Geology of the Kaikoura Area

Home , Awatere River, Blue Lake (Tasman), Clarence Fault, Ellis Basin cave system, Geology of New Zealand, Hanmer Springs

13 Geology of the Kaikoura Area

1 : 2 5 0 0 0 0 G e o l o g i c a l M a p

M. S. Rattenbury D. B. Townsend M. R. Johnston (Compilers) Age Oxygen New (ka) isotopeZealand International New Zealand Age International New Zealand events stages 251.0 (Ma) 0 Changhsingian ‘Makarewan’ YDm Haweran Wq 1 2 ‘Waiitian’ YDw 3 Castlecliffian Wc 4

Late

ocene Wuchiapingian Pleist- ‘Puruhauan’ YDp Quat 100 5 d'Urville 1.8 260.4 (Lopingian) Gelasian Nukumaruan Wn 6 Capitanian Flettian YAf Late Piacenzian Mangapanian Wm Wanganui 200 Waipipian Wp 7 3.6 Haweran

Middle Wordian 8

Pliocene Zanclean Opoitian Wo

(Guadalupian) Roadian 270.6 Barrettian YAr Early 300 5.3 9 Kungurian Kapitean Tk 10 Aparima Messinian Mangapirian YAm 400 11 Permian Artinskian 12 Telfordian YAt 500 13 Early Tortonian Tongaporutuan Tt

Taranaki Sakmarian Late 14 (Cisuralian) (unassigned) Ypt 600 15 Asselian 16 299.0 11.2 17 Gzhelian 700 18 Waiauan Sw 19 Serravallian 20 Castlecliffian Kasimovian 21 800 Moscovian

Southland

Middle Lillburnian Sl Miocene 900

Pennsylvanian Bashkirian Langhian Clifdenian Sc 16.4 1000 318.1 Serpukhovian Altonian Pl

Tertiary Burdigalian

Pareora (unassigned) F CENOZOIC Early Otaian Po Aquitanian Waitakian Lw 23.8 Carboniferous Visean Chattian Duntroonian Ld 28.5 Late

Landon Mississippian Rupelian Whaingaroan Lwh

Oligocene

Early 33.7 Runangan Ar Late Priabonian Bartonian Kaiatan Ak 41.3

Arnold Bortonian Ab Tournasian Lutetian Porangan Dp

Middle

Eocene Heretaungan Dh 49.0 359.2 Mangaorapan Dm Famennian Ypresian Early Waipawan Dw JU 55.5 Late Frasnian Thanetian

385.3 Dannevirke Givetian Late Selandian Teurian Dt 61.0 JM Danian

Middle

Eifelian Early 397.5 65.0 Paleocene Maastrichtian Emsian Jzl Haumurian Mh

Campanian Mata

Devonian

Pragian Jpr Santonian Piripauan Mp

Late Early Coniacian Teratan Rt Mangaotanean Rm Lochkovian Jlo Turonian Arowhanan Ra

Raukumara

417.2 PALEOZOIC Cenomanian Ngaterian Cn Pridoli 99.6 Motuan Cm Albian Ludlow Clarence Cretaceous Urutawan Cu 423.5 E Korangan Uk

Silurian Wenlock Aptian Llandovery Barremian 443.2 Early Undifferentiated Hauterivian Hirnantian (7) Taitai Bolindan Vbo Taitai Valanginian Series

Stage 6 Eastonian Vea Berriasian

Late 145.5 Puaroan Op

Stage 5 Gisbornian Vgi Tithonian Oteke 460.5 Darriwilian (4) Darriwilian Vda Ohauan Ko Yapeenian Vya Kimmeridgian

Middle Stage 3 Castlemainian Vca Late 472.0 Vch Chewtonian Heterian Kh

Ordovician Oxfordian Bendigonian Vbe 157.0 Stage 2 Callovian

Bathonian Kawhia

MESOZOIC Temaikan Kt

Middle

Early Lancefieldian Vla Bajocian

Jurassic

Tremadocian (1) Aalenian 175.6 pre-Lancefieldian Vpl 490.0 Stage 6 Datsonian Xda Toarcian Ururoan Hu Payntonian Xpa Paibian (5) Xiv Late Iverian 501 Idamean Xid Pliensbachian Mindyallan Xmi Herangi

Stage 4 Early Boomerangian Xbo Sinemurian Undillan Xun Aratauran Ha Stage 3 Hettangian Floran Xfl 199.6 Stage 2 Rhaetian Otapirian Bo

Middle Warepan Bw Ordian/Lower Stage 1 Xor Norian Templetonian Balfour Otamitan Bm

Late Cambrian Oretian Br

Carnian Kaihikuan Gk 237.0

Triassic

Early Ladinian XL Etalian Ge

Middle 542.0 Gore Anisian New Zealand geological Precambrian Z 245.0 Malakovian Gm Olenekian time scale from Cooper Nelsonian Gn

Early Induan 251.0 (2004). Geology of the Kaikoura Area

Scale 1:250 000

M. S. RATTENBURY D. B. TOWNSEND M. R. JOHNSTON (COMPILERS)

Institute of Geological & Nuclear Sciences 1:250 000 Geological Map 13

GNS Science Lower Hutt, New Zealand

2006 BIBLIOGRAPHIC REFERENCE Rattenbury, M.S., Townsend, D.B., Johnston, M.R. (compilers) 2006: Geology of the Kaikoura area. Institute of Geological & Nuclear Sciences 1:250 000 geological map 13. 1 sheet + 70p. Lower Hutt, New Zealand. GNS Science.

Edited, designed and prepared for publication by P.J. Forsyth, P.L. Murray, P.A. Carthew and D.W. Heron. Printed by Graphic Press & Packaging Ltd, Levin

ISBN 0-478-09925-8

FRONT COVER The Kaikoura Peninsula or Te Taumanu o Te Waka a Maui has an extensive shore platform cut into gently folded Late Cretaceous to Oligocene sedimentary rocks. The coastal cliffs are capped by beach deposits on raised marine terraces resulting from Late Quaternary uplift. In the background the Seaward Kaikoura Range rises from the active Hope Fault at the base of the range.

Te Taumanu o Te Waka a Maui, meaning the oarsman’s bench or thwarts of the canoe of Maui, is according to legend where Maui stood and cast his magical fish hook into the ocean. From his cast, he pulled up a giant fish, Te Ika a Maui, the North Island of New Zealand. Photo CN 23908/19: D. L. Homer ii CONTENTS

ABSTRACT ...... v Pahau terrane ...... 25 Late Jurassic to Early Cretaceous sedimentary and KEYWORDS ...... v volcanic rocks ...... 25 Esk Head belt ...... 27 INTRODUCTION ...... 1 Late Triassic to Early Cretaceous sedimentary and THE QMAP SERIES ...... 1 volcanic rocks ...... 27 The QMAP geographic information system ...... 1 CRETACEOUS TO PLIOCENE ...... 29 Data sources ...... 1 Cretaceous sedimentary and volcanic rocks ...... 29 Reliability ...... 1 Cretaceous igneous rocks ...... 34 REGIONAL SETTING ...... 3 Paleocene to Eocene sedimentary rocks ...... 35 Late Eocene to Pliocene sedimentary and volcanic GEOMORPHOLOGY ...... 6 rocks ...... 38 Southeast of the Alpine Fault ...... 38 Main Divide ranges ...... 6 Northwest of the Alpine Fault ...... 41 Kaikoura ranges ...... 6 Hanmer Basin ...... 6 QUATERNARY ...... 43 Northern Canterbury basins and ranges ...... 9 Alluvial terrace and floodplain deposits ...... 43 Coastal landforms ...... 9 Unmapped surficial deposits ...... 44 Alpine Fault ...... 11 Alluvial fan and scree deposits ...... 44 Lakes ...... 11 Till deposits ...... 46 Rivers ...... 11 Landslide deposits ...... 46 Offshore physiography ...... 11 Swamp and lake deposits ...... 46 STRATIGRAPHY ...... 13 Marine deposits ...... 47 Sand deposits ...... 47 CAMBRIAN TO CRETACEOUS ...... 13 OFFSHORE GEOLOGY ...... 47

Buller terrane ...... 13 TECTONIC HISTORY ...... 48 Early Ordovician sedimentary rocks ...... 13 Early to mid-Paleozoic ...... 48 Takaka terrane ...... 13 Late Paleozoic to Early Cretaceous ...... 48 Middle Cambrian to Late Ordovician sedimentary Mid- to Late Cretaceous and Paleogene ...... 48 rocks ...... 13 Neogene ...... 49 Karamea Batholith...... 13 GEOLOGICAL RESOURCES ...... 50 Late Devonian to Early Carboniferous intrusive rocks ...... 13 Metallic minerals ...... 50 Non-metallic minerals ...... 50 Median Batholith ...... 14 Rock ...... 51 Late Triassic to Late Jurassic igneous rocks and Coal ...... 53 associated sedimentary rocks ...... 14 Water ...... 53 Early Cretaceous intrusive rocks ...... 15 Oil and gas ...... 53 Brook Street terrane ...... 16 ENGINEERING GEOLOGY ...... 54 Early Permian volcanic and sedimentary rocks ...... 16 Basement rocks ...... 54 Murihiku terrane...... 16 Late Cretaceous-Pliocene rocks ...... 54 Late Middle Triassic and Early to Late Jurassic Quaternary sediments ...... 54 sedimentary rocks ...... 16 GEOLOGICAL HAZARDS ...... 55 Dun Mountain-Maitai terrane ...... 17 Early-Middle Permian ultramafic and mafic igneous Landslides ...... 55 rocks ...... 18 Coastal erosion ...... 55 Late Permian to Early Triassic sedimentary rocks ...... 19 Earthquake hazards ...... 56 Tsunami ...... 59 Caples terrane ...... 19 Late Permian to Early Triassic sedimentary rocks ...... 19 ACKNOWLEDGMENTS ...... 60 Mesozoic mélange ...... 21 AVAILABILITY OF QMAP DATA ...... 60 Torlesse composite terrane...... 22 REFERENCES ...... 61 Rakaia terrane ...... 22 Late Triassic sedimentary rocks ...... 22 Permian to Late Triassic semischist and schist ...... 24

iii Toka Anau – Barney’s Rock or Riley’s Lookout

Toka Anau is a strategic landmark that historically has been used for spotting whales. The island lies within a kilometre of the steep western wall of the submarine Kaikoura Canyon and was used by Maori and early European whalers to sight breaching whales. The famed Paramount Chief Kaikoura Whakatau gave permission to Barney Riley to establish the first European whaling station in the district in 1857.

Photo: T. Kahu, Te Runanga o Kaikoura iv ABSTRACT

The Kaikoura 1:250 000 geological map covers 18 100 km2 widespread, passive margin limestone and mudstone in of Westland, Nelson, Marlborough and northern the Paleocene, Eocene and Oligocene. Late Cenozoic clastic Canterbury in the South Island of New Zealand, and sedimentation reflects development of the present oblique- straddles the boundary between the Pacific and Australian compressional plate boundary and uplift of the Southern tectonic plates. The map area is cut by the Alpine, Awatere, Alps and other ranges. Clarence, Hope and other major strike-slip faults, and includes a wide range of Paleozoic to Mesozoic rocks which Quaternary glaciation deposited tills and glacial outwash form parts of eight tectonostratigraphic terranes. The early gravels. During warmer interglacial periods, high sea levels Paleozoic Buller and Takaka terranes, comprising cut flights of marine terraces that have been subsequently sedimentary and volcano-sedimentary rocks respectively, uplifted. are intruded by mid-Paleozoic granitic rocks of the Karamea Batholith and form the Western Province. This province is Mined mineral resources within the map area include separated from the Eastern Province by Mesozoic plutonic alluvial gold, salt, coal, limestone, and rock aggregate. rocks of the Median Batholith. North of the Alpine Fault, Recorded seeps and shows of oil and gas are sparse in the the Eastern Province comprises the Permian-Jurassic, area; there has been no commercial hydrocarbon extraction, predominantly volcano-sedimentary Brook Street, and the only petroleum exploration wells have been in the Murihiku, Dun Mountain-Maitai and Caples terranes. Murchison basin. South of the Alpine Fault the Eastern Province comprises the Triassic-Early Cretaceous sedimentary Rakaia and The Kaikoura map area is subject to severe natural hazards, Pahau terranes, collectively termed the Torlesse composite including a high level of seismic activity from the Alpine, terrane. Awatere, Clarence, Hope and other active faults. These have potential for earthquake shaking, landsliding, The Eastern Province and Western Province were liquefaction and ground rupture. Several large earthquakes juxtaposed in Late Jurassic to Early Cretaceous time, and with epicentres within or immediately adjacent to the map subsequently formed a comparatively stable basement to area have occurred within the last 160 years. Tsunami younger Cretaceous and Cenozoic sedimentation. hazard may be from remote or local earthquakes or from Localised fault activity and clastic sedimentary basin submarine slumping, particularly within the Kaikoura development in the late Early to Late Cretaceous, and again Canyon immediately offshore. Storm-induced landsliding, in Late Cenozoic time, contrast with the deposition of rockfall and flooding are ongoing hazards.

Keywords

Kaikoura; Marlborough; Westland; Nelson; Canterbury; 1:250 000 geological map; geographic information systems; digital data; bathymetry; Buller terrane; Takaka terrane; Karamea Batholith; Median Batholith; Median Tectonic Zone; Brook Street terrane; Murihiku terrane; Dun Mountain-Maitai terrane; Caples terrane; Rakaia terrane; Pahau terrane; Torlesse terrane; plutons; Greenland Group; Haupiri Group; Mount Arthur Group; Karamea Suite; Brook Street Volcanics Group; Dun Mountain Ultramafics Group; Livingstone Volcanics Group; Maitai Group; Tasman Intrusives; Rotoroa Complex; Teetotal Group; Separation Point Suite; Glenroy Complex; Richmond Group; Patuki mélange; Esk Head belt; Coverham Group; Tapuaenuku Igneous Complex; Mandamus Igneous Complex; Wallow Group; Hapuku Group; Seymour Group; Eyre Group; Muzzle Group; Motunau Group; Awatere Group; Rappahannock Group; Tadmor Group; marine terraces; alluvial terraces; alluvial fans; scree; rock glaciers; moraines; till; outwash; landslides; peat swamps; Alpine Fault; Awatere Fault; Clarence Fault; Hope Fault; Marlborough Fault System; Quaternary tectonics; active faulting; economic geology; alluvial gold; salt; sub- bituminous coal; limestone; aggregate; groundwater; engineering geology; landslides; natural hazards; seismotectonic hazard; tsunami. v 170° E 175° E

New Caledonia Basin

35° S Kaitaia 35° S 2000 Whangarei 2000

Auckland

Waikato Rotorua 47 mm/yr Challenger Taranaki Raukumara Plateau Basin Hawkes Taranaki Bay

40° S 40° S Australian Plate Nelson Wellington Wairarapa

2000 Hikurangi Trough Greymouth 41 mm/yr QMAP Kaikoura 38 mm/yr Alpine Fault Christchurch Aoraki Haast Chatham Rise Pacific S Wakatipu Waitaki 45° S 45° S Fiordland Plate

Bounty 37 mm/yr Murihiku Dunedin Trough

2000 0 100 200 Campbell Plateau Kilometres

Puysegur Trench 165° EE 170° E 175° E 180° E

Figure 1 Regional setting of New Zealand, showing the location of the Kaikoura geological map and other QMAP sheets, active faults and major offshore features (as illustrated by the 2000 m isobath). The Kaikoura sheet lies on the boundary between the Australian and Pacific plates where the subduction in the Hikurangi Trough is transitional into continental collision in the Southern Alps of the South Island. The arrows indicate the direction and rate of convergence of the Pacific Plate relative to the Australian Plate. After Anderson & Webb (1994).

vi INTRODUCTION

THE QMAP SERIES Digital topographic data were provided by Land Information New Zealand. The QMAP database is The geological map of the Kaikoura area (Fig. 1) is one of complementary to, and can be used in conjunction with, the national QMAP (Quarter million MAP; Nathan 1993) other spatially referenced GNS Science digital data sets, series produced by GNS Science. The series replaces the e.g. gravity and magnetic surveys, mineral resources and earlier 1:250 000 series geological maps covering the localities, fossil localities, active faults, and petrological Kaikoura area (Lensen 1962; Bowen 1964; Gregg 1964). samples. Since the publication of those earlier maps, important geological concepts such as plate tectonics, terranes and The QMAP series and database are based on detailed sequence stratigraphy have been developed, and a vast geological information plotted on 1:50 000 NZMS260 series amount of new geological research has been undertaken. topographic base maps. These data record sheets are This research includes detailed mapping, at 1:50 000 scale, available for consultation at GNS Science. The 1:50 000 of large areas (e.g. Johnston 1990; Suggate 1984; Reay data have been simplified for digitising during a 1993; Challis & others 1994; Warren 1995), fault studies compilation stage, with the linework smoothed and (e.g. Kieckhefer 1979), detailed investigations for economic geological units amalgamated to a standard national system and engineering projects, university theses, and published based on age and lithology. Point data (e.g. structural papers on tectonic, stratigraphic, petrological, geochemical measurements) have not been simplified. All point data are and many other aspects of geology. stored in the GIS, but only selected representative structural observations are shown on the map. Procedures The geology of the Kaikoura map area is in many places so for map compilation and details of data storage and complex that the map has been considerably simplified in manipulation techniques are given by Rattenbury & Heron order to present it legibly at 1:250 000 scale. Rock units are (1997). mapped primarily in terms of their age of deposition, eruption, or intrusion. As a consequence, the colour of the Data sources units on the map face reflects their age, with overprint patterns used to differentiate some lithologies. Letter The map and text have been compiled from published maps symbols (in upper case, with a lower case prefix to indicate and papers, unpublished university theses, GNS Science early, middle or late if appropriate) indicate the predominant technical and map files, mining company reports, field trip age of the rock unit and the following lower case letter or guides, the New Zealand Fossil Record File in its digital letters indicates a formally named lithostratigraphic unit form (FRED), and GNS Science geological resources and/or the predominant lithology. Metamorphic rocks are (GERM) and petrological (PETLAB) digital databases (Fig. mapped in terms of age of protolith (where known), with 2). Additional field mapping between 2000 and 2004 overprints indicating degree of metamorphism. Age resolved some geological problems and increased data subdivision is in terms of the international time scale. coverage in less well-known parts of the map area. Correlation between international and local time scales and Quaternary deposits, landslides and active faults have absolute ages in millions of years (Ma) are shown inside largely been mapped from aerial photos, with limited field the front cover (Cooper 2004). checking. Offshore data have been compiled from published studies of the northern Canterbury-Marlborough This text is not an exhaustive description or review of the region (Field, Browne & others 1989; Barnes & Audru various rock units mapped. Names applied to geological 1999a,b; Field, Uruski & others 1997) and unpublished data units are those already published and revision of from the National Institute of Water and Atmospheric nomenclature to remove anomalies has not been attempted. Research. Data sources used in map compilation are In some cases, correlation of stratigraphic units has summarised in Fig. 2 and are cited in the references together resulted in only one name being retained as the mapping with other studies relating to the Kaikoura map area. unit. For more detailed information on individual rock units, specific areas, natural hazards or minerals, the reader is Reliability referred to data sources cited throughout the text and listed in the references. The 1:250 000 map is a regional scale map only, and should not be used alone for land use planning, planning or design The QMAP geographic information system of engineering projects, earthquake risk assessment, or other work for which detailed site investigations are The QMAP series uses computer methods to store, necessary. Some data sets incorporated with the geological manipulate and present topographic and geological data (for example the Geological Resources Map of New information. The maps are drawn from data stored in the Zealand [GERM] data) have been compiled from old or QMAP geographic information system (GIS), a database unchecked information of lesser reliability (see Christie developed and maintained by GNS Science. The primary 1989). software used is ArcInfo®.

1 60 77 48 61 66 83 Langridge 2000 Beck & Annear 1968 Johnston 1964 Andrews 1970 Campbell 1980 Cooper 1980 Cutten & Tulloch 1990 Van Dissen 1990 Van Dissen 1995 Crampton 1995 Crampton & Isaac 1997 Langridge 2002 Pettinga & Campbell 2003 Barnes 2004 Suggate 1956 Browne 1984 Fyfe 1936 Fyfe 1946a,b 38 Suggate 1949 56 49 36 45 57 75 85 84 80 76 68 78 74 70 67 71 77 81 72 73 82 83 79 69 53 Unpublished maps 51 59 78 76 79 71 7 50 71 42 41 44 35 67 70 ces. 64 65 62 84 63 Audru 1996 Lihou 1991 Mould 1992 Vickery 1994 Lowry 1995 Worley 1995 Jones 1995 Townsend 1996 Clegg 2001 Slater 2001 Smith 2001 Stone 2001 Townsend 2001 Harker 1989 Cowan 1989 Kirker 1989 84 58 55 65 56 66 58 54 64 60 57 61 62 63 59 53 51 52 68 82 84 84 72 47 55 46 80 81 85 37 52 54 69 73 43 75 Adamson 1966 Challis 1960 Hall 1964 Grapes 1972 Stewart 1974 Cutten 1976 Nicol 1977 Montague 1981 Botsford 1983 Powell 1985 Ritchie 1986 Rose 1986 McLean 1986 Waters 1988 Melhuish 1988 Robertson 1989 47 35 45 36 46 38 48 44 40 50 37 41 47 42 39 49 43 Student theses 40 39 43 74 26 24 12 32 Lihou 1993 Browne 1992 McCalpin 1992 Roberts & Wilson 1992 Baker & others 1994 Wood & others 1994 Ota & others 1996 Benson & others 2001 Bacon & others 2001 Litchfield & others 2003 Crampton & Laird 1997 31 29 24 25 26 27 30 32 28 34 33 31 21 30 28 9 33 23 11 20 1 13 5 Fleming 1958 Suggate 1965 Clayton 1968 Bradshaw 1972 Cutten 1979 Turnbull & Forsyth 1986 McPherson 1988 Crampton 1988 Browne & Maxwell 1992 Campbell 1992 Grapes & others 1992 19 8 20 13 22 19 15 16 21 17 18 14 23 Published papers 6 29 34 3 15 4 25 10 2 18 16 7 15 27 Lensen 1962 Gregg 1964 Bowen 1964 Fyfe 1968 Freund 1971 Kieckhefer 1979 Suggate 1984 Johnston 1990 Reay 1993 Challis & others 1994 Warren 1995 Field, Uruski & others 1997 22 2 3 5 1 4 7 8 9 6 11 12 10 Published map sheets 14 17 Figure 2 Location of data sources used in compiling the Kaikoura map. Unpublished maps and reports, including mining company are held in the map archive and files of GNS sources are listed in the referen All data Science, Lower Hutt. Unpublished university theses are held in libraries.

2 REGIONAL SETTING The basement geology of the Kaikoura map is dominated by quartzofeldspathic sedimentary rocks of the Rakaia and The Kaikoura geological map covers much of northern Pahau terranes (Bradshaw 1989), of dominantly Mesozoic Canterbury, southern Marlborough and southern Nelson, age, that amalgamated to form the Torlesse composite including many of the northeastern mountains of the South terrane (Fig. 4). Northwest of the Alpine Fault the basement Island. The map area is sparsely populated with the largest rocks include the early Paleozoic sedimentary and towns – Kaikoura, Hanmer and Murchison – servicing volcanogenic rocks of the Buller and Takaka terranes agricultural industries. The other main industries are (Cooper 1989), and mid-Paleozoic to Early Cretaceous tourism, fishing and exotic forestry. Much of the igneous intrusions of the Karamea and Median batholiths northwestern part of the Kaikoura map area is covered in (Tulloch 1988; Mortimer & others 1999). The Permian to indigenous forest and is under Department of Conservation Jurassic volcanic and sedimentary Brook Street, Murihiku, (DoC) stewardship. DoC administers Nelson Lakes and Dun Mountain-Maitai and Caples terranes occur in south Kahurangi national parks, Lewis Pass Scenic Reserve, Nelson. Victoria, Hanmer and Lake Sumner conservation parks, Mt Richmond Forest Park and Molesworth Farm Park. Covering mid- and Late Cretaceous, Paleogene and Neogene sedimentary rocks have been mostly removed The Kaikoura map area straddles the boundary between by erosion, particularly in the central part of the map area. the Australian and Pacific plates which are converging at The sedimentary rocks resulted from an initial period of about 40 mm per year (Fig. 1). This area also covers the widespread erosion followed by marine transgression and plate boundary transition from subduction of the Pacific subsequent regression in the early to middle Cenozoic. plate under the Australian plate (Fig. 3), exemplified in the The Neogene development of the modern plate boundary southern North Island, to continental collision between through New Zealand, and associated convergence, the plates, manifest by uplift of the Southern Alps and resulted in uplift and further erosion. Widespread other ranges of the South Island. Much of the plate Quaternary terrestrial sedimentation reflects continuing boundary movement in the Kaikoura map area is uplift and erosion, with glaciation having a major influence accommodated by oblique, dextral strike-slip along the on sedimentation. Alpine Fault and the Awatere, Clarence, Hope and other faults of the Marlborough Fault System (Van Dissen & Yeats 1991; Knuepfer 1992; Holt & Haines 1995).

