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Late Neogene sedimentation adjacent to thetectonically evolving North Island axial ranges:Insights from Kuripapango, western Hawke's BayGreg H. Browne aa Institute of Geological & Nuclear Sciences , P.O. Box 30 368, Lower Hutt, New ZealandE-mail:Published online: 21 Sep 2010.

To cite this article: Greg H. Browne (2004) Late Neogene sedimentation adjacent to the tectonically evolving North Islandaxial ranges: Insights from Kuripapango, western Hawke's Bay, New Zealand Journal of Geology and Geophysics, 47:4,663-674, DOI: 10.1080/00288306.2004.9515082

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New Zealand Journal of Geology & Geophysics, 2004, Vol. 47: 663-6740028-8306/04/4704-0663 © The Royal Society of New Zealand 2004

663

Late Neogene sedimentation adjacent to the tectonically evolving North Islandaxial ranges: insights from Kuripapango, western Hawke's Bay

GREG H. BROWNEInstitute of Geological & Nuclear SciencesP.O. Box 30 368Lower Hutt, New Zealandemail: g.browne@gns.cri.nz

Abstract Kuripapango-Blowhard is a relatively smallregion in western Hawke's Bay, but one that displays astratigraphically diverse Neogene sedimentary record.Earliest sedimentation on greywacke basement consistedof late Miocene (?Tongaporutuan-Kapitean) conglomerate,sandstone, and calcareous sandstone of the BlowhardFormation (new). Deposition of siliciclastic and mixedcarbonate sediments of the Mangatoro, Te Waka, Kaumatua,and Sentry Box Limestone Formations continued throughto late Pliocene (Nukumaruan) time. These sediments aredivided into a broadly transgressive to regressive successionthat is up to 2 km thick. The lithologies indicate a strong linkbetween sediment supply and active tectonism through time.An initial pulse of uplift is suggested during the late Miocene,followed by widespread subsidence and relative tectonicquiescence. A later, and temporally distinctive period of latePliocene tectonic uplift in the region has continued to thepresent day. Contrasts in the sedimentary record in adjacentfault-bounded blocks suggest different sedimentary historiesrelated to whether the fault blocks were uplifted and eroded,or were subsiding and were depocentres for sediment.

Keywords sedimentation; tectonic uplift; BlowhardFormation (new); Spiral Conglomerate Member (new);Waikarokaro Member (new); Mangatoro Formation; Te WakaLimestone; Kaumatua Formation; Sentry Box Limestone;Kaweka Range; Ruahine Range; Kuripapango; Hawke'sBay; new stratigraphic names

INTRODUCTION

Neogene sedimentary rocks are widely distributed throughoutthe central North Island, and have been well studied in boththe Wanganui and Hawke's Bay Basins on either side of theaxial ranges (Haywick et al. 1991, 1992; Erdman & Kelsey1992; Ballance 1993; Abbott & Carter 1994; Naish & Kamp1995; Field & Uruski 1997; Naish et al. 1999). Neogene rocksoccur atop the eroded central North Island ranges in severalrelatively small fault-bounded blocks or outliers, where theyare known in considerably less detail (Kingma 1957; Crippen

G03039; Online publication date 1 December 2004Received 9 April 2003; accepted 31 October 2003

1977; Browne 1978, 1981, 1986; Beu et al. 1981). Theselater occurrences, however, provide important insights into thesedimentary cover that once existed over a larger area, prior toand synchronous with Neogene uplift, as well as insights intothe tectonic evolution of the axial ranges themselves.

Kuripapango and the Blowhard is a comparatively smallregion located 50 km west of Napier, immediately southeastof the Kaweka Range, at the northern margin of the RuahineRange (Fig. 1). This region displays both a stratigraphicallydiverse Neogene succession and some of the structurallymost significant outcrops of Neogene strata in the centralNorth Island axial ranges. Up to 2 km of late Miocene tolate Pliocene non-marine and marine sediments are recordedfrom the region, comprising an initially transgressive, thenregressive succession.

The aim of this paper is to present detail on the range ofstratigraphic units preserved in the region, and to use theserelationships to illustrate how the sedimentary pattern evolvedwith changes in the tectonic evolution of the axial ranges.The interplay between sedimentation and tectonism indicateschanges in the tempo of tectonic uplift during the Neogene,and differences in fault block evolution through time.

NEOGENE STRATIGRAPHY

Transgressive late Miocene to early Pliocenesedimentation

BLOWHARD FORMATION (new)

The oldest sediments overlying the basement Torlesse Terranecomprise a <150 m thick, crudely upward-fining succession,which includes conglomerate and minor interbedded sandstoneat the base, becoming increasingly sandy and muddy up-sequence. The Blowhard Formation comprises conglomerate,sandstone, and minor siltstone and occurs east of the KawekaFault and west of the Ruahine Fault (Fig. 1). The formation isextensively developed over The Blowhard, from which it isnamed, though similar lithologies occur farther west towardTimahanga Station, where they were mapped but not formallynamed by Beu et al. (1980). Two members are recognisedfrom the Kuripapango region.

