core). In this study, 3 outcrop and 15

borehole localities (represented by geophysical borehole logs - 7 with core) were examined.

Outcrop and OSAP borehole locations are shown in Figure 6.

5.0 REGIONAL SUBSURFACE STRATIGRAPHY

A stratigraphic cross section through the preserved palaeozoic units in South-central

Ontario is presented in Figure 7. The cross section runs from northwest to southeast along the

Niagara escarpment and shows the generalized progression of lithologic units upwards from the

Precambrian discontinuity. The units have been grouped into Johnston et al.’s (1991)

depositional sequences 1 through 6 (see discussion of depositional sequences in section 3). The

cross section was based on the subsurface correlation work conducted by Armstrong and Carter

(2006) and generalized lithologic descriptions of formation units in Johnston et al. (1991). Table

1 (after Johnston et al., 1991) below, compares the relevant six depositional sequences to the

North American Sequences of Sloss (1963, 1988) (Johnston et al., 1991) and provides the epoch,

period and generalized depositional mode.

7

Table 1

Period, Epoch and Sequence Comparison

Period Epoch Depositional Sequence North American Sequence

Silurian

Late Upper 6 - carbonate and evaporitic deposits. Some orogen derived clastic sediments

Tippecanoe

Middle 5 - extensive carbonate deposition with some shale

Early 4 - orogen derived fluvial to shallow marine clastics

and marine carbonates Lower

Ordovician

Late 3 - orogen derived clastic rocks

2 - initial craton derived clastics then dominated by shallow marine carbonates Middle

Early 1 - predominantly craton derived clastic sediments Sauk

Cambrian Upper

After Johnston et. al. (1991)

8

6.0 MICROFACIES ANALYSIS

The Collingwood Mbr. was reported by Russell and Telford, (1983) to consist of

interbeded limestone and marlstone. The mineral content was reported to be calcite (up to or

greater than 50%), quartz (35%), clays (15% illite and iron chlorite), pyrite, phosphate, and

locally dolomite (Russell and Telford, 1983; Snowdon, 1984; Macauley et al., 1991; Churcher et

al., 1991). Although the lithology and mineralogy of the Collingwood Mbr. has been

investigated and generalized little has been discussed with respect to stratigraphic and lateral

variation of these components. Therefore samples from core and outcrops were collected from

the nodular limestone of the Lower Mbr., marlstones and carbonate interbeds of the Collingwood

Mbr., and shales of the Blue Mountain Fm. A thin phosphatic bed observed at the upper

Collingwood Mbr. boundary, Clarksburg locality, was also sampled.

Thin sections made from core and outcrop samples collected from the nodular limestones

of the Lower Lindsay Mbr., marlstones and carbonates of the Collingwood Mbr., and shales of

the Blue Mountain Fm. were prepared and examined under reflected and transmitted plain and

cross-polarized light using a petrographic microscope. The sections were described by

comparison to the carbonate microfacies of Wilson (1975) and Flugel (1982). A representative

image for each microfacies type appears beside the description. In addition acid resistant

microfossils and minerals were obtained through acid digestion of carbonate samples (2 kg each)

collected from outcrop localities. The microfossils were used as palaeoenvironmental indicators

(note: microfossils collected during this study have been lost).

6.1 Lower Mbr. (Lindsay Fm.) Nodular Limestones. SMF 9, Facies Zone 2

Samples of nodules represent highly bioturbated

argillaceous, organic biomicrite/wakestones with

burrows. The sample shown here was imaged under

transmitted light.

Circular cross-sections of burrows indicate early burial lithification with compression of

burrow cross-sections increasing (up to 100%) toward the darker envelopes surrounding the

nodules. The micritic fabric may be described as microsparite. Pockets of sparry calcite

2mm

9

replacement are common in areas of coarser bioclastic concentration (see Appendix A, Plate 1,

slides 3 &4).

Sparry dolomite replaces much of the calcite at the Manitoulin Island localities (see

Appendix A, Plate 1, slides 1&2). At the Manitoulin Island outcrop locality, the upper contact is

marked by a brecciated quartzite and fining upward (subangular to rounded) Quartzite cobbles,

pebbles, sand and silt. The quartzite clasts appeared in association with a local Precambrian

metaquartzite outlier. Sparse disseminated quartz silt was observed at other localities. At the

Manitoulin Island outcrop locality the Lower Mbr. did not exhibit the nodular bedding. Lack of

nodular bedding at this locality may be due to deposition within a zone of higher energy

associated with the "short-lived boulder beach" interpretation of Johnson and Jia Yu, (1989).

The lack of nodular bedding at the Manitoulin Island locality negated the use of Russell and

Telford’s (1983) described criteria for locating the upper boundary (i.e. – last nodular interbed).

In general these Lower Member samples were comparable with microfacies SMF 9 of

Wilson (1975), in Flugel (1982). While type SMF 9 is associated with either Facies Zone 7 (FZ

7 - Shelf Lagoons with open circulation) or Facies Zone 2 (FZ 2 - Open sea shelf - Deep

undatherm below wave base) Flugel (1982), the nodular bedding and marl associations indicate

they belong to the later Facies Zone (FZ 2).

Recurrent textural inversion from 1 to 8cm thick grainstone interbeds (Facies SMF 10 of

Wilson (1975); Facies Zone 2 of Flugel (1978), is a common feature of these facies and

continues to be a feature in the Collingwood beds described below. These grainstone units were

noted by Tufnell (1986) and Moffat et al. (1998). Tufnell (1986) described these units as

laterally extensive graded storm beds and noted that within drab carbonate facies these units

were often obliterated due to bioturbation. Moffat and Brett (1998) interpreted these units as

autochthonous condensed sections formed during short-term fluctuations in relative sea-level.

Handford and Louks (1993) state that down-dip transport of carbonate turbidites can be initiated

by storms or changes in relative sea-level. According to the carbonate platform facies models of

Read (1985, 1995); Handford and Louks (1993) and Loucks and Sarg (1993), argillaceous

nodular limestone facies represent deep-shelf facies common to drowning carbonate platforms.

Residues produced by acid digestion of outcrop samples contained hexactinellid sponge

spicules, phosphate nodules and conodonts. Preliminary analysis of conodont elements indicated

that Amorphognathus superbus(?) was representative of these facies. At locality 2, abundant

10

large rounded conodont fragments suggested energy sorting and support the higher energy zone

interpretation of Johnston and Jia Yu, (1989) for that locality.

A deep, phosphate rich, cool-water environment is indicated by the presence of

Amorphognathus (Sweet, 1988). However, Sweet (1988) argued that upwelling of cool

phosphate-rich waters may have brought Amorphognathus into shallower water.

6.2 Collingwood Mbr. (Lindsay Fm.) Marlstone SMF 3, Facies Zone 1

Samples represent fine grained (often

fossiliferous) dark organic-rich mudstones, ranging

from calcareous shale to argillaceous micrite. The

sample shown here was imaged under transmitted light.

Alternating dark and light grey laminations are common. Bioturbation is rare to absent

with marked reduction in macrofauna diversity noted. Fine disseminated pyrite with pyrite

replacement of fossils common. Dolomite replaces most of the Calcite at the Manitoulin Island

localities (Appendix A, Plate 1, slide 1&5). At the Manitoulin Island localities a quartz- sand

and silt component, associated with a local Precambrian metaquartzite outlier is restricted to the

base of this unit and rapidly fines upward (Appendix A, Plates 1, slides 1&5). Sparse

disseminated quartz silt was occasionally observed elsewhere – often as a component of

grainstone interbeds. Thin to fine carbonate grainstone units (SMF 10) (textural inversion) fine

upward and are absent in the upper-most Collingwood Mbr. They also appear to be much

reduced in number, thickness, and grain size at localities southeast and northwest of the

Algonquin Arch region.

These samples are comparable with SMF 3 of Wilson (1975) and are associated with

Facies Zone 1 of Flugel (1982) (Basin fondotherm below oxygenation level). Within the Facies

Zone scale of Flugel (1982), (FZ 1) represents an incremental increase in palaeodepth relative to

FZ 2.

Residues produced by acid digestion of outcrop samples (2kg) produced some conodonts

including Amorphognathus superbus? but not hexactinellid spicules or phosphatic pellets. It is

2mm

11

unknown whether or not this was due to environmental exclusion or a shift in preservation

potential.

In the Clarksburg locality core (Clarksburg site is located

within the Collingwood cluster, Figure 6) a phosphatic bed

presumably the “phosphatic” bed described by Churcher et al.

(1991) as erosional remnants of the Collingwood strata was

observed. The sample shown here was imaged under re

transmitted light.

The sample represents an intrasparite/ironstone

(Appendix A, Plate 1, slide 1 through 6) that contains lithoclasts, worn bioclasts, peloids,

ooids(?), and clasts of phosphatic micrite. The carbonate matrix appeared to be dolomitic.

Geopetal filling of shell fragments can be observed.

This unit was comparable to SMF 14 of Wilson (1975)(slow accumulation of coarse

material in a zone of winnowing) and is associated with Facies Zone 6 (FZ 6 - Winnowed

platform edge sands) Flugel (1982). Although autochthonous components are typical of SMF 14

(Wilson, 1975), in this case the dramatic environmental and textural inversion from the deep-

water laminated marlstone facies, SMF 3, (below), indicates a down-dip transport of this material

(allochthonous carbonate turbidite).

According to Churcher et al. (1991), this phosphatic unit was reported to be found where

Rouge River Mbr. and Collingwood Mbr. strata were absent and was interpreted to represent

erosional remnants of these members. However, a review of the geophysical log for the

Clarksburg locality indicated that the locality contains one of the thicker Collingwood sections.

The Clarksburg log will be presented and discussed further in later sections of this report.

12

6.3 Collingwood Mbr. (Lindsay Fm.) Pale Grey and Buff -coloured Carbonate interbeds SMF 9, Facies Zone 2

Samples represent biomicrite/wackestones. The

sample shown here was imaged under transmitted light.

Pockets of sparry calcite replacement are

common in areas of coarser bioclastic concentration. Sparse disseminated quartz silt. Fine

pyrite crystals occasionally cluster around fossils. Grainstone interbeds (1 to 8cm

packstone/coquina interbeds), representing SMF 10 of Wilson (1975), Facies Zone 2 of Flugel

(1982), occur, as textural inversion.

The absence of well developed and or total lack of nodular bedding distinguishes these

facies from the Nodular Limestone of the Lower Mbr. of the Lindsay Fm. These carbonate

interbeds were not observed in core from localities north and south of the Algonquin Arch

region.