Hikurangi Trough (oceanic crust) Pacific Australian Plate Plate Chatham Rise (continental crust)

Hope

N Fault Clarence Fault

Alpine Awatere Fault Fault

Depth (km) 0-17 17-30 subducting 30-45 oceanic crust 45-70 70-95 95-120 120-150 150-180 180-210 >210

Figure 3 Block model of the Kaikoura map area and surrounding regions showing active faults at the surface and the position of the subducting Pacific Plate under the Australian Plate defined by earthquake hypocentres (mostly concentrated on the upper surface of the subducting plate). After Barnes (1994b), Eberhart-Phillips & Reyners (1997).

3 SEDIMENTARY AND VOLCANIC ROCKS

Northland and East Coast allochthons

Waipapa composite terrane Torlesse composite (western North Island) terrane (eastern NZ)

Eastern Morrinsville facies Pahau terrane Northland Hunua facies Rakaia terrane Allochthon

Caples terrane Province Dun Mountain - Maitai terrane Murihiku terrane Brook Street terrane East Coast

Province Takaka terrane Western Tuhua Allochthon Buller terrane terrane undifferentiated

PLUTONIC ROCKS ?

Median Batholith Karamea Batholith ? Paparoa Batholith Hohonu Batholith

REGIONAL TECTONIC- METAMORPHIC OVERPRINTS

Esk Head Belt and deformed zones in the Pahau terrane Haast Schist Trough Gneiss Hikurangi N

200 km

FAULT Kaikoura E PIN AL

Puysegur Trench

Figure 4 Pre-Cenozoic basement rocks of New Zealand, subdivided into tectonostratigraphic terranes and batholiths; after Mortimer (2004). Cretaceous to Oligocene rocks of the Northland and East Coast allochthons were emplaced as a series of thrust sheets in the Miocene.

N hta Rise Chatham

20 km

iuag Trough Hikurangi enoBank Mernoo shelf continental Clarence Fault

Awatere Fault

o y Hope Fault Valleys n

Kowhai Sea C

a r u o

wtr valley Awatere ik a Kaikoura Peninsula K

Trough

Conway

lrnevalley Clarence

ewr akuaRange Kaikoura Seaward nadKior Range Kaikoura Inland Alpine (Wairau) Fault Basin

Cheviot aruvalley Wairau Hanmer Basin Culverden Basin

Moutere Depression pne Mountains Spenser

Basin otenAlps Southern Murchison Shaded relief model of QMAP Kaikoura illuminated from the northwest. The has been generated a digital terrain built from 20 m contour Alpine Fault Hope Fault Kakapo Fault Awatere Fault Clarence Fault Figure 5 and spot height data supplied by LINZ (on land) bathymetric contours NIWA (offshore). Major faults are arrowed and significant physiographic features are labelled.

5 GEOMORPHOLOGY angle depressions on the southeastern sides of the faults. The summit heights of the ranges are generally concordant, Main Divide ranges reflecting uplift of relatively planar Late Cretaceous and later erosion surfaces cut in the basement rocks of Torlesse The ranges and mountains at the northernmost end of the composite terrane. The distinctive peaks of Mt Tapuae-o- Southern Alps (Fig. 5), rise southeast of the Alpine Fault Uenuku and Blue Mountain result from more erosion- and form the “Main Divide” drainage boundary between resistant igneous rock intrusions and associated the east and west coasts of the South Island. The mountains hornfelsing of the Torlesse composite terrane country rock. include a complex array of mostly north-trending ranges with numerous peaks over 2000 m, culminating at Mt Hanmer Basin Franklin (2340 m) in the Kaikoura map area. The higher range crests are generally bare rock and lack permanent Hanmer Basin is a rhomb-shaped topographic depression snowfields or glaciers (Fig. 6). (Figs 5, 8) 15 km by 7 km at about 300 m elevation, surrounded by ranges up to 1500 m elevation. The Waiau Kaikoura ranges River enters the basin area from the west, joins with the smaller Hanmer River, and drains through a gorge on the The northeastern Kaikoura map area is dominated by the south side. Active traces of the Hope Fault are present on northeast-trending Inland and Seaward Kaikoura ranges the northern side of the western part of the basin, are absent (Figs 5, 7) that reach their greatest elevation in Tapuae-o- from the central area, and reappear on the southern side of Uenuku (2885 m) and Manakau (2608 m) respectively. These the eastern part of the basin. This basin formed at a ranges and lower ranges to the northwest are influenced releasing bend between the right-stepping western Hope by the major dextral strike-slip Alpine (Wairau), Awatere, River and Conway segments of the dextral strike-slip Hope Clarence and Hope faults, which traverse long straight Fault. Seismic and gravity studies indicate Quaternary valleys with intervening low saddles and aligned river sediment fills the basin to a depth of more than 1000 m segments. Except in the Wairau valley, remnants of (Wood & others 1994). Cretaceous-Pliocene covering rocks are preserved in fault-

Figure 6 Lake Constance and Blue Lake (far right) at the head of the Sabine River resulted from landslide dams in a deglaciated valley, and the smaller, unnamed tarn in the foreground fills a glacial cirque. The unvegetated greywacke- dominated Mahanga Range (middle distance) and the schistose Ella Range (behind) were occupied by glaciers until the early Holocene. Photo CN25744/19: D.L. Homer. 6 Figure 7 The Inland Kaikoura Range is bounded to the southeast by the major Clarence Fault, which has an average Holocene right-lateral slip rate of 4-7 mm/yr (Pettinga & others 2001). The fault separates Early Cretaceous Pahau terrane (left) from Late Cretaceous to Miocene sedimentary and igneous rocks (right). The high peaks on the skyline are Mts Alarm (2877 m) and Tapuae-o-Uenuku (2885 m). Photo CN4938/5: D.L. Homer.

Figure 8 The Hanmer Basin is a depression caused by a right step in the dextral strike-slip Hope Fault. The western Hope River segment of the fault (lower left) branches into many splays on the northern side of the basin (middle left). The Conway segment of the fault begins near the Waiau gorge (middle right) and follows the Hanmer River eastwards towards the coast. The basin sediments are over 1 km thick and are probably all Late Quaternary in age.

Photo CN14438/27: D.L. Homer. 7 Figure 9 Basin and range topography in the Waikari area, with Oligocene limestone outlining folds in the foreground. Late Cretaceous and Cenozoic rocks have largely been eroded off the Lowry Peaks Range in the left middle distance.

Photo CN3665/2: D.L. Homer.

Figure 10 The cliffed North Canterbury coastline results from ongoing tectonic uplift. These cliffs 4 km north of the Waiau River mouth are cut into Pahau terrane (left) and the unconformably overlying Neogene Greta Formation siltstone (right). Photo CN19635/10: D.L. Homer.

8 Figure 11 Resistant, folded Muzzle Group limestone at Needles Point forms a barrier to sand and gravel brought northwards (from left to right) by long-shore currents. Dunes are also preserved in places (upper left).

Photo CN23980/5: D.L. Homer.

Northern Canterbury basins and ranges Coastal landforms

South of the Hope Fault, the ranges are lower in altitude Much of the coast between the Clarence River mouth and and generally less rugged (Fig. 5). Between the ranges, the Gore Bay consists of steep slopes and cliffs cut largely in extensive intermontane Culverden, Cheviot and other Pahau terrane rocks (Fig. 10). At Kaikoura, the peninsula is basins are partly rimmed by Cretaceous-Miocene composed of Late Cretaceous-Paleogene limestone and sedimentary rocks (Nicol & others 1995). These include other rocks (front cover), and similar rocks form the smaller, the erosion-resistant Paleogene limestones that form but equally impressive Haumuri Bluffs south of Kaikoura. distinctive landscapes near Waikari and Hawarden (Fig. Paleogene rocks, capped by marine terraces, form the 9). Sinkholes are locally developed where the limestone is dominant exposures at the Conway River mouth and from flat-lying, such as the summit plateau of Mt Cookson and the Hurunui River southwards. Slope failures are on the Kaikoura Peninsula. Where the Late Cretaceous to widespread, particularly in fine-grained rocks that are rich Miocene rocks have been stripped off relatively recently, in montmorillonitic clays. More competent conglomerates the range crests are broad with little local relief. Some of and limestones form coastal cliffs and offshore rocks such the northeast-trending ranges are asymmetrical in as those at Needles Point (Fig. 11) and Chancet Rocks. transverse profile with reverse faults or thrusts on their Clifford Bay and the adjacent shallow Lake Grassmere generally steeper northwestern sides. The intermontane occupy the northern end of the northeast- plunging Ward basins are filled with Late Quaternary gravel. Syncline. Inland, along the syncline axis to the southwest, is the even shallower Lake Elterwater.

9 Figure 12 The active Alpine (Wairau) Fault crosses the northern end of Lake Rotoiti at St Arnaud, and continues northeast into the Wairau valley (distant). Neogene dextral strike-slip has juxtaposed Median Batholith, Brook Street, Murihiku, Dun Mountain-Maitai and Caples terrane rocks to the northwest (left) against Rakaia terrane and Esk Head belt rocks of the Travers, St Arnaud and Raglan ranges to the southeast (right). Photo CN46400/16: D.L. Homer.

Figure 13 The Buller River flows south along the axis of the Longford Syncline to Murchison (centre distance). The thick Eocene to Miocene strata of the Murchison Basin have been tightly folded since the Late Miocene, completing a remarkably short but significant period of basin formation and deformation. Photo CN4181/4: D.L. Homer. 10 Parallel to the coast, raised interglacial shorelines form near Lake Tennyson, then east and northeast along the narrow benches and terraces, the latter being more traces of the Elliott and Clarence faults, and then southeast extensive between Haumuri Bluffs and the Waiau River. through a gorge at the northern end of the Seaward Intermittent narrow beaches of sand and gravel, commonly Kaikoura Range to the coast. fringed or capped by sand dunes, also occur along the coast (Fig. 11). The Conway, Waiau and Hurunui rivers have each cut several antecedent gorges through the ranges of northern Alpine Fault Canterbury and have wide braided channels where they traverse the intervening basins to reach the Pacific Ocean. The Alpine Fault is marked by a succession of low saddles, Most of the rivers are flanked by sets of terraces carved depressions, and aligned stream and river valleys. Between into glacial outwash gravel or formed by aggradation. Many Tophouse and St Arnaud the fault traverses two low of the outwash gravel surfaces can be traced inland to saddles (695 and 710 m; Fig. 12) that separate the Buller, terminal moraines on both sides of the Main Divide. Motupiko and Wairau rivers, which drain to the West Coast, Tasman Bay and Pacific Ocean, respectively. The fault Offshore physiography prominently displaces a peninsula of moraine at the northern end of Lake Rotoiti. The Alpine Fault also marks The offshore physiography of the Kaikoura map area is a significant change in topography, especially south of St dominated by four elements: the continental shelf, the Arnaud; ranges to the southeast of the fault are typically continental slope, the Hikurangi Trough and the Chatham 500 m higher than those to the northwest (Fig. 5), reflecting Rise. The continental shelf has a smooth sea floor at shallow net Quaternary uplift. depth (<400 m) that tapers from about 50 km wide in the north to about 10 km wide near Kaikoura Peninsula (Fig. Lakes 5). Immediately south of the peninsula, the spectacular Kaikoura Canyon is deeply incised into the shelf to within The largest lakes in the Kaikoura map area have formed in c. 500 m of the shoreline (Lewis & Barnes 1999). At the glaciated valleys behind terminal moraines, e.g. lakes head of the canyon, the sea floor falls away abruptly so Rotoiti (Fig. 12), Rotoroa, Sumner, Guyon and Tennyson. that only 4 km offshore the water is 1000 m deep. This deep Most other lakes have resulted from landslide damming canyon is responsible for interruption of the north-flowing e.g. lakes Constance (Fig. 6), McRae and Matiri, and in Southland current, and the coincidence of the Subtropical many cases the landslides have fallen from previously Convergence Zone with the Chatham Rise (Lewis & Barnes glaciated and oversteepened valley sides, possibly 1999) leads to the local upwelling of plankton which attracts triggered by earthquakes. Tarns occupying cirques are marine life such as whales, seals, and dolphins widespread in the higher mountains in the west. (Childerhouse & others 1995). South of the canyon near the Kaikoura map boundary the continental shelf broadens Rivers to 30 km width. The Conway Trough and Hurunui Canyon are incised into the Canterbury continental shelf. Large rivers traverse many parts of the Kaikoura map area and originate from the Main Divide, within or beyond the The edge of the continental shelf abruptly gives way to map area. Northwest of the Alpine Fault, the Buller River the continental slope. The slope is incised by many cuts through several mountain ranges from its source at canyons and small basins, which are predominantly Lake Rotoiti. Close to its source, the river flows westward controlled by fault movement (Field, Uruski & others 1997; through a gorge cut in granitic rocks of the Median Barnes & Audru 1999a). Directly east of Kaikoura Peninsula Batholith before crossing the Murchison Basin. On the Kowhai sea valleys form a series of narrow ridges and entering the basin the river follows the axis of the Longford canyons that cut into the slope (Fig. 5). The continental Syncline to Murchison (Fig.13). Tributary valleys around slope is bounded to the east by the northeast-trending Murchison commonly follow north-south trending faults Hikurangi Trough, which reaches depths of 2500 m within and fold axes. the Kaikoura map area and 3500 m off the East Coast of the North Island (Lewis & Barnes 1999). Southeast of the The course of the Awatere River and sections of the trough, the continental slope (here known as Mernoo Bank) Clarence, Waiau and Wairau rivers have been strongly climbs to the Chatham Rise, part of a submerged continental influenced by movement of the active faults of the plateau (Barnes 1994b). The Mernoo Bank is incised by Marlborough Fault System and related uplift of adjacent the Pukaki, Pegasus and Hurunui canyons. ranges. The Clarence River flows south from its source

11 PAHAU ungrouped TERRANE N PAHAU 20 km TERRANE Esk Belt Head are marked with an asterisk. PAHAU TERRANE CAPLES TERRANE ungrouped RAKAIA TERRANE TERRANE TORLESSE COMPOSITE ESK BELT HEAD DUN MOUNTAIN- MAITAI TERRANE Group Caples CAPLES TERRANE

TERRANE MURIHIKU

t l

)

TERRANE a

BROOK ST r

Maitai Wai DUN Group (

MAITAI Livingstone ESK

e BELT HEAD

Dun Mountain

TERRANE n

Volcanics Group i p

MOUNTAIN- l Ultramafics Group

ere

w A MEDIAN BATHOLITH Group Volcanics BROOK STREET Brook Street TERRANE TERRANE MURIHIKU Richmond Group RAKAIA TERRANE KARAMEA SUITE Rotoroa Complex Suite Glenroy Complex MEDIAN Pepin Group* Tasman Separation Point Intrusives BATHOLITH BULLER TAKAKA TERRANE TERRANE

e v

e Group Haupiri

e g n

Group a l TAKAKA e Ellis Group* TERRANE Devil River Mount Arthur Baton Group* Group*

m Volcanics Riwaka Complex* Parapara Group* TUHUA TERRANE Terrane amalgamation Group* Rahu Suite* BULLER Golden Bay TERRANE Karamea Suite Reefton Group* Kirwans Dolerite* Greenland Group Topfer Formation* Eastern Province Western Province Late Early Early Middle Middle Silurian Triassic Permian Jurassic Devonian Devonian Cambrian Cambrian Ordovician Cretaceous Late Devonian Carboniferous 443 505 354 490 391 417 290 370 Tectonostratigraphic relationships within and between basement terranes. Stratigraphic units not appearing on the Kaikoura map units relationships within and between basement terranes. Stratigraphic Tectonostratigraphic Figure 14

12 STRATIGRAPHY

Cambrian to Cretaceous basement rocks, including folds and a penetrative cleavage (Rattenbury & Stewart volcanic, metasedimentary, granitic and ultramafic rocks, 2000). outcrop over 70% of the Kaikoura map area. The basement rocks are overlain by remnants of Late Cretaceous and Takaka terrane Cenozoic, terrestrial and marine, sedimentary and igneous rocks, preserved in basins around Murchison and A small area of the Takaka terrane outcrops in the Kaikoura throughout eastern Marlborough and northern Canterbury. map area along the Alpine Fault, near Lake Daniells. Further In the east these younger rocks contain local volcanic north the terrane is concealed by Tertiary rocks in the sequences. Quaternary fluvioglacial and alluvial deposits Murchison Basin (see section C-C’), but is well exposed in are widespread but Quaternary marine rocks occur only Northwest Nelson, where the type localities of the Haupiri locally. and Mt Arthur groups are located (Rattenbury & others 1998). Southwest of the Kaikoura map area, the terrane CAMBRIAN TO CRETACEOUS progressively narrows and is truncated by the Alpine Fault (Nathan & others 2002). The basement rocks of the Kaikoura map area, of Gondwanaland origin, have been divided into the largely Middle Cambrian to Late Ordovician sedimentary rocks early Paleozoic Western Province and the late Paleozoic to Mesozoic Eastern Province (Landis & Coombs 1967). The In the vicinity of Lake Daniells, volcanogenic sedimentary volcano-sedimentary and mafic intrusive rocks are mapped rocks with conglomerate and minor basaltic flows are in tectonostratigraphic terranes (Figs 4, 14; Coombs & correlated with the Haupiri Group of Northwest Nelson others 1976; Bishop & others 1985; Bradshaw 1993; (Münker & Cooper 1999; Nathan & others 2002). Three Mortimer 2004) within which traditional lithostratigraphic informal units (Nathan & others 2002) are recognised, formations and groups are recognised. The Western comprising dolomitic mudstone and ankeritic sandstone Province contains the Buller and Takaka terranes (Cooper with minor conglomerate ($hr), polymict pebble to granule 1989) that amalgamated in the mid-Devonian (collectively conglomerate ($ha), and grey laminated dolomitic termed the Tuhua composite terrane). The Eastern Province mudstone and sandstone with widespread interlayered in the Kaikoura map area comprises the Brook Street, Dun felsic volcanic rocks ($hh). In Northwest Nelson the group Mountain-Maitai, Murihiku, and Caples terranes west of has been assigned a Middle-Late Cambrian age (Münker the Alpine Fault and the Rakaia and Pahau terranes & Cooper 1999). (collectively the Torlesse composite terrane) east of the fault (Coombs & others 1976; Mortimer 2004). Many of the In the Lake Daniells area the Mt Arthur Group overlies the plutonic rocks occur within the originally contiguous Haupiri Group (Bowen 1964), separated by a detachment Median and Karamea batholiths (Tulloch 1988; Mortimer fault (R. A. Cooper in Nathan & others 2002). The Sluice & others 1999). Box Limestone (|ms) consists of recrystallised grey, commonly siliceous, limestone and minor sandstone with Buller terrane mudstone layers. Conodonts, trilobites and disarticulated brachiopods indicate a Late Cambrian to Middle Ordovician Early Ordovician sedimentary rocks age (Cooper 1989). The formation is correlated with the Arthur Marble 1 and Summit Limestone formations of The Buller terrane, comprising the Greenland Group (|g) Northwest Nelson (Rattenbury & others 1998). The within the Kaikoura map area, occupies a few square conformably overlying siltstone and minor quartz kilometres near Maruia Saddle. The group consists of well- sandstone of the Alfred Formation (|mw) contains Late to poorly bedded, greenish-grey quartzose sandstone and Ordovician (Gisbornian) graptolites and is correlated with mudstone (Stewart 1974). The rocks are intruded by Late the Wangapeka and Baldy formations in Northwest Nelson Devonian-Carboniferous Karamea Suite granite in the (Rattenbury & others 1998). northwest and faulted against Miocene conglomerate to the southeast. Greenland Group sandstone typically Karamea Batholith contains abundant detrital quartz, minor sodic plagioclase and subordinate volcanic and sedimentary rock fragments Late Devonian to Early Carboniferous intrusive rocks (Nathan 1976; Roser & others 1996). The group has been interpreted as a turbidite succession within a submarine The Karamea Batholith extensively intrudes the Tuhua fan deposit (Laird 1972; Laird & Shelley 1974). Graptolites terrane in the northwest of the South Island and is from near Reefton, 30 km west of the Kaikoura map area, dominated by the Karamea Suite of Late Devonian-early are early Ordovician (Cooper 1974). K-Ar and Rb-Sr ages Carboniferous granites (Tulloch 1988; Muir & others 1994). from Greenland Group beyond the map area indicate a The suite has S-type geochemistry, commonly containing widespread Late Ordovician to Early Silurian greenschist muscovite and generally lacking hornblende. Within the facies (chlorite zone) metamorphic event (Adams & others Kaikoura map area the rocks are only exposed at Mts 1975; Adams 2004). Adjacent to the granite, the group has Newton and Mantell, north and south of Murchison been thermally metamorphosed to biotite hornfels (Stewart respectively, but are inferred to underlie much of the 1974). Metamorphism probably accompanied deformation Paleogene-Miocene strata of the Murchison Basin. At Mt that resulted in generally steep bedding dips, tight upright Newton the suite comprises coarse-grained, inequigranular