Spiral Conglomerate Member (?Tt-Tk) (new)

DESCRIPTION: The earliest transgressive deposition is recordedby poorly sorted conglomerate comprising well rounded toangular, Torlesse-derived clasts, with thinner interbedded palegrey, non-calcareous, moderately well sorted, fine to mediumgrained sandstone and rare siltstone (Fig. 2,3). The memberrests unconformably on Torlesse Terrane greywacke, and isconfined to the western portion of the Blowhard Plateau inareas adjacent to the Waikarokaro Fault (Fig. 1,2). The nameis derived from the colloquial name for this portion of the

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664 New Zealand Journal of Geology and Geophysics, 2004, Vol. 47

Undifferentiated Holocene sediments

Sentry Box Limestone 1Te AutesedimentsKaumatua Formation

Te Waka Limestone J

Mangatoro Formation Wo

Blowhard Formation Tt-Tk

Torlesse Supergroup Mesozoic

Wm-Wn

Bedding attitude

»* Major fault

^ _ Thrust fault (teethtoward thrust block)

•** Major fault inferred

^ Syncline

• B46 Trig station (height in metres)

- - ' " ^ Road

Fig. 1 Geological map of theKuripapango region, westernHawke's Bay.

Napier-Taihape Road, and this section is designated the typesection (U20/996958-001956; Fig. 3)

The coarsest and most angular clasts occur in the basalportion of the member. Conglomerates form poorly defined,typically erosionally based (erosional relief <50 cm) beds, 50-200 cm thick. Beds are typically clast-supported in the basalportion of the member, but display better sorting, increasedclast roundness and an increase in fine to coarse grained

sandstone matrix up-sequence. At some localities, a crudepebble imbrication is developed. Thinner bedded (20-150 cmthick), scour-based (relief <1 m) sandstone beds occur c. 15 mabove the base of the member and increase in abundance andthickness upward. These beds are moderately to well sorted,fine to coarse grained (generally medium-grained sandstone),massive, horizontally laminated, and trough cross-beddedfeldspathic litharenite and sublitharenite.

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Browne—Neogene sedimentation, Kuripapango 665

Fig. 2 Spiral Conglomerateadjacent to the Napier-TaihapeRoad. A, Poorly sorted angular tosubrounded Torlesse-derived clasts(U20/997957). B, Stratigraphicallyhigher conglomerate withinterbedded, scour-based sandstone(U20/998957).

Up-sequence, these sandstones eventually dominate overconglomerate lithofacies. Carbonaceous debris associatedwith pyrite occurs sporadically throughout the conglomerateand sandstone lithofacies. Near the top of the member inthe type section (at U20/000956) a 1.7 m thick lenticular,greenish grey, non-calcareous, slightly sandy, carbonaceoussiltstone is intercalated within conglomerates (Fig. 3). Thetop of the member is taken arbitrarily to be where sandstonebeds dominate over conglomerates.

DICUSSION: The member is thickest and best developed alongthe Napier-Taihape Road (locality A) and in the WaikarokaroStream catchment where it is >100 m thick (Fig. 1).

A palynological sample from this interval (U20/f129;Fig. 3) contained scattered spores and pollen, dominatedby Nothofagidites lachlaniae (Couper), with N. cranwelliae

(Couper) and common Asteraceae (D. C. Mildenhallpers. comm.). The dominance of N. lachlaniae indicatesa Tongaporutuan (late Miocene) or younger age (D. C.Mildenhall pers. comm.). As the member is overlain byKapitean age sediments of the Waikarokaro Member (seebelow), a Tongaporutuan-Kapitean age is adopted.

The basal portion of the member (the basal 15 m in thetype section) displays scoured bases to beds, angular andpoorly sorted clasts, clast-support, and poor stratification.Sandstone interbeds are rare and very thin in this lowerinterval. These features suggest a mass flow (debris flow)origin for the lower portion of the member, consistent witha non-cohesive debris flow mechanism in a series of alluvialfans.

The greater proportion of sandstone interbeds, matrixsupport, and pebble alignment in higher portions of the

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666 New Zealand Journal of Geology and Geophysics, 2004, Vol. 47

100 -

-

-

-

50 -

-

-

K ~

X

X

XX

XX

• • • • )

\

\ I

- . )

• • • : !

• , )

(=) U20H129

U20/f130

TorlesseSupergroup <=)

Conglomerate

Sandstone

Siltstone

Carbonaceousdebris

Massive bedded

Laminated

Well bedded

Moderately

bedded

Fig. 3 Stratigraphic section for the type section of the SpiralConglomerate Member, Napier-Taihape Road (U20/996958 [base]to U20/001956 [top]).

suggests a low-sinuosity (braided) fluvial setting. Where fineshave been recognised, they occur in lenticular erosionallybased bodies interpreted as mud-plugs deposited withinabandoned fluvial channels. Pollen from these mudstones(U20/f129) represents a kauri swamp forest with beaches,podocarps, and broadleafed trees, and a cool climate (D. C.Mildenhall pers. comm.).

The preferred paleogeographic setting in the earliestparts of the member is therefore as a series of alluvial fansdominated by debris flow deposition, which developedadjacent to fault blocks in the Torlesse Terrane basement(Fig. 4). The distribution of the member in the western portionof the Blowhard Plateau near to the Waikarokaro Fault,and an inferred west-east transport direction determinedfrom imbricate pebble fabrics (Browne 1981), suggeststhe Waikarokaro Fault was active during sedimentation.The inference is therefore that the uplifted basement rockswest of this fault provided the coarse clastic material. Thefault became less active and the topography more subduedwith time. The stratigraphically higher and laterally moredistal portions of the depositional succession represent aprogressively greater degree of fluvial sedimentation incoarse-grained braided river depositional settings.