Residues produced by acid digestion of outcrop samples (2kg) contained hexactinellid

sponge spicules, phosphate nodules and conodonts. Preliminary analysis of conodont elements

indicates that Amorphognathus superbus(?) is representative of these facies.

6.4 Blue Mountain Fm. Shale/calcareous shale

Samples are best described as calcareous

claystones (often dolomitic) with sparse to rare

disseminated pyrite, bioclasts and silt. The sample

shown here was imaged under reflected light.

The dolomitic component of the shales make Russell and Telford’s (1983) criteria for

locating the upper Collingwood boundary (i.e. the “last calcareous shales” problematic.

6.5 Microfacies Analysis Results

The observed progression of carbonate microfacies types from SMF 9, FZ 2 (Lower

Mbr.) to SMF 3, FZ 1(Collingwood Mbr.) indicated deepening upward conditions. At some

localities upward deepening appeared to be intermittently interrupted as evidenced by brief

2mm

2mm

13

periods of re-established carbonate deposition (SMF 9, FZ 2). In South-central Ontario these

localities were invariably associated with the centroid (represented by the Collingwood cluster

and Corbetton locality) of the study area from the Lower Mbr. through the Collingwood Mbr.

There was a distinct upward reduction in carbonate content, though dynamic, accompanied by an

increase in clay until the carbonate dominated system was ultimately replaced by a clastic clay

dominated system (Blue Mountain Fm.).

7.0 BIOSTRATIGRAHY AND PALAEOBIOLOGY

The data for the biostratigraphic component of this study consists of published ranges for

trilobites, graptolites, conodonts, and chitinazoa (Figure 8). Data obtained from OSAP core and

outcrop localities, published by others, was restored to stratigraphic position and will be

presented and discussed in a latter section of this report. The use of current nomenclature for

generic and specific names was adopted here but reference is made to synonymous names

appearing in the original literature.

7.1 Trilobites

The high abundance of Triarthrus trilobite remains in the shaley interval equivalent to the

Collingwood Mbr through Blue Mountain Fm. inspired Parks (1928) to construct a

biostratigraphic scheme based on the trilobite genus Triarthrus. Utilizing data collected by

Tuffnell (1986) from OSAP core - restored in Figure 1A - Tuffnell (1986); Tuffnell and

Ludvigsen (1984); Ludvigsen and Tuffnell (1984), re-evaluated Park's (1928) trilobite

biostratigraphy. These authors concluded that ranges of Triarthrus species overlapped and

cautioned against the use of Triarthrus as a conventional biostratigraphic tool. However, because

certain species appeared more representative of specific lithostratigraphic intervals, Tuffnell and

Ludvigsen (1984); Ludvigsen and Tuffnell (1984), proposed a battleship type Triarthrus

biostratigraphy (Figure 8). According to Tuffnell and Ludvigsen (1984); Ludvigsen and Tuffnell

(1984), a higher abundance of Triarthrus etoni was associated with Collingwood Mbr. strata

while higher abundances of T. canadensis, T. rougensis and T. spinosus were associated with

Blue Mountain strata (Figure 8).

7.2 Graptolites

According to Riva (1974), strata equivalent to the Collingwood Mbr. were assigned to

the Climicograptus pygmaeus syn. Geniculograptus pygmaeus zone while strata equivalent to the

14

Blue Mountain Fm. were assigned to the Amplexograptus manitoulinensis zone (Riva, 1974).

The Upper Geniculograptus pygmaeus zone was later designated as lower Maysvillian in age

while the A. manitoulinensis zone was designated as upper Maysvillian in age (Bergstrom and

Mitchell, 1986) (Goldman and Bergstrom, 1997) (Figure 8).

7.3 Conodonts

Conodont zonation is reported to be coarse during Maysvillian times and is represented

by a single conodont zone (Amorphagnathus superbus zone) (Goldman and Bergstrom, 1997)

(Figure 8). Conodont specimens recovered during this study appeared consistent with the

Amorphognathus superbus conodont zone.

7.4 Chitinozoa

Chitinozoan data (Figure 8) support a lower Maysvillian age for Collingwood Mbr. strata

but do not offer further time-stratigraphic resolution (Melchin et al., 1994).

The lower sub-unit of the Lower Mbr. (Lindsay Fm.) contains chitinozoan assemblage

ChA-6 dominated by species of Herchochitina with species of Angochitina and Belochitina also

representative (Melchin et al., 1994). The upper Lower Mbr. (Lindsay Fm.) contains chitinozoan

assemblage ChA-8 marked by high species diversity with no individual species dominant

(Melchin et al., 1994). Chitinozoan assemblage ChA-8 is also representative of the Collingwood

Mbr. (Lindsay Fm.). Upward-increasing chitinozoan diversity (from ChA-6 to ChA-8) (Figure

8) in the Lindsay Fm. is interpreted to indicate deepening-upward conditions (Melchin et al.,

1994). Based on the persistence of high planktic chitinozoan diversity across the lower

Collingwood Mbr. Boundary, environmental change, indicated by marked reduction in (a)

bioturbation, (b) infaunal and benthic macrofaunas and (c) increased organic preservation

relative to the Lower Mbr., is interpreted to be restricted to bottom waters (Russell and Telford,

1983; Melchin et al., 1994).

7.5 Biostratigraphy and Palaeobiology Results

The biostratigraphic and palaeobiology data appear to support three conclusions:

• Upward deepening conditions from the Lower Mbr. through the Collingwood Mbr.

• Gradational change from the Lower Mbr. through to the Blue Mountain Fm.

15

• The Lower Mbr. and Collingwood Mbr. strata appear to be Lower Maysvillian in age

with the Blue Mountain Fm. strata assigned as upper Maysvillian in age.

16

8.0 GEOPHYSICAL BOREHOLE LOG CORRELATION

8.1 Method

Churcher et al. (1991) produced a “schematic” gamma log signature depicting the

Collingwood as a linear transition from argillaceous limestone (Lower Member of the Lindsay

Formation) to shale (Blue Mountain Fm.) (Figure 9). According to Churcher et al. (1991), if the

transition zone was absent then the Collingwood was absent. For comparison, Churcher et al.

(1991) presented two examples of each type of “actual” gamma-logs (figure 10). The sample

localities illustrated were from Southwestern Ontario where Collingwood strata, according to

Churcher et al. (1991), exist in a few areas as outliers – presumably the Collingwood was eroded

away from the rest of Southwestern Ontario (see location of outliers in Figure 4). In the

Collingwood distribution/isopach maps presented in Churcher et al. (1991), localities with

Collingwood strata present were identified with the pre-fix WC (“With Collingwood”) while

holes without Collingwood were denoted with the pre-fix NC (“No Collingwood”). A

significant technical problem with their comparison reproduced in figure 10 is that the gamma

log scale (API units) for the NC holes should read 0 to 200 API and not 0 to 100 API. In

addition transposition of signals higher than 100 API units in the WC logs was not conducted for

the comparison. When scaled for comparison the geophysical log signatures for the WC holes

no longer appeared significantly different from the NC hole logs (Figure 11).

WC-36 (with Collingwood) was compared to NC-36 (no Collingwood) (Figure 12). The

two holes are approximately 25 kilometres apart. Re-scaled and normalized NC-36 showed a

very similar “transition zone” and the Collingwood unit (gamma log/petrophysical

chemostratigraphic unit) appeared to be equally present in NC-36 -then why do we not recognize

Collingwood strata in NC-36? – or in general Collingwood strata in Southwestern Ontario?

8.2 Geophysical Borehole Log Identified Unit (Petrophysical Chemostratigraphic approach)

The gamma log line is used to review down-hole changes in stratal clay content. Natural

gamma radiation detected by the tool emanates from radioisotopes of potassium, thorium, and

uranium associated with clay (shale) and organic deposits. The more clay and/or organic

enriched the strata are the higher the gamma log signals are until levels reach the theoretical

“shale line” - indicating shale strata. The resistivity log line is a measure of electrical resistance

to current flow. Accumulation of organic material (hydrocarbons) results in high electrical

17

resistance and thus is an important tool for hydrocarbon exploration. The neutron log line is

produced by irradiating the strata and measuring induced radioactivity. The amount of induced

radiation is proportional to the density of the strata. Therefore the neutron log line is used to

examine differences in stratal density.

Geophysical borehole logs (gamma, neutron, and resistivity) from OSAP holes were

traced, scanned and scaled/normalized for comparison. The upper Trenton boundary (upper

Collingwood Mbr. boundary) was used as the datum. For initial review purposes the

Collingwood boundaries/contacts identified in the OSAP logs by Johnston et al. (1983-1985)

were used. During review of the geophysical and written logs it was noticed that discrepancies

in logged depth existed for many of the Collingwood cluster holes. In those cases where

discrepancies existed between written and geophysical logs the upper and lower Collingwood

boundaries were estimated based on the authors interpretation of the geophysical logs (core was

not available to qualify the estimates).

In South-central Ontario, OSAP data was obtained from three geographically isolated

regions. Within each region a cluster of shallow boreholes exists. These clusters were located in

Toronto, Collingwood, and on Manitoulin Island (Figure 13). There were three deep OSAP

boreholes advanced to tie-in the three clusters (Figure 14). Two of the deep boreholes were

located between the Toronto and Collingwood clusters (the Corbetton and Nobelton holes) and

the other hole was located between the Collingwood and Manitoulin Island clusters (the Wiarton

hole).

Figure 15 shows the Collingwood as it appears in the geophysical record from the three

OSAP clusters in South-central Ontario. A review of Collingwood petrophysical

chemostratigraphy in the Collingwood cluster, Figure 15, revealed that the strata were consistent

and mappable over the entire Collingwood region. Note that Collingwood strata were not fully

penetrated at CLGD4b, CLGD6a, and CLGD7a. The same cannot be said for the Toronto and

Manitoulin Island clusters in Figure 15, where signatures showed differences between localities

within each cluster and between clusters. In the Toronto cluster , Collingwood signatures

indicated that strata thin from left to right (from northeast to southwest). In the Manitoulin

Island cluster the two signatures were similar but did not share the “carbon copy” appearance

that the Collingwood cluster signatures exhibited. Overall the signatures were different between

clusters and the transition interval (Collingwood) showed significant variation in length.

18

Collingwood section thickness ranged from approximately 11.5 to 1.5 metres. The signatures

presented in Figure 15 also revealed that the transition from carbonate dominated to shale

dominated deposition was dynamic.

In order to better evaluate the relatedness of these clusters, geophysical borehole log

signatures for OSAP “tie-in” localities were examined and compared to the cluster signatures.