13 biotite granite, locally with megacrystic K-feldspar, and rich layers. Within the Delaware-Speargrass Fault Zone fine-grained muscovite-biotite granite (Dkg). At Mt the diorite grades into the foliated Rotoiti Gneiss (Tar) Mantell, biotite granodiorite and tonalite (Dkt) composed of quartz, plagioclase (oligoclase), K-feldspar, predominate (Stewart 1974). U-Pb dating of the Karamea biotite, muscovite and porphyroblastic garnet. Radiometric Suite beyond the map area gave crystallisation ages of dating of the Buller Diorite yielded Late Triassic ages of 388–358 Ma (Muir & others 1994, 1996). 225 Ma (K-Ar, Johnston 1990) and 228 Ma (U-Pb zircon, Kimbrough & others 1994). Other rock types within the Median Batholith Delaware-Speargrass Fault Zone include altered coarse- to fine-grained gabbro and minor pyroxenite of the The rocks separating the Eastern and Western provinces Seventeen Gabbro (Jas) of Mesozoic age (Johnston 1990). include a range of mafic, intermediate and felsic plutonic intrusions, some extrusive equivalent rocks and several The One Mile Gabbronorite (Jao) consists of diorite, significant sedimentary units in and to the north of the tonalite and hornblende gabbronorite that are commonly map area. The Median Tectonic Zone (MTZ, Bradshaw altered (Tulloch & others 1999). The pluton intrudes the 1993) was defined to include these diverse and, in places, Rainy River Conglomerate in the east and is bounded by structurally dismembered rocks. Mortimer & others (1999) the Flaxmore Fault in the west. U-Pb dating of zircons recognised that the MTZ is more than 90% plutonic in indicates a 147 Ma (Late Jurassic) intrusive age (Kimbrough origin and that much of the deformation was superimposed & others 1994). in the Cenozoic. Moreover the plutonic rocks extend beyond the western limit of the MTZ into parts of the Big Bush Andesite (Jeb) of the Teetotal Group (Johnston Western Province and are viewed as part of an originally 1990) forms an 800 m wide strip in the upper Rainy River contiguous batholith, the Median Batholith (Fig. 4, and consists of grey to greenish-grey, fine- to medium- Mortimer & others 1999; Mortimer 2004). The batholith is grained andesite and overlying andesitic breccia. The dominated by I-type plutonic rocks ranging from ultramafic andesite is largely massive but flows, up to 2 m thick, with through to felsic compositions (Mortimer & others 1999). dark, fine-grained margins are locally recognisable. It is characterised by andesine phenocrysts with a dominant In the Kaikoura map area the Median Batholith is obliquely trachytic texture. The breccia is predominantly unstratified truncated by the Alpine Fault to the southeast, and the although locally fragments are weakly aligned. The breccia western contact is obscured under the Murchison Basin. grades eastwards, and probably stratigraphically upwards, Northwards from the Alpine Fault the Median Batholith into the c. 2000 m thick Rainy River Conglomerate (Jer). becomes increasingly obscured by a cover of late Cenozoic Within the conglomerate are rare sills or flows of porphyritic rocks, dominated by the Moutere Gravel, although it re- Big Bush Andesite. The lower 200 m of the Rainy River emerges northeast of Nelson city. In Northwest Nelson Conglomerate is dominated by andesitic breccia with layers the batholith intrudes the Takaka terrane (Rattenbury & of subrounded to rounded andesitic pebbles. This breccia others 1998). In the east the batholith is separated from the grades upwards into very poorly sorted, greenish-grey Brook Street terrane by the Delaware-Speargrass Fault conglomerate with a variety of clasts, up to 0.5 m across, in Zone (Johnston & others 1987; Johnston 1990; Rattenbury a fine- to coarse-grained grey or greenish-grey sandstone & others 1998). The Median Batholith includes the Rotoroa matrix (Fig. 15b). The clasts include andesite, felsic Complex, Tasman Intrusives and Separation Point Suite. plutonics, basalt, and altered sandstone and siltstone. In The latter two intrusive units are separated by the Flaxmore places the clasts are dominated by diorite eroded from the Fault. Adjacent sedimentary and volcanic rocks, ranging underlying Buller Diorite (Tulloch & others 1999). The from subgreenschist to amphibolite facies metamorphic Rainy River Conglomerate contains rare, very thick grade, are volumetrically minor and some have been derived sandstone beds locally with coal seams up to 0.4 m thick, from extrusive equivalents or erosion of the Median and minor siltstone. The formation has undergone zeolite Batholith intrusive rocks. facies metamorphism and the coal is of high-volatile bituminous rank. Late Triassic to Late Jurassic igneous rocks and associated sedimentary rocks Clasts within the Rainy River Conglomerate are sourced from the Median Batholith and the Brook Street terrane, The Tasman Intrusives group several Late Triassic to Late the closest terrane of the Eastern Province. No clasts from Jurassic plutons in the southeast of the Moutere the Western Province have been identified. The ages of Depression (Johnston 1990). The Buller Diorite (Tab), near the Big Bush Andesite and Rainy River Conglomerate are Lake Rotoiti, consists of medium-grained, commonly not known, although they are constrained by the altered, diorite to tonalite (Fig. 15a) with sparse dikes of underlying Buller Diorite and the intruding One Mile fine-grained diorite and quartz-rich pegmatites. The Buller Gabbronorite (see above). U-Pb zircon dating of two quartz Diorite characteristically contains plagioclase (oligoclase/ monzonite clasts from the Rainy River Conglomerate andesine) and hornblende with minor interstitial quartz and yielded 273–290 Ma (Early Permian) and 176–185 Ma (Early accessory minerals. Southeast, towards the Delaware- Jurassic) ages. A late Middle or Late Jurassic age is Speargrass Fault Zone, it becomes progressively foliated assigned to the Big Bush Andesite and Rainy River with the development of alternating white to greyish-white, Conglomerate (Tulloch & others 1999). feldspar-rich and dark grey to black, biotite and hornblende-

14 Figure 15 Median Batholith rocks. (a) Buller Diorite with steeply east-dipping foliation defined by alternating light coloured feldspar-rich and dark grey biotite- and hornblende-rich layers; Rainy River. (b) Well-rounded, predominantly granitic and mafic volcanic clasts within the Rainy River Conglomerate are derived from other Median Batholith rocks; Rainy River. (c) The hornblende-plagioclase-dominated Howard Gabbro includes trains of xenoliths of finer grained amphibolite, as shown here at Harleys Rock in the Buller River. (d) Outcrops of the Separation Point Batholith are typically weathered but this relatively fresh biotite granite boulder from Granity Creek is part of a landslide deposit that partly blocked the Buller River.

The Rotoroa Complex comprises a layered intrusion epidiorite is generally more felsic and has relict igneous consisting of gabbro, gabbronorite, norite, anorthosite, textures. Shearing occurs in many places, and the rocks diorite and trondhjemite, and rare hornblendite with lenses are locally schistose. of amphibolite (Challis & others 1994). Relatively unaltered gabbronorite layered with anorthosite, hornblende gabbro, U-Pb zircon dating of gabbronorite from near Lake Rotoroa leucogabbro and biotite gabbro (Howard Gabbro, Jrh, Fig. at 155 Ma indicates a Late Jurassic age for the Rotoroa 15c) occurs mainly in the east of the complex. Opaque Complex (Kimbrough & others 1993). mineral-rich plagioclase (typically An60-70) gives the gabbro a dark appearance, even where it is highly feldspathic. Early Cretaceous intrusive rocks Dioritic rocks are widespread, particularly in the west of the complex, and include gneissic mafic to leucocratic The Separation Point Suite is the dominant component of diorite, microdiorite, quartz diorite, and trondhjemite the Separation Point Batholith, here incorporated in the (Braeburn Diorite, Jra). Migmatite and gneissic intrusion Median Batholith (Mortimer & others 1999). The granite- breccia are common within the diorite and have resulted dominated suite intrudes Rotoroa Complex within the from the later intrusion of Early Cretaceous granitoids. Kaikoura map area and intrudes rocks of the Takaka terrane Layering, defined by alternating felsic and mafic bands or northwest of the map area (Rattenbury & others 1998). In by coarse and finer grained rocks, is common. Fine-grained, the map area the Tainui Fault separates the suite from dark grey amphibolite and epidiorite of the Kawatiri Tertiary rocks of the Murchison Basin to the northwest Amphibolite (Jrk) are concentrated in the northwest of (Suggate 1984). The suite is dominated by massive, the complex. The amphibolite and epidiorite are composed equigranular biotite and biotite-hornblende granite with mainly of hornblende and plagioclase, and are probably minor tonalite, quartz diorite and quartz monzonite (Ksg; metamorphosed basalt and dolerite dikes and sills. The Fig. 15d). In the southeast the suite is extensively

15 interlayered with the Rotoroa Complex along a northeast The Kaka Formation (Ybk), the dominant unit in the group trend (Challis & others 1994). Quartz diorite occurs with within the map area, comprises green, coarse-grained mafic intrusion breccias adjacent to unfaulted contacts with the volcanic flows and shallow intrusives with widespread Rotoroa Complex. The suite is intruded by late-phase dikes pyroclastic and clastic rocks derived from the igneous and sills of fine-grained tonalite, aplite and granite rocks. The volcanic rocks are basaltic andesite to calc- pegmatite. Rb-Sr ages of 116 Ma (Aronson 1965) and alkaline basalt, with augite and plagioclase the dominant 114 Ma (Harrison & McDougall 1980) and, from beyond minerals. The sedimentary rocks are dominated by breccia, the map area, U-Pb dating of zircons between 109 and with clasts of augite-rich igneous rocks up to 0.4 m across. 121 Ma (Kimbrough & others 1994; Muir & others 1994, Minor rock types are green siltstone and sandstone, and 1997) indicate that the Separation Point Suite was emplaced rare lenses of grey calcareous siltstone and impure in the Early Cretaceous. limestone, the latter having a foetid smell when freshly broken. The lenses contain atomodesmatinid shell The Glenroy Complex (Kg), dominated by coarse-grained fragments and, at Speargrass Creek, a 3 m thick limestone biotite-hornblende granite, occurs east of the lower Glenroy has abundant impressions of Maitaia obliquata River and around the Upper Matakitaki settlement Waterhouse (Johnston & Stevens 1985). Conformably (Adamson 1966; Cutten 1987). The complex also contains overlying the Kaka Formation is the 1500 m thick Brough metasedimentary gneiss with an amphibolite facies garnet- Formation (Ybb), dominated by dark, fine-grained basalt biotite-sillimanite-kyanite mineral assemblage and two- and dolerite with minor gabbro and tuffaceous sequences. pyroxene granulite facies dioritic orthogneiss (retrogressed The formation grades upwards into Groom Creek to amphibolite facies). The orthogneiss was emplaced into Formation (Ybg), which is dominated by poorly bedded the lower crust in the Early Cretaceous (Tulloch & Challis grey, greenish grey and whitish grey, tuffaceous siltstone 2000). and sandstone (Fig. 16). The Brough and Groom Creek formations are intruded by lensoidal masses, up to 100 m Brook Street terrane thick, of very altered dolerite and fine-grained gabbro.

Early Permian volcanic and sedimentary rocks The Brook Street Volcanics Group typically has been metamorphosed to prehnite-pumpellyite facies. The Kaka The Brook Street Volcanics Group (Yb) is the only Formation is of Permian age and a late Early Permian age is stratigraphic group mapped within the Brook Street terrane inferred for the group based on better constrained dating in the Kaikoura map area. It crops out around the northern in Southland (Turnbull & Allibone 2003). end of Lake Rotoiti, where it forms the southern end of the Permian sequence of east Nelson (Johnston 1990). Farther Murihiku terrane southwest the group is concealed by Quaternary deposits except for a fault-bounded sliver at the south end of Lake Late Middle Triassic and Early to Late Jurassic Rotoroa (Challis & others 1994). The group is bounded in sedimentary rocks the northwest by the Delaware-Speargrass Fault Zone and to the southeast by the Waimea and Alpine faults. It The Murihiku terrane encompasses the Murihiku comprises a southeast-dipping and younging sequence Supergroup which, in the Kaikoura map area, forms two of intermediate to mafic volcanic-derived sedimentary rocks fault-bounded blocks of zeolite facies rocks, 6 km in length, and associated igneous rocks. along the Waimea Fault north of Tophouse (Johnston 1990). The eastern block comprises the 1000 m thick Blue

Figure 16 Green tuffaceous sandstone with light coloured tuff beds of the Groom Creek Formation, Brook Street Volcanics Group. The beds dip WNW here in Rocky Creek, in the upper Motupiko valley. 16 Glen Formation (Trb) of the Richmond Group (Johnston Dun Mountain-Maitai terrane 1990). The formation dips and youngs eastwards and consists of bedded grey sandstone, siltstone and The Dun Mountain-Maitai terrane is a distinctive feature mudstone with numerous tuffaceous beds and local of South Island geology. In the Kaikoura map area the conglomerate. The finer grained rocks are commonly terrane crops out between Tophouse and Red Hills Ridge bioturbated, with sparse ammonites, bivalves, palynofloras (Figs 14, 17) at the southern end of the east Nelson section and marine acritarchs of late Middle Triassic age. The (e.g. Rattenbury & others 1998). To the south the terrane formation was deposited in an outer shelf environment has been truncated and displaced by the Alpine Fault with periodic incursions of submarine fans. (Johnston 1990) and a fault-bounded outlier of the terrane occurs between the Matakitaki and Glenroy valleys, west To the west of the Blue Glen Formation, and separated of the bend in the Alpine Fault (Waterhouse 1964; from it by Paleogene rocks, is a >250 m thick fault-bounded Adamson 1966; Johnston 1976). The Dun Mountain-Maitai sliver of the non-marine Berneyboosal Formation (Jb; terrane reappears on the southeast side of the Alpine Fault Johnston 1990). The formation consists of grey, poorly in northwest Otago, northern Southland and south Otago, bedded sandstone and siltstone with interbedded an apparent displacement of 480 km. In all areas the rocks carbonaceous horizons and coarse sandstone and are very similar although some lithological units have been conglomerate. The sandstones contain andesitic debris reduced in thickness, or are missing, due to subsequent and the conglomerate clasts include intermediate to mafic faulting. volcanics, granitoids and sedimentary rocks. The carbonaceous horizons are dominated by dark mudstone The terrane contains Early Permian ultramafic and mafic with rare coal seams up to 0.5 m thick. Miospores indicate igneous rocks of the Dun Mountain Ophiolite Belt, an Early to Late Jurassic (Ururoan to Puaroan) age. comprising the Dun Mountain Ultramafics Group and the

Figure 17 The Dun Mountain Ultramafics Group forms the distinctive red-brown, forest-free Red Hills Ridge at the northern edge of the Kaikoura map area. Vegetation growth is inhibited by higher and more toxic levels of extractable nickel and/or magnesium in the soils derived from the ultramafic rocks. The Alpine Fault, extending southwest from the Wairau River (middle left) towards Lake Rotoiti (distant centre), truncates the Dun Mountain Ultramafics Group. The plateau on the southern end of the ridge is an erosion surface capped by Pleistocene Plateau Gravel.

Photo CN7120/1: D.L. Homer. 17 overlying mafic Livingstone Volcanics Group. The Dun dikes (Johnston 1990). The Dun Mountain Ultramafics Mountain Ophiolite Belt is unconformably overlain by Group in the Matakitaki outlier is poorly defined but is sedimentary rocks of the Maitai Group. Mélange occurs at composed of serpentinised harzburgite and minor dunite the suture between the Dun Mountain-Maitai and Caples up to 500 m wide (Adamson 1966). Elsewhere in the South terranes. The ophiolite belt produces the Junction Island the ultramafics have been dated, using the U-Pb Magnetic Anomaly or Eastern Belt of the Stokes Magnetic method, at 280–265 Ma (Early-Middle Permian; Kimbrough Anomaly (Hunt 1978). & others 1992).

Early-Middle Permian ultramafic and mafic igneous The Livingstone Volcanics Group (Yl) is present on the rocks western margin of the Red Hills and in the Matakitaki outlier. In the Matakitaki outlier the group, which is about 1800 m The Dun Mountain Ultramafics Group within the Kaikoura thick, is not differentiated. In the Red Hills the poorly map area crops out in the Porters Knob and Red Hills Ridge exposed and fault-disrupted Tinline Formation (Ylt) area where it reaches a maximum width of 10 km (Walcott consists of vertical to steeply northwest-dipping, 1969; Davis & others 1980), and also in the Matakitaki alternating coarse- and fine-grained tholeiitic gabbro, outlier. The rocks weather to a distinctive red-brown (dun) emplaced as a dike complex with individual intrusions up colour and tend to be sparsely vegetated (Fig. 17). In the to several metres thick. Cross-cutting the complex are Red Hills the group is dominated by harzburgite, which in irregular coarser grained dikes, with augite crystals up to the east is massive to very poorly layered with a 15 mm in length, containing gabbro xenoliths. The dike protoclastic texture (Ydp, Fig. 18). Westward the complex is approximately 400 m thick. Unfaulted parts of protoclastic rocks grade into layered harzburgite with minor the Tinline Formation grade upwards through fine-grained, dunite, chromite segregations and sparse eucrite, wehrlite, apparently massive, microgabbro or dolerite, into the poorly lherzolite and pyroxenite (Ydm). Dikes of dark grey exposed Glennie Formation (Ylg). The Glennie Formation microgabbro and amphibolite, largely striking NNW and is about 800 m thick in the Red Hills and consists of dark up to 10 m thick, are relatively common in the central part green or greenish-grey, spilitic augite basalt with lenses of of the Red Hills. Along the western margin of the Red Hills basaltic breccia in its upper part. The basalt has a sub- is a tectonised zone of serpentinised, layered harzburgite ophitic texture and forms sheets several metres thick with and minor dunite, pyroxenite and gabbro with rodingite locally brecciated margins; pillow basalt is absent (Johnston 1990).

Figure 18 Blocky, dark, massive, partly serpentinised harzburgite of the Dun Mountain Ultramafics Group, locally weathered to a characteristic dun colour, in a creek draining south from the Red Hills Ridge. The streaky white surfaces are shears with fibrous serpentine.

18 In both formations primary augite crystals are completely mudstone and lenses of conglomerate. The conglomerate or partly replaced by hornblende, and plagioclase is clasts, up to 0.2 m across, include mafic tuff and breccia. partially replaced by hydrogrossular, prehnite, pumpellyite, The Waiua Formation (Tmw) differs mainly from the chlorite and epidote. In east Nelson the upper basaltic part underlying Greville Formation in the reddish-purple of the Livingstone Volcanics Group has been hematite in the finer grained beds (Fig. 19b). The formation metamorphosed to greenschist facies (Davis & others is >750 m thick in east Nelson where it occupies the core of 1980). The group has subsequently been affected by the Roding Syncline. In the Matakitaki outlier the Waiua prehnite-pumpellyite metamorphism. Zircon U-Pb dates Formation has a maximum reported thickness of only from outside the map area indicate an Early Permian age 180 m (Adamson 1966). (Kimbrough & others 1992). The Stephens Subgroup (Tms) is over 2000 m thick and Late Permian to Early Triassic sedimentary rocks conformably overlies the Waiua Formation in the Matakitaki outlier but near Tophouse is separated from the rest of the The Maitai Group is exposed north of Tophouse in the Matai Group by the Whangamoa Fault. It consists Roding Syncline (Johnston 1990) and in the Matakitaki predominantly of variably bedded, green or grey sandstone outlier as a northwest-younging sequence in which the with dark grey siltstone and mudstone, and beds are beds are commonly overturned (Waterhouse 1964; generally thicker than those in the Waiua and Greville Adamson 1966; Johnston 1976). The basal Upukerora formations. Thin conglomerate horizons also occur, and in Formation (Ymu) in the Matakitaki outlier is several the Matakitaki outlier the subgroup contains a 220 m thick hundred metres thick and consists of coarse tuffaceous coarse conglomerate composed mainly of sandstone, sandstone with lenses of hematitic breccia overlain by grey siltstone and igneous clasts (Adamson 1966). calcareous siltstone (Adamson 1966). In the Red Hills the formation comprises lenses of conglomerate with The lower part of the Maitai Group was deposited on the tuffaceous horizons. Because of very poor exposure in flanks of a submarine high of Livingstone Volcanics with east Nelson and Matakitaki, the stratigraphic relationship the Wooded Peak Limestone being largely derived from with the underlying Livingstone Volcanics Group is unclear, atomodesmatinid shell banks with influxes of volcanic- although north of the Kaikoura map area, an unconformity derived sand (Johnston 1990). The abundance of complete between them is preserved (Johnston 1981). The Wooded atomodesmatinid fossils in parts of the Tramway Peak Limestone (Ymw) is up to 750 m thick, dominantly Sandstone suggests relatively shallow water deposition, grey, and consists of a basal poorly bedded limestone and but the source of the detrital quartz remains unknown. The an upper well-bedded limestone, separated by well-bedded Little Ben Sandstone was deposited as submarine fans calcareous sandstone with minor siltstone and derived from the Livingstone Volcanics, probably at the conglomerate. In the Matakitaki outlier the limestone is beginning of the Triassic. The remaining Maitai Group units about half the thickness of the east Nelson limestone and were deposited in deeper water with widespread submarine the lithological distinctions are less well defined. The fan deposition in the Stephens Subgroup. Following limestone has a strong foetid smell when freshly broken. deposition, the group was subjected to burial The Wooded Peak Limestone grades upwards into the grey metamorphism to prehnite pumpellyite facies, or locally Tramway Sandstone (Ymt). The Tramway Sandstone, up lawsonite albite chlorite facies (Landis 1969), and folded to 800 m thick, contains more quartz than the rest of the into the Roding Syncline. Maitai Group (but still less than 10%). In east Nelson it ranges from well-bedded calcareous sandstone and Caples terrane siltstone to poorly bedded fine-grained sandstone and siltstone. Fragmentary atomodesmatinid fossils, including Late Permian to Early Triassic sedimentary rocks Maitaia trechmanni Marwick, are widespread. By contrast, the formation in the Matakitaki outlier is a poorly bedded, Caples terrane sedimentary rocks and their schistose calcareous, dark grey to black siltstone or mudstone with equivalents were formerly mapped as Pelorus Group but, green sandstone interbeds. Wellman (1953) reported an following stratigraphic nomenclature rationalisation Orthoceras from float downslope from Baldy, but between Nelson/Marlborough and Otago/Southland, are atomodesmatinid fossils are less abundant here. now assigned to the Caples Group (Yc). The rocks crop out extensively to the north of the map area (Rattenbury & In east Nelson the Tramway Sandstone is conformably others 1998) but in the Kaikoura map area they occupy overlain by up to 700 m of poorly to locally well-bedded, only about 20 km2 in the Wairau valley, north of the Alpine green volcanogenic Little Ben Sandstone (Tml), but this Fault (Walcott 1969; Johnston 1990), and formation has not been recognised in the Matakitaki outlier. approximately 8 km2 in the east of the Matakitaki outlier. Thin dark grey siltstone beds and rare lenses of The group is separated from the Dun Mountain Ultramafics conglomerate contain calcareous siltstone and limestone Group by the Patuki Mélange (see below). In the east the but no fossils. The Little Ben Sandstone grades upwards group becomes increasingly metamorphosed to form part into the generally thin-bedded or laminated, grey sandstone of the Marlborough Schist Zone of the Haast Schist. The and mudstone of the c. 1700 m thick Greville Formation less metamorphosed rocks in the Wairau valley comprise (Tmg; Fig. 19a). The upper 200 m in east Nelson consists an east-dipping, but overturned, succession >4000 m thick. of poorly bedded green sandstone, with thin, dark grey The oldest rocks in the group belong to the

19 Figure 19 Maitai Group sedimentary rocks.

(a) Laminated fine-grained sandstone and mudstone of the Greville Formation east of Tophouse. The conglomerate boulder is derived from the upper part of the formation.

(b) Finely bedded greenish grey sandstone and purplish red mudstone of the Waiua Formation, from Beebys Knob. Cross-bedding and other sedimentary features show that the beds young upwards (southeast).

Figure 20 Moderately foliated and transposed Caples Group semischist east of Wether Hill in the Wairau valley.

20 Star Formation (Ycs), comprising poorly bedded green Permian (?Late Permian) to Triassic age (Johnston 1996). sandstone with grey siltstone and mudstone beds, Rb-Sr and K-Ar whole rock ages date regional particularly in the upper part. To the west the overlying metamorphism at about 200 Ma (Late Triassic to Early Wether Formation (Ycw) is bedded green sandstone and Jurassic), and uplift and cooling at about 200–110 Ma purplish-red siltstone and mudstone. The youngest rocks (Jurassic to Early Cretaceous), indicating a minimum age in the sequence, the Ward Formation (Yca), are grey to for deposition of the Caples Group (Adams & others 1999; greenish-grey sandstone and siltstone with subordinate Little & others 1999). Caples Group sediments were derived thick, grey or green sandstone and grey mudstone. Caples from erosion of an andesite-dacite source area and Group sedimentary rocks are predominantly feldspathic deposited in submarine fans in a trench slope and trench with abundant lithic (volcanic) rock fragments and environment. subordinate quartz. Mesozoic mélange In the Matakitaki outlier, and parts of the eastern Wairau valley, rocks are mapped as undifferentiated Caples Group. The Patuki Mélange (Tmp) crops out extensively in the In the Wairau valley these rocks have a weak southeast- head of Station Creek in the Matakitaki outlier and is up to dipping foliation that becomes more pronounced eastward 1 km wide. The mélange is also present as fault-bounded as the rocks grade into semischist (Fig. 20). The foliated slivers on the east side of the Red Hills between the Dun rocks have been mapped in textural zones (t.z. IIA, IIB; see Mountain-Maitai and Caples terranes, where it is locally box). In lower Chrome Stream adjacent to the Wairau River, more than 1 km wide but more typically <600 m wide. poorly exposed, crushed metavolcanic rock (basalt, Another mélange zone about 1 km wide is present on the gabbro) and phyllonite occur with green sandstone and northwest side of the Red Hills and is inferred to be an red mudstone in fault contact with t.z. IIA and IIB infaulted block of Patuki Mélange along the tectonically semischist to the north. In the Matakitaki outlier the group complex contact between the Dun Mountain Ophiolite Belt comprises massive to poorly bedded green and grey and the Maitai Group (Johnston 1990). Blocks within the sandstone and grey siltstone (Adamson 1966) that is mélange are dominantly grey siltstone or mudstone, but weakly foliated (t.z. IIA). The Caples Group rocks grade gabbro, basalt, ultramafic rocks and rare rodingite are also from prehnite-pumpellyite facies into pumpellyite-actinolite present. Because the blocks are more resistant to erosion facies, and possibly into lower greenschist facies in the than the sheared serpentinitic matrix, a characteristic south adjacent to the Wairau River. hummocky topography defines the mélanges on either side of the Red Hills. The siltstone and mudstone blocks have North of the Kaikoura map area the Caples Group contains been altered by the introduction of albite and tremolite to sparse, poorly preserved radiolaria, atomodesmatinid form argillite (or pakohe). The emplacement age of the Patuki fragments, palynomorphs and leaves, that indicate a Mélange is poorly constrained but is no older than Late Triassic.