Waikarokaro Member (Tk) (new)

member, together with lamination and trough cross-beddingin the sandstones, suggest a transition to fluvial-dominateddeposition up-sequence. Outcrop is not sufficiently good togauge lateral lithofacies relationships, but the scarcity ofoverbank fine-grained sediment, and of lateral accretion sets,

DESCRIPTION: Waikarokaro Member rests unconformablyon either Torlesse Terrane basement (Fig. 5) or the SpiralConglomerate (Fig. 6A). The member comprises threelithofacies, which in order of abundance are: well-sortedsandstone, sandy greywacke conglomerate, and gravelly

Tt-Tk: Spiral Conglomerate Member,Blowhard Formation

E

alluvial fans

B Tk: Waikarokaro Member,Blowhard Formation

Wcarbonate banks

tectonic uplift &^ erosion

active faulting

Wm-Wn: Te Aute lithologies(Kaumatua and Sentry Box Formations)

shelf sanddeposition

topographically subduedhinterland

developmentif erosion surface

ransgressive depositiondirectly on greywacke

lenticular conglomerate lithofacies related toproximity to fluvial distributary mouths, storm, or rip

current deposition

carbonate banksrenewed tectonic uplift & erosion

local deposition on greywacke highs

transgressive shoreline

active faulting

NOT DRAWN TO SCALE

| % *»°| Sentry Box Limestone

Kaumatua Formation

Te Waka Formation

Unconformity

Mangatoro Formation

Waikarokaro Member

Spiral Conglomerate Member

Unconformity

Greywacke

Fig. 4 Summary of the sedimentation and tectonic evolution of the Kuripapango-Blowhard region during late Neogene time.

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Browne—Neogene sedimentation, Kuripapango 667

Fig. 5 Stratigraphic columns forthe Waikarokaro Member at theBlowhard Plateau. A, Castle RocksRoad (U20/016994). B, Napier-Taihape Road (U20/004953). C,Run 20 Road, Makareturetu Stream(U20/988913-985917).

B U20 004953

6 -

2 -

0metres

8 -

2 -

C U20/988913-U20/985917

50-~

4 0 -

• 0

30 i

2 0 -

10 -

Torlesse

Supergroup

| I Conglomerat

| | Calcareous s

|- \' • | Sandstone

I | Siltstone

f—\

6•0-

Massively bedded

Moderately bedded

Lenticular bedded

Cross-bedded

Vertical bun

Burrowed s

calcareous sandstone (Fig. 5, 6A-C). The member is up to70 m thick, and occurs in mostly isolated outcrops across theBlowhard Plateau. A type section is defined from a quarryexposure on Kuripapango Road (U20/994981; Fig. 6A). Thespelling is taken from the NZMS 1 map series, rather than thealternative "Waikarekare" spelling that appears on the NZMS260 topographic sheet.

The dominant lithofacies is medium brown, massiveand trough cross-bedded, very well sorted, fine-grainedmicaceous sandstone or feldspathic litharenite (Fig. 5A). Bedsare typically decimetre bedded, though may be as much as2 m thick, usually planar based, but may show broad scoursup to 2 m deep. Mudstone rip-up clasts occur at the base ofsome beds.

A second lithofacies comprises centimetre- to decimetre-bedded, poorly to moderately well sorted lensoidal sandyconglomerate, most abundant in the lower portions of themember (Fig. 6B). Basal contacts of conglomerate beds areerosive (amplitude <50 cm) and tops are planar or gradational.A sandstone matrix support is characteristic and consists ofwell-sorted fine-grained sandstone with a minor proportion ofmudstone. Pebble clasts are dominated by Torlesse greywackesandstone, and may show normal grading or crude imbricationfabrics.

A third, less abundant lithofacies of the WaikarokaroMember are <2 m thick, coarse pebble to granule-sized,gravelly calcareous sandstones (Fig. 6C). The coarser clastsconsist of rounded to well-rounded Torlesse greywacke andminor intraformational mudstones. Trough and planar cross-bedding is common. CaCO3 may constitute as much as 30%of the lithology, and occurs both as sparry veins and as shellfragments. Macrof ossils are dominated by molluscs of whichSectipecten wollastoni and Crassostrea ingens are the mostabundant, but include less common bryozoans, serpulids,echinoderms, and barnacle fragments.

DISCUSSION: The Waikarokaro Member reflects a change fromthe earlier non-marine deposition of the coarse-grained SpiralConglomerate to open marine conditions on a shallow shelf(Fig. 4B). In places, marine deposition occurred adjacent to,and onlapping, a seabed topography composed of basementgreywacke, which in detail displays considerable localisedrelief. At the type section, for example, oyster shells withassociated gravels occur within metre-deep depressions inwhat was, at the time of deposition, a very irregular rockyshoreline (Fig. 6A). In other places, the occurrence of channels,trough cross-bedding, and rip-up clast and greywacke clastconglomerates indicate high-energy channelised deposition,such as offshore subtidal channels. More calcareous lithofacieswere deposited in areas of carbonate accumulation, such asoffshore shell banks, in areas removed from major influxesof siliciclastics. The occurrence of Sectipecten wollastoniindicates a Kapitean (late Miocene) age (Beu et al. 1980;Beu & Maxwell 1990).

MANGATORO FORMATION (Wo) (after Lillie 1953)

DESCRIPTION: Pliocene-age sandstones and siltstones of theKuripapango area are included in the Mangatoro Formation(of Lillie 1953). In the study area, Mangatoro Formationincludes grey, moderately sorted, bioturbated, micaceous, veryfine and fine-grained muddy sandstone and sandy mudstone.Most outcrops are massive, but horizontally laminated siltysandstone intervals up to 40 cm thick also occur. Foraminiferaare abundant and well preserved, and occur with ostracods,molluscs, echinoid spines, bone fragments, and fish teeth(M. P. Crundwell pers comm.). Dolomitic sandstoneconcretions are common throughout.