First, tie-in locality logs were compared to the Collingwood cluster signatures (Figure 16).

Comparison of the Collingwood cluster with the Corbetton Tie-in log (approximately 40

kilometres away) showed little change in stratal composition and revealed that Collingwood

strata were readily mappable between these localities. Collingwood section thickness changed

from approximately 9.58 to 11.5 metres. Comparison between the Collingwood cluster and the

Wiarton Tie-in locality (approximately 30 kilometers away) showed that signatures/strata,

though mappable, were more condensed (reduced in thickness) from Collingwood (9.58 metres)

to Wiarton (6.2 metres). Note the contacts were transposed from the positions indicated in the

Johnston et al. (1983-85) log for Wiarton. The transposition is indicated in Figure 16.

A comparison between the three clusters and tie-in localities is presented in Figure 17.

While Figure 17 provides the reader with a good comparison of overall Collingwood strata

characteristics from north to south in central Ontario, the OSAP tie-in localities are not sufficient

to map changes north and south of the tie-in localities to the Manitoulin Island and Toronto

cluster localities.

The tie-in localities provided the data necessary to map with confidence Collingwood

strata over an approximately 100km distance within the centroid of the study area. However, an

environmental gradient exited somewhere between the Tie-in localities and the Toronto and

Manitoulin Island clusters. An investigation was conducted to determine if logs from sources

other than the OSAP, existed to serve as additional tie-in localities. The unpublished OSAP log

for the Nobelton hole was obtained from the Ministry of Northern Development and Mines.

Other localities that could be used as Tie-in logs were not found. Review of the Nobleton log

indicated that Johnston et al. (1983-1985) placed the lower contact boundary at a

stratigraphically lower position in this well. The boundary was moved to a position that was

more consistent with other localities. This decision will be supported further in latter sections of

this report. The OSAP Nobelton hole was located between the Corbetton hole and the Toronto

cluster (see Figures 14 and 18). Examination of Collingwood strata in the Nobelton log showed

19

that condensation of strata there was comparable in degree to the Toronto cluster and that the

signature did not appear to be serviceable as a tie-in log. In order to proceed with the study a

different approach was needed.

Because the carbonate microfacies and palaeobiology indicated that the nodular

limestone facies of the Lower Mbr. were, like Collingwood strata, consistent with a drowning

carbonate ramp scenario the author decided to determine if these strata too were mappable in the

subsurface and whether or not they could be used to better understand the stratigraphic

relationship between the clusters. However, only three OSAP logs (represented by the tie-in

localities) fully penetrated the Lower Mbr. Therefore, borehole logs from other sources were

obtained and examined.

Comparison of Lower Mbr. strata in the centroid of the study area showed that mappable

geophysical units could be constructed (Figure 19). Comparison of these geophysical borehole

log units to the Toronto and Manitoulin Island clusters (Figure 20) showed that like Collingwood

strata Lower Mbr. strata too exhibited regional differences in relative stratal condensation.

Moreover, like Collingwood strata Lower Mbr. strata become more condensed (thin) north and

south of the Collingwood cluster. The use of geophysical units below the Collingwood provided

stratigraphic control from which to review, in context, regional changes in Collingwood strata in

South-central Ontario. While the correlation of strata from the tie-ins to the Manitoulin Island

and Toronto clusters is here presented as tentative it is clear that Collingwood and Lower Mbr.

strata are more condensed north and south of the centroid (Wiarton, Collingwood cluster, and

Corbetton) of the study area. In some cases the added control required that the lower

Collingwood boundary be moved. The resultant differences are indicated in Figure 20. The

implication of these boundary changes will be discussed in subsequent sections. The next

section is dedicated to an explanation and discussion on condensation and a comparison between

the geophysical signatures and correlative facies observed in core.

8.3 Condensation

The statement that strata are “condensed” implies deposition occurred during a period of

diminished sedimentation rates. Potential causes of diminished sedimentation rates might

include sediment starvation during relative sea-level rise, depth related carbonate stress,

sediment bypass (hard grounds or omission surfaces). While there are many references to

“condensed sections” in the literature including descriptions of how to recognize them and

20

comments about their utility in stratigraphic correlation it is not often stated that condensation is

a relative term. The term is relative because a sediment interval at any given locality may be

more or less condensed compared to the same time correlative interval at other localities within

the region. For example, during drowning of a carbonate dominated system, the effects of depth

related carbonate stress would occur later in shallower areas and earlier in deeper areas. While

both areas will eventually be stressed the shallower area will be less condensed overall. The

converse is true in a clastic dominated deposition system.

In clastic dominated systems chemical/biochemical deposition and preservation are not

important factors therefore, when sediment supply to the basin is interrupted, for example during

sea level rise, a single (hypo) deposition mode (slow rate of sediment supply and accumulation)

produces a thin ”starved” sediment deposit across the basin. Sediment by-pass of topographic

highs may intensify starvation. Therefore in regions of variable palaeotopographic relief we

should expect to observe a range of condensation intensity with gradations in between expressed

in the facies and ultimately time correlative section thickness. In carbonate dominated systems

strata will be thickest over topographic highs and thin toward topographic lows such as basins.

In clastic dominated systems strata may be thickest in topographic lows and thin toward

topographic highs (see schematic drawing in Figure 21). Recognition of these two different

condensation responses to relative sea level rise is important and will be revisited.

Note in Figure 22a, that the “transition intervals” (Collingwood strata) observed in the

gamma logs for the Corbetton and Toronto cluster locality SIS3 are quite different. In the

Corbetton gamma log the transition does not start from the base of the Collingwood like it does

in the SIS 3 log. The less condensed Corbetton section which contains recurrent interbeded

carbonates does not transition until carbonate sedimentation all but ceases in the uppermost

portion of the section. This is in contrast to the Toronto cluster locality SIS 3. In the SIS 3

gamma log the transition begins at the base of the Collingwood and continues upward throughout

the Collingwood. If Collingwood section thickness at SIS 3 were reduced in thickness compared

to the Corbetton section due to post depositional erosion as proposed by others then the SIS 3 log

would appear more carbonate rich and lack a ”transition” (Figure 22b).

To demonstrate how regional differences in stratal condensation indicated in the

geophysical record are exhibited in the lithofacies a comparison of OSAP core with

corresponding gamma logs was conducted. Some of the core recovered during the OSAP project

21

was available for study through the Ontario Ministry of Northern Development and Mines

(MNDM). The core was re-measured, sampled, and described. A comparison of the available

core sections with their corresponding gamma log signatures is presented in Figure 23.

One significant observation to be made in Figure 23 is that the thickest Collingwood

strata which are located in the centroid of the study area (represented by the Collingwood cluster

and Corbetton hole) contained interbeded light coloured carbonates while Collingwood strata in

the Toronto and Manitoulin Island clusters did not. Much of the core in the Manitoulin Island

locality was missing, however, in the Toronto localities Collingwood strata were very dark,

graptolitic, and finely laminated throughout indicating they are more condensed compared to the

Collingwood cluster and Corbetton localities. In addition the grainstone interbeds observed in

the Collingwood cluster and Corbetton cores were in the Toronto cluster localities significantly

reduced in thickness and grain size indicating their position as more distal to the source

compared to the centroid of the study region. Clearly the Collingwood sections in Toronto could

not have been reduced to their observed thickness simply by having eroded the tops of thicker

Collingwood cluster like sections – a conclusion already supported by the chemostratigraphic

petrophysical signatures presented in Figures 22a and 22b. This study proposes that variability

in Collingwood section thickness observed in this study resulted from variability in stratal

condensation.

In South-central Ontario the Algonquin Arch (a palaeotopographic high) underlies the

centroid of the study area (refer back to see Figure 5). The presence of less condensed strata

overlying a palaeotopographic high (a topographic high known to pre-date deposition of

Collingwood strata) is consistent with the drowning carbonate ramp scenario supported by the

microfacies and palaeobiology and will be discussed further in later sections.

During review of Collingwood strata in OSAP core it was often difficult to distinguish

grossly between dark coloured carbonates and “marlstones”. This fact resulted in the appearance

(see Figure 23) of carbonate interbeds appearing to dissolve into marlstone from north to south in

the Collingwood cluster through to the Corbetton core. Note however, in the same figure that in

corresponding gamma logs the carbonate rich intervals are indicated to be consistent and

mappable. A look at the outcrop section in the Collingwood area shows that due to weathering it

was more readily subdivided making it appear different from the Collingwood cluster core.

Clearly the gamma log line provides a more accurate measure of lithic changes compared to

22

gross examination. That said gross examination of the strata and comparison with the gamma

logs revealed that Collingwood strata exhibit significant regional differences in light vs. dark

colouring (the reader is notified that the fill pattern used in Figure 23 does not show the reader

the range in dark colouring – from dark grey to black and even brown-black).

The Clarksburg core, which shared the same “carbon copy” gamma log signature with the

other Collingwood cluster sites, was the lightest in colour overall and appeared to contain the

fewest number of “marlstone” interbeds (Figure 23). This was noteworthy because the light

coloured appearance of these strata made them look less Collingwood-like. Furthermore, at the

top of this Collingwood section was a “thin phosphatic bed” like that reported by others to

replace the Collingwood at localities where it was interpreted to be removed due to erosion.

Another OSAP hole (CLGD No. 17, geophysical log unpublished and unavailable)

located just west of the Clarksburg hole was described by Johnston et al. (1983), to contain only

2 metres of Collingwood strata. This seems anomalous since the same authors reported

approximately 10 metres of Collingwood strata throughout the rest of the Collingwood cluster.

CLDG No. 17, like the Clarksburg hole may have contained light coloured facies much of which

were not recognized as “Collingwood”. The association of lighter coloured lithology and the

phosphatic bed (interpreted here as a down dip transport deposit from shallower water) in the

Clarksburg hole suggests that shallower water with relatively higher oxygen content must have

existed locally.

In Figure 20, compared to Collingwood cluster holes, the Collingwood base appears to be

placed (by OSAP workers) in a stratigraphically older position in the Nobelton hole. Evidently

increased condensation experienced in the Nobleton area resulted in formation of Collingwood-

like strata at an earlier period in time (also refer to Figure 23). Similarly gross examination of

the lighter coloured lithologies in the Clarksburg and CLGD No. 17 localities might result in a

decision to place the Collingwood base at a stratigraphically younger position. In summary,

regional differences in stratal condensation have led to miss-identification of the lower

Collingwood boundary. That said the lighter coloured facies variant though related to

condensation was not necessarily accompanied by differences in Collingwood section thickness

(see Figure 23). Differences in light vs. dark colouring observed in the carbonate interbeds are

interpreted to be due to variation in organic preservation potential. It would appear that organic

preservation potential like condensation increased off-Arch.