Textural zones

Textural subdivision is a useful method for mapping low grade metamorphic rocks and major structures within the Haast Schist. The textural zonation system established by Bishop (1974) has been revised by Turnbull et al. (2001). Textural zones (t.z.) separated by “isotects” are independent of metamorphic facies boundaries, and can cut across isograds or foliation. Characteristics of these revised textural zones are: t.z. I: Rocks retain their sedimentary (primary) appearance. Detrital grain texture is preserved, and bedding (when present) dominates outcrops. Metamorphic minerals may be present, but are very fine-grained (<75 µm), and there is no foliation. t.z. IIA: Rocks retain their primary appearance and sedimentary texture, although detrital grains are flattened. Metamorphic minerals are fine-grained (<75 µm), and impart a weak cleavage to sandstones. Mudstones have slaty cleavage. Bedding and foliation are equally dominant in outcrop. Rocks are termed semischist. t.z. IIB: Rocks are well foliated, although primary sedimentary structures may still be seen. Bedding is transposed or flattened. Clastic grains are flattened and metamorphic overgrowths are visible in thin section. Metamorphic mica grain size is still <75 µm and metamorphic segregation appears. Mudstone is changed to phyllite; meta- sandstone is well foliated and forms parallel-sided slabs. Rocks are termed semischist. t.z. III: Planar schistosity identified by metamorphic micas is developed in all rocks. Bedding is barely recognisable, and is transposed and parallel to foliation. Clastic grains may still be recognisable in sandstones, but are recrystallised and overgrown, and metamorphic segregation laminae are developed. Rocks are termed schist. Quartz veins develop parallel to foliation, or are rotated and flattened. Metamorphic micas are typically about 75-125 µm long (very fine sand size). t.z. IV: Primary sedimentary structures and clastic grains are destroyed at a mm-cm scale, although primary sedimentary units may be discernible in outcrop. Schistosity tends to be irregular due to porphyroblast growth. Metamorphic mica grain size is 125-500 µm. Schistosity and segregation are ubiquitous and rocks are termed schist. Gneissic textures may be developed. Quartz veins are abundant in most lithologies.

21 Torlesse composite terrane dominated by sandstone, commonly well graded with cross bedding, sole markings and ripples. Thick mudstone beds, The Torlesse composite terrane comprises predominantly with or without thin- to medium-bedded sandstone, are quartzofeldspathic indurated sedimentary rocks, commonly less common in the map area. Calcareous lenses up to called greywacke, which range in age from Carboniferous 0.6 m in length and rare phosphatic nodules occur rarely in to Early Cretaceous in the South Island, and Late Triassic the graded-bedded lithotype. Locally within the sandstone to Early Cretaceous in the North Island. In the Kaikoura are angular, unsorted rip-up fragments of grey mudstone, map area the composite terrane encompasses all of the and comminuted leaf and wood fragments that form basement rocks southeast of the Alpine Fault to the eastern carbonaceous laminations. Conglomerate (Ttc) occurs coast (Fig. 14). It includes the Rakaia and Pahau terranes sparingly and is more obvious in river boulders than in (Bradshaw 1989), which can be distinguished from each outcrop. Thicker lenses of conglomerate are present on other on the basis of petrographic, geochemical, isotopic the Travers, Ella and Mahanga ranges and Emily Peaks and age differences (Andrews & others 1976; Mackinnon (Rose 1986; Johnston 1990). The clasts range from sub- 1983; Roser & Korsch 1999; Adams 2003). The two terranes angular to well-rounded and are dominated by pebble- to are separated by the Esk Head belt which consists of cobble-sized indurated quartzo-feldspathic sandstone and deformed elements of both terranes and locally mudstone, with lesser amounts of felsic igneous and allochthonous lithologies. quartz-rich metamorphic rocks.

Rakaia terrane Distinctively coloured mudstone (Ttv) is a minor rock type in the map area. The mudstones are typically dark red to Late Triassic sedimentary rocks brown or pale green to grey, the difference reflecting the oxidation state of contained iron (Roser & Grapes 1990). Grey, indurated, quartzofeldspathic sandstone (greywacke) The red and green mudstone occurs in bands up to several and mudstone (argillite) of the Rakaia terrane (Tt) occur hundred metres thick (Fig. 22), commonly associated with in the Southern Alps within the Kaikoura map area. Formal dark grey mudstone, sandstone, minor basalt, chert and lithostratigraphic groups within the terrane have been rare limestone. These bands are one of the few distinct proposed, for example, Mt Robert and Peanter groups marker horizons within the Rakaia terrane that can be used (Johnston 1990) but their geographical extents are not to map regional structural trends. One prominent band, known outside their mapped areas. In keeping with adjacent locally offset by strike-slip faults, extends for over 90 km QMAP sheets no lithostratigraphic groups have been through the map area, and continues for at least another adopted for the Rakaia terrane of the Kaikoura map. Rakaia 50 km southwest towards Arthurs Pass (Nathan & others terrane sandstones are typically poorly to moderately 2002). The basalt, of tholeiitic composition, occurs as red, sorted, fine- to medium-grained, and contain abundant green or grey bands or lenses, commonly with pillow form. lithic clasts of felsic igneous and sedimentary rock. It is generally accompanied by purplish red to red, white or Sedimentary lithotypes (facies) are dominated by thick to grey chert that may form layers up to several metres thick. very thick, poorly bedded sandstone and thin- to medium- The basalt and/or chert are rarely more than a few tens of bedded, graded sandstone and mudstone (Fig. 21; Andrews metres thick or several hundred metres in length. & others 1976). The graded-bedded lithotype is generally

Figure 21 Thin- to medium-bedded sandstone and mudstone interlayered with very thick-bedded sandstone of the Rakaia terrane on the St Arnaud Range near Rainbow Skifield. Bedding-parallel shearing has caused the changes in bed thickness.

22 Figure 22 Red and green mudstone occurs as a minor but widespread Rakaia terrane rock type, usually interlayered with thin- bedded graded sandstone and mudstone. This partly sheared example from Henry River is part of a semi-continuous band up to 400 m wide that extends over 140 km strike length.

Figure 23 Rakaia terrane broken formation is characterised by discontinuous lenses of sandstone in a sheared mudstone matrix, with numerous thin quartz veins. Rainbow Skifield access road, St Arnaud Range.

Fossils are rare in the Rakaia terrane. Although trace fossils Rakaia terrane rocks are difficult to interpret because of are the most common, they are of limited use for dating structural complexity, multiple folding events, few marker purposes. Microfossils, including radiolaria and horizons, poor age control and widespread shearing and conodonts, occur in relatively rare rock types such as chert faulting. Fold hinges are rarely preserved but widespread and limestone. In the St Arnaud Range, east of Lake Rotoiti, macroscopic folding can be inferred from sedimentary scattered macrofossils occur in poorly sorted siltstone younging reversals. Slaty cleavage and fracture cleavage within graded-bedded lithotype rocks (Campbell 1983). are weakly developed in finer grained lithologies and range Monotis (Inflatomonotis) cf hemispherica Trechmann, from parallel or sub-parallel, to locally oblique to bedding. Monotis sp. indet. and Hokonuia limaeformis Trechmann, Burial and deformation have metamorphosed the non- of Warepan (Late Triassic) age, have been formally schistose Rakaia rocks to zeolite facies in the east, described (Campbell 1983). increasing to prehnite-pumpellyite facies in the northwest. A 206 Ma Rb-Sr isochron from Rakaia terrane rocks at Lewis The Rakaia terrane contains zones of deformed rocks (Ttm) Pass is interpreted to date Late Triassic burial and regional that have preferentially developed in the graded-bedded metamorphism (Adams & Maas 2004) whereas K-Ar data lithotype, and which range in width from less than a metre ranging mostly between 133 and 170 Ma reflect progressive to over a kilometre. The zones are characterised by layer- uplift and cooling in the Jurassic (Adams 2003). parallel extension resulting in pinching and swelling of individual beds to form sandstone boudins in a pervasively Two depositional environments for the Rakaia terrane sheared mudstone. Quartz veining is widespread, clastic rocks have been inferred. These are large, deep particularly where a weak shear fabric has developed (Fig. submarine fans fed by channelised turbidity currents 23). The zones are commonly referred to as broken (Howell 1980; Johnston 1990) and relatively shallow-water formation, or as mélange where “exotic” rock types are fan-deltas (Andrews 1974). It is possible that both present. Although generally poorly exposed, some zones environments may have been operating at different times can be traced for many kilometres. Contacts with the and/or locations (Andrews & others 1976). surrounding Rakaia rocks typically show a gradational change in the shearing intensity, except where separated by younger faults.

23 Permian to Late Triassic semischist and schist sedimentary rocks, it contains more mudstone than other Rakaia terrane rocks, and has numerous bands of The Rakaia terrane rocks are increasingly metamorphosed greenschist derived from mafic igneous rocks and rare chert. to semischist and schist of the Alpine Schist (Fig. 24a, b) The southeastern contact with the sandstone-dominated northwest towards the Alpine Fault. The metamorphosed Rakaia terrane schist is probably a ductile shear zone rocks are subdivided into textural zones (IIA, IIB, III; see (Nathan & others 2002). The depositional age of the text box) after Bishop (1974) and Turnbull & others (2001). Aspiring lithologic association is poorly constrained in The schists grade westwards from quartz-albite-muscovite- the northern South Island, and the Permian age inferred chlorite through biotite-albite-oligoclase to garnet zone for the association in northwest Otago (Turnbull 2000) mineral assemblages within greenschist facies. Bands of has been adopted for the Kaikoura map area. greenschist (Ttg; Fig. 24c), rarely thicker than 10 m and generally of limited strike length, occur in places. The Metamorphism of Rakaia terrane rocks to schist occurred greenschist bands are metamorphosed igneous rocks, about 210 Ma (Late Triassic), followed by uplift and cooling possibly originally tuffs, dikes, sills or flows. The between 200 and 110 Ma (Jurassic to Early Cretaceous; depositional age of the semischist and schist protolith is Little & others 1999; Adams 2003). Fission track apatite assumed to be Late Triassic based on the fossils from less and zircon data suggest more than 10 km uplift of the schist metamorphosed (t.z. 1) rocks in the St Arnaud Range and around Lewis Pass since 5 Ma (Tippett & Kamp 1993; 30 km west of the Kaikoura map area (Wellman & others Kamp & others 1989). 1952). Within 1–2 km of the Alpine Fault southwest of Lake The Aspiring lithologic association (Ya) is the protolith of Rotoroa, non-schistose Rakaia terrane becomes a strip of t.z. III schist adjacent to the Alpine Fault that is increasingly tectonised with the development of a about 2 km wide in the southwest and is obliquely truncated pronounced shear foliation and cleavage. The tectonism by the Alpine Fault between the Glenroy and Matakitaki and foliation result from Late Cenozoic movement of the rivers. Although largely derived from quartzofeldspathic Alpine Fault (Challis & others 1994).

Figure 24 The Rakaia terrane is increasingly metamorphosed west towards the Alpine Fault. (a) t.z. IIB semischist showing strong intersection lineation between transposed bedding (light and dark bands) and penetrative cleavage (parallel to slope) near Mt Mueller. Photo: P.J. Forsyth.

(b) Folded t.z. III schist showing relict mudstone (dark bands in centre) with injected quartz veins (pale), Nardoo Stream headwaters. Photo: I.M. Turnbull.

(c) Greenschist comprising t.z. III metamorphosed volcanic tuffs, shown here in Branch Creek, is common in the Aspiring lithologic association. Photo: I.M. Turnbull.

24 Pahau terrane bedded sandstone lithotype is up to several kilometres thick with the larger beds traceable over tens of kilometres. Late Jurassic to Early Cretaceous sedimentary and Conglomerate lenses (Ktc) are present throughout the volcanic rocks terrane but are volumetrically significant only locally e.g. in the upper Pahau and Hossack rivers. The conglomerates The Pahau terrane forms the bulk of the basement rocks are generally poorly sorted with sub-rounded to rounded in the Kaikoura map area. Formal lithostratigraphic groups granule to pebble size clasts enclosed in a sandstone matrix. within the terrane have been proposed, for example, The clasts are dominated by quartzofeldspathic sandstone, Waihopai Group (Johnston 1990) and Pahau River Group mudstone, volcanics, granitoids, quartz and chert and the (Bassett & Orlowski 2004) but the geographical extent of volcanic clasts include rhyolite, dacite, andesite and basalt these groups is not yet clear and they have not been (Smale 1978; Johnston 1990; Reay 1993; Bassett & Orlowski adopted in this map. As with the Rakaia terrane, Pahau 2004; Wandres & others 2004). terrane is dominated by indurated, grey, quartzofeldspathic, thin- to medium-bedded and commonly graded sandstone Calcareous concretions, up to 0.3 m across, are distributed and mudstone, and poorly bedded, very thick-bedded sparsely throughout the Pahau terrane. The graded sandstone lithotypes (Ktp; Andrews & others 1976). sandstone and mudstone lithotype, particularly where These rocks are collectively (and loosely) termed mudstone is dominant, contains concretionary lenses, greywacke. Other rock types include conglomerate, green generally less than 10 cm thick, composed of dark grey, sandstone, purplish red and green mudstone, sparse very fine-grained limestone. These, and rare phosphatic limestone and, particularly in the northeast, basalt and nodules, contain variably preserved dinoflagellates. dolerite. The Pahau sandstones are generally slightly lighter in colour and have a more “sugary” appearance than similar Igneous rocks (Ktv), consisting of basalt and dolerite, are low-grade Rakaia terrane sandstone. Pahau terrane rocks present as flows and sills up to 2 km thick from the head of also differ in that they locally contain more carbonaceous the Avon valley to the lower Awatere valley, and as less matter, conglomerate bands and volcanic rocks. continuous, thinner bands farther south (Fig. 26a). The flow rocks are commonly pillowed and include tuffaceous Within the Pahau terrane the graded bedded lithotype (Fig. horizons and thin igneous breccia. They are usually 25) is commonly planar and relatively undisrupted over accompanied by green and red tuffaceous mudstone (Fig. large areas. The poorly bedded to massive, very thick- 26b), red and white chert (Ktt) and, locally, limestone.

Figure 25 The Pahau terrane contains large areas of coherent sub-parallel strata comprising two dominant sedimentary facies: thick-bedded sandstone (centre) and thin-bedded graded sandstone and mudstone. Middle Clarence River gorge downstream of Dillon River. Photo: C. Mazengarb. 25 Zones of intra-Pahau mélange, characterised by relatively abundant boudins of mafic volcanic rock, chert and red and green mudstone (Fig. 26c), occur widely and are in places large enough to map separately (Ktm). A zone of relatively sheared rocks, up to 7 km wide in the Waihopai valley, extends south to the Awatere Fault. Another prominent zone, up to 10 km wide, in the Cheviot-Waiau area separates planar-bedded northeast-striking Pahau rocks in the Lowry Peaks Range from northwest-striking Pahau rocks in the Hawkswood Range. This zone extends into the Kaiwara valley where it has been termed the Random Spur Mélange (Bandel & others 2000). These zones have Late Triassic and Early Jurassic faunas and Early Cretaceous microflora.

Fossils in the Pahau terrane are sparse and poorly preserved (Andrews & others 1976). Plant remains, although widespread, are largely comminuted and indeterminate. In the Leatham valley (N29/f44) plant fragments are better preserved and include Taeniopteris cf daintreei, ?Fraxinopsis sp., a gymnosperm seed, and fern-like pinnules. Basaltic conglomerate in the Leatham valley (N29/ f94) is fossiliferous but few species are recognisable (Johnston 1990). Dinoflagellates preserved within some of the thin calcareous mudstone beds indicate that the Pahau rocks are predominantly Early Cretaceous, but may be locally as old as Late Jurassic (G.J. Wilson pers. comm. 2004). Bivalves including Buchia, Anopaea and “Inoceramus” as well as belemnites of the genus Hibolithes occur in the Clarence River (Reay 1993) and indicate an Early Cretaceous age.

Outside the mélange zones there is little variation and no systematic change in sedimentation age across the entire >70 km width of Pahau terrane in the map area. Together with the widespread steep dips, inconsistent younging directions, rarely preserved large fold hinges and relatively uniform metamorphic grade, this suggests that the Pahau terrane consists of imbricated slices and/or recumbent folds of largely Early Cretaceous rock, locally incorporated with mélange containing rocks as old as Late Triassic.

Figure 26 (a) Basalt, here showing relict pillow structure, The environment of deposition of the clastic rocks of Pahau occurs sporadically within Pahau terrane, Seaward terrane, like the Rakaia terrane, has been interpreted as Kaikoura Range. deep water submarine fans (Johnston 1990; Reay 1993) Photo: M. J. Isaac. and marginal marine fan-deltas (Bassett & Orlowski 2004). It is also possible that both environments may have been (b) Red mudstone beds with scattered red chert horizons, present at different locations and at different stratigraphic within a northwest-dipping and -younging succession of levels and times (Andrews & others 1976). finely bedded, sheared grey sandstone-mudstone of the Pahau terrane, southeast face of Barometer, Awatere The metamorphic grade of Pahau terrane in the map area valley. varies between zeolite facies (Reay 1993) and prehnite- pumpellyite facies (Bradshaw 1972; Crampton 1988; (c) Broken formation and mélange occur widely in the Johnston 1990). Local hornfelsing of the Pahau terrane Pahau terrane of the Seaward Kaikoura Range. rocks (Kth) occurs adjacent to mafic intrusions at Tapuae- o-Uenuku and Blue Mountain.

26 Esk Head belt Wairau valley and lack the layer-parallel shearing usually associated with the belt elsewhere. Late Triassic to Early Cretaceous sedimentary and volcanic rocks The main rock types within the Esk Head belt are quartzofeldspathic sedimentary rocks, incorporated from The generally well-bedded Pahau terrane is separated from the Rakaia and Pahau terranes. Alternating sandstone and the Rakaia terrane by a zone of more sheared rocks, the mudstone sequences and thick, poorly bedded to massive Esk Head belt (Te, after Begg & Johnston 2000). The zone sandstone are dominant, but minor conglomerate and other has also been named the Central Belt (Johnston 1990) and lithologies are also present. Chert, with associated the Esk Head subterrane (Silberling & others 1988), greenish-grey sandstone and red mudstone, igneous rocks incorporating the Esk Head Mélange of Bradshaw (1973). (Tev) and limestone (Tel) are common within fault zones Although significant zones of mélange (Tem) with blocks and generally more abundant within the Esk Head belt of “exotic” material such as limestone, basalt and chert are than in the less deformed Rakaia and Pahau terrane rocks. present, the belt is composed largely of mixed, weakly to Igneous rocks include gabbro, green dolerite and reddish- strongly deformed Rakaia and Pahau rocks. The belt is up purple basalt, some with pillow structures. Along the to 20 km wide in the northern and southern parts of the eastern margin of the Esk Head belt, in the Leatham valley, Kaikoura map area but is narrower in the central part, due thin and discontinuous lenses of grey to white, crystalline to subsequent faulting. The Esk Head belt is also offset by limestone are present. The limestone is locally fossiliferous strike-slip movement on numerous faults of the and may be part of a dismembered seamount (Johnston Marlborough Fault System. 1990). In the north, phyllonitic rocks of the Silverstream Fault Zone separate Rakaia- and Pahau-derived parts of Deformation within the Esk Head belt is highly variable the Esk Head belt (Johnston 1990). due to the degree of tectonism and differences in the competency of the rocks. Well-bedded graded sandstone Fossils are sparse in the Esk Head belt but the limestone in and mudstone which have had significant layer-parallel the Leatham valley contains a restricted macrofauna shearing are termed broken formation, or where exotic rock indicating a Jurassic or Early Cretaceous age. Limestone types are present, mélange. The sandstone beds and other in the Okuku River contains fossils including Monotis, competent rock types have undergone relatively brittle possible “Inoceramus” and a Late Jurassic belemnite deformation and form boudins or discontinuous lozenges (Bradshaw 1973). Other limestones in the map area contain (Fig. 27). Preferential erosion of the sheared enveloping Monotis, radiolaria and conodonts of Late Triassic age mudstone matrix has resulted in hill crests with numerous (Silberling & others 1988). Chert contains radiolaria of Late pinnacles. Large areas dominated by poorly bedded Triassic to Jurassic age and may represent part of the sandstone occur between the Hurunui River and the upper seafloor basement to the younger quartzofeldspathic rocks of the Pahau terrane (Johnston 1990).

Figure 27 Broken formation resulting from deformation of the thin-bedded graded sandstone and mudstone lithotype is common in the Esk Head belt. The lenticular and discontinuous sandstone boudins are enveloped in sheared mudstone, shown here in the lower Leatham River.