DISCUSSION: The formation occurs northeast of Kuripapango,and a fault-bounded slither west of the Ruahine Fault

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668 New Zealand Journal of Geology and Geophysics, 2004, Vol. 47

Fig. 6 Lithofacies from the Waikarokaro Member at the Blowhard Plateau. A, Massive, faintly bedded, and cross-bedded fine-grainedsandstone at the type section, a quarry exposure on Kuripapango Road (U20/994981). Lenticular, dark, resistant bands are CaCO3 cementedfossiliferous sandstone bands. Waikarokaro Member sandstone rests unconformably on greywacke exposed in the lower portion of thequarry. The very irregular contact (as seen at the left side of the image) is interpreted as an original sea-stack topography. The topographicallylower portions between the stacks are filled with oyster shells, valves of Sectipecten wollastoni, and a single whale bone (John Begg pers.comm.). Oyster shells are in places cemented to the greywacke contact. Numerous faults cut both the greywacke and the WaikarokaroMember. B, Centimetre-decimetre-bedded sandstone with thinner interbedded lenticular conglomerate, Castle Rock Road (U20/004957).Scale bar is 50 cm with 5 cm divisions. C, Trough cross-bedded sandstone and pebbly calcareous sandstone at the top of the photo, CastleRock Road (U20/015994). Scale bar is 50 cm with 5 cm divisions.

(Fig. 1). A basal sedimentary contact to the formation isnot exposed, and the formation is always in fault contactwith older formations. The exact thickness is not known,but on the basis of regional mapping, the formation maybe as much as 1500 m thick. A gravity profile through theformation immediately east of the Kaweka Fault modelled adepth to basement of c. 1 km (Browne 1981). A middle-lateOpoitian (early Pliocene) age is indicated for the formationbased on foraminifera, which also indicate mid-shelf waterdepths during deposition (Kingma 1957; M. P. Crundwellpers. comm.).

Mangatoro Formation records a period of significantsubsidence in the Kuripapango area, and marks the peakof the transgressive phase. Foraminifera from Kuripapangoindicate a mid-shelf depositional setting (M. P. Crundwellpers. comm.). Cotton (1916) and Grant-Taylor & Hornibrook(1964) suggested that the Kuripapango area during thePliocene was a marine strait, "the Kuripapango Strait",which provided a narrow connection between the Wanganui

and Hawke's Bay regions. Several other localities in thesouthern part of the North Island experienced subsidence atthis time (Grant-Taylor & Hornibrook 1964; Beanland et al.1991; Kampetal. 2002).

Regressive late Pliocene sedimentation

No record of Waipipian (early late Pliocene age) sedimentationis known from the Kuripapango area (or from the adjacentRuahine Ranges; Beu 1995), in contrast to adjacent regionsin Hawke's Bay and Wanganui Basins where sediment of thisage is abundant (Beu et al. 1980; Beu 1995; Journeaux et al.1996; Naishetal. 1999).

The Mangapanian-Nukumaruan regressive phase atKuripapango is dominated by carbonate lithofacies, includedwithin the Te Aute sediments, common throughout Hawke'sBay. Use of Te Aute follows the informal classification ofBeu (1995), rather than the formal designation of a Te Aute"Group" as proposed by Harmsen (1985).

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Browne—Neogene sedimentation, Kuripapango 669

Fig. 7 Stratigraphic column fromthe western side of Mt Kohinga(U20/978936-980936), throughthe Mangatoro, Te Waka, andKaumatua Formations. Locationof faunal samples are prefixedwith "U20/f."

N150 —

100

LLJ

C

LL

ODC

i

5 0 "

metres

T

<ft>

Grainstone

Sandstone

Siltstone

Massive bedded

Moderately bedded

Well bedded

Trough cross-bedded

Paleocurrent direction

(from trough cross-

bedding)

Bivalves

Gastropods

Brachiopods

Barnacles

Bryozoans

Echinoids

Broken macrofossils

Foraminifera

Bioturbation

Fig. 8 Te Waka Formationlimestone lithofacies on thewestern side of Mt Kohinga.Prominent cliffs in the middledistance are c. 20 m high. Notethe peneplained surface at rightdeveloped on Torlesse Terranerocks in the distance (northernRuahine Range).

Te Aute sediments (Wm-Wn)Three formations are recognised from the study area. Theywere previously given different names and assigned lithof aciesstatus by Browne (1981).

TE WAKA FORMATION (after Beu 1995)

DESCRIPTION: In the study area, the formation consists ofgreyish to pinky brown grainstone, locally rudstone orfloatstone, with abundant mollusc, barnacle, bryozoan, and

foraminiferal bioclasts (Fig. 7-9). Rounded to subangular,granule- to cobble-sized greywacke clasts are common,which with poorly sorted to moderately well sorted, angularto subangular fine-grained sandstone, form two distinct bi-modal siliciclastic populations. Thin sandstone beds are oftenintercalated with the limestone. The sand-sized component isdominantly quartz, with less abundant rock fragments, androunded (allogenic) glauconite. CaCO3 constitutes 50-90% ofthe lithology (cf. Beu 1995, appendix C). Te Waka Formationrests conformably or with slight angular unconformity

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670 New Zealand Journal of Geology and Geophysics, 2004, Vol. 47

Fig. 9 Unconf ormable contact between the Torlesse Terrane (below)and the Te Waka Formation at Sandy Ridge (U20/046923).

(up to 5°) on older sediments. The lithology is well exposed inthe upper flanks of Mt Kohinga, where it is up to 70 m thick,and along the Lizard and Glenross Range where it formsprominent bluffs. Abundant trough cross-bedding indicatespaleocurrent directions toward the east and southeast.