23

The characteristic and mappable petrophysical chemostratigraphic signatures presented in

this study are interpreted by the author to be formed in the following manner. Concomitant with

carbonate sedimentation on the ramp is entrainment of trace amounts of terrigenous clay

minerals from suspension. While carbonate sedimentation rates fluctuate over time and across

the region the clay content at any given time in suspension would remain somewhat uniform

regionally. Thus due to dynamic fluctuations in sedimentation through time the entrained clay

minerals at a given point in time produce a signal that is regionally encoded. Together these clay

mineral encoded points in time begin to stack and produce unique mappable signatures across the

region.

8.4 “Collingwood” Strata in Central Ontario and the Michigan Basin

In order to better understand the relatedness between Collingwood strata in Ontario and

the Michigan Peninsula their respective stratigraphic positions in the geophysical record were

reviewed in context to the entire carbonate ramp sequence from the “Collingwood” down to the

Shadow Lake Fm. In South-central Ontario these combined strata are referred to as the Simcoe

Group while in Southwestern Ontario and in the Michigan Peninsula they are referred to as the

Trenton and Black River Group. A comparison between representative Trenton and Black River

Group sections in the Michigan Peninsula with the Corbetton hole in South-central Ontario is

presented in Figure 24a & b.

The Michigan Peninsula correlation was conducted by others using the “TG-1 and TG-2

doublets” (highly mappable bentonites) used by subsurface workers to locate boundaries in the

subsurface (Wilson and Sengupta, 1985; Wilson et al., 2001). Figure 24a & 4b illustrate 3

important facts:

1) there is significant regional variation in combined section thickness. (Note: this

comparison does not present the full range of regional differences in section

thickness. Sections in the southern portion of the basin in Ontario and the US are

much thicker still).

2) while overall Trenton -Black River Group sections in the Michigan Peninsula

correlation thin northward in a shallowing direction – Collingwood strata become

significantly thicker in that direction.

3) Collingwood strata are mappable into the Michigan Peninsula but the base of the

Collingwood in the Michigan Peninsula correlation appeared to be placed

24

stratigraphically lower/older than in Ontario (again like the Nobelton hole in

Ontario, the increased degree of condensation exhibited in these Michigan

Peninsula localities compared to the Corbetton locality appeared to result in

earlier deposition of Collingwood-like strata there).

In the Michigan Peninsula correlation and in the South-central Ontario study area

Collingwood strata appear to become less condensed in a shallowing direction, north toward the

basin rim in the Michigan Basin and over the Algonquin Arch in South-central Ontario.

8.5 Datum, Stratal Condensation and Boundary Contacts

The “Upper Collingwood boundary” is reportedly equivalent to Johnson et al.’s (1991),

“upper boundary for depositional sequence 2”, and was used as the datum in this study.

According to Johnson et al. (1991), the datum is supposed to represent the boundary between

two modes of deposition (from carbonate dominated to clastic dominated) (see Johnson et al.

(1991). However, due to regional differences in stratal condensation and palaeotopography the

datum, like the lower Collingwood boundary, may not represent a strict time-stratigraphic feature

– a result that should be expected. To explain this fully we need to return to the discussion on

differences in carbonate vs. clastic deposition response to sea level rise. During initial deposition

of “Collingwood” strata under upward deepening conditions, rate of carbonate deposition was

the limiting factor in Collingwood section condensation. However, during clastic dominated

deposition the limiting factor in section condensation would be sediment supply (proximity of

the locality to the prograding clastic wedge and potential by-pass of topographic highs.

In South-central Ontario the datum was placed at the upper Collingwood Mbr. boundary

identified in the OSAP geophysical logs. Placement of the datum in the centroid of the study and

to a lesser degree in the Toronto cluster appeared intuitive; however, placement of the datum in

the Manitoulin Island cluster appeared to be more arbitrary. In the Manitoulin Island sections,

upper Collingwood like conditions appeared to re-establish above the datum. The reader can

observe this by reviewing the Upper Collingwood boundary in Figure 17. To understand better

these uppermost Collingwood strata more extensive borehole coverage linking tie-in localities

with the Toronto and Manitoulin Island clusters would be necessary.

The conventional explanation for the more concentrated upper Collingwood boundary in

the Collingwood area is that the bituminous Rouge River Mbr. shales of the Blue Mountain Fm.

25

identified in the Toronto area were subsequently eroded from the Collingwood area sites (see

Churcher et al., 1991). An alternative explanation but similar in result would be that sediment

by-pass of the Arch may have produced a much condensed interval/surface there while

accumulation of organic clays was experienced in deeper localities (less condensed) north and

south of the Algonquin Arch. In either event the biostratigraphic zonation boundaries and

palaeobiology data presented in Figures 8 and 25 do not offer evidence for a natural boundary

(upper Collingwood boundary). The upper “Collingwood” boundary appeared to be transitional

with no significant loss of time indicated.

The phosphatic unit observed at the upper Collingwood boundary in the Clarksburg

locality and apparently found at other localities in Southwestern Ontario and the Michigan Basin,

suggests that shallower water conditions existed in proximity to those localities. In the Michigan

Basin, Wilson and Sengupta (1985), report that sections consistently reflect facies that grade

from crinoidal shoal facies in the south along the north flank of the Findley Arch (southwestward

extension of the Algonquin Arch) to deeper water dark organic wakestone facies in the north.

With the Taconic foreland basin to the south of the shoal shelf-like environment along the

Findley Arch these authors concluded that a restricted lagoon environment existed north of the

Findley Arch and that Collingwood strata were deposited in the lagoon during a period of

maximum restriction (during sea level drop) – a similar conclusion was drawn in Ontario by

Churcher et al. (1991). However, in Central Ontario maximum observed Collingwood unit

thickness occurs in the region over the Algonquin Arch and since it is well established that the

Algonquin Arch pre-dates the Collingwood, a “restricted lagoonal environment” was unlikely.

Moreover, as previously discussed above, microfacies analyses of the “nodular limestones” and

“marlstones” over the Algonquin Arch region in South-central Ontario indicated a deep open

shelf and deeper environments rather than a lagoonal one. That said the observation of less

condensed Collingwood strata in the Algonquin Arch region in Central Ontario was consistent

with the findings of Wilson and Sengupta (1985) and Hiatt and Nordeng (1985), that the Findley

Arch (southwestward extension of the Algonquin Arch) was the site of shallower higher energy

water relative to regions north and south of the arch.

26

9.0 DISCUSSION AND CONCLUSIONS

CONCLUSIONS

The OSAP drilling program/sampling strategy, designed primarily to assess the economic

potential of Ontario’s oil shales, resulted in some regions being under- represented (where

Collingwood strata were located deep within the subsurface) while other regions (where

Collingwood strata were located at or near surface) were well represented by clusters of shallow

boreholes. Presumably with “economic potential” being the main consideration, Collingwood

strata located deep within the subsurface would not be readily exploitable and thus not as

important to the OSAP mandate. Only 3 deep boreholes exist from which to tie-in and

investigate Collingwood strata between outcrop localities – some tens of kilometers apart. While

this sampling strategy was considered adequate for the gross lithostratigraphic survey conducted

by Johnson et al. (1983-1985), and Russell and Telford (1983), the sampling bias presents a

challenge to those who wish to study in more detail development of strata across the region. To

this limitation was added the fact that where Collingwood strata were well represented by drill

holes the drill holes did not penetrate much if at all beyond the Collingwood.

These limitations were in part overcome by the use of data from strata located below the

Collingwood and by incorporating geophysical data from sources other than the OSAP. To

qualify further the conclusions made using the geophysical correlation of Collingwood strata a

microfacies analysis was conducted using core and outcrop samples. In addition a

palaeobiologic and a palaeostratigraphic review were also conducted. The Lower Mbr. strata of

the Lindsay Fm. like Collingwood strata appeared to be deposited during upward drowning of

the ramp. Both “Collingwood” and “Lower Mbr.” strata appeared to be highly correlatable

across the region in South-central Ontario.

The gross lithostratigraphic correlation and lithostratigraphic formation re-assignment

advanced by Russell and Telford (1983) did not appear to resolve questions regarding

palaeoenvironmental context and timing. The failure to recognize in the “Collingwood” both

regional and temporal changes in facies as related to changes in environment has led to historic

confusion about Collingwood boundaries and composition and frustrated attempts to reconstruct

palaeoenvironmental conditions. Historically, palaeoenvironmental interpretations tended to be

isostatic environmental settings such as “normal shallow marine shelf”, “deepest shelf”, stranded

27

basin” or “lagoonal” and neither of these static environments would explain the wide variety of

facies collectively referred to in South-central Ontario as the “Collingwood”.

A study of the geophysical borehole log records, core, palaeobiologic and

biostratigraphic data were used to examine Collingwood strata in South-central Ontario. The

following is a brief summary of results:

• Carbonate Microfacies types: in Ontario, carbonate microfacies types grade

upwards and off arch from SMF 9 (FZ2) to SMF 3 (FZ1). This facies progression

represents a shift from open sea shelf –deep undatherm below wave base to basin

fondotherm below oxygenation level – consistent with deepening upward

conditions.

• Palaeobiologic and Biostratigraphic data: a shift from Chitinozoan assemblage

ChA-6 to ChA-8 in the upper Lower Member, Lindsay Formation and extension

into the Collingwood Mbr. indicated upward deepening conditions. The

dominance of the Triarthrus trilobites (a slope biofacies) and deep cool water

conodonts Amorphognathus are consistent with a deeper water interpretation.

• Geophysical: An upward and off-arch increase in strata condensation was

observed in the petrophysical chemostratigraphic data. The data was consistent

with the carbonate microfacies observed in core and outcrop samples.

Comparison of a South-central Ontario section with a Collingwood correlation in

the Michigan Basin showed that upward deepening conditions caused a

significant regional shift in overall stratal geometry from basinward thickening

carbonate sequences to strata that thicken in a shallowing direction – toward the

Algonquin arch and the Michigan basin rim. Together the data presented in this

study support an upward drowning ramp scenario.