27 SW NE

Group Group

Awatere Valley

Wandle/ Mt Cookson

Waikari

Waiau

Grassmere/ Cape Campbell

Parnassus

Haumuri

Monkey Face

Kaikoura Greta

Mangamaunu

Mandamus Clarence Valley

Hanmer Kekerengu

Culverden 0 Cheviot Pleistocene 1.7 Kowai Kowai Pliocene Whanganui* Starborough 5.3 Upton Awatere Greta Medway Greta

Miocene

Motunau Mt Brown Mt Brown Scargill* Waikari Waima Glenesk* Waima Motunau Waikari Waikari Pahau* Waikari Spyglass* 24 Isolated Hill* Hanmer* Whalesback* ? Weka Pass* Weka Pass* Tekoa* Tekoa* Cookson Spyglass* Tekoa* ? Marshall Paraconformity

Olig

No group Amuri 34

Amuri upper marl* Homebush* Karetu* Fells* Grasseed Karetu* Woodside* Homebush* Ashley*

Eocene Ashley* upper limestone* Ashley* Amuri lower marl* Muzzle 56 Waipara* Waipara* Eyre Teredo* lower limestone*

Paleocene Loburn* 65 Claverley* Mead Hill Branch* Conway* Lagoon Stream* ? Conway* Herring* Woolshed* Mirza* Butt* Conway* Broken River*

erosion or non-deposition ? Stanton* Seymour Broken River*

Tarapuhi* ? Okarahia* Paton Ess Creek*

Late Cretaceous Burnt Nidd* Creek* Hapuku

Tapuae- Bluff Wallow nuku Willows* Bluff Mandamus Gridiron 99 Warder Lookout Warder Split Rock Hungry Hill* Winterton Gladstone Coverham Champagne Totara*

Pahau Pahau terrane

Early Cretaceous

Figure 28 Late Early Cretaceous and Cenozoic stratigraphy of the eastern part of the Kaikoura map area highlighting areas of deposition and non-deposition (grey background). In some areas, intervening erosion has probably removed stratigraphic units. A large number of stratigraphic units have been described and formalised within the area but many (shown with asterisks) have not been used in this publication. After Field, Browne & others (1989), Field, Uruski & others (1997). 28 CRETACEOUS TO PLIOCENE Browne & others 1989; Field, Uruski & others 1997). Within both areas there are many formalised formations and Following amalgamation of the basement terranes and after members that have been defined on key stratigraphic the mid-Cretaceous cessation of convergent margin sections but are difficult to map out areally. The following tectonics along the Gondwanaland margin, much of the descriptions refer to many of these stratigraphic units but New Zealand area was uplifted and then eroded to a low- only the bold named units are distinguished on the map. lying landscape. This landscape was subject to extension Where formations are thin, in areas that are geologically as the Tasman Sea opened and the New Zealand continent complex, and offshore, the rocks are mapped as separated from Gondwanaland in the late Early Cretaceous. undifferentiated Late Cretaceous (lK), Paleocene-Eocene In the west, there was extensive pluton intrusion followed (PE), Oligocene (O) or Miocene (M). by rifting and the development of sedimentary basins (Bishop & Buchanan 1995; King & Thrasher 1996). Cretaceous sedimentary and volcanic rocks Opening of the Tasman Sea ceased in the Paleocene and the New Zealand area entered a period of prolonged tectonic Cretaceous rocks are locally well preserved in stability coupled with subsidence and, in the east, Marlborough. In the middle Awatere valley and the widespread marine sedimentation. In the Kaikoura map area northern Clarence valley, a late Early Cretaceous these conditions persisted until the Miocene, when a succession is preserved that has elsewhere presumably compressional tectonic regime was initiated as the been eroded or was never deposited. boundary between the Australian and Pacific plates propagated through New Zealand. Rapid uplift and The earliest confirmed post-Pahau deposition is that of consequent erosion provided a vast amount of sediment the Champagne Formation (Kcc; Ritchie and Bradshaw that filled developing basins adjacent to major strike-slip 1985; Crampton & others 1998) of the Coverham Group faults. (Kc; Lensen 1978). The Champagne Formation is exposed in a narrow, 10 km long band in the middle Clarence valley, With the exception of a small area of Late Cretaceous from Ouse Stream (Fig. 29) to Dee Stream and in Wharekiri conglomerate in the Moutere Depression, all of the Late Stream (too small to be shown on the map). It consists of Cretaceous to Middle Eocene rocks in the Kaikoura map highly deformed sandstone, mudstone and minor area occur southeast of the Alpine Fault. These rocks crop conglomerate, typically with boudinage of sandstone beds, out in two geographically distinct areas, eastern faults, asymmetric folds, remobilisation of mud from fold Marlborough and northern Canterbury. Despite many hinges and soft-sediment deformation (Crampton & others geological similarities, the two areas have acquired two 1998). The Champagne Formation unconformably overlies separate systems of stratigraphic nomenclature (Fig. 28) Pahau terrane and its base is late Early Cretaceous although some rationalisation has been attempted (Field, (Crampton & others 2004).

Basement versus cover

Despite a wealth of previous work, the stratigraphic location of the top of the Torlesse composite terrane in New Zealand is difficult to pinpoint. For example, in the East Cape region, the contact between Early Cretaceous (Korangan) Torlesse Waioeka terrane and overlying Early Cretaceous “cover” rocks is a fault, a high angle unconformity or series of unconformities, an olistostrome breccia, or a channelled contact (Laird & Bradshaw 1996; Mazengarb & Speden 2000). In the Wairarapa region, Early Cretaceous (Motuan) Pahaoa Group is placed within the Torlesse composite terrane and the oldest overlying “cover” rocks are also of Motuan age (Lee & Begg 2002). Radiometric dating of zircons from both below and above the unconformity yields ages of c. 100 Ma (Laird & Bradshaw 2004) suggesting derivation from the same or similar-aged source rocks or recycling of the zircons.

In Marlborough the contact cannot always be defined on the basis of metamorphic grade, degree of induration or by changes in clastic composition (Montague 1981; Powell 1985). Fossils are rarely preserved in the Pahau terrane and these rocks are comparatively poorly dated. Lensen (1962) included latest Early Cretaceous (Motuan) rocks within the Torlesse composite terrane and Field, Uruski & others (1997) state that a regional unconformity exists between older and younger, more fossiliferous rocks, but that rocks both above and below the unconformity are Motuan in age. This implies that the “regional unconformity” was intra-Motuan and of very short duration in Marlborough, even though bedding discordance across the unconformity can be marked. Crampton & others (2004) show no significant stratigraphic break during the Motuan at Coverham, in the Clarence valley, but they note the presence of older late Early Cretaceous unconformities (intra-Urutawan).

A mid-Cretaceous unconformity is widespread throughout New Zealand. The diachronous nature of the unconformity surface (Laird & Bradshaw 2004) in Marlborough probably reflects ongoing deposition in localised, syntectonic basins adjacent to areas of uplift and erosion. However, there are many locations where a clearer stratigraphic break is apparent, i.e. where the Pahau terrane is overlain by significantly younger Cretaceous or Cenozoic rocks.

29 Figure 29 Typically deformed Champagne Formation in Ouse Stream. Soft sediment folding has been overprinted by brittle shearing and fault- related folding. Scale bar is 1 m.

Photo: J.S. Crampton.

Figure 30 The Split Rock Formation (Coverham Group) in Wharekiri Stream showing internal slump-related deformation and brittle faulting.

Photo: J.S. Crampton.

The Split Rock Formation (Kcs) is preserved in a fault- section. Localised slump-folding is common (Montague angle depression on the footwall of the Clarence Fault 1981) and the formation unconformably overlies Pahau (Suggate 1958). Except in the northeast where it lies terrane, commonly with minor shearing along the contact. unconformably on Champagne Formation, Split Rock Formation rests on Pahau terrane with sharp angular The overlying Winterton Formation (Kcw; Challis 1966), discordance. The formation includes basal, mass flow of latest Early Cretaceous (Motuan) age, is preserved to conglomerate overlain by mudstone and locally ridge- the south, east and northeast of Mt Lookout with forming sandstone, and interbedded sandstone and correlative rocks exposed to the northeast in the middle mudstone (Reay 1987, 1993; Crampton & others 1998; Fig. Awatere valley and Penk River (Montague 1981). It 30). In the northeast Clarence valley, the upper part of the consists of laterally discontinuous lenses of moderately formation consists of poorly bedded to massive, laminated indurated, mildly deformed conglomerate and siltstone. The mudstone containing abundant concretions and minor formation onlaps and unconformably overlies Pahau sandstone beds (Crampton & others 1998, 2004). The Split terrane and Gladstone Formation. Rock Formation is no older than middle Early Cretaceous (Korangan; Reay 1993) and is as young as earliest Late The Coverham Group is interpreted to represent parts of a Cretaceous (Ngaterian; Crampton & others 2004). fan-delta complex that filled local, fault-controlled basins. Collectively, the Gladstone and Winterton formations In the Awatere valley, Coverham Group rocks are preserved contain three fining upward successions that are typical in a fault angle depression to the south of the Awatere of fan-delta complexes associated with faults (Laird 1992). Fault. The late Early Cretaceous Gladstone Formation The Mt Lookout and Penk River successions formed in (Kcg; Challis 1966) is exposed east of Mt Lookout between separate, unconnected half-grabens (Lewis & Laird 1986). the Awatere and Winterton rivers. The formation comprises The Coverham Group fills channels and canyons cut into poorly fossiliferous, indurated conglomerate, sandstone, the underlying Pahau terrane and is locally up to 800 m siltstone and mudstone and it becomes finer grained up- thick (Laird 1981, Montague 1981; Powell 1985; Reay 1993).

30 Figure 31 Interbedded sandstone and mudstone of the Warder Formation overlain by columnar jointed basalt flows of the Gridiron Formation (both Wallow Group) in Seymour Stream. Photo CN4895: D.L. Homer. The Wallow Group (Kw; Reay 1993) includes fluvial, the Gridiron Formation; elsewhere it overlies Pahau terrane terrestrial and shallow marine deposits that locally or Split Rock Formation with angular unconformity. Sparse interfinger with subaerial basalt flows. The group crops macrofossils indicate an early Late Cretaceous age (Reay out in the northern half of the Kaikoura map area from the 1993). Crampton (1988) suggested that the base of the Bluff Awatere valley in the west to Monkey Face in the east Sandstone may be diachronous, being Ngaterian in the (Crampton 1988; Reay 1993; Warren 1995) and is well west and as old as late Motuan in the east near Monkey preserved in the middle Clarence valley. The earliest Late Face. The depositional environment of Bluff Sandstone is Cretaceous Warder Formation (Kww; Fig. 31) consists of interpreted as a marginal to shallow marine fan-delta (Reay moderately indurated, non-marine sandstone, siltstone, 1993) in an asymmetrically subsiding basin (Crampton minor conglomerate lenses, thin coal seams and lake silt 1988). deposits (Browne & Reay 1993). The formation unconformably overlies Pahau terrane or Split Rock The Lookout Formation (Kwl; Challis 1960, 1966; Formation (Reay 1993; Crampton & others 2004) and was Montague 1981) comprises basal pebble conglomerate and deposited in a fluvial, coastal plain environment. coal measures overlain by extensive volcanic flows (Fig. 32). It crops out extensively around Mt. Lookout and The earliest Late Cretaceous Gridiron Formation (Kwg; extends discontinuously as fault-bounded slivers for Suggate 1958; Reay 1993) encompasses the volcanic part of the Wallow Group in the middle Clarence valley. It includes subaerial basalt flows, pillow basalt and volcanogenic conglomerate, breccias, dikes and sills (Fig. 31). The lavas include alkaline basalt to trachybasalt, with minor olivine basalt (Reay 1993). The lower flows of the Gridiron Formation are locally interbedded with the Warder Formation, and elsewhere the flows lie on the laterally correlative Bluff Sandstone (see below). The lowest lava flows have been K-Ar dated at 93–99 Ma (Reay 1993) and Ar/Ar dated at 96 Ma (Crampton & others 2004).

The Bluff Sandstone (Kwb; Reay 1993) is dominated by massive and thick-bedded sandstone but also includes conglomerate and alternating sandstone and mudstone and is locally carbonaceous. The conglomerate clasts are cobble to boulder-size and include Pahau sandstone, chert, Figure 32 Multiple basaltic flows with interbedded vein quartz, jasper, rhyolite, granite and basalt (Reay 1993). sandstone and rare conglomerate of the Lookout Formation (Wallow Group), Castle River, Awatere valley. The Bluff Sandstone conformably overlies Warder Formation or is locally interstratified with the upper part of Photo: M.J. Isaac.

31 30 km along the Awatere valley to the northeast (Allen (Piripauan) Paton Formation (Kyp; Webb 1971) consists 1962). Extrusive trachybasalt and trachyandesite are of glauconitic, fine- to medium-grained sandstone and interbedded with volcanic conglomerates, sandstone and graded sandstone and siltstone. The formation is limestone lenses (Weaver & Pankhurst 1991). In the lower commonly bioturbated and locally contains abundant part of the formation, the flows are terrestrial, but near the inoceramid fossils, as fragments or as whole valves. The top pillow basalts are interbedded with marine tuffs (Challis Paton Formation unconformably overlies Bluff Sandstone 1966). The flows are petrologically similar to the (Reay 1993), is locally scoured into the Hapuku Group Tapuaenuku Intrusive Complex (see below). The Lookout (Crampton and Laird 1997), or conformably and Formation and Gridiron Formation volcanics are inferred gradationally overlies the Burnt Creek Formation (Field, to have been fed by numerous basanitic dikes emanating Uruski & others 1997). The formation is inferred to have from the Mt Tapuae-o-Uenuku intrusion during the earliest formed in an inner to mid-shelf environment, based on Late Cretaceous. sedimentary structures and dinoflagellates (Laird 1992; Schiøler & others 2002). The Hapuku Group (Kh; Laird & others 1994) crops out between the Hapuku and Kekerengu rivers and in the Undifferentiated rocks of the Seymour Group (Ky) include northeast Clarence valley. Near Ouse Stream, the Hapuku latest Cretaceous (Haumurian) Herring and Woolshed Group is structurally subdivided by the synsedimentary formations, and to the east of the London Hill Fault, the Ouse Fault. West of the fault the group consists of the Butt and Mirza formations (Suggate & others 1978; see Nidd and Willows formations and other unnamed below). Collectively, these rocks are time-equivalents of sedimentary rocks. The Willows Formation comprises the Whangai Formation of the North Island’s East Coast purplish-brown, epiclastic conglomerate of basaltic (Lee & Begg 2002). In the Clarence valley-Kekerengu area, composition (Reay 1993). The Nidd Formation (Lensen Herring Formation overlies Paton Formation with a sharp 1978) is preserved as fault-bounded slivers southeast of contact. It is predominantly a light grey, sulphurous muddy the Clarence Fault and comprises richly fossiliferous, siltstone interbedded with pale, well-sorted fine sandstone. weakly bedded, purple-brown siltstone to very fine-grained The formation has a characteristic rusty brown appearance sandstone, commonly glauconitic and burrowed. West of when weathered, due to iron staining leaching from joint the Ouse Fault the Hapuku Group rests with erosional planes. Jarosite staining and pyrite nodules are common. contact on the Wallow Group. The formation commonly contains spectacular ovoid concretions, up to 3 m diameter (Reay 1993), and locally East of the Ouse Fault, Hapuku Group consists of the Burnt abundant sandstone dikes. Microfossils indicate a mid- to Creek Formation (Lensen 1978). The formation has basal outer shelf environment of deposition (Schiøler & others poorly sorted, clast-supported conglomerates containing 2002; Crampton & others 2003). The Woolshed Formation clasts of sandstone, mudstone, quartzite, chert, and felsic (Fig. 34a) is a local facies variant exposed north of volcanic and plutonic rocks. These conglomerates grade Kekerengu and consists of muddy siltstone containing upwards into pebbly mudstone, sandstone and siltstone abundant concretions (Suggate & others 1978). (Fig. 33). The Burnt Creek Formation lies with sharp angular unconformity on Pahau terrane and it is inferred to have In the Ward coastal area, east of the London Hill Fault, the been deposited in a tectonically controlled basin in the upper Seymour Group includes conglomerates, slumped middle Late Cretaceous (Crampton and Laird 1997). horizons and channelled sandstone bodies of the Mirza Formation (Suggate & others 1978), white micritic limestone The Seymour Group occurs in the northern part of the (Flaxbourne Limestone) and turbidites deposited by Kaikoura map area between Cape Campbell and Whales sediment gravity flow processes (the Butt Formation (Fig. Back, north of Waiau. The middle Late Cretaceous 34b); Laird & Schiøler 2005; Hollis & others 2005b). The stratigraphy east of the London Hill Fault more closely resembles that of Late Cretaceous rocks of the Wairarapa area, rather than Marlborough (Laird & Schiøler 2005).

From the Clarence valley to the coast, the uppermost Seymour Group includes latest Cretaceous Branch Sandstone, which overlies the Herring Formation with sharp but conformable contact. The formation consists of massive, well-sorted, muddy fine sandstone, typically about 10 m thick, but locally up to 40 m, and is interpreted as an offshore sand bar (Reay 1993).

South of Kaikoura, Late Cretaceous rocks equivalent in age to the Seymour Group are mapped as the lower part of the Eyre Group (lKe; Warren & Speden 1978; Browne & Figure 33 The Burnt Creek Formation siltstone and Field 1985; Andrews & others 1987; Warren 1995; Fig. 28). sandstone in Ouse Stream are typical of the upper Hapuku Group. Undifferentiated Eyre Group (KEe) may also include Photo: J.S. Crampton. Cretaceous sedimentary rock, where it is too thin to 32 Figure 34 The Seymour Group includes (a) Jarositic siltstone of the Woolshed Formation, shown here in Ben More Stream with deformation typical of that area. (b) Well-bedded Butt Formation sandstone at the mouth of Flaxbourne River. distinguish from the upper part of the group. In the Haumuri In the southern part of the Kaikoura map area, the lower Bluffs-Parnassus area, the lower part of the Eyre Group part of the Eyre Group consists of thin conglomerate beds includes quartzose sandstone, thin conglomerate beds, which grade upwards into fine-grained quartzose sandstone calcareous and carbonaceous beds and granule and mudstone, with thin, rare coal seams of the Broken conglomerate (Okarahia Sandstone and Tarapuhi Grit). River Formation (Gage 1970; Browne & Field 1985). Grey, These coarse clastic rocks grade up into 240 m of massive, slightly calcareous silty fine sandstone of the Conway jarositic, grey siltstone to very fine-grained sandstone of Formation overlies, and in turn grades upwards into, the the Late Cretaceous Conway Formation (Warren 1995; Fig. jarositic, sandy Loburn Mudstone. 35), in which sub-spherical concretions up to 5 m in diameter are common (Browne 1985). Overlying the Conway The Eyre Group unconformably overlies Pahau terrane (Fig. Formation, the Claverley Sandstone (Warren & Speden 28). At its northernmost extent, at Haumuri Bluffs, it is 1978) constitutes up to 40 m of poorly bedded, yellow- entirely Late Cretaceous, but towards the south of the grey glauconitic sandstone. Dinoflagellates indicate a mid- Kaikoura map area it includes progressively younger rocks Haumurian age near the base and a late Haumurian-early (as young as Eocene; see below). Rocks in the lower part Teurian age near the top (Warren 1995). of the Eyre Group were deposited in alluvial, estuarine and shallow marine environments with progressive deepening Inland, north of Waiau, Late Cretaceous Eyre Group to a restricted basin (Browne & Field 1985; Field, Browne includes conglomerate, comprising well-rounded clasts of & others 1989). Pahau-derived sandstone, quartzite, rhyolite, granite and schist (Stanton Conglomerate; Browne & Field 1985). In the southeast of the Moutere Depression, the Late Sparse plant fossils and pieces of coalified or silicified Cretaceous Beebys Conglomerate (Kbc; Johnston 1990) wood are interspersed with sandstone beds and pebbly rests unconformably on Brook Street terrane rocks. The sandstone layers. The conglomerate is locally overlain by formation has a preserved thickness of 2400 m and in fine sandy siltstone and interbedded sandstone of the addition to conglomerate it contains sandstone, siltstone Lagoon Stream Formation or by the Conway Formation. and mudstone beds, and rare seams of medium- to high-

Figure 35 The Conway Formation near Haumuri Bluffs comprises sandstone and siltstone with horizons of calcareous concretions.

Photo: G. H. Browne.

33 volatile bituminous coal. The conglomerate clasts, up to carbonatite (Fig. 36a). The upper part is intruded by syenite 0.4 m across, include felsic igneous intrusives, intermediate sills and dikes (Baker & others 1994). Magnetite and to mafic volcanic and igneous rocks, and indurated ilmenite, largely within the anorthosite, are responsible for sedimentary rocks. Plant fossils are locally present and a major magnetic anomaly centred on the Inland Kaikoura microfloras indicate an early Late Cretaceous (Raukumara Range (Reilly 1970). The intrusion is surrounded by a Series) age. The formation has been weakly contact-metamorphosed hornfels zone (Kth) up to 400 m metamorphosed to zeolite facies. It is interpreted as part of wide in the surrounding Pahau terrane rocks (Baker & an extensive braided and locally meandering river deposit others 1994). A radial suite of basanitic dikes (Fig 36b,c) that accumulated in a fault-angle depression or half-graben extends outwards from the main body for a distance of under a warm oxidising climate (Johnston 1990). more than 10 km, and the top of the intrusion was probably emplaced at a depth of 3–4 km. A 96 Ma intrusion age for Cretaceous igneous rocks the Tapuaenuku Igneous Complex, based on U-Pb dating (Baker & Seward 1996), is supported by K-Ar ages of A northeast-southwest aligned belt of isolated igneous cogenetic dike intrusion between 100 and 60 Ma (Grapes bodies extends for over 150 km through Marlborough and & others 1992). The complex is genetically related to the northern Canterbury (the Central Marlborough igneous 96 Ma Gridiron Formation (Crampton & others 2004) and province of Nicol 1977). Undifferentiated Cretaceous the Lookout Formation (Challis 1966; Nicol 1977; Reay igneous rocks (Ki) include an alkaline ultramafic gabbro 1993), but has a greater age range. ring complex and associated hornfels zone preserved at the summit of Blue Mountain (Grapes 1975), and basalt The Mandamus Igneous Complex (Kim) is exposed in the flows and breccia preserved at Hungry Hill north of the hills at the northwestern edge of the Culverden Basin. The Waima River. Neither of these occurrences has been dated complex is generally erosion-resistant compared with its directly, but Hungry Hill basalt rests unconformably upon Pahau host-rock and is the southernmost of the alkaline Cretaceous Pahau terrane and is overlain by Late gabbro intrusives in the map area. It is composed principally Cretaceous (Piripauan) Paton Formation (Waters 1988).

The Tapuaenuku Igneous Complex (Kit; Nicol 1977) crops out as a sub-circular intrusion, 7 km in diameter. Approximately 600 m of vertical section is exposed on Mt. Tapuae-o-Uenuku. The complex is composed of layered pyroxenite, peridotite, anorthosite, gabbro and minor

(b) Basanite dike intruding gabbro and earlier dike intrusions, Hodder River headwaters.

Figure 36 The Tapuaenuku Igneous Complex. (c) Aerial view (200 m wide) of dikes intruding poorly bedded Pahau terrane in the Inland Kaikoura Range. (a) Boulders of gabbro, syenite and basanite in the Hodder River. Photo CN25914/2: D.L. Homer. 34 of feldspar-clinopyroxene-biotite-amphibole syenite and have become remobilised or intruded into underlying and clinopyroxene-labradorite-olivine-biotite gabbro. Volcanic overlying units since deposition (Browne & Field 1985). flow rocks are predominantly trachytic with minor basalt, The environment of deposition of upper Eyre Group rocks including possible vent-lavas/breccias around Hurunui includes shallow marine, low energy outer shelf (bathyal), Peak. The Mandamus Igneous Complex has been Rb-Sr and relatively high-energy near-shore beach settings. dated at 97 Ma (Weaver & Pankhurst 1991). The Muzzle Group (Reay 1993) consists of mainly strongly Paleocene to Eocene sedimentary rocks indurated micritic limestone and calcareous mudstone, chert, and minor greensand and volcanic rocks. The group In the south of the Kaikoura map area, deposition of the contains two formations, the Mead Hill Formation and the Eyre Group including Conway Formation and Loburn Amuri Limestone, and in areas where both formations are Mudstone (see above) continued through into the thin the Muzzle Group is undifferentiated (KPz) on the Paleocene. The upper part of the Eyre Group is commonly map. The Mead Hill Formation (Kzm; Webb 1971) is too thin to differentiate from lower parts and is mapped as typically a greenish-grey, chert-rich, micritic limestone, undifferentiated (KEe; Fig. 28). Paleogene Eyre Group (PEe) weathering to white and black (Fig. 37), with calcareous includes the Paleocene to Early Eocene Waipara Greensand, mudstone and nodular chert. The formation is limited to consisting of fine- to medium-grained, glauconitic the northeastern part of the map area and varies greatly in sandstone that becomes increasingly muddy up section thickness. In Branch Stream it is about 120 m thick but it (Browne & Field 1985). The overlying Early to Middle pinches out in the middle Clarence valley and is absent in Eocene Ashley Mudstone consists of glauconitic, Seymour Stream (Reay 1993); it reaches its greatest calcareous sandy mudstone, siltstone and sandstone. In thickness in Mead Stream, where it is over 250 m thick general the Ashley Formation rests disconformably on (Strong & others 1995). In the northern Clarence valley Waipara Greensand (commonly with a burrowed, and in coastal eastern Marlborough, the formation contains phosphatised contact) but, locally, around the lower the Cretaceous-Paleogene boundary, which is particularly Hurunui River-Culverden area, it is unconformable on well exposed in Mead Stream (Fig. 38) and is marked by Pahau terrane (Fig. 28). In the far south of the Kaikoura major changes in microfossil assemblages (see text box). map area, the Middle to Late Eocene Homebush Sandstone At Mead Stream the top of the formation is as young as overlies the Ashley Mudstone. It is a massive, glauconitic, Late Paleocene (Strong & others 1995; Hollis & others unfossiliferous, well-sorted, quartzose sandstone, that may 2005a).