DISCUSSION: At the type section at the Te Waka Range,30 km to the northeast (Beu 1995), the formation overliesTitiokura Limestone (35 m thick) of Waipipian age, withan intervening, unnamed siliciclastic unit (100 m thick).In the Kuripapango area, a similar sandstone unit occurs(20+ m thick) below the Te Waka Formation, and is middle-late Opoitian in age (M. P. Crundwell pers. comm.).

The presence of Phialopecten triphooki triphooki indicatesa Mangapanian (late Pliocene) age (Beu 1995) for the TeWaka Formation in the study area. The broken condition ofthe bioclastic material and abundance of trough cross-beddingindicates deposition by strong traction currents. In keepingwith Beu's (1995) interpretation of Te Aute sediments, it isconcluded that the rocks at Kuripapango were deposited ascarbonate dunes or mounds, in inner to mid-shelf depths.Strong swell-dominated and storm-related shelf currents werelikely during the deposition of the unit.

KAUMATUA FORMATION (after Erdman & Kelsey 1992)

DESCRIPTION: In the study area, the formation consists ofinterbedded lithic grainstone (biosparite/biosparrudite),sandstone, and less abundant and thinner bedded mudstonelithofacies, conformable on Te Waka Formation. Paleocurrentdirections are generally toward the north to southeast.

The carbonates display a lenticular geometry, formingdiscrete pods or lenses up to 5-10 m thick, and extendingfor up to 50 m along-strike (Fig. 7,10). Generally, the tops ofthese pods are relatively flat and display an irregular contactthat progressively downsteps into stratigraphically lowerand surrounding sandstone lithofacies. A well-developedcentimetre- and decimetre-scale flaggy stratification occursin the carbonates, with trough and planar cross-bedding(sets up to 50 cm thick) being common (Fig. 11). Bioclastsare dominated by barnacles with less abundant molluscs,echinoderms, brachiopods, bryozoans, and foraminifera.Conspicuous macrofauna include Phialopecten triphooki,Patro undatus, Crassostrea ingens, and Tawera subsulcata.The siliciclastic components (boulder to sand) within thelimestone are greywacke derived.

Sandstone interbeds surrounding the lenticular limestonesare greyish orange to brown, non-calcareous, bioturbated,horizontally and less commonly cross-bedded, ripple andclimbing ripple laminated, well sorted, medium grainedsandstone. They are intercalated with centimetre-decimetre-thick brownish mudstone often occurring as mudstone rip-upclasts. Trace fossils are locally abundant, and include Scolicia,Ophiomorpha, Teichichnus, and Phycodes.

Centimetre-thick foraminifera-rich mudstones also occurwithin the grainstone lithofacies, and are laterally extensiveover tens of metres along-strike.

DISCUSSION: The formation occurs as ridge-top exposuresup to 80 m thick at Mt Kohinga, Sandy Ridge, and theGlenross Range. Based on published descriptions, theformation appears to contain considerably more mudstoneand conglomerate in the south (Erdman & Kelsey 1992), andrelatively less sandstone and limestone at Kuripapango. Thepresence of Phialopecten triphooki indicates a Mangapanianage (Beu 1995).

The formation is characterised by shallow-water taxasuch as Crassostrea ingens, Tawera subsulcata, Chlamysgemmulata, Anomia trigonopsis, and Gari lineolata. Thelenticular limestone beds could be interpreted as high-energyshelf-depth (i.e., fair-weather wave to above storm wave-base)carbonate ridges or bars. However, the base of these units inplaces appears to have a channel-like geometry that is severalmetres deep, and tens of metres wide, and in these cases,carbonate-rich distributary channels across a shallow shelfseem to be a more plausible explanation. The intercalatedsandstone lithofacies is interpreted as relatively high energyshelf and associated storm deposits, while the interbeddedmudstones indicate that these high-energy deposits wereinterspersed by periods of low sediment supply.

SENTRY BOX LIMESTONE (after Erdman & Kelsey 1992)

DESCRIPTION: At Kuripapango, two lithofacies arerecognised: gravelly grainstone and fossiliferous sandstoneand siltstone.

At Mt Miroroa, the formation comprises a 30 m thick,dark yellowish, very poorly sorted, fine-grained sand to

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Fig. 10 Laminated sandstonesinterbedded with lenticulargrainstones in the KaumatuaFormation, Mt Kohinga (U20/982937). Outcrop view in middleforeground is c. 150 m wide.

Fig. 11 Grainstone lithofaciesof the Kaumatua Formation withtypical flaggy appearance at thesummit of Mt Kohinga (U20/981937). Scale is 50 cm long with5 cm gradations.

gravelly grainstone. At Mt Kohinga, and in the vicinity ofKuripapango (Beu et al. 1981), the lithology comprisesgrey to yellowish, soft, moderately sorted, fine to mediumgrained fossiliferous (shell hash) sandstone. This alternateswith pale grey coloured fossiliferous siltstone. Concretionsand carbonaceous debris are abundant. The formation restson poorly defined limestone at Mt Miroroa, or is in faultcontact with older lithologies along the Gentle Annie portionof the Napier-Taihape Road, and west flanks of Mt Kohinga,Kuripapango (Beu et al. 1981).

DISCUSSION: An early Nukumaruan (late Pliocene) age isindicated by the diverse fauna, which includes Zygochlamysdelicatula (Beu et al. 1981; Browne 1986). Deposition ina shallow marine (<50 m depth) setting is inferred based

on the fossil content and sedimentary facies; the varietyof sediments from gravel to siltstone suggest varied, verylocalised sedimentation histories.