DISCUSSION

Without a stratigraphic reference point from which to compare Collingwood strata

to extrabasinal formations such as the Boas River Fm. it is not possible to

determine whether or not they represented part of an extensive time correlative

event or if they represent separate events staggered in time. Even comparison of

28

Collingwood strata in South-central Ontario with localities in Ottawa, Ontario,

would be problematic. Not only are these Ottawa sections isolated by hundreds of

kilometers from sections to the west but thermal maturation experienced in the

Ottawa region had significantly altered the electrical resistance of the unit and

therefore the “Characteristic” resistivity borehole log profile. That being said

Ottawa localities exhibited both bio- and litho-facies development most

comparable to Collingwood cluster localities suggesting they shared a similar

palaeoenvironmental history. Raymond (1912) first coined the “Collingwood

Formation” based on similarities between these two localities.

In Ontario, the Collingwood has been reported to share the same geochemical

characteristics as reservoir hydrocarbons in Southwestern Ontario Snowdon,

(1984); Obermaeyer et al. (1999). However no satisfactory explanation existed to

account for the migration of hydrocarbons from South-central Ontario to

Southwestern Ontario. Currently Trenton strata in Southwestern Ontario (where

Collingwood strata were reported absent) are now thought to be self- sourcing

(see Obermaeyer et al. 1999). Based on the conclusion here that the Collingwood

was deposited under a widespread drowning ramp scenario combined with a

preliminary look at the petrophysical chemostratigraphic data in a few localities

located in Southwestern Ontario it is likely that the “self sourcing strata” are time

correlative with the Collingwood. In part the time correlative facies in

Southwestern Ontario may be a lighter coloured facies variant. According to the

drowning carbonate ramp model hydrocarbon accumulation is expected to occur

in palaeotopographic highs which are often dolomitic much like the reservoirs in

Southwestern Ontario.

Beyond the academic interest in Collingwood strata there may be an economic

reason to advance further the work initiated by this study. A recent study by

Carter et al. (2005) states that since 1984, 39 new Trenton-Blackriver oil and gas

pools have been discovered with oil production up from 60,000 barrels/year to

over 1,000,000 barrels/year. Carter et al. (2005) estimated that 83% of the natural

gas and 40% of the oil resources are still undiscovered. A detailed borehole-log

and facies study of Southwestern Ontario should prove invaluable both from the

standpoint of hydrocarbon exploration and to further our recognition of the extent

29

and scope of facies produced during this drowning event. Because this region of

the basin contains hydrocarbons many boreholes were advanced from which data

is available for future investigation.

Since initiation of this study two significant geophysical subsurface studies have

been conducted (one in the Michigan Basin by Wilson et al. (2001), and one in

central and Southwestern Ontario by Armstrong and Carter (2006)). It appears in

both cases that the researchers constructed the correlations using a

lithostratigraphic approach for control rather than using the petrophysical

chemostratigraphic data and core to examine facies progressions. For example, if

the Collingwood was not recognized in the core then regardless of the

petrophysical chemostratigraphic data/signature the Collingwood would be

dismissed from the correlation at that point.

30

10.0 REFERENCES

Armstrong, D.K., Carter, T.R., 2006, An Updated Guide to the Subsurface Paleozoic

Stratigraphy of Southern Ontario, Open File Report 6191.

Bergstrom, S.M., Mitchell, C.E., 1986. The graptolite correlation of the north American Upper

Ordovician Standard. Lethaia, 19, p. 247-266

Bradley, D. C., and Kidd, W.S. F., 1991, Flexural extension of the upper continental crusts in

collisional foredeeps: Geological Society of America Bulletin, c. 103, p. 1416-1438.

Bradley, D. C., and Kusky, T. M., 1986, Geologic evidence for rate of plate convergence during

the Taconic arc-continent collision: Jour. Geology, b. 94, p. 667-681

Carter, T. R., McFarland, S., Trevail, R. A., Gorman, J. Walsh, P., 2005, Trenton-Black River

Hydrothermal Dolomite Resevoirs in Ontario: Geology, Reserves and Potential Resources.

AAPG Annual Meeting, June 19-22, 2005, Calgary, Alberta,(Abstract).

Churcher, P.L., 1986. Middle Ordovician (Trenton) disconformity in Michigan and lllinois

Basins: subaerial or submarine origin? American Association of Petroleum Geologists,

Bulletin, 70(8):1064 (abstract).

Churcher, P.L., Johnson, M.D., Telford, P.G., & Barker, J.F., 1991. Stratigraphy and oil shale

resource potential of the Upper Ordovician Collingwood Member, Lindsay Formation,

Southwestern Ontario. Ontario Geological Survey, Open File Report 5817, 98p.

Cisne, J. L., Karig, D.E., Pabe, D.D., and Hay, B.J., 1982, Topography and tectonics of the

Taconic outer trench slope as revealed through gradient analysis of fossil assemblages:

Lethaia, v. 15, P. 229-246

Coniglio, M., Melchin, M.J., and Brookfield, M.E., 1990. Stratigraphy, sedimentology and

biostratigraphy of Ordovician rocks of the Peterborough-Lake Simcoe area of southern

31

Ontario; A.A.P.G., 1990 Eastern Section Meeting, hosted by Ontario Petroleum Institute,

Field Trip Guidebook no. 3, 82p.

Delano, J. W., Shirnick, C., Bock, B., Kidd, S. F., Heizler, T., Putnam, G. W., Delong, S. E., and

Ohr, M., 1990, Petrology and geochemistry of Ordovician K-bentonites in New York State:

Constraints on the nature of a volcanic arc: Journal of Geology, v. 98, p. 157-170.

Flugel, E., 1982. Microfacies analysis of limestones. Berlin-Heidelberg-New York: Springer

Goldman, D., & Bergstrom, S.M., 1997. Late Ordovician graptolites from the North American

midcontinent. Palaeontology, 40(4): 965-1010.

Handford, C.R., Louks, R.G., 1993. Carbonate depositional sequences and systems tracts;

responses of carbonate platforms to relative sealevel rise. AAPG Memoir 57, p3-41.

Hay, H. B., and Cisne, J.L., 1988. Deposition in the oxygen-deficient Taconic foreland basin,

Late Ordovician, in Keith, B. D., ed., The Trenton Group (Upper Ordovician Series) of

Eastern North America: American Association of Petroleum Geologists, Studies in Geology,

v. 29, p. 113-134.

Haq, B.U., Hardenbol, J. and Vail, P.R., 1987, Chronology of fluctuating sea levels since the

Triassic. Science,235,p.1156-1166.

Hiatt, C.R., 1985. A petrographic, geochemical and well log analysis of the Utica Shale-Trenton

Limestone transition in the northern Michigan Basin; unpublished M.Sc. thesis, Michigan

Technical University, Michigan, 152p.

Hiatt, C.R. & Nordeng, S., 1985. A petrographic and well log analysis of five wells in the

Trenton-Utica transition in the northern Michigan Basin, in Michigan Basin Geological

Society, Special Paper No.4, 1985

Johnson, M.D., Russell, D.J., & Telford, P.G., 1983. Oil shale assessment project, Volume 1

Shallow drilling results 1981/82. Ontario Geological Survey Open File Report 5458, 36p.

32

Johnson, M.D., Russell, D.J., & Telford, P.G., 1983. Oil shale assessment project, Volume 2

Drillholes for regional correlation 1981/82. Ontario Geological Survey Open File Report

5459, 20p.

Johnson, M.D., Russell, D.J., & Telford, P.G., 1985. Oil shale assessment project, Volume 2

Drillholes for regional correlation 1983/84. Ontario Geological Survey Open File Report

5565, 20p.

Johnson, M.E., Jia-Yu, R., 1989. Middle to Late Ordovician rocky bottoms and rocky shore from

the Manitoulin Island area, Ontario, in Canadian Journal of Earth Sciences, v.26,Number4,

p.642-653.

Johnson, M.D., Armstrong, D.K., Sanford, B.V., Telford, P.G., & Rutka, M.A., 1991. Paleozoic

and Mesozoic geology of Ontario. Ontario Geological Survey, Special Volume 4, Pt. 2, 907-

1008.

Lash, G. G., 1988a, Middle and Late Ordovician shelf activation and foredeep evolution, central

Appalachian orogen, in Keith, B. D., ed., The Trenton Group (Upper Ordovician Series) of

eastern North America: American Association of Petroleum Geologists, Studies in Geology,

v. 29, p. 37-54.

Lehmann, D.L., Brett, C.E., Cole, R., & Baird, G., 1995. Distal sedimentation in a peripheral

foreland basin: Ordovician black shales and associated flysch of the western Taconic foreland,

New York State and Ontario. GSA Bulletin 107(6): 708-724.

33

Liberty, B.A., 1969. Paleozoic geology of the Lake Simcoe area, Ontario; Geological Survey of

Canada, Memoir 355,201p.

Loucks, R. G. & Sarg, J. F. (EDITED BY) Carbonate Sequence Stratigraphy : Recent

Developments and Applications, Tulsa, Oklahoma, U.S.A., American Association of

Petroleum Geologists, 1993. 545p.p. (ISBN: 0-89181-336-5)

Ludvigsen, R., Tuffnell, P., 1984, The last Olenacean trilobite: Triarthrus in the Whitby

Formation (Upper Ordovician) of Southern Ontario, New York State Bulletin 481.p.183-212.

Macauley, G., Fowler, M.G., Goodarzi, F., Snowdon, L.R., & Stasiuk, L.D., 1990. Ordovician

oil shale - Source rock sediments in the central and eastern Canada mainland and eastern

Arctic areas, and their significance for frontier exploration. Geological Survey of Canada,

Paper 90-14, 51p.

Melchin, M. J., Brookfield, M. E., Armstrong, D. K., and Coniglio, M., 1994. Stratigraphy,

Sedimentology and Biostratigraphy of the Ordovician Rocks of the Lake Simcoe Area, South-

Central Ontario, in Geological Association of Canada/Mineralogical Association of Canada

Joint Annual Meeting, 1994, Waterloo, Ontario, Canada: Field Trip A4: Guidebook 13-15

May 1994.

Mitchum, R.M., Vail, P.R., and Thompson,S., 1977. Seismic stratigraphy and global changes of

sea level; Part2: The depositional sequence as a basic unit for stratigraphic analysis, in

Payton,C.E.(ed.):Seismic Stratigraphy –applications to hydrocarbon exploration: AAPG

Memoir 26, p.53-62.

Moffat, H.A., Brett, C.E., Soldani, D., 1998, Comparative taphnofacies within Ordovician and

Jurassic meter-scale cycles; implications for depositional processes. Geological Society of

America, 1998 Annual Meeting. Geological Society of America 30 (7) p.383.

Parks, W. A., 1928. Faunas and stratigraphy of the Ordovician black shales and related rocks in

Southern Ontario. Transactions of the Royal Society of Canada, 3rd series, section IV,22,p.39-

92.