Figure 37 The Mead Hill Formation, Muzzle Group, is a well-bedded siliceous limestone, shown here in Mead Stream.

Figure 38 The Cretaceous-Paleogene boundary occurs within the Mead Hill Formation in Mead Stream. The hammer handle rests on the thin bed marking the boundary.

35 The Cretaceous - Paleogene Boundary The Cretaceous-Paleogene boundary marks a global mass extinction event and associated paleoenvironmental changes brought about by a meteorite impact in Central America (Alvarez & others 1980). Complete or near- complete boundary sections are preserved at many locations throughout Marlborough and northern Canterbury (e.g. Strong & others 1987; Hollis 2003). In Mead and Branch streams a disconformity spanning <100 ka is present at the boundary and part of the lowermost Paleocene is missing at Woodside Creek (Hollis 2003; Hollis & others 2003). A near-complete record is preserved within the bathyal siliceous limestone at Flaxbourne River (Strong & others 1987; Strong 2000; Hollis 2003) and on the southern edge of the Kaikoura map area, in the shallow marine Conway Formation. Elsewhere the boundary is a significant erosion surface and latest Cretaceous and/or earliest Paleocene rocks are not always preserved, e.g. south of Branch Stream in the Clarence valley (Reay 1993) and at Monkey Face southwest of Kaikoura (Crampton 1988). Paleoenvironmental changes across the boundary include a major decrease in calcareous plankton, matched in some sections by an increase in biosiliceous productivity (Hollis 2003). Biosiliceous rocks are initially diatom- rich then radiolarian-rich, indicating a pronounced cooling at this time. In the Mead Stream section, the sedimentation rate drops from 16 to < 2.5 mm/ka, largely due to the extinction of calcareous plankton. The proportion of terrigenous sediment and total organic carbon increases across the boundary, possibly due to soot/charcoal from forest fires that would have accompanied meteorite impact (Hollis & others 2003). Pollen records from the Paleocene Waipara Greensand indicate an abrupt disappearance of mixed-forest vegetation and a rapid expansion of opportunistic fern species (Hollis 2003; Vajda & Raine 2003). The Cretaceous-Paleogene boundary in the Kaikoura map area is commonly marked by geochemical changes, including elevated levels of iridium, inferred to be of extraterrestrial origin, and enrichment of nickel and chromium (Brooks & others 1986; Hollis 2003).

= T4 P-Eza Marine OIS T3 P-Eza terrace age* = o30 30 T1 5c = o = T2 5a = Kaikoura E = = o40 1km T3 4 = = Kzm T4 T2 } 3 Ky T5 P-Eza Ky? Q1b beach deposits Q1af 35 75 Avoca fan deposits o 45 o Point *Ota and others (1996). o Kwb Kzm Kzm Kwb Ky Q1b Mnw Waima Formation

Q1b T3 P-Eza N

Onl Oligocene limestone

80 (Spy Glass Formation)

Q1b o v Onl Unconformity Ky o 75

50 o o 45 P-Eza

o Amuri Limestone

Q1af T2 75

Kwb 60 o Kzm Mead Hill Formation

Kwb o

o Ky 60 T4 60 Seymour Group

o T2 Mnw Ky = Kwb Bluff Sandstone 60o Q1af 60 = Point Kean 50 5865000 Ktp Pahau terrane

o Mnw

= T1 T4 = Q1b o = Onl T5 o Mnw Anticline T2 20

35 20 Ky Kzm P-Eza o

= o35 Syncline

o T4 T5

45 = 8

Q1b T4 o Fault

Kzm T5 o

o 20 o Mnw

o 60

35 Bedding o

o Onl v T3

o ¥

T5 33 Upright bedding

60 75 o P-Eza 45 o T4

Q1b v Vertical 50 Onl Mnw T5 Onl 15 o o o 48 bedding Onl 50 19

Mnw T4 5 o 5864000

o50 = Sinkhole

24 P-Eza

o o 10 Onl

22 o 44 o 60 T5 o ¥ Q1b o Road

o 22o o 62 35

South Bay 16 45 Lighthouse

25 o ¥ 20o

23 o

o 85 Mnw

o 20 20 o 75

o P-Eza E’ o

Mnw o East Head 10 o

Onl Atia Point o Mnw

2566000

2565000

2569000 2568000 5863000 500 northwest no vertical exageration southeast E E’ T1 Onl T3 T4 T2 T3 T3 T3 T2 T2 T2 Q1b Mnw Sea Level P-Eza 0m Mnw Mnw Kzm Ky P-Eza Onl Ky 500 Kwb Kzm

Ktp Kwb

1000 Figure 39 Geological map of the Kaikoura Peninsula with the considerable shore platform geology shown. The area has been uplifted and gently folded. NZMS 260 series 1 km grid is shown for reference. After Campbell (1975); Fyfe (1936); Ota & others (1996). 36 The Amuri Limestone (Pza, Eza) is widely preserved in south of the map area it varies considerably in thickness, the eastern part of the Kaikoura map area (Figs 39, 40). In but rarely exceeds 50 m, and it rests conformably (locally the north it is included within the Muzzle Group (Reay unconformably) on older Eyre Group (Browne & Field 1985). 1993; Field, Uruski & others 1997), but south of Kaikoura it has not previously been assigned to any group (e.g. Both the base and top of the Amuri Limestone are highly Browne & Field 1985; Field, Browne & others 1989). The time-transgressive (Fig. 28). In the Clarence valley the age southern occurrences of the Amuri Limestone are now range of the formation is Paleocene to latest Eocene (Reay included within the Eyre Group on the Kaikoura map 1993; Strong & others 1995; Hollis & others 2005b). At following stratigraphic rationalisation (e.g. Forsyth 2001). Kaikoura Peninsula, earliest Eocene Amuri Limestone rests The formation consists predominantly of white, hard, disconformably on Late Cretaceous Mead Hill Formation siliceous, micritic limestone or interbedded limestone and (Hollis & others 2005b). From Kaikoura southwards, the marl (Fig. 40), composed of coccolith and foraminifera tests Amuri Limestone youngs progressively: at Haumuri Bluffs, and clay. Other lithologies, not differentiated on the map, the age range is Early to Late Eocene; at Hurunui River it is include dark siliceous mudstone (equivalent of the entirely Late Eocene; at Napenape it is Late Eocene to Waipawa Formation in the North Island; Lee & Begg 2002), Early Oligocene; and at Waipara River, on the southern yellow-grey sandy limestone (Teredo limestone member), edge of the Kaikoura map area, the formation is entirely bedded greensand (Fells Greensand member) and graded Oligocene (Field, Browne & others 1989). sandstone and siltstone couplets (Woodside “formation”). The bulk of the Amuri Limestone was deposited under At Mead Stream the Amuri Limestone rests with apparent pelagic to hemipelagic conditions (Strong & others 1995; conformity on Mead Hill Formation (Hollis & others 2005a), Hollis & others 2005a) and bentonitic parts of the Amuri but south of the middle Clarence valley, Mead Hill Limestone indicate increased influx of terrigenous mud Formation pinches out and the Amuri Limestone rests (Reay 1993), most likely during globally warm periods (e.g. unconformably on the Seymour Group (Reay 1993). In the Hollis & others 2005a,b). Microfossils indicate an upper to Clarence valley, the limestone reaches 400 m thick; in the lower bathyal setting (Field, Uruski & others 1997).

Figure 40 The Amuri Limestone, consisting of interbedded siliceous limestone and bentonitic marl, at Haumuri Bluffs. Photo: D.L. Homer CN30428.

37 The Grasseed Volcanics member (Ezg; Reay 1993) occurs within the Amuri Limestone as isolated bodies in the middle Clarence valley and in the Waima River-Kekerengu area. The member comprises both intrusive and extrusive igneous rocks, including dikes, flows, sills, pillow lavas (Fig. 41) and agglomerate of peridotite, gabbro, dolerite and basalt. Gabbro sills up to several tens of metres thick locally intrude the limestone. The dikes intrude the Seymour Group and the Mead Hill and Amuri formations, becoming extrusive in the upper parts of the Amuri Limestone. The extrusive parts of the Grasseed Volcanics are within-plate alkali basalts and K-Ar dating of phlogopite from the Clarence valley yielded ages of 43–53 Ma (Early to Middle Eocene). Microfossils in the overlying limestone constrain Figure 41 Pillow basalt of the Grasseed Volcanics in Blue the minimum age to Late Eocene (Reay 1993). Mountain Stream. The interstitial pale pink carbonate rock is similar to the Amuri Limestone that encloses the Late Eocene to Pliocene sedimentary and volcanic rocks volcanics. During the Late Eocene, the New Zealand continent area was partly emergent but remained low-lying. Late Eocene terrestrial coal measures were widely deposited, followed by a variety of marine rocks. Within the Kaikoura map area the rate of sedimentation was highly variable. Thick deposits accumulated in the rapidly subsiding Murchison Basin (see below), but on the east coast, no latest Eocene or Oligocene rocks are preserved north of the Waima River to the Kaikoura map boundary (Townsend 2001). Elsewhere in the map area, Late Eocene to Middle Miocene rocks are preserved locally along the Waimea Fault in the northwest and more extensively in northern Canterbury. Subsequently carbonate rocks were deposited above extensive erosion surfaces that developed during the Oligocene (including the Marshall Paraconformity; Carter & Landis 1972; Carter 1985; Fig. 42). Early to Middle Figure 42 The Marshall Paraconformity at Gore Bay is an Miocene clastic deposition in the Kaikoura-Kekerengu area Oligocene erosion surface marked by the degree of was in response to an increasing component of bioturbation in the underlying Amuri Limestone and the convergence on the plate margin and consequent uplift. numerous phosphate nodules at the base of the overlying Rapid clastic deposition in the northeast (Awatere Sub- Spy Glass Formation (Motunau Group) limestone. basin) during the Late Miocene and Early Pliocene resulted from the formation of localised, tectonically controlled sub- Photo: G.H. Browne. basins (Browne 1995).

Southeast of the Alpine Fault

The Cookson Volcanics Group (Oc; Browne & Field 1985) crops out extensively in the middle Clarence valley and from Whales Back southwards along the edges of the Culverden Basin. The group comprises basaltic plugs, flows, pillow lavas, dikes, and sills (Fig. 43), with breccia, conglomerate and volcaniclastic sandstone, interbedded with calcareous rocks. The group is up to 50 m thick in the Clarence valley (Reay 1993) and up to 1200 m thick in a syncline north of Waiau township (Field, Browne & others 1989). It unconformably overlies the Amuri Limestone and forms laterally discontinuous lenses. In the Clarence valley, the sandstone contains Early Oligocene foraminifera and the basalt plug at Limestone Hill has been K-Ar dated at 27.6 Ma (Reay 1993). Figure 43 Basaltic rock agglomerate of the Cookson Volcanics Group exposed in a road cutting near Whales The Motunau Group occurs widely through the eastern Back Saddle. Kaikoura map area and in most cases unconformably

38 overlies older rocks (Carter & Landis 1972; Findlay 1980; Field 1985). Many of the formations within the group are too thin to be shown on the Kaikoura map, and these are mapped as undifferentiated (Mn).

Widespread, undifferentiated Late Oligocene basal greensands, limestones and calcareous mudstones (Onl) are included within the lower Motunau Group. The limestone commonly forms prominent bluffs and distinctive landforms with local stratigraphic names including Omihi and Spy Glass formations, Tekoa, Flaxdown, Isolated Hill, Weka Pass and Whales Back limestones, and Hanmer Marble (Fig. 44a,b). Collectively, however, these undifferentiated rocks are shallow to deep-water sedimentary facies variants of a semi-continuous blanket of Late Oligocene carbonate deposition that only locally exceeded 50 m in thickness. These rocks conformably overlie or are locally interbedded with the Cookson Volcanics Group but are generally unconformable on older rocks such as the Amuri Limestone.

The Early to Middle Miocene Waima Formation (Mnw) is widespread throughout the northern and eastern parts of the Kaikoura map area (Browne & Field 1985; Field, Uruski & others 1997). It comprises more than 360 m of generally massive to poorly bedded, greenish to bluish-grey calcareous silty mudstone (Fig. 45a). The Waima Formation is generally conformable on Oligocene limestone with a gradational, usually interbedded, contact. Locally the formation is disconformable on Amuri Limestone (e.g. Figure 44 Oligocene limestone (Motunau Group) includes between Bluff and Dart streams in the Clarence valley; (a) Isolated Hill limestone at Mt Cookson, which forms Reay 1993). Microfossil evidence suggests that the age the spectacular headscarp of a landslide block (on right) ranges from early Late Oligocene to late Early Miocene; and (b) Folded Spy Glass Formation limestone on the shore platform of Kaikoura Peninsula. Underlying Amuri deposition may have locally continued into the Middle Limestone forms the base of the cliffs in the background.

39 Figure 45 The upper Motunau Group contains many different rock types. (a) Gently-dipping, well-bedded Waima Formation siltstone forms the Haumuri Bluffs. The horizontal surface is an elevated marine terrace. Photo CN30458/23: D.L. Homer. (b) The Great Marlborough Conglomerate facies within the Waima Formation contains clasts from most of the Cretaceous and Paleogene rocks of the eastern Kaikoura map area. Photo: G.H. Browne. (c) The interbedded sandstone and conglomerate of the Greta Formation at Gore Bay exhibits “badlands”-type, vertical erosive fluting. Photo CN30528/16: D.L. Homer. siltstone; massive blue-grey siltstone; and bedded, yellow- Miocene (e.g., at Haumuri Bluffs; Browne 1995; Warren brown sandstone. The Waikari Formation unconformably 1995). In the north the Waima Formation includes the Early overlies Oligocene limestone (Andrews 1963), except where Miocene Great Marlborough Conglomerate (not mapped), it conformably overlies Waima Formation (Warren 1995). an extremely poorly sorted pebble to boulder conglomerate (Fig. 45b). Clasts are derived from Pahau terrane, Late In the south of the map area, the Early to Middle Miocene Cretaceous igneous rocks, Seymour Group, Mead Hill and Mt Brown Formation (Mnb) consists of siltstone, Amuri formations, with large rafts of Oligocene limestone sandstone and bioclastic limestone with interbedded debris and rip-up clasts of Waima Formation siltstone. The flow conglomerate that conformably overlies the finer conglomerate generally forms lenses within the Waima grained Waikari Formation. It is locally up to 830 m thick Formation, or is locally unconformable on Pahau terrane and was deposited in mid- to outer shelf environments in a or on Oligocene limestone. The conglomerate was rapidly subsiding basin (Browne & Field 1985). deposited by a number of debris flow mechanisms and accumulated in broad, shallow feeder channels (Lewis & The conformably overlying Middle Miocene to Early others 1980) or locally filled canyons that were incised Pleistocene Greta Formation (^ng; Fig. 45c) is dominated into the Miocene continental shelf (Townsend 2001). In by fine-grained siltstone (Browne & Field 1985; Warren the Clarence valley the Great Marlborough Conglomerate 1995). Other facies are only locally developed and include reaches almost 300 m in thickness (Reay 1993). poorly bedded marine, deltaic and fluvial mudstone, limestone and debris flow conglomerate, and a small The Early Miocene Waikari Formation (Mnk) (Andrews proportion of sandstone. Up to 800 m of siltstone is 1963) is widespread in the south of the Kaikoura map area. recorded near Waiau (Browne & Field 1985), but the The formation includes basal calcareous glauconitic thickness of the formation varies greatly (e.g. Warren 1995).

40 Late Miocene to earliest Late Pliocene rocks of the Awatere Group crop out in the northeast of the Kaikoura map area. The group is divided into three formations (Roberts & Wilson 1992). The oldest rocks of the middle Late Miocene Medway Formation (Mam) crop out extensively in the Medway valley and thin eastwards into the Awatere valley. The formation consists of a basal conglomerate, 50–100 m thick, which grades upwards into 200 m of sandstone with conglomerate lenses, in turn overlain by mudstone and siltstone (Browne 1995). Isolated Miocene fossiliferous conglomeratic sandstone on the west limb of the Ward Syncline, and a single occurrence of fine sandstone with poorly preserved macrofossils in the Waihopai valley, Figure 47 Well-bedded Kowai Formation fluvial or deltaic indicate that the Medway Formation originally extended Pahau-derived gravel, exposed in the Kaiwara valley west well to the north and east of the Medway and upper of Cheviot. Flaxbourne valleys. The formation is interpreted as a syntectonic, inner to mid-shelf deposit (Melhuish 1988), conglomerate (Whanganui Siltstone; ^u) occurs north of formed near an actively rising Pahau terrane hinterland at the Clarence River mouth (Browne 1995). sedimentation rates of up to 870 m/Ma (Browne 1995). The Pliocene Kowai Formation (^k) crops out in the Unconformably overlying the Medway Formation or, southern part of the Kaikoura map area where it locally, Pahau terrane, is the Late Miocene Upton Formation unconformably overlies Mt Brown and Greta formations. (Mau). It consists of basal sandstone or conglomerate that It consists of up to 650 m of Pahau-derived fluvial and grades upward into siltstone-dominated rocks, with shallow marine conglomerate (Fig. 47) with interbedded scattered macrofossils and shellbeds. The lower part of sandstone and mudstone (Browne & Field 1985). Like the the Upton Formation was deposited near actively rising conglomerates of the Awatere Group, Kowai Formation ranges, while the finer grained parts were deposited in a resulted from the accumulation of debris shed from actively bathyal setting (Browne 1995). The upper part of the rising mountain ranges. formation coarsens upwards into sandstone in the northwest. The overlying latest Miocene to Late Pliocene Northwest of the Alpine Fault Starborough Formation (^as) is generally poorly exposed and consists of poorly bedded brownish-grey fossiliferous Late Eocene to Early Pleistocene rocks crop out extensively sandstone and sandy siltstone (Fig. 46). in the northwest of the map area and are up to 9 km thick in the Murchison Basin. The basin has been shortened by The lower part of the Awatere Group comprises a up to 60% since the Late Miocene resulting in steeply transgressive sequence resulting from the incursion of the dipping fold limbs and faulted-out anticlinal axes (Suggate sea over a low-lying landscape cut in Pahau terrane. The 1984; Lihou 1993). upper part represents a regressive phase with shallowing of the sea (Roberts & Wilson 1992; Browne 1995). Slivers of Late Eocene to middle Oligocene Brunner Coal Measures (Eb) and massive mudstone are preserved along Undifferentiated Early Pliocene blue-grey calcareous the Waimea Fault in the southeast of the Moutere siltstone and sandstone, with Pahau-derived debris-flow Depression. The coal measures, up to 300 m thick, have close similarities to the Eocene rocks of the Jenkins Group in Nelson (Johnston 1990; Rattenbury & others 1998).

In the northeast of the Murchison Basin, latest Eocene to earliest Oligocene Maruia Formation (Em, Fyfe 1968) is composed of 50 to 500 m of coarse, quartzofeldspathic sandstone with minor conglomerate, carbonaceous mudstone and thin seams of bituminous coal. These rocks are overlain by up to 500 m of largely massive, dark brown, micaceous mudstone or siltstone with minor bands of feldspathic sandstone, becoming more calcareous towards the top. The Maruia Formation was deposited unconformably on basement rocks, initially in a terrestrial environment. The mudstone represents deposition in an Figure 46 North-dipping, poorly fossiliferous sandstone estuarine to partly enclosed inner shelf environment with of the Starborough Formation (Awatere Group) upstream of the State Highway 1 bridge at Awatere River. The periodic incursion of submarine fans derived from a rising capping alluvial gravels are of last glaciation age (OIS2). area of Separation Point Batholith granite, probably to the east (Suggate 1984). Photo: G.H. Browne.

41 its top, pebbly sandstone and thick conglomerate beds containing schist clasts, Separation Point granite, and sedimentary rock from the Caples and Maitai terranes.

The youngest formation in the Murchison Basin is the late Early to Middle Miocene Longford Formation (Ml; Fyfe 1968), in the core of the Longford Syncline (Fig. 48). It comprises thick beds of conglomerate, sandstone, mudstone with thin coal seams, and interbedded fine sandstone and mudstone. In the south, the lower part of the formation contains proportionately less conglomerate and more sandstone and mudstone. Clast provenance was mostly from the Separation Point Suite granite, with a significant component derived from the Dun Mountain- Maitai and, in its upper part, Caples terranes (Suggate 1984). Figure 48 The Longford Formation in the Mangles valley The formation accumulated in an estuarine environment in includes coarse clastic material deposited in the the south with extensive deposition farther north by Murchison Basin in response to Miocene uplift of adjacent mountain ranges including the Southern Alps. meandering rivers in an alluvial plain setting. Farther south, at an equivalent stratigraphic level to the Longford Formation, is the poorly dated terrestrial Rappahannock Group (Cutten 1979). The lower Rappahannock Group (eMr) consists of conglomerate interbedded with sandstone and, more commonly at the base, carbonaceous mudstone with thin coal seams. Near the base, the conglomerate is dominated by clasts of Caples Group sandstone, but Rakaia terrane Alpine Schist clasts become more common higher in the succession. The upper part of the Rappahannock Group (mMr) is also dominated by conglomerate with clasts of chlorite and biotite schist derived from Rakaia terrane (Cutten 1979).

In the southwest of the Moutere Depression, weakly consolidated sandstone and mudstone with conglomerate and minor lignite seams comprise the Glenhope Formation Figure 49 Gently northeast-dipping, weakly stratified (^tg) at the base of the Tadmor Group. Clasts in the Moutere Gravel on the north bank of the Buller River contains poorly sorted quartzofeldspathic sandstone formation are dominated by Separation Point granite with (greywacke) clasts eroded from Rakaia terrane. The gravel minor amounts of Rotoroa Complex and, towards the top, is the result of rapid uplift and erosion of the Southern an increasing percentage of Torlesse-derived sandstone. Alps during the Pliocene. The formation is Late Miocene to Early Pliocene (Mildenhall & Suggate 1981). The overlying Moutere Gravel (^tm) is of early Late Pliocene (Waipipian to The overlying Late Oligocene to Early Miocene Matiri Mangapanian) age, and in the Kaikoura map area is up to Formation (Om; Fyfe 1968) comprises calcareous 500 m thick where it is down-faulted along the Waimea- mudstone with bioclastic and crystalline limestone, and is Flaxmore Fault System (Lihou 1992). In the west it channelled by sandstone and conglomerate. It locally rests conformably (locally disconformably) overlies the unconformably on basement and elsewhere is conformable Glenhope Formation. The Moutere Gravel is characterised on the Maruia Formation. The Matiri Formation is up to by rounded, slightly to deeply weathered, Rakaia-derived 1200 m thick and was deposited in an open sea environment sandstone clasts, up to 0.6 m across but mostly less than that reached bathyal depths. 0.2 m, in a yellow brown muddy matrix (Fig. 49). Palynofloras are dominated by cool temperate species (Mildenhall & The conformably overlying Mangles Formation (Mm; Fyfe Suggate 1981; Johnston 1990). 1968), of Early Miocene age, consists of graded quartz- mica sandstone and mudstone beds, and is up to 1600 m Unconformably resting on the Moutere Gravel in the south thick. The lower Mangles Formation was deposited from of the Moutere Depression are Torlesse-derived till, lake deep-water turbidity currents when the Murchison Basin beds and moderately well-sorted outwash gravel of the rapidly deepened, but as subsidence slowed, the basin Porika Formation (eQp). The formation is up to 150 m filled with shallow marine sediments in which sandstone thick and records a Late Pliocene to Early Pleistocene became dominant (Suggate 1984). The upper part of the piedmont glacial advance that extended from the Spenser Mangles Formation is dominated by thick-bedded Mountains into the developing Moutere Depression sandstone with dark mudstone and siltstone and, towards (Suggate 1965; Johnston 1990; Challis & others 1994).