SIGNIFICANCE OF THE SEDIMENTARY-TECTONIC RECORD AT KURIPAPANGO

The Kuripapango region offers a small but varied stratigraphicwindow of Neogene strata, in which observations can be madeof stratigraphic relationships that existed over a much broaderregion of the central North Island. Elsewhere these sedimentshave been removed through subsequent uplift and erosion. TheKuripapango outlier, bounded by the Kaweka and RuahineFaults in particular, offers a more complete record of Neogenesedimentation, in contrast to adjacent fault-bounded blocks.

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The occurrence of a thick conglomeratic facies in theSpiral Conglomerate indicates a phase of late Miocenedeposition and uplift in the Kuripapango region. Currently,this phase has not been fully appreciated in models of thetectonic development of the central North Island axialranges. These models recognise widespread uplift of theaxial ranges from latest Pliocene (Mangapanian)-Recenttime but not earlier (Grant-Taylor in Smale et al. 1978; Beuet al. 1981; Melhuish 1990; Beanland et al. 1991; Erdman &Kelsey 1992). There is, however, evidence from fission trackthermochronology for >4 km erosion of basement underlyingthe Ruahine Range starting c. 15 m.y. ago, and providingconsiderable sediment flux to adjacent basins from 7-8 m.y.ago (Kamp et al. 2002). The late Miocene tectonic eventrecognised at Kuripapango is likely to be part of this uplift;certainly the stratigraphic ages reported here are compatiblewith such an inference. However, the distinction should bemade that in the Kuripapango region, this latest Mioceneto early Pliocene uplift was temporally separate from thelater and more widely appreciated Pliocene-Recent event,and is stratigraphically separated from it at Kuripapango bysubsidence and deposition of the Mangatoro Formation.

There is supporting evidence that the latest Miocene toearly Pliocene tectonic event may have been more widespread.Similar lithofacies occur 5-10 km to the southwest ofKuripapango at Timahanga Station (Beu et al. 1980), andareas adjacent to the axial ranges. Greywacke conglomeratesuccessions of this age or presumed equivalent age occurto the west of the North Island ranges at Santoft-1A well,where Pliocene (?Opoitian) conglomerates rest on greywackebasement (Anderton 1981; Melhuish etal. 1996). Lillie (1953),Wells (1987), and Nicol et al. (2002) report a major phase oflatest Miocene to early Pliocene uplift and syn-sedimentaryfaulting in southern Hawke's Bay and Wairarapa duringdeposition of Te Aute units and Mapiri, Mangaoranga, BellsCreek Mudstone, and Sunnyside Conglomerate formations.In the Wanganui Basin, Nelson & Hume (1977) report alate Tertiary peak in relative tectonism at this time (5 Ma),and regional uplift and inversion of previous structures waswidespread in the adjacent Taranaki Basin (King & Thrasher1996; King 2000). On a larger scale, these observations arelikely to be synchronous and linked kinematically to anacceleration of uplift in the central South Island at 5 Ma(Turnbull & Uruski 1993; Manville 1996; Sutherland 1996;King 2000), and were likely associated with the change inthe rotation pole between the Australian and Pacific platesat 6-5 Ma (Molnar et al. 1975; Sutherland 1995). Althoughthis deformation is widely recognised, it has not previouslybeen appreciated with regard to the central North Island axialranges.

Not only do we see evidence for this latest Miocenetectonic uplift and consequent sedimentary response, but thesedimentary record at Kuripapango indicates that differentfault blocks had distinctly different sedimentary histories. Thearea between the Kaweka and Ruahine Faults, for example,displays a more extensive sedimentary record atop basement,spanning late Miocene to late Pliocene time, while east ofthe Ruahine Fault, on uplifted blocks such as Sandy Ridge,Blowhard, and Glenross Ranges, late Pliocene sedimentsrest unconformably on basement. In the area east of theRuahine Fault, we can surmise that either: (1) late Mioceneand early Pliocene rocks were deposited but removed by pre-Mangapanian uplift and erosion, followed by subsidence inthe Mangapanian; or (2) the area east of the Ruahine Fault

was uplifted during the late Miocene to early Pliocene, andthese older rocks were never deposited in this area, with theblock subsiding in Mangapanian time.

The Kuripapango region also shows that some of themajor faults that were active in the past cease to be majoractive systems today. The Waikarokaro Fault, for example,was a principal fault in the late Miocene, while the CometFault terminates the western end of the Miroroa Fault, andmust have been active through the evolution of the thrust(Browne 1986). Neither of these faults displays evidence ofRecent active movement.

Several recent papers have discussed the sequencestratigraphic implications of cyclic Neogene stratigraphicunits in both Hawke's Bay and Wanganui Basins. Tectonismis considererd a major driver influencing the Neogenesedimentary record, particularly in Hawke's Bay (Melhuish1990; Erdman & Kelsey 1992; Ballance 1993; Field & Uruski1997), while other authors recognise eustatically driven sea-level fluctuations in these sedimentary cycles (Haywick etal. 1991,1992; Abbot & Carter 1994; Naish & Kamp 1995;Naish et al. 1999).