34

Raymond, P.E., 1912, Invertebrate. Notes on field work in the Ottawa Valley. In summary report

1911. Geological Survey of Canada, p.351-357.

Quinlan, G. M., and Beaumont, C., 1984, Appalachian thrusting, lithospheric flexure, and the

Paleozoic stratigraphy of the eastern interior of North America: Canadian Journal of Earth

Sciences, v. 21, p. 973-996.

Read, J. Fred., 1985. Carbonate platform facies models, AAPG Bulletin, 69(1),p.1-21.

Read, J.F., 1995, Overview of carbonate platform sequences, cycle stratigraphy and reservoirs in

greenhouse and icehouse worlds: in Read, J.F., Kerans, C., Weber, L.J., Sarg, J.F., and Wright

F.W., Milankovitch sea level changes, cycles and reservoirs on carbonate platforms in

greenhouse and icehouse worlds, SEPM Short Course Notes No. 35, p. 1-102.

Riva, J., 1974. A revision of some Ordovician Graptolites of eastern North America.

Palaeontology. Volume 17.

Russell, D.J., & Telford, P.G., 1983. Revisions to the stratigraphy of the Upper Ordovician

Collingwood beds of Ontario - a potential oil shale. Can. J. Earth Sci., 20: 1780-1790.

Rowley, D.B., and Kidd, W.S.F., 1981, Stratigraphic relationships and detrital composition of

the Medial Ordovician flysh of western New England: Implication for the tectonic evolution

of the Taconic orogeny: Journal of Geology, v. 89, p.199-218.

Snowdon, L.R., 1984. A comparison of Rock-Eval pyrolysis and solvent extraction results from

the Collingwood and Kettle Point oil shales, Ontario; Bulletin of the Canadian Society of

Petroleum Geology, 32(3): 327-334.

Sweet, W.C., 1988. The conodonta; morphology, taxonomy, paleoecology, and evolutionary

history of long extinct animal phylums, Oxford monographs of geology and geophysics, 10

p.212.

35

Tuffnell, P. 1986. Triarthrus biostratigraphy of the Whitby Formation (Upper Ordovician) of

Southern Ontario. Masters Thesis, University of Toronto.

Tuffnell, P., Ludvigsen, R., 1984. The trilobite Triarthrus in the Whitby Formation (Upper

Ordovician) of Southern Ontario and a biostratigraphic framework, in Ontario, Geological

Survey, Open File Report 5516.

Wilson, J.L., 1975. Carbonate facies in geologic history. 471pp.30Pls., 183Figs., Berlin-

Heidelberg-New York: Springer.

Wilson, J.L. & Sengupta, A., 1985. The Trenton Formation in the Michigan Basin and environs:

pertinent questions about its stratigraphy and diagenesis, in Michigan Basin Geological

Society, Special Paper No.4, 1985.

Wilson, J.L., Budai, J.M., Sengupta, A., (2001) Trenton-Blackriver Formations of Michigan

Basin. Masera Corporation, Tulsa, Oklahoma, summarized in Search and Discovery Article

#10020 (2001).

Winder, C.G., 1961, Lexicon of Paleozoic names in Southwestern Ontario. University of Toronto

Press, Toronto, Ont.,121p.

0

W

Inferred Isopac map of Collingwood according to Churcher et.al. (1991)

Canadian Shield (Precambrian)

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Figure 1

0m

2.5m

5m

5m 2.5m 0m

10m

7.5m

Collingwood distribution and Isopach Map, Collingwood Member, Lindsay Formation

0m

G.M. Kay1960 (1943, 1948)

Richmondian

Maysvillian

EdenianCn

cin

at

in

ian

Gloucesterian

Collingwoodian

Tre

no

nia

nt

it

in

Pc

on

a

Cobourgian

Shermanian

Kirkfieldian

Rocklandian

Ne

on

tian

alm

Chaumontianian

Lowvillian

Pamelian

lc

eB

akr

ivria

n

B. A. Liberty1964 and present

report

Silurian

Queenston

Georgian Bay

Whitby

Nt

so

ta

wa

ag

aG

rou

p

U

M

L

L

U

Precambrian

Shadow Lake

Gull River

Bobcaygeon

Verulam

Lindsay

ie

p

Sm

coG

rou

BasalGp

L

U

U

L

M

U

L

M

B. A. LibertyLitho-and Biostratigraphy

Interpretation

BasalGp

ie

p

Sm

coG

rou

Nt

so

ta

wa

ag

aG

rou

p

Queens-ton

Silurian

Richmondian

Maysvillian

Edenian(after

Sinclair 1964)

ae

dB

rne

vl

Wild

er

sn

es

oa

Bl

ria

nT

ren

on

ian

t

Cobourgian

Shermanian

Nealtonian

(=Rocklandian;see text underBobcaygeon)

Chaumontian

Lowvillian

Pamelian

Silurian

Upper

Ordovician

?

Middle

Ordovician

Cambrian

Precambrian

G

F

E

D

C

B

A

2

11

2

1

2

1

3

21

3

4

Biostratigraphy Lithostratigraphy BiostratigraphyLitho-

Time

Si

ce

Gr

pm

oo

u

Verulam Fm.

Lindsay Fm.

Bobcaygeon Fm.

Gull River Fm.

Shadow Lake Fm.

(Collingwood Mbr.)

(Lower Mbr.)

after Johnston et. al., (1991)

South CentralOntario

Litho-

ro

Te

nt

nia

n

Shermanian

Kirkfieldian

Rocklandian

Edenian

Maysvillian

Blackriverian

Stage

Se

qu

ee

n

c2

eq

ue

S

en

c3

Sie

se

r

rd

o

Up

pe

Or

vici

an

Mi

dle

Ord

ovi

cia

n

d

Maysvillian

Richmondian

Blue Mountain Fm.

Georgian Bay Fm.

Queenston Fm.

(Craigleith Mbr.)

after B.A.Liberty (1969)

cS

equ

en

e

B.V. Sanford1960

Silurian

Queenston

Meaford-Dundas

Precambrian

Shadow Lake

Gull River

Kirkfield

Sherman Fall

Cobourg

rG

Te

nto

n

rou

p

BasalGp

Blue Mountain

Collingwood

Coboconk

B.A. Liberty1953, 1955

Silurian

Queenston

Dundas-Meaford

Rouge River

iW

htb

yG

rou

p

Precambrian

Shadow Lake

Gull River

Kirkfield

Verulam

Cobourg

ie

p

Sm

coG

rou

BasalGp

Blue Mountain

Craigleith

ota

wN

ta

-sa

gG

pa

Coboconk

L

U

lc

p

Ba

k R

ive

rG

rou

(South-Central Ontario)

(South-Central Ontario)

HISTORIC CURRENT

J.F. Caley and B.A.- Liberty 1950-1952

B.A. Liberty 1952-1953

Queenston

MeafordDundas ‘Fm’

‘Fm’

Gloucester strata

pr

Up

er

Od

ovi

cia

n

Precambrian

Basal beds

Lowville beds

Rockland-Hull beds

Sherman Fall beds

Cobourg beds

ro

Go

Te

nt

n

ru

p

Not recognized

Collingwood Srata

Leray Coboconk

Bla

ck R

ive

r G

rou

p

Pamelia ? beds

Hall beds

Rockland beds

Transition beds

G.M. Kay1937

Gloucester

Chaumont

Sherman Fall

Cobourg

Tre

nto

n G

ou

pr

Collingwood

Rockland = Coboconk

lc

p

Ba

k R

ive

rG

rou

Hillier

Hallowell

Hull

Not recognized

W.A. Parks 1928

Lower Gloucester

Trenton

Upper Cobourg

Upper Collingwood

Lower Collingwood

Lower Cobourg

Trenton (restricted)

Upper Cobourg

Collingwood

Lower Cobourg

Hull Rockland

ren

on

Go

up

Tt

r

Praspora beds

Upper

Collingwood

Lower

Hull Rockland

Picton

Gloucester

Praspora

Fusipira and Hormotoma

Ogygites canadensis

Rafinesquina deltoidea

Crinoid Triplecia extans

Climacogratus typicalis

Goniaceras anceps

Tetradium cellulosum

Onchometopus simplex

Fauna variable

Trenton

Upper Picton

Collingwood

Lower Picton

Hull

Rockland

Utica

Leray

Lowville

Upper Pamelia

Lower Pamelia

reo

nl

eo

Gr

Tn

t i

mst

ne

o

up

Bl

ckR

iv G

rp

a

er

ou

P.E. Raymond

1914 1914 1916 1921

Climacogratus typicalis beds

Ogygites canadensis beds

Hormotoma and Fusispira beds

Rafinesquina deltoidea beds

Praspora beds

Crinoid beds

Damanella beds

Gonioceras anceps Transition beds

‘Calcarenite ‘ beds (Liberty)

Columnaria beds

Tetradium cellulosum beds

Onchometoptus beds

Basal beds

Beatricea beds

‘pre O: simplex beds’ (Liberty)

icG

roU

ta

u

p

aM

pp

ing

Ro

ck-

un

it n

um

be

rs

Silurian

Upper

Ordovician

?

Middle

Ordovician

Precambrian

Time

A2

13

4

O

B1

B2

B3

C1 A

B

C2

D

E AE B

F1

2

G1

G2

oS

imc

e G

roup

Verulam Fm.

Lindsay Fm.

Bobcaygeon Fm.

Gull River Fm.

Shadow Lake Fm.

(Collingwood Mbr.)

(Lower Mbr.)

after Johnston et. al., (1991)

South-CentralOntario

Litho-

reo

Tnt

nia

n

Shermanian

Kirkfieldian

Rocklandian

Edenian

Maysvillian

Blackriverian

Stage

Se

quen

e 2

ce

Sq

uence

3

Sie

s

er

eO

ri

Upp

r d

ov

cian

M

iddle

do

ian

Or

vic

Maysvillian

Richmondian

Blue Mountain Fm.

Georgian Bay Fm.

Queenston Fm.

Tre

nto

n G

rou

p

Sherman Fall Fm.

Cobourg Fm.

Coboconk Fm.

Gull River Fm.

Shadow Lake Fm.

Blue Mountain Fm.

Georgian Bay Fm.

Queenston Fm.

Kirkfield Fm.B

lck

Re

r G

rou

a

ivp

South WesternOntario

Litho-

eS

eq

ue

nc

( Ontario)

CURRENT

ta

oup

Otaw

Gr

Shadow Lake Fm.

Gull River Fm.