42 QUATERNARY Alluvial terrace and floodplain deposits

The tectonic regime initiated in the Early Miocene The gravel deposits forming terraces and floodplains (Q1a, continued into the Quaternary, with uplift of the Southern Q2a, Q3a, Q4a, Q6a, Q8a, Q10a, eQa, uQa) are dominated Alps, and other Marlborough, Nelson and northern by poorly to well-sorted gravel with sand and silt (Fig. Canterbury ranges. The widespread Late Quaternary 50a,b). Many gravel units originated as outwash from deposits in the map area formed in response to both rising glaciation episodes. Within the gravel deposits, clasts are ranges and alternating glacial and interglacial climatic up to a metre across but most are less than 0.3 m. In general fluctuations. However, in many localities the deposits are the average clast size decreases, and degree of sorting thin (less than 5 m) and/or of restricted distribution and increases, in direct proportion to the distance from the have been omitted from the map. source of the gravel. Torlesse-derived sandstone is the

Figure 50

(a) The alluvial delta at the Clarence River mouth showing a muddy sediment plume being dispersed northwards by the longshore current. Flanking the present day flood plain are remnants of older, uplifted late Pleistocene gravels.

Photo CN23903/8: D.L. Homer.

(b) Over 160 m of alluvial outwash gravel, sand and silt underlie an extensively developed last glaciation terrace surface on the south bank of the lower Hope River.

43 predominant rock type but in the northwest, granite and (Fig. 51) may help to broadly distinguish the ages of ultramafic clasts are locally present. Lenses of silt and sand aggradation terraces. In the northeast of the map area, the are also present throughout the gravel deposits but are 26.5 ka Kawakawa tephra (Oruanui fall deposit; Wilson rarely significant. 2001), sourced from the central North Island, commonly occurs as a layer in loess deposits on terraces older than Except on present-day floodplains, the alluvial deposits OIS 2 and locally in fan gravel deposits (Campbell 1986; form flights of aggradational terraces, with the older terraces Eden 1989; Benson & others 2001; Townsend 2001). The preserved at progressively higher levels above the valley c. 340 ka Rangitawa tephra (Kohn & others 1992; Berger & floors. Although stratigraphic or glacial episode names others 1994), also from the central North Island, occurs have been applied in local settings (Suggate 1965; Eden rarely in loess older than OIS 10 in the northeast of the 1989; Townsend 2001), the deposits are differentiated here map area. by age based on oxygen isotope stages (OIS). Most deposits are poorly dated and their ages are generally based Fill, of varying levels of compaction, is common under on the height of the capping terrace surface relative to roads and railways, particularly in gullies and approaches others in the valley. The extent of terrace dissection, degree to bridges. Small areas of uncompacted fill, the result of of clast weathering and the number and thickness of loess the dumping of domestic rubbish, are present adjacent to units (see below) have also helped to constrain terrace many of the townships in the map area. All of these deposits deposit ages. are too small to show on the geological map.

The Plateau Gravel (eQl) occurs as isolated remnants that Alluvial fan and scree deposits overlie the Dun Mountain Ultramafics Group on the crest of Red Hills Ridge (Fig. 17). The formation is up to 25 m Alluvial fan deposits (Q1a, Q2a, Q3a, Q4a, Q6a, Q8a, thick and comprises poorly sorted and weakly stratified Q10a, eQa, uQa) are widespread throughout the map area ultramafic clasts, commonly less than 0.5 m across but and many merge into the aggradation surfaces in the main with large angular blocks near the base and sparse, well- valleys (Fig. 52). Many of the fans are too small to be rounded pebbles of Torlesse sandstone. The formation shown on the map and are either omitted or incorporated owes its preservation to the sandy matrix being cemented into the corresponding alluvial terrace. Mappable scree by magnesium compounds released from weathering of deposits (Q1s) occur in the higher mountains and consist the ultramafic rocks. The age of the gravel is uncertain but of locally derived, slightly weathered, angular clasts of is inferred to be no older than Middle Pleistocene (Johnston pebble to boulder size. Screes commonly merge with more 1990). gently sloping, water-borne alluvial fans towards the valley floors. Rock glacier deposits (Q1r) consisting of poorly Unmapped surficial deposits sorted gravels up to boulder size occur on the Inland Kaikoura Range (Fig. 53). Eight rock glaciers up to 1.2 km Loess deposits are not differentiated on the Kaikoura map, length and 500 m wide occur at elevations exceeding 2100 but they sometimes form significant sheets up to several m (Bacon & others 2001). These are probably actively metres thick on older terraces (Q4 to Q10) adjacent to major expanding and moving, and result from permafrost rivers or in gullies in the lee of the prevailing westerly conditions in an arid climate where there is a high ratio of winds. Identification of one or more loess-soil horizons rock debris to snow supply.

Figure 51 Loess on the south bank of the Clarence River near SH 1 showing typical vertical fluting. The faint darker banding part way up the loess may be a paleosol, or buried soil. The thickness of the loess and the presence of the paleosol suggest that the age of the underlying gravel deposit is at least OIS 4 (Q4a).

44 Figure 52 Screes on the southern flanks of Dillon Cone merge into alluvial fans near a prominent gradient change mid-slope towards the Clarence River valley. The Elliott Fault crosses the range close to the change in slope. Q1a and remnant Q2a alluvial terraces occur close to the river. Photo CN8171/25: D.L Homer.

Figure 53 Rock glaciers (left, lower right) and screes mantling the southern slopes of Mt Alarm on the Inland Kaikoura Range.

Photo CN25751/11: D.L. Homer.

45 Till deposits Swamp and lake deposits

The aggradational terrace surfaces capping the alluvial Holocene swamp deposits (Q1a) are common in many gravels (see above) can commonly be traced up the valleys valleys but are generally small in area. Adjacent to the to terminal moraines and associated till deposits (Q1t, Q2t, coast, swamps have developed where drainage has been Q4t, Q6t, Q8t, Q10t, eQt, uQt) in the mountains. The tills impeded by dunes and marine sand and gravel. Lake consist of subrounded to subangular clasts up to boulder deposits of Late Pleistocene age are present in many size in a tight clayey matrix, and older tills are generally valleys, either upstream of terminal moraine dams, or in more weathered than younger. side valleys dammed by lateral moraines or aggrading fans. The lake deposits range from silt to gravel, the latter locally Landslide deposits displaying foreset bedding. Most deposits are intermingled with or overtopped by alluvial gravel. Late Holocene lake Mass movement deposits (Q1l, uQl) are widespread, sediments are present behind landslide dams, many of although large deep-seated landslides are relatively rare. which were produced by earthquake ground shaking. Near Small superficial failures, rock falls and slope creep are Murchison township the Murchison Lake Beds (Q7k), of common, but only deposits >1 km2 in area are shown on middle Quaternary age, consist of consolidated banded the map. The large landslide deposits (Fig. 54) range from silt, gravel and sand. As the upper and lower contacts of masses of shattered, but relatively coherent rock, to silty the beds have not been seen, the processes that led to clay containing unsorted angular rock fragments. Large lake formation are not known (Suggate 1984). landslide deposits, many triggered by severe earthquake ground shaking, dam several lakes such as lakes Matiri, A swamp deposit at Pyramid Valley (too small to be shown Constance, Alexander and McRae. Moderately large on the map) contains numerous well-preserved fossil landslides, commonly with ill-defined margins, have vertebrates including at least 46 species of birds (waterfowl, occurred in areas of Pahau terrane in the Flaxbourne River, moa, kiwi, weka, parrots amongst others), as well as tuatara, and in mélange zones in the lower Waiau valley and near bats and geckos (Scarlett 1951; Holdaway & Worthy 1997). Cheviot. Extensive failures, mostly along bedding planes, Other swamp sites and some alluvial and colluvial deposits are common in the Late Cretaceous to Cenozoic rocks and around Waikari and limestone cave sites around Mt have resulted in chaotically mixed landslide deposits. Late Cookson contain more examples of these and other species Cretaceous and Eocene rocks containing montmorillonite- (Worthy & Holdaway 1995, 1996). The deposits have rich clays (smectite) are particularly prone to instability. accumulated over the last 40 000 years.

Figure 54 The large landslide deposit in Gore Basin, near the crest of the Seaward Kaikoura Range, has originated from Pahau terrane rocks forming the ridge on the right.

46 Marine deposits central part of the basin, but around the edges Miocene (Motunau and Awatere groups) to Pleistocene rocks are Marine sand and gravel deposits (Q7b, Q9b, uQb) crop exposed at the sea floor (Barnes & Audru 1999b). Up to out as poorly exposed remnants up to 280 m above sea seven Pleistocene unconformities are present within the level, particularly on eastern slopes of the Hawkswood basin. Range. The older deposits are partly dissected and tilted, and their altitude largely reflects tectonic uplift rather than The basin is being deformed by active, dextral strike-slip the height of the interglacial sea levels (Ota & others 1984; and oblique-slip faults that offset and fold Late Quaternary Warren 1995). Younger marine deposits (Q4b, Q5b) are sediments (Barnes & Audru 1999a,b). These faults include more extensively preserved along the coast (e.g. Ota & reactivated NNE- to northeast-striking Miocene structures others 1995, 1996; Figs 39, 45a). All the deposits generally and younger (<1 Ma?) faults striking ENE that have formed consist of boulders, rounded gravel and moderately sorted approximately parallel to the current plate motion vector. coarse sand. They are generally poorly fossiliferous, but The northeast trend of the basin probably also results locally contain remarkably well-preserved trace fossil from inheritance of a Miocene structural fabric (Barnes & assemblages (Ekdale & Lewis 1991). Holocene marine sand Audru 1999b). and gravel (Q1b) crop out in a narrow strip along much of the coast. South of the Kaikoura Peninsula, the Kaikoura Canyon is deeply incised into the continental shelf. Although no large Sand deposits rivers feed into the canyon, it is a major sink for north- drifting sand and mud, most of which bypasses the Sand deposits (Q1d) occur locally along the coast and continental shelf sediment prism and is transported further comprise wind-blown sand forming dunes that may extend offshore along the Hikurangi Channel and into the up-slope onto the fringing hills (Fig. 11). The Kaikoura Hikurangi Trough (Lewis & Barnes 1999). Gravel and map area characteristically has coarser beach sand and coarse sand turbidites, interbedded with pelagic mud that gravel than many other parts of the country and dunes are reflects background sedimentation conditions, are common comparatively poorly developed. in the lower part of the canyon. A seismically non-reflective layer in the central part of the canyon, overlain by bedded OFFSHORE GEOLOGY turbidites, is probably a slump that may have been generated by (c.1833) earthquake shaking. Offshore, from the Clarence River mouth north towards Cook Strait, the continental shelf is underlain by a The northern slope of the Chatham Rise has been subjected sedimentary basin identified from abundant seismic data. to strong, north-flowing ocean-bottom currents since at This Flaxbourne (Clarence) Basin contains up to 4.5 km of least the mid-Pliocene (Barnes 1994a). Sea-floor scour probable Late Cretaceous to Recent strata (Uruski 1992; channels are evident in the bathymetry and in the Field, Uruski & others 1997; Barnes & Audru 1999b). Basal underlying geology, suggesting episodic erosion and sequences in the basin thicken to the southeast and onlap sediment blanketing events. Lenticular, Late Quaternary older units towards the northwest, indicating a rifted half- sediment drifts have accumulated at the mouths of the graben. Growth strata of probable Miocene age resulted channels where they open out onto the toe of the Chatham from subsequent compressional tectonics (Uruski 1992). Rise, reflecting the localised nature of erosion and A blanket of Holocene mud up to 45 m thick covers the deposition in this area.

47 TECTONIC HISTORY

Early to mid-Paleozoic Kaikoura map area) is within a zone of greenschist to amphibolite facies schist with multiple generations of Greenland Group rocks of the Buller terrane were deposited recumbent folds and penetrative foliations (Mortimer on the Australo-Antarctic margin of Gondwanaland in the 1993a,b; Johnston 1994; Begg & Johnston 2000). In the Early Ordovician (Cooper & Tulloch 1992). In the Silurian Kaikoura map area the Caples-derived schist was later the group was tightly folded and metamorphosed to lower juxtaposed by Cenozoic movement of the Alpine Fault greenschist facies (Adams & others 1975). The Haupiri against non-schistose Rakaia terrane rocks. Greenschist Group of the Takaka terrane formed in a volcanic island arc facies (garnet zone) schist is present in the western part of and back-arc setting at a convergent plate boundary the Rakaia terrane (Turnbull & Forsyth 1986), including (Münker & Cooper 1999). The carbonate-rich Mt Arthur the Aspiring lithological association, but farther east Group rocks were deposited on a passive continental weakly metamorphosed, lithologically monotonous, margin, east of the volcanic arc, after cessation of quartzofeldspathic sedimentary rocks predominate. These subduction; they were subsequently thrust over the rocks accumulated in a Late Triassic to Early Jurassic volcanic rocks of the Haupiri Group and folded (Cooper & subduction setting and were progressively imbricated and Tulloch 1992). Accretion of the Takaka terrane onto the deformed in an accretionary wedge (MacKinnon 1983; Buller terrane occurred in the mid-Devonian, in part by Bradshaw 1989). The Esk Head belt, comprising mélange movement along the Anatoki Fault. The tectonic suturing and generally more deformed rock, including the was followed shortly afterwards by the intrusion of Silverstream Fault Zone in Branch River, is the tectonic voluminous granitic rocks of the Karamea Batholith suture between the Rakaia terrane and the Pahau terrane between 370 and 328 Ma (Cooper & Tulloch 1992). to the east. Rocks of the Pahau terrane were deposited in a subduction setting and deformed in an accretionary wedge Late Paleozoic to Early Cretaceous in the Late Jurassic to Early Cretaceous. The Caples, Rakaia and Pahau terranes were amalgamated during convergent The emplacement of the Median Batholith, dominated in tectonism along the Gondwanaland margin between the the Kaikoura map area by Triassic to Early Cretaceous Middle Jurassic and the late Early Cretaceous, when intrusions, occurred along the margin of Gondwanaland subduction ceased (Coombs & others 1976; Bradshaw and sutured the Western Province to the western part of 1989). Major igneous intrusion occurred in and beyond the Eastern Province (Bradshaw 1993; Mortimer & others the west of the Kaikoura map area in the Early Cretaceous 1999). Subsequently much of the eastern part of the with the emplacement of the Separation Point suite and batholith has been excised by the Delaware-Speargrass other granitoids (Tulloch 1983). Fault Zone (Johnston & others 1987; Johnston 1990). The Eastern Province contains six terranes within the map area Mid- to Late Cretaceous and Paleogene and all record convergent margin tectonism and volcano- sedimentary processes (Coombs & others 1976; Bradshaw Following cessation of subduction and amalgamation of 1989; Mortimer 2004). The westernmost is the volcanogenic the Eastern Province terranes, a prolonged period of Brook Street terrane, consisting of a tectonically extensional tectonics resulted in the opening of the Tasman dismembered remnant of a calc-alkaline island arc. An Sea and, within the Kaikoura map area, widespread erosion intrusive contact between the Brook Street terrane and the and deposition into numerous mid-Cretaceous basins Median Batholith in Southland constrains accretion of the (Crampton & others 2003). Intrusion of the Tapuaenuku terrane to Gondwanaland to between 230 and 245 Ma Igneous Complex and associated dikes was accompanied (Middle to Late Triassic; Mortimer & others 1999). In east by extrusive basalt flows, which interfingered with Nelson the contact between the Brook Street and Murihiku terrestrial and shallow marine sedimentary rocks. terranes is faulted. However the Brook Street terrane may have originally been overlain by the volcaniclastic In the Late Cretaceous, subsidence become more regional Murihuku terrane in a Triassic-Jurassic back-arc basin. in extent (Crampton & Laird 1997) as the tempo of extensional tectonics waned and a passive margin Farther east, a “slab” of Permian oceanic ridge or back-arc developed. Relative quiescence from the end of the basin crust, the Dun Mountain Ophiolite Belt, was Cretaceous resulted in regional subsidence and marine obducted onto Murihiku and Brook Street terranes during transgression, followed by the slow accumulation of Early to mid-Permian subduction (Coombs & others 1976; widespread, fine-grained clastic and carbonate rocks (Field, Sano & others 1997). Overlying Late Permian to Triassic Browne & others 1989). This was punctuated by sporadic Maitai Group accumulated in a trench forearc setting intraplate volcanism, particularly in the Canterbury Basin adjacent to a convergent margin. Although faulted, and (Browne & Field 1985). In the northeast of the map area folded into the Roding Syncline, the group has largely this passive, basinal regime continued through into at least retained internal stratigraphic coherence. the Middle Eocene (Strong & others 1995; Crampton & others 2003). In northern Canterbury, deposition on a broad, The Patuki Mélange separates the Dun Mountain-Maitai relatively sheltered shallow shelf led to accumulation of terrane rocks from the Caples terrane; the latter fine-grained clastic rocks and glauconitic sands. The accumulated as an accretionary wedge in a Late Permian northern basins extended southwards during the Eocene to Triassic trench or trench slope. The original suture and Oligocene, resulting in the deposition of a blanket of between the Caples and Rakaia terranes (not seen in the carbonate rocks. The Early Oligocene period of erosion

48 and/or non-deposition (including the Marshall triggered by thickened oceanic lithosphere of the Hikurangi Paraconformity), was accompanied by mild deformation plateau entering the trench system, and also because the associated with the initiation of the modern plate boundary relatively buoyant continental crust of the Chatham Rise (Lewis 1992; Nicol 1992). Apart from localised basaltic was pinned against the Australian plate to the west (Lamb volcanism the remainder of the Oligocene was characterised & Bibby 1989; Eberhart-Phillips & Reyners 1997; Little & by tectonically subdued, regional deposition of carbonate Roberts 1997; Reyners 1998). rocks into several distinct depocentres (Browne 1995). In the Late Miocene, strike-slip faulting dominated in Neogene Marlborough and associated local, fault-bounded grabens, half-grabens, and folded sedimentary basins are The early Neogene is marked by a major influx of coarser characteristic of this period (Figs 39, 55). In the Pliocene clastic sediment eroded from rising mountains in the west. the component of convergence across the plate boundary Uplift of mountain ranges was in response to increasingly increased (Walcott 1998), as did transpression on the convergent tectonics across the developing Australian- Alpine Fault and other strike-slip faults (Little & Roberts Pacific plate boundary through the New Zealand continent 1997), resulting in the uplift of the Southern Alps and other (Walcott 1978). Convergence associated with the plate mountains in the west. North of the fault, the Moutere boundary in Marlborough is recorded by Early Miocene Depression developed between the rising mountains of thrust faults preserved north of Kaikoura (e.g. Rait & others east and west Nelson. Early Miocene uplift of the Inland 1991; Townsend 2001). Erosion of the rapidly rising Kaikoura Range was followed by Late Pliocene uplift of Kaikoura ranges, Spenser Mountains and Southern Alps the Seaward Kaikoura Range (Kao 2002). Rotation of the resulted in deposition of the Early Miocene Great Hikurangi margin continued, but on a more localised scale, Marlborough Conglomerate (Reay 1993) and western in the lower Awatere valley (Roberts 1992). conglomerate units such as the Rappahannock (Cutten 1979) and Tadmor (Johnston 1990) groups. Uplift and As the Chatham Rise continued to impinge onto the cooling of the Tapuaenuku Igneous Complex at 22 Ma Australian plate, new faults developed at the edge of the (Baker & Seward 1996) indicates significant convergence Pacific plate, widening the plate boundary zone and on the Clarence Fault by the earliest Miocene (e.g. Browne resulting in the redistribution of fault slip towards the south 1992). (Knuepfer 1992; Holt & Haines 1995; Little & Roberts 1997; Little & Jones 1998; Barnes & Audru 1999b). The Hope Paleomagnetic and sea floor spreading data suggest that Fault is currently the most active structure of the the entire coastal part of northeastern Marlborough rotated Marlborough Fault System with a right-lateral slip rate of clockwise about a vertical axis by as much as 100º in the 20–40 mm/yr (Cowan 1990; Van Dissen & Yeats 1991). The Middle Miocene (Sutherland 1995; Vickery & Lamb 1995; northern Canterbury basin and range topography is a Townsend 2001; Hall & others 2004). The dominant consequence of spreading deformation associated with northeast strike of the steeply dipping Torlesse rocks in the Australian-Pacific plate boundary. Some of the ranges Marlborough is inferred to have been folded from an are bounded by northeast-striking reverse faults or thrusts original northwest strike at this time (Little & Roberts 1997). and associated folding (Nicol & others 1995; Pettinga & The rotation was probably due to locking of the others 2001; Litchfield & others 2003). subduction interface beneath Marlborough, possibly

Figure 55 The south-plunging Puhipuhi Syncline north of Kaikoura is a spectacular example of folds developed along the eastern coast. The Miocene core of the syncline lies in the valley (centre) and the fold limbs are dominated by Paleogene limestones underlain by mid- to Late Cretaceous sandstones. Folding, together with mountain uplift, occurred in response to increasing convergence across the Australia-Pacific plate boundary in the Neogene.