Models have been recently developed for cyclothemic TeAute sediments within the Hawke's Bay region (Caron et al.2004, this issue). These authors have recognised two types ofsequence motif from limestone units in central and westernHawke's Bay: (1) aggrading sequences consisting of stackedtabular system tract units of comparable thickness, boundedbelow by an erosional contact and above by a flooding surface;and (2) complete sequences having a lower retrogradationaland an upper progradational (shallowing-upwards) faciestrend, typically bounded by flooding surfaces. Based on thesemodels, the Te Waka Formation in the Kuripapango regionmay correspond to the aggrading sequence model, built up ofa series of stacked cross-bedded bioclastic bodies, with thininterbedded sandstone. However, Caron et al. (2004) regardTe Waka Formation to the north as complete sequences. TheKaumatua Formation, and to some extent the Sentry BoxLimestone, with a greater abundance of interbedded sandstoneand mudstone, appear to be complete sequences after Caronet al. (2004), though further work is needed to test thesemodels and determine the degree to which the cycle motifswere modified by the volume of siliciclastic sediment supplyrelated to tectonic uplift.

ACKNOWLEDGMENTS

Several former staff members of the Geology Department atAuckland University contributed ideas and discussions on variousaspects of this study while I was undertaking my MSc degree.Principal amongst these were Peter Ballance, Graham Gibson,Jack Grant-Mackie, Murray Gregory, and Bernhard Spörli.Contributions in the field by the late Tom Wilson, Viv Beaufoy,Dave Robertson, Huntly Cutten, John Begg, Kyle Bland, and PeterKamp are appreciated. Paleontological samples were examined byDallas Mildenhall (palynology) and Martin Crundwell (foraminiferalmicropaleontology). Permission to work and to use accommodationin the region was kindly offered by Wally Drayton of the formerNew Zealand Forest Service, the Department of Conservation, OjiSankohu Mohaka Forests Ltd, and by Pan Pac Forests. Figures weredrafted by Sue Shaw. Earlier drafts of the manuscript were improvedby reviews from Alan Beu, Huntly Cutten, and Jim Kennett. Reviewsof a later version of the manuscript were made by Peter Kamp andBob Stewart, while Cam Nelson provided editorial assistance.Funding from the Foundation for Research, Science and Technologyis acknowledged. GNS publication number 2678.

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REFERENCES

Abbott, S. T.; Carter, R. M. 1994: The sequence architecture of mid-Pleistocene (c. 1.1-0.4 Ma) cyclothems from New Zealand:facies development during a period of orbital control on sea-level cyclicity. In: de Boer, P. L.; Smith, D. G. ed. Orbitalforcing and cyclic sequences. International Association ofSedimentologists Special Publication 19: 367-394.

Anderton, P. W. 1981: Structure and evolution of the South WanganuiBasin, New Zealand. New Zealand Journal of Geology andGeophysics 24: 39-63.

Ballance, P. F. 1993: The New Zealand Neogene forearc basins.In: Ballance, P. F. ed. South Pacific sedimentary basins.Sedimentary basins of the world 2. Amsterdam, Elsevier.Pp. 177-193.

Beanland, S.; Berryman, K. R.; Kelsey, H.; Cashman, S. 1991: LateNeogene stratigraphic and structural development of theEketahuna Basin, northern Wairarapa. Abstract. GeologicalSociety of New Zealand Annual Conference, PalmerstonNorth. Geological Society of New Zealand MiscellaneousPublication 59A: 34.

Beu, A. G. 1995: Pliocene limestone and their scallops. Institute ofGeological & Nuclear Sciences Monograph 10. 243 p.

Beu, A. G.; Maxwell, P. A. 1990: Cenozoic Mollusca of NewZealand. New Zealand Geological Survey PaleontologicalBulletin 58. 518 p.

Beu, A. G.; Grant-Taylor, T. L.; Hornibrook, N. de B. 1980: The TeAute Limestone facies Poverty Bay to northern Wairarapa.1:250 000. New Zealand Geological Survey MiscellaneousSeries Map 13. Wellington, New Zealand, Department ofScientific and Industrial Research.

Beu, A. G.; Browne, G. H.; Grant-Taylor, T. L. 1981: New Chlamysdelicatula localities in the central North Island and uplift ofthe Ruahine Range. New Zealand Journal of Geology andGeophysics 24: 127-132.

Browne, G. H. 1978: Wanganui strata of the Mangaohane Plateau,northern Ruahine Range, Taihape. Tane 24: 199-210.

Browne, G. H. 1981: The geology of the Kuripapango-Blowharddistrict, western Hawke's Bay. Unpublished MSc thesis,lodged in the Library, University of Auckland, Auckland,New Zealand. 178 p.

Browne, G. H. 1986: Basement-cover relationships and tectonicsignificance of Mt Miroroa, western Hawke's Bay. Journalof the Royal Society of New Zealand 16: 381–402.

Caron, V.; Nelson, C. S.; Kamp, P. J. J. 2004: Contrasting carbonatedepositional systems for Pliocene cool-water limestonescropping out in central Hawke's Bay, New Zealand. NewZealand Journal of Geology and Geophysics 47: 697-717(this issue).

Cotton, C. A. 1916: The structure and later geological history of NewZealand. Geological Magazine 11: 243-320.

Crippen, T. F. 1977: Geology of part of the Kaweka Range, Hawke'sBay. Unpublished MSc thesis, lodged in the Library,University of Auckland, Auckland, New Zealand. 150 p.

Erdman, C. F.; Kelsey, H. M. 1992: Pliocene and Pleistocenestratigraphy and tectonics, Ohara Depression and WakararaRange, North Island, New Zealand. New Zealand Journalof Geology and Geophysics 35: 177-192.

Field, B. D.; Uruski, C. I. 1997: Cretaceous-Cenozoic geology andpetroleum systems of the East Coast region, New Zealand.Institute of Geological & Nuclear Sciences Monograph19.