Bobcaygeon Fm.

Verulam Fm.

Lindsay Fm.

Eastview Mbr.)

Rockcliffe Fm.

Boas River Fm.

?

Litho- Litho-

Eastern Ontario

Hudson BayMoose River

Basins

Queenston Fm.

Carlsbad Fm.

Billings Fm.

Red Head Rapids Fm.

Churchill River Gp.

Figure 2

Historic and Current Collingwood Nomenclature for Central Ontario

W

Canadian Shield (Precambrian)

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Figure 3Location of Collingwood outcrops in South-central Ontario

Collingwood outcrop

BowmanvilleCraigleith

Sheguiandah

0

W

Inferred Isopac map of Collingwood according to Churcher et.al. (1991)

Canadian Shield (Precambrian)

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Figure 4

0m

2.5m

5m

5m 2.5m 0m

0m

0m

0m0m

0m

0m

0m

10m

7.5m

Isopac Map showing outliers, Collingwood Member, Lindsay Formation

0W C

W

Michigan Basin

Appalachian Basin

Western (W), Central (C) St. Lawrence Platform

Arch Appalachian structural front

Contour on Precambrian basement in metres (Datum: sea level)

Erosional limit of Collingwood Mbr.

Canadian Shield (Precambrian) Utica Trough

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

Frase

rdale Frontenac

rA ch

et

Laur n ian

chAr

Alg

onq

inu

Arhc

rh

Find

lay

Ac

N

-5 00

-1000

-2000

4-000

-6000

8-000

-100

00-1

2000

0

1000-

-4000

-3000

-2000

-1000

-5000

0

-5 00

Figure 5Structural setting

NOTTAWASAGA BAY

COLLING- WOOD

MEAFORD

OWEN SOUND

HANOVER

o44 30'

o80 30'

0 10 km

N

OTOR NTO

LAKE ONTARIO

AURORA

MARKHAM

AJAX

OSHAWA

o79 30' 30'

o44

o44

N

0 10 km

30'o82

o45 30'

o46

0 10 km

N

LITTLE CURRENT

MANITOULIN ISLAND

LAKEURON

H

GA

BA

GEO

RI

N

Y

Manitoulin Island Cluster

Collingwood Cluster

Toronto Cluster

City/Township Limits

International boundary

Railway tracks

SIS4

SIS1

SIS2

SIS3

Bowmanville

CLGD16

ClarksburgCLGD2

CLGD1Craigleith

CLGD4CLGS6a

CLGD7a

SIS5

Sheguiandah

SIS6

** Outcrop

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

NobletonCorbetton

Wiarton

Figure 6

Borehole Outcrop

Nobleton

Corbetton

OSAP Borehole and outcrop location map.

Toronto Cluster

Collingwood Cluster

Manitoulin Island Cluster

300

250

200

150

100

50.0

0.00

-50.0

-150.0

-200.0

-250.0

-300.0

-350.0

-400.0

-100.0

-450.0

-500.0

-550.0

450

400

Precambrian

Cambrian

Shadow Lake

Gull RiverGull River

Coboconk

Bobcageon/Kirkfield

Verulam/Sherman Fall

Lindsay/Cobourg

Collingwood

Blue Mountain and Georgian Bay

Queenston

Manitoulin

Cabot Head

Fossil Hill

Amabel

Guelph

A1-Carb.

Grimsby

Irondequoit

Reynales

RochesterRochester

Gasport

Dyer Bay

St. Edmond

Wingfield

Niagara Escarpment

Niagara Escarpment

Algonquin Ach

r

Elevation(metres above or below sea level)

A

B

Canadian Shield (Precambrian)

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Figure 7Cross section through palaeozoic units (southcentral Ontario) withdepositional sequences indicated by (S#). Based on subsurface correlation work conducted by Armstrong and Carter (2006) and generalized lithologic descriptions of formations in Johnston et. al. (1991).

B

A

S1

S2

S3

S4

S5

S2

S6

S5

S4

Manitoulin IslandOGS-83-5 6V

Howland

Based on:Imperial Oil 528

St. Edmund

OGS-82-4Wiarton

Moray Enterprises Inc.Moray No. 1

Egermont-4-VI.#

Buxton Oil & Gas Ltd..Buxton Bozian No. 1

Arthur 8-25-V

OGS 83-1Halton

Nassagaweya-9-VII

Imperial Oil Ltd.Imperial Oil

Saltfleet-12-IV

Lowrie Holdings Inc.Imperial

Grantham-3-III

RANGES OF GRAPTOLITE SPECIES RANGES OF CONODONT SPECIESTRILOBITEBIOSTRAT

CHITINOZOANDIVERSITY

20 30 40

#OF CHITINOZOAN SPECIES PER ASSEMBLAGE

GraptolitebiozonesN

.A.

Sta

ge

s

N.A

.Se

ries

CIN

CIN

NATI

AN

RIC

HM

ON

DIA

NM

AYS

VIL

LIA

NED

EN

IAN

Am

ple

xog

rap

tus

ma

nito

ulin

ensi

s

Ge

nic

ulo

gra

ptu

sp

ygm

ae

us

C. (D.)Spiniferus

Dic

ello

gra

ptu

sc

om

pla

na

tus

Conodontbiozones

Am

orp

ho

gna

thus

sub

erb

us

Am

orp

ho

gna

thus

ord

ovi

vic

us

From Goldman and Bergstrom (1997)From Ludvigsenand Tufnell (1984)

From Melchin et al. (1994)

SEQ

UEN

CE 3

SEQ

UEN

CE 2

Johnson et al.(1991)

Sequence Stratin Ontario

Re

cto

gra

ptu

sa

mp

lexi

ca

ulis

Ort

ho

gra

ptu

sq

ua

drim

uc

rona

tus

Ort

ho

gra

ptu

s sp

ing

eru

sG

enic

ulo

gra

ptu

s ty

pic

alis

typ

ica

lis

Ge

nic

ulo

gra

ptu

s p

ygm

ae

us

Clim

ico

gra

ptu

stu

bulif

ero

us

‘Gly

pto

gra

ptu

s’ lo

rra

ine

nsi

s

Oth

og

rap

tus

euc

ha

ris

Ge

nic

ulo

gra

ptu

s ty

pic

alis

ma

gnifi

cus

Am

ple

xog

rap

tus

ma

nito

ulin

ensi

sC

limic

og

rap

tus

putil

is

Arn

he

imo

gra

ptu

s a

na

ca

nth

us

Re

cto

gra

ptu

s p

eo

sta

Clim

ico

gra

ptu

s ne

vad

ensi

s

Dic

ello

gra

ptu

s g

ravi

s

Dic

ello

gra

ptu

s c

om

pla

na

tus

Dic

ello

gra

ptu

s o

rna

tus

Clim

ico

gra

ptu

s ha

sta

tus

Ap

he

log

na

thus

po

litus

Am

orp

ho

gna

thus

sup

erb

us

Icrio

de

lla s

up

erb

a

Rho

de

sog

na

thus

ela

ga

ns

Pe

rio

do

n g

rand

isR

hip

ido

gna

thus

sym

etr

icus

Co

lum

bo

din

a o

cc

ide

nta

lis

Co

lum

bo

din

a p

enna

Pro

top

and

ero

dus

insc

ulp

tus

Pse

ud

ob

elo

din

a in

clin

ata

Ple

cto

din

a flo

rid

a

Am

orp

ho

gna

thus

ord

ovi

vic

us

Pse

ud

ob

elo

din

a v

ulg

aris

vulg

aris

Olu

lod

us

ulric

hi

Tria

rthru

s b

ec

kii

Tria

rthru

s e

ato

ni

Tria

rthru

s c

ana

de

nsi

s

Tria

rthru

s ro

ug

ensi

s

Tria

rthru

s sp

ino

sus

Figure 8Comparison of biostratigraphic ranges.

Figure 9Schematic illustration showing how to determine if Collingwood strata are present in the subsurface (Figure 9 from Churcher et al. (1991)).

Actual gamma log examples comparing two holes where collingwood are indicated (WC-35 and WC-36) and two holes where Collingwood strata are not indicated (NC-42 and NC-44) (from Curcher et al. (1991), Figures 10 and 11). Note that the API scales are not comparable. WC-35 and WC-36 log responses above 100 API have not been transposed.

Figure 10

WC-35 and WC-36 from Figure 9 have been re-scaled (approximate) to provide a more meaningful comparison with NC-44 and NC-42. Note that in WC-35 and WC-36, when scaled, the transition from carbonate to shale no longer appears distinctively gradual as was proposed by the authors.

Figure 11

N. DORCH.

NC-36DEREHAM

WC-36

Gamma Neutron

}Collingwood unit identified by Churcher et al. (1991)

Borehole- no Collingwood (NC)

Borehole With Collingwood (WC)

Gamma Neutron

Figure 12

Note that the petrophysical chemostratigraphic units are very similar yet Collingwood strata were not identified in NC-36. Both NC-36 and WC-36 localities are located in Southwestern Ontario approximately 25km apart.

0

100

Scale ft.

NOTTAWASAGA BAY

COLLING- WOOD

MEAFORD

OWEN SOUND

HANOVER

o44 30'

o80 30'

0 10 km

N

TOONTO

R LAKE ONTARIO

AURORA

MARKHAM

AJAX

OSHAWA

o79 30' 30'

o44

o44

N

0 10 km

30'o82

o45 30'

o46

0 10 km

N

LITTLE CURRENT

MANITOULIN ISLAND

LAKEURON

H

GA

BA

GEO

RI

N

Y

Manitoulin Island Cluster

Collingwood Cluster

Toronto Cluster

City/Township Limits

International boundary

Railway tracks

SIS4

SIS1

SIS2

SIS3

Bowmanville

CLGD16

ClarksburgCLGD2

CLGD1Craigleith

CLGD4CLGS6a

CLGD7a

SIS5

Sheguiandah

SIS6

** Outcrop

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Toronto Cluster

Collingwood Cluster

Manitoulin Island Cluster

Figure 13

Borehole Outcrop

Location map for boreholecluster and outcrop localities

NOTTAWASAGA BAY

COLLING- WOOD

MEAFORD

OWEN SOUND

HANOVER

o44 30'

o80 30'

0 10 km

N

OTOR NTO

LAKE ONTARIO

AURORA

MARKHAM

AJAX

OSHAWA

o79 30' 30'

o44

o44

N

0 10 km

30'o82

o45 30'

o46

0 10 km

N

LITTLE CURRENT

MANITOULIN ISLAND

LAKEURON

H

GA

BA

GEO

RI

N

Y

Manitoulin Island ClusterCollingwood Cluster

Toronto Cluster

City/Township Limits

International boundary

Railway tracks

SIS4

SIS1

SIS2

SIS3

Bowmanville

CLGD16

ClarksburgCLGD2

CLGD1Craigleith

CLGD4CLGS6a

CLGD7a

SIS5

Sheguiandah

SIS6

** Outcrop

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Nobleton

Corbetton

Wiarton

Figure 14

Borehole Outcrop

Nobleton

Corbetton

Location Map for tie-in boreholes, borehole clusters and outcrops

G R N

G R N

CLGD2 CLGD4b

G GG

GR RR

RN NN

NG R N

G R N

CLGD16 CLGD1 CLGD6a CLGD7a

G GG

GR RR

RN NN

N

Datum (U)

G R N

G R N

SIS5

SIS6

Datum (U)

SIS1

SIS2

SIS3SIS4

GG

G

G

RR

R

R

NN

N

N

Datum (U)

Comparison of Collingwood strata represented in OSAP geophysical logs from the 3 clusters (Manitoulin Island, Collingwood, and Toronto) in Central Ontario. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. Each locality is numbered for reference to Locality Map Figure 6.

Manitoulin Island Cluster

Toronto Cluster

Collingwood Cluster

(L)

(L)

(L)

Figure15

G R N

G R N

CLGD2

G GR RN NG R N

G R N

CLGD16 CLGD1 CLGD4b

G GR RN N

Datum (U)

Comparison between representative Collingwood cluster signatures and signatures from OSAP tie-in localities (Wiarton and Corbetton). The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. The two grey lines on the Wiarton log show the position of the contacts in the Johnston et al. (1983-1985) log.

Collingwood Cluster

(L)

FIGURE 16

G R N

G R N

Tie-inWiarton

Tie-inCorbetton

G R NG R N

Datum(U)

Comparison between OSAP tie-in localities and the Manitoulin Island, Collingwood, and Toronto clusters. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.

(L)

FIGURE 17

G R N

G R N

G R N

G R N

GG

G

G

RR

R

R

NN

N

N

Manitoulin Island Cluster Toronto ClusterTie-inCorbetton

Tie-inWiarton

Collingwood ClusterRepresentative

SIS5

SIS6

CLGD16SIS3

SIS2

SIS1SIS4

G R NG R N

Datum (U)

Comparison between OSAP tie-in localities (including the Nobleton locality) and the Manitoulin Island, Collingwood and Toronto clusters. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. In the Nobleton log the two gray lines mark the position of the Collingwood boundary contacts indicated in the Johnston et al. (1983-1985) log.

(L)

FIGURE 18

G R N

G R N

G R N

G R N

SIS6SIS4SIS1

SIS2

GG

G

G

RR

R

R

NN

N

N

Manitoulin Island Cluster Toronto ClusterTie-inCorbettonWiarton

Collingwood ClusterRepresentative

G PR

Tie-inNobleton

SIS5 CLGD16 SIS3

Datum (U)

Comparison between deep OSAPborehole Tie-in localities and signatures from two localities outside of the known Collingwood range. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.

(L)

FIGURE 19

Tie-inCorbetton

G PR

Elma Maryborough

G

G

N

NG R N

Tie-inWiarton

G R N

Tie-inNobleton

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Wiarton

Maryborough

ElmaNobleton

Corbetton

Shadow Lake Fm.

Shadow Lake Fm.

Datum (U)

Comparison between signatures of representative Collingwood, Toronto, and Manitoulin Island clusters, OSAP tie-in localities, and two additional borehole logs (Elma and Mayrborough). The Elma and Maryborough localities are located outside of the recognized range of Collingwood strata. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.

Collingwood ClusterRepresentative

(L)

FIGURE 20

G R N

G R N

G R N SIS2

SIS3

G

G

R

R

N

N

Manitoulin Island ClusterRepresentative

Toronto ClusterRepresentatives

Tie-inCorbetton

Tie-inWiarton

G PR

Elma

G

G

N

N

SIS5

G R NG R N

CLGD16

Tie-inNobletonMaryborough

LEGEND

Carbonate

Cross section through topographic high

Cross section through topographic high

Terriginous clay

Figure 21

Comparison of condensation response between (A) carbonate vs (B) clastic dominated systems over a topographic high.

(A)

(B)

Tie-inCorbetton

G

G

R

R

N

N

SIS3

{Collingwood {Collingwood

Figure 22a

Variability in Collingwood strata thickness and apparent rate in transition from carbonate to shale chemistry observed in two south-central Ontario borehole logs.

Tie-inCorbetton

G R N

Hypothetical Toronto ClusterLocality.

{Collingwood

Figure 22b

Variability in Collingwood strata thickness if caused by post depositional erosion ( the upper portion of the Corbetton section was removed to create the hypothetical Toronto Cluster locality). Note that the transition would be lost and the gama log indicates that the Collingwood is much more carbonate like which is in contrast to the shale/clay rich composition indicated in the actual Toronto Cluster logs such as SIS3 in Figure 21a above.

G R

N

{Collingwood

-S 5-S 4

77.18m-

425.83m-

414.34m-

120.12m-

118.66m-

37.16m —

30.97m-

62.10m-

52.52m-67.65m-

22.38m-

15.93m-

3

233.93m-

221.01m-

-S 20-S 21

-S16 -S 17

-S 18-S 19

-S 11-S 10

-S 9-S 8

-S 3

-S 2

-S 6-S 1-S 7

-S 26-S 27

-S 28-S 29

-S 30-S 31

DatumP

-S 22-S 23-S 24-S 25

G GG G GGG

Figure 23Comparison between geophysical data and facies. The lower contacts indicated in the Johnston et al. (1983-1985) logs are shown as light grey lines.

SIS5 Corbetton Nobleton SIS3 SIS4Clarksburg CLGD1

U

L

DARK ORGANIC DOLOSTONE AND MARL (UNDIFERENTIATED)

DARK ORGANIC LIMESTONE AND MARL (UNDIFERENTIATED)

Nodular Limestone

Limestone

Sand

=SiltstoneST

=Breccia

Covered interval

=Unconformity

Missing core

P = Phosphate bed

Nodular Dolostone

0.93m-

0.00m-

Craigleith

0m-

3.92m-

Bowmanville

0.00m-

0.30m-

Sheguiandah

-S 40-S 41-S 42

-S 43

-S 44

-S 45

-S 46

-S 36-S 35-S 38-S 37

-S 34

Outcrop Localities

G Gamma Log

Legend

4500

4500

3500

0

100

200

0 200

GAMMA RAY

API UNITS

0 100

GAMMA RAY

API UNITS

100 200

0 150

GAMMA RAY

API UNITS

150 300

DATUM

TRENTON

BLACKRIVER

Pan American Petroleum Co.

D.E. Draysey No 1

Sec. 29, T 35 N. R. 2 E.

Ground Level Elevation 795 5’

Northern Michigan Exploration Co.

State-Waverly No 1-24

Sec. 24, T 35 N. R. 1 W.

Ground Level Elevation 788.9’

Atlantic Inland Oil Corp.

E.G. White & T.R. Burns No1

Sec. 35, T 37 N. R. 4 W.

Ground Level Elevation 704.0’

TG-1

BR-1

Tie-inCorbetton

-A- -B-

-C-

L

S

G

B

B

LOGS FROM MICHIGAN PENINSULA REGION

NOTE: Published pics (base of formations) for well logs are included for comparison as follows:

Bl = Bluemountain Fm.S = Sherman Falls Fm.L = Lindsay Fm.C = Coboconk Fm.Bo = Bobcageon Fm.Gu = Gull River Fm.S = Shadow Lake Fm.

G R

RG

Datum

4500

4500

3500

0

100

200

0 200

GAMMA RAY

API UNITS

0 100

GAMMA RAY

API UNITS

100 200

0 150

GAMMA RAY

API UNITS

150 300

DATUM

TRENTON

BLACKRIVER

Pan American Petroleum Co.

D.E. Draysey No 1

Sec. 29, T 35 N. R. 2 E.

Ground Level Elevation 795 5’

Northern Michigan Exploration Co.

State-Waverly No 1-24

Sec. 24, T 35 N. R. 1 W.

Ground Level Elevation 788.9’

Atlantic Inland Oil Corp.

E.G. White & T.R. Burns No1

Sec. 35, T 37 N. R. 4 W.

Ground Level Elevation 704.0’

TG-1

BR-1

Tie-inCorbetton

-A- -B-

-C-

L

S

G

B

B

LOGS FROM MICHIGAN PENINSULA REGION

G

G

Datum

Figure 24a

Figure 24b

76 W80 W84 W88 W92 W

40 N

44 N

48 N

44 N

48 N

40 N

76 W80 W84 W88 W92 W

0 100 200 km

N

Corbetton

A

B

C

Appendix A, Plate 1

Quartz clast

(1) Gradational contact  between Lower Mbr. and Collingwood Mbr. showing angular quartz clasts in organic rich dolomite matrix. Transmitted light (Manitoulin Island Outcrop) . 

(2) Sparry dolostone, Lower Mbr.. Transmitted light  (Manitoulin Island , SIS 5). 

(3) Secondary sparry calcite infilling of brachiopod.  Note pressure solution features in 

(4) Secondary sparry calcite replacement.  Carbonate interbed.  Transmitted light (Ottawa 

2 mm

calcite on right hand side of slide. Transmitted light (Ottawa Outcrop).

outcrop). 

romb

(5) Collingwood Mbr. Transmitted light (Manitoulin Island outcrop).  Note dolomite rombs.  Quartz is now rare to absent.

(6) Dolomitic Bluemountain Fm.. Transmitted light (Manitoulin Island, SIS 5).

BLithoclast

Appendix A, Plate 2

B

C

ContactAA(1) Phosphatic intrasparite/ironstone.  Upper Collingwood Mbr. contact. Transmitted light (Clarksburg) Note lithoclast. Also see details A,B,C.

(2) Upper Collingwood contact detail showing soft sediment inversion – not erosional.  Transmitted light (Clarksburg).

A

Iron sulphide

B B2 mm

(3) Detail showing iron sulfide replacement of bioclasts. Reflected light (Clarksburg).

(4) Detail showing iron sulfide replacement of bioclasts. Transmitted light (Clarksburg).

C C

Concentric rings

C C

(5) Detail of cluster (pelloids?) Note concentric rings in central body.  Transmitted light (Clarksburg).

(6) Detail of cluster (pelloids?).  Reflected light (Clarksburg).