Grant-Taylor, T. L.; Hornibrook, N. de B. 1964: The Makara faultedoutlier and the age of Cook Strait. New Zealand Journal ofGeology and Geophysics 7: 299-313.

Harmsen, F. J. 1985: Lithostratigraphy of Pliocene strata, Central andSouthern Hawke's Bay, New Zealand. New Zealand Journalof Geology and Geophysics 28: 413-433.

Haywick, D. W.; Lowe, D. A.; Beu, A. G.; Henderson, R. A.;Carter, R. M. 1991: Pliocene-Pleistocene (Nukumaruan)lithostratigraphy of the Tangoio block, and origin ofsedimentary cyclicity, central Hawke's Bay, New Zealand.New Zealand Journal of Geology and Geophysics 34:213-225.

Haywick, D. W.; Carter, R. M.; Henderson, R. A. 1992:Sedimentology of 40 000 year Milankovitch-controlledcyclothems from central Hawke's Bay, New Zealand.Sedimentology 39: 675-696.

Journeaux, T. D.; Kamp, P. J. J.; Naish, T. R. 1996: Middle Pliocenecyclothems, Mangaweka region, Wanganui Basin, NewZealand: a lithostratigraphic framework. New ZealandJournal of Geology and Geophysics 39: 135-149.

Kamp, P. J. J.; Vonk, A. J.; Bland, K. J.; Griffin, A. G.; Hayton, S.;Hendy, A. J. W.; McIntyre, A. P.; Nelson, C. S.; Naish, T.2002: Megasequence architecture of Taranaki, Wanganui,and King Country basins and Neogene progradation of twocontinental margin wedges across western New Zealand.Proceedings of the New Zealand Petroleum ExplorationConference, Auckland, February 2002. Pp. 464-481.

King, P. R. 2000: Tectonic reconstructions of New Zealand: 40Ma to the Present. New Zealand Journal of Geology andGeophysics 43: 611-638.

King, P. R.; Thrasher, G. P. 1996: Cretaceous-Cenozoic geologyand petroleum systems of the Taranaki Basin, New Zealand.Institute of Geological & Nuclear Sciences Monograph 13.243 p.

Kingma, J. T. 1957: The geology of the Kohurau fault block,central Hawke's Bay. New Zealand Journal of Science andTechnology B38: 342-353.

Lillie, A. R. 1953: The geology of the Dannevirke Subdivision. NewZealand Geological Survey Bulletin 46.

Manville, V. 1996: Sedimentology and stratigraphy of ProspectFormation, Te Anau Basin, western Southland, NewZealand. New Zealand Journal of Geology and Geophysics39: 429-444.

Melhuish, A. 1990: Timing and mechanism of Ruahine Range uplift.Abstract. Geological Society of New Zealand MiscellaneousPublication 50A: 95.

Melhuish, A.; Van Dissen, R.; Berryman, K. 1996: Mount Stewart-Halcombe Anticline: a look inside a growing fold in theManawatu region, New Zealand. New Zealand Journal ofGeology and Geophysics 39: 123-133.

Molnar, P.; Atwater, T.; Mammerickx, J.; Smith, S. M. 1975:Magnetic anomalies, bathymetry and the tectonic evolutionof the South Pacific. The Geophysical Journal of the RoyalAstronomical Society 40: 383–420.

Naish, T. R.; Kamp, P. J. J. 1995: Late Pliocene marine cyclothems,Wanganui Basin, New Zealand. New Zealand Journal ofGeology and Geophysics 38: 223-243.

Naish, T. R.; Carter, R. M.; Pillans, B. J. 1999: High-resolutionchronology for the Plio-Pleistocene, Wanganui Basin,New Zealand. In: Carter, R. M.; Naish, T. R. ed. The high-resolution, chronostratigraphic and sequence stratigraphicrecord of the Plio-Pleistocene, Wanganui Basin, NewZealand. Institute of Geological & Nuclear Sciences FolioSeries 2.

Nelson, C. S.; Hume, T. M. 1977: Relative intensity of tectonic eventsrevealed by the Tertiary sedimentary record in the NorthWanganui Basin and adjacent areas, New Zealand. NewZealand Journal of Geology and Geophysics 20: 369-392.

Nicol, A.; Van Dissen, R.; Vella, P.; Alloway, B.; Melhuish, A. 2002:Growth of contractional structures during the last 10 m.y.at the southern end of the emergent Hikurangi forearcbasin, New Zealand. New Zealand Journal of Geology andGeophysics 45: 365-385.

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Smale, D.; Houghton, B. F.; McKellar, I. C.; Mansergh, G. D.; Moore,P. R.; Grant-Taylor, T. L.; Te Punga, M. T. 1978: Geologyand erosion in the Ruahine Range. New Zealand GeologicalSurvey Report G20. 120 p.

Sutherland, R. 1995: The Australia-Pacific boundary and Cenozoicplate motions in the SW Pacific: some constraints fromGeosatdata. Tectonics 14: 819-831.

Sutherland, R. 1996: Transpressional development of the Australian-Pacific boundary through southern South Island, NewZealand: constraints from Miocene-Pliocene sediments,Waiho-1 borehole, South Westland. New Zealand Journalof Geology and Geophysics 39: 251-264.

Turnbull, I. M.; Uruski, C. I. 1993: Cretaceous and Cenozoicsedimentary basins of western Southland, South Island,New Zealand. Institute of Geological & Nuclear SciencesMonograph 1. 86 p.

Wells, P. E. 1987: The stratigraphy and structure of the Mt Bruce area,northern Wairarapa, North Island, New Zealand. Journal ofthe Royal Society of New Zealand 17: 101-113.

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