Photo CN11019/4: D.L. Homer. 49 GEOLOGICAL RESOURCES

The mineral resources of the Kaikoura map area are from river beds or from ground sluicing of small alluvial relatively limited, both volumetrically and economically, claims on adjacent terraces (Fyfe 1968). Larger claims were and have been described in detail by Doole & others (1987) developed in the Matakitaki valley downstream from and Eggers & Sewell (1990). The following account is terminal moraines. The gold is largely derived from quartz summarised from these publications with some updating. reefs in Rakaia terrane semischists and schists, and was The most significant resources in the map area are carried westwards by Quaternary glaciers to accumulate aggregate, limestone and salt. in moraines and outwash gravels. Further erosion and reworking of the deposits has concentrated the gold in Metallic minerals flood plains and riverbeds. Minor amounts of gold have also been eroded from the basement rocks west of the Chromium, occurring as grains and up to 15 cm thick lenses Alpine Fault, such as in the Owen valley, and from reworking of chromite, is widespread in dunite and harzburgite of the of the basal Tertiary sequences of the Murchison Basin. Dun Mountain Ultramafics Group in the Red Hills. Two No economic quartz reefs have been found in the mapped analyses gave relatively low Cr2O3 percentages of 38.01 area. and 39.51. No economic deposits are known or are likely to be found. Iron in the form of magnetite (up to 50%) is associated with ilmenite and forms layers up to several metres thick in Cobalt in the form of the cobalt-iron mineral wairauite has leucogabbro and anorthosite in parts of the Tapuaenuku been reported from the Dun Mountain Ultramafics Group, Igneous Complex (Brathwaite & Pirajno 1993). in the Wairau valley, but is of academic interest only (Challis & Long 1964). Nickel is widespread throughout the Dun Mountain Ultramafics Group, with up to 0.5% Ni present within the Copper, commonly present as sparse malachite staining, is lattice of olivine crystals, or as the iron-nickel alloy awaruite found on surfaces or fractures of igneous rocks of the (Challis & Long 1964), but economic deposits are unlikely Dun Mountain Ultramafics and Livingstone Volcanics to be present. Copper-nickel sulphide mineralisation forms groups, and in igneous rocks of the Pahau and Rakaia sub-economic disseminations within the Tapuaenuku terranes. The richest known deposit is near Mt Baldy, in Igneous Complex and at Blue Mountain (see above). gabbro of the Tinline Formation of the Livingstone Volcanics Group. The deposit comprises chalcopyrite Platinum group minerals (PGMs) are present in some of within a quartz vein stockwork, up to 1 m thick and possibly the gravels in the northwest of the map area and have continuous over a distance of 3 km, from which a series of been noted during alluvial gold mining (Morgan 1927). samples gave between 0.58 and 7.7% Cu (Johnston 1976). The greatest concentrations are in the tributaries of the In the northeast of the map area, at Tapuae-o-Uenuku and Howard River, between lakes Rotoiti and Rotoroa, and river- Blue Mountain in the Inland Kaikoura Range, mafic- flattened nuggets up to 4 mm across have been reported. ultramafic complexes of Cretaceous age contain sub- The minerals consist of platinum and Cu-rich economic, disseminated copper-nickel and magnetite- isoferroplatinum probably derived from the nearby layered ilmenite mineralisation (Pirajno 1979; Brathwaite & Pirajno Rotoroa Complex (Challis 1989; Challis & others 1994). 1993). The Tapuaenuku Igneous Complex consists of a Platinum group metals have been found in creeks draining layered intrusion with widespread but irregular the Dun Mountain Ultramafics Group in the Red Hills and disseminated pyrite, pyrrhotite and chalcopyrite at or near in the Matakitaki valley. There is restricted outcrop of likely the contact between pyroxenite and gabbro layers. Chip source rocks, and the amount of PGMs in deposits derived samples contain up to 1% Cu and 0.3% Ni. At Blue from them is likely to be insignificant. Mountain, disseminated pyrrhotite and chalcopyrite mineralisation forms irregular zones within a marginal ring Titanium in ilmenite is present in the Tapuaenuku and dike of titanaugite-ilmenite gabbro, and at the contact Blue Mountain layered intrusions (see above). Ilmenite is between the ring dike and olivine-pyroxenite. The highest a very minor component of black sand in tributaries of the rock geochemical values are 1.6% Cu and 1.3% Ni (Pirajno Buller River which drain the garnet zone of the Haast Schist. 1979). The Late Jurassic layered Rotoroa Complex in southeast Nelson contains minor quartz-pyrite- Non-metallic minerals chalcopyrite veins and disseminations adjacent to diorite, on the margins of intrusions of Separation Point granite. Clay deposits are widespread throughout the map area Copper values of up to 0.25% have been reported (Challis although there are no large deposits of uniform quality. & others 1994). Most of the clay deposits are residual, being derived from the weathering of bedrock units. In the northwest, clay Gold occurs widely as placer deposits in and adjacent to minerals are widespread in the Moutere Gravel and Porika the rivers draining west from the Main Divide. Gold was Formation but mostly as matrix to greywacke-derived first discovered in the late 1850s with the last significant gravel. Porika Formation lake beds contain large volumes find being in 1915 in the Howard valley, between lakes of clay to sandy clay, with chlorite and a minor component Rotoiti and Rotoroa. Most gold production occurred during of vermiculite or interlayered chlorite-vermiculite (Johnston the 1860s in the Mangles, Matakitaki and Glenroy valleys 1990). Southeast of the Alpine Fault, illite and interlayered

50 hydrous mica clay are widespread as the result of Rock weathering of Torlesse-derived loess. Bentonitic clay, consisting largely of montmorillonite and derived from the Aggregate is the most important rock material produced in weathering of volcanic ash, is associated with Late the Kaikoura map area, in terms of both volume and value. Cretaceous and Early Eocene volcanic rocks in the With few exceptions, it is obtained from gravels forming southeast of the Kaikoura map area. Early Eocene the beds of the major rivers. Roading uses include gravel bentonite of marine origin is more extensive and thicker, on unsealed roads, and the production of sealing chip and but relatively low grade (Ritchie & others 1969). material for base course. A small amount is produced adjacent to the townships in the map area for concrete Glauconite, a possible source of potassic fertiliser, occurs aggregate. Most of the aggregate is processed from widely within the Late Cretaceous and Tertiary rocks in sandstone clasts from the rivers draining Torlesse rocks, the east of the map area, but no economic deposits are but granite clasts are a major component in the northwest likely to exist. of the map area. Suitable gravel also exists in flood plains and Late Pleistocene outwash deposits. However, in the Salt is produced from the evaporation of seawater in Lake older outwash deposits the clasts are commonly weathered Grassmere (Fig. 56) in the northeast of the map area. The and may be unsuitable for high quality uses. Quarrying of seawater flows into shallow holding ponds or paddocks unweathered bedrock units can also provide suitable and evaporation is aided by a low rainfall, high sunshine aggregate although softer lithologies, such as mudstone hours and frequently strong, warm, northwesterly wind. (“argillite”) in the Torlesse composite terrane, are generally Between 60 000 and 70 000 tonnes of salt is produced unsuitable. Rocks of Late Cretaceous-Tertiary age, older annually, mostly for national and international industrial gravel deposits such as Moutere Gravel, and foliated schist uses (http://www.domsalt.co.nz/profile.html). are unsuitable as sources of high quality aggregate. Continuing uplift and erosion of the mountains ensures Serpentinite, or partly serpentinised harzburgite and that the rivers generally supply more gravel than is required dunite, is widespread within the Dun Mountain Ophiolite to meet demand. Belt, but most of it is inaccessible. North of the Kaikoura map area near Nelson serpentinite has been quarried from Sand is present in many of the river deposits and is these ultramafic rocks and used as a source of magnesium widespread in the Holocene marine deposits and dunes fertiliser (Roser & others 1994). adjacent to the coast.

Figure 56 Lake Grassmere is a modified estuarine lagoon where salt is mined from evaporated sea water.

Photo CN46332/25: D.L. Homer. 51 Figure 57 St Oswalds Church on State Highway 1 at Wharanui is built from blocks of Mead Hill Formation, quarried locally from Woodside Creek.

Rip-rap is readily obtainable. Potential sources include Limestones occur widely in the Kaikoura map area. In igneous rocks northwest of the Alpine Fault, and Mesozoic basement rocks, however, limestone deposits sandstone-dominated parts of the Torlesse composite are sparse and largely restricted to the Esk Head belt in the terrane and Paleogene limestones southeast of the fault. Leatham valley of Marlborough. This grey to white

Rip-rap is used for river bank or coastal protection and is limestone is fine-grained and crystalline with a CaCO3 largely obtained from hard rock quarries. Talus deposits, content of 97–99% (Kitt 1962). In Enchanted Stream in the such as ultramafic-derived boulders on the southwest of Leatham valley a 20 m thick limestone lens has been the Red Hills, have been used locally because of their intermittently quarried with the greatest annual production proximity to the area of demand. not exceeding 6000 tonnes. On the western flank of the Red Hills, the steeply dipping and faulted Permian Wooded Argillite blocks within the serpentinitic Patuki Mélange Peak Limestone is largely inaccessible. Some of the more of east Nelson have been altered by the introduction of accessible Wooded Peak Limestone in the Matakitaki valley minerals such as albite and tremolite. River boulders of has been sporadically quarried. Near Lake Daniells the altered argillite (pakohe) are tough with a characteristic Ordovician Sluice Box Limestone consists of crystalline conchoidal fracture. They were worked by Maori into adzes limestone with between 50 and 98% CaCO3 (Willett in and other implements. Williams 1974), but it is not easily accessible.

Dimension and ornamental stone of varying rock type are Limestones of Paleogene age northwest of the Alpine Fault readily available, but the quantities obtained to date have are generally inaccessible and of poor quality. Along the been small. Basement rocks are commonly jointed and eastern part of the map area immense reserves of Mead fractured, and generally difficult to access. A black Hill Formation and Amuri Limestone crop out but much of gabbronorite in the Rotoroa Complex in the Howard valley the limestone is too isolated to be used and the quality is near Lake Rotoroa has been investigated as a source of also variable, ranging from a soft marly limestone to a hard, dimension stone. Although it is readily accessible, closely highly siliceous rock. Quarries in the softer limestone exist spaced jointing would limit the size of blocks to <1 m near Cape Campbell and Ward, where the limestone has (Challis & others 1994). been crushed by faulting or landsliding.

Oligocene pink limestone from the middle Waiau River In northern Canterbury a number of Oligocene limestone

(Hanmer Marble) and Mead Hill Formation have been used units are quarried. While CaCO3 content is generally high locally as a building stone (Fig. 57). Several rock types (Eggers & Sewell 1990), thickness is highly variable. South would be suitable for ornamental chips, either loose or in of Waiau, at Isolated Hill, well-bedded Oligocene limestone decorative paving and precast panels. Rocks suitable for is broken up by landsliding, which assists quarrying. South this purpose include calcareous and siliceous components of the Hanmer Plain on SH 7, limestone (Hanmer Marble) of the Mead Hill Formation and Amuri Limestone, and red forms an easily quarried dip slope. argillite and chert in the Torlesse composite terrane.

52 Dunite boulders are sporadically collected from streams the ranges of northern Canterbury (Mongillo & Clelland draining from the Red Hills into the Wairau River for use in 1984). These springs are the result of groundwater saunas and hangi because they withstand rapid cooling percolating to considerable depth along fault zones before without explosively disintegrating. discharging on valley floors (Barnes & others 1978; Allis & others 1979). Measured temperatures range from 27.5°C Coal to 60°C and are commonly accompanied by a sulphurous discharge (Mongillo & Clelland 1984). Commercial thermal Coal occurs locally in rocks of Late Cretaceous age and resorts have been developed at Hanmer Springs and Maruia commonly near the base of Paleogene sequences. However, Springs along the Hope and Fowlers faults respectively. the only coal of economic significance in the map area is in the Murchison Basin (Suggate 1984). Up to five seams Oil and gas have been recorded from the basal Maruia Formation near the lower Matiri valley. Although the coal is strongly Oil and gas shows are present in a number of places within swelling and of high-volatile bituminous rank, the seams the Murchison Basin. The basin contains approximately have a maximum thickness of only 1.2 m, the structure is 9000 m of Late Eocene to Miocene sedimentary rocks in its unfavourable for mining and the coal has a medium to high centre and up to a further 3000 m may have been removed sulphur content. The Longford Formation in the lower by erosion (Nathan & others 1986). The basin was drilled Matakitaki and Owen valleys contains several seams of in the late 1920s and in 1968, 1970 and 1985 although only low-swelling, low-moisture, high-volatile bituminous coal the last hole, Matiri-1, reached bedrock (at 1467 m; Dunn with low (c. 1%) sulphur. The seams pinch and swell, & others 1986). The rocks in the basin are generally steeply reaching a maximum thickness of 3 m, and the coal is dipping, having been folded into a series of synclines commonly crushed. The easily accessible coal has been separated by faulted anticlines. No closed structural traps worked out and, because of the irregularity of the seams are known and there are few potential reservoir rocks with and structure, the prospects for renewed mining are poor. sufficient permeability or porosity, and consequently the Total production was probably in the order of 150 000 hydrocarbon prospects are assessed as low (Nathan & tonnes (Suggate 1984). others 1986).

Water In Marlborough, oil seeps are known from Pahau terrane rocks at London Hill and the Amuri Limestone in Isolation Groundwater availability is generally restricted east of the Creek, south of the Waima River. Both seeps occur in close Main Divide where rainfall is lower and aquifers have limited proximity to major faults. The oil is likely to have been extent. The best yields occur in Late Quaternary alluvial sourced from the Late Cretaceous Seymour Group and have gravel, particularly adjacent to the major rivers draining migrated up the fault zones to the surface (Field, Uruski & the hard basement rocks or from the fan gravel aprons on others 1997). While both source rocks and potential the flanks of the major ranges (Brown in Eggers & Sewell reservoir rocks are favourable, deformation has limited the 1990). In the lower Awatere valley, the gravels are thin and possibility of any significant hydrocarbon traps. Mudstone overlie Pliocene siltstone of low permeability that restricts at the base of the Amuri Limestone in Mead Stream has river recharge. In the minor rivers and streams, including been correlated with the Waipawa Formation, a those draining soft and/or weathered rock, an increase in hydrocarbon source rock in the eastern North Island (Field, fine-grained material in the gravel deposits tends to reduce Uruski & others 1997). However, in Marlborough, the permeability. Along the coast, Holocene beach sands and mudstone is only a few metres thick, and significant dunes have a high permeability and porosity but recharge hydrocarbon potential from this rock is unlikely. in many areas is dependent on frequent rainfall, and over- extraction can result in saline intrusion (Doole & others In northern Canterbury hydrocarbons have been reported 1987; Brown in Eggers & Sewell 1990). The Neogene to from a number of locations, principally in the Cheviot area Pleistocene gravel and sand deposits have generally low, (Field, Browne & others 1989). Several seeps occur in the but usually reliable yields. Torlesse rocks although the hydrocarbons are most likely to have originated in adjacent Late Cretaceous-Paleogene The pre-Quaternary Cenozoic rocks in the mapped area rocks (e.g., the Eyre Group), which include potential source generally have few open joints, and except along fault and reservoir rocks as well as other seeps. Significant planes and in limestones, groundwater yields are low. The structural traps have not yet been identified, and there is basement rocks have numerous joints, particularly along the potential for stratigraphic traps. Gas containing a very fault zones, which provide sufficient permeability to yield high ethane content escapes from the Hanmer thermal small quantities of groundwater. In some basement rocks, springs (Field, Browne and others 1989). such as schist, igneous and early Paleozoic rocks, the presence of sulphide minerals tends to reduce water quality. The offshore area of the Kaikoura map has had limited However, where this occurs surface water supplies are petroleum exploration but seismic data of varying quality abundant. has identified several deep sedimentary basins (Uruski 1992; Field, Uruski & others 1997). The basins may contain Thermal and mineralised hot springs are widespread, potential source rocks that have been buried sufficiently although not common, throughout the Southern Alps and to generate hydrocarbons.

53 ENGINEERING GEOLOGY

It is beyond the scope of this summary text to discuss mudstone are soft. Finer grained lithologies tend to weather engineering geological parameters of Kaikoura map area more rapidly on exposure, forming clay-rich material with a rocks except in very general terms. Site specific further reduction in rock strength and an increased potential investigations should always be undertaken with to fail, particularly where water saturated and/or sheared. exploratory trenching and/or drilling, and other testing as Where constituent clay minerals have high plasticity or appropriate under geotechnical supervision. have swelling properties, such as smectite, the risk of failure on slopes or in excavations is extreme (Fig. 58). Limestones Basement rocks and most igneous rocks are usually competent, with the exception of uncemented or weathered tuff. Rocks with The majority of the basement rocks, of Cambrian to Early only a slightly elevated carbonate content tend to be more

Cretaceous age, are generally hard and strong. Rock competent than those lacking CaCO3. strength may be diminished or influenced by grain size, degree of weathering, joint spacing, cleavage, shearing Quaternary sediments and bedding. Examples of weaker rocks are the higher grade schists that have a well-developed foliation and minerals Quaternary sediments are characteristically weak, such as micas, which decrease rock strength. Mélange particularly where weathered. Deposits dominated by and other zones of deformed rocks commonly have a serpentinite or Cenozoic mudstone clasts are particularly fractured, sheared fine-grained matrix and are consequently prone to a loss in strength on weathering. However, many less competent than less-deformed basement rocks such deposits have a silty or sandy clay matrix making them as greywacke. Slope failure is common in these zones. less prone to failure on slopes, even where weathered. An example is weathered Moutere Gravel which is usually Late Cretaceous-Pliocene rocks stable in steep natural or artificial cuts. Loess is widespread in the east of the map area and, on older terraces and in The Late Cretaceous to Pliocene rocks vary considerably gullies, may form deposits up to several metres thick. Loess in lithology and although some of the older sandstones has a relatively high internal strength but on hillsides it is have characteristics similar to Torlesse greywackes, most prone to tunnel gully erosion. Landslide deposits are are less indurated or are only weakly cemented. As a generally composed of incompetent materials, contain consequence their engineering properties are diverse. numerous failure planes and are extremely weak. Many are While most sandstones and conglomerates are relatively currently active or are only marginally stable (see below). hard, fine-grained lithologies such as siltstone and

Figure 58 Bentonitic mudstone within the relatively weak Waima Formation is prone to slipping, and movement of this landslide north of Kekerengu (known as Blue Slip) periodically closes State Highway 1 and the Main Trunk Railway. The active trace of the Kekerengu Fault lies at the base of the steeper slopes behind.

Photo CN8369/2: D.L. Homer.

54 GEOLOGICAL HAZARDS

Parts of the Kaikoura map area are subject to geological attributed to fault movement and earthquake shaking hazards including landslides, earthquakes, tsunami, and (Eusden & others 2000). Landsliding is widespread in weak coastal erosion. The main hazards are discussed here in mélange rocks and in Cretaceous and Cenozoic rocks, where general terms, but the information presented in this map bedding dips parallel to the slope, or where weak rocks are and text should not be used for detailed natural hazard undercut by the sea or rivers. Examples are the large zonation or assessment of specific sites without additional landslides that dammed the Matakitaki (Fig. 59) and other geotechnical advice. Recording of site-specific natural rivers during the 1929 Murchison earthquake. There are hazard information is the responsibility of local authorities, many failures involving Cenozoic rocks in the Waima River and an awareness of the presence of major hazards, and area. Late Cretaceous to Early Eocene rocks containing their potential for recurrence, is essential for regional and bentonitic clays also tend to be unstable (Fig. 58). In district planning purposes. mountainous terrain, rock falls are relatively widespread and superficial failures involving soil regolith are common Landslides on most steep slopes in the map area.

Slope instability is widespread in the map area in all rock Coastal erosion units underlying sloping ground. Some failures are the result of weak, water-saturated ground, but many are Hard basement rocks form about half of the coastline in earthquake-induced, as demonstrated during the 1888 the Kaikoura map area and coastal erosion is only locally a Hope and 1929 Buller (Murchison) earthquakes. Excluding significant hazard. North and south of Kaikoura township, failures triggered by earthquakes, extensive failures are SH 1 is cut into coastal cliffs or built out into the heads of rare in the Cambrian-Early Cretaceous rocks northwest of small bays and rip-rap is placed as necessary to mitigate the Alpine Fault. Large, isolated failures occur in Rakaia local marine erosion. Even where more extensive coastal and Pahau rocks southeast of the fault. Prominent, plains (composed of softer terrestrial, aeolian or marine probably earthquake-induced, failures have damned lakes sediments) are present, adjacent headlands of hard rock Constance, Alexander and McRae as well as Lake Matiri tend to stabilise the coast. Between 1942 and 1974, along a northwest of the Alpine Fault. The Hope Fault scarp 30 km stretch of coastline from Oaro to Mangamaunu there between Hanmer and Kaikoura has numerous landslides has been overall net coastal accretion (up to 40 m in places)

Figure 59 The 1929 Buller (Murchison) earthquake triggered widespread landsliding, causing considerable damage and some loss of life. This example originated from east-dipping Mangles Formation on the west bank of the Matakitaki valley, and slid over 1 km to demolish an occupied farmhouse and temporarily dam and divert the river. Photo CN46447/21: D.L. Homer.

55 but locally up to 15 m of land lost because of coastal erosion is generally determined where faults displace Late (Gibb 1978). The effects of coastal erosion, and short-term Quaternary surfaces and deposits, particularly those of phenomena such as storm and tsunami surges, can be alluvial terraces and fans (Q1a, Q2a). Activity may only be mitigated by ensuring new housing and other structures evident at a single locality along a fault but for mapping are set back a prudent distance from the coast. Provision purposes the fault activity has been extrapolated (or should be made for a potential rise in sea level in response interpolated where there are multiple localities) along strike. to global warming. A rise in sea level is likely to initiate An active fold has been mapped near Ward where Late increased coastal erosion and increase the risk of marine Quaternary surfaces are measurably tilted. The basin and flooding of very low-lying areas inland of beach ridges or range topography in northern Canterbury is in part due to dunes. ongoing active folding (Litchfield & others 2003).

Earthquake hazards Since written records of earthquakes have been kept in New Zealand (from about 1840), eight shallow magnitude The Kaikoura map area is situated within a region of high 6.0 or greater earthquakes have originated within the seismicity (earthquake activity) as historical records Kaikoura map area. Two of these earthquakes, the 1848 indicate (Figs 3, 60). Large shallow earthquakes, in Marlborough and 1888 North Canterbury earthquakes, had particular, commonly result in surface rupture and the magnitudes over 7.0. They both caused moderate to strong numerous active faults in the Kaikoura map area are shaking over a large part of the Kaikoura map and were testament to the relatively high frequency of large and associated with significant, clearly identifiable surface fault shallow earthquakes in the region (Table 1). ruptures. Historical documents record that in the 1848 M7.5 Marlborough earthquake, rupture occurred along more Offshore faults include the Needles, Campbell Bank and than 105 km of the Awatere Fault, from the coast to at least Boo Boo faults and the Chancet and North Mernoo fault as far as Barefell Pass (Grapes & others 1998). Shaking zones. Many more unnamed faults have been mapped intensities of MM9, possibly MM10, were experienced in onshore and offshore. Active faults by definition have the Wairau and Awatere valleys where most buildings had demonstrable displacement in the last 125 000 years, (predominantly cob structures) were extensively damaged or two or more movements in the last 500 000 years. Activity or destroyed. There were many instances of ground

172 E° 173 E° 174 E° 175 E°

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ 1855 Wairarapa 1888 ^ ^ ^ ^

1929 Buller 1968 Inangahua ^ 1991 Hawks LT 1977 Cape Campbell Crag AU 1848 FAULT FAULTF Marlborough

ALPINE FAULT AWATERE 42 S° FAULT 42 S° 1913 Westport

1990 Lake CLARENCE FAULT Tennyson 1960 ^Acheron River

FAULT N HOPE FAULT

1948 Waiau 1888 North Canterbury

1929 1951 Cheviot Magnitude Arthur’s Pass 1965 Chatham Rise Shallow Deep 1995 (<40km) (>40km) Cass 1901 Cheviot 4-5 43 S° 5-6 ^ 43 S° 1994 1922 Motunau Arthur’s Pass 100 km 6-7 ^ 1946 Lake Coleridge >7

172°E 173 E° 174 E° 175 E°

Figure 60 Major historic earthquakes within and adjacent to the Kaikoura map area.

56 The Modified Mercalli Intensity scale (MM) (in part; summarised from Downes 1995) MM 2: Felt by persons at rest, on upper floors or favourably placed. MM 3: Felt indoors; hanging objects may swing, vibration similar to passing of light trucks. MM 4: Generally noticed indoors but not outside. Light sleepers may be awakened. Vibration may be likened to passing of heavy traffic. Doors and windows rattle. Walls and frames of buildings may be heard to creak. MM 5: Generally felt outside, and by almost everyone indoors. Most sleepers awakened. A few people alarmed. Some glassware and crockery may be broken. Open doors may swing. MM 6: Felt by all. People and animals alarmed. Many run outside. Objects fall from shelves. Glassware and crockery broken. Unstable furniture overturned. Slight damage to some types of buildings. A few cases of chimney damage. Loose material may be dislodged from sloping ground. MM 7: General alarm. Furniture moves on smooth floors. Unreinforced stone and brick walls crack. Some pre- earthquake code buildings damaged. Roof tiles may be dislodged. Many domestic chimneys broken. Small slides such as falls of sand and gravel banks. Some fine cracks appear in sloping ground. A few instances of liquefaction. MM 8: Alarm may approach panic. Steering of cars greatly affected. Some serious damage to pre-earthquake code masonry buildings. Most unreinforced domestic chimneys damaged, many brought down. Monuments and elevated tanks twisted or brought down. Some post-1980 brick veneer dwellings damaged. Houses not secured to foundations may move. Cracks appear on steep slopes and in wet ground. Slides in roadside cuttings and unsupported excavations. Small earthquake fountains and other instances of liquefaction. MM 9: Very poor quality unreinforced masonry destroyed. Pre-earthquake code masonry buildings heavily damaged, some collapsing. Damage or distortion to some post-1980 buildings and bridges. Houses not secured to foundations shifted off. Brick veneers fall and expose framing. Conspicuous cracking of flat and sloping ground. General landsliding on steep slopes. Liquefaction effects intensified, with large earthquake fountains and sand craters. MM 10: Most unreinforced masonry structure destroyed. Many pre-earthquake code buildings destroyed. Many pre-1980 buildings and bridges seriously damaged. Many post-1980 buildings and bridges moderately damaged or permanently distorted. Widespread cracking of flat and sloping ground. Widespread and severe landsliding on sloping ground. Widespread and severe liquefaction effects.

Table 1. Rupture event displacement, slip rate, last rupture, recurrence interval and likely magnitude of significant active faults and associated earthquakes in the Kaikoura map area (after Pettinga & others 2001; Yetton 2002; Fraser & others 2006).

Average Last rupture Recurrence Magnitude Fault name (segment) displacement Slip rate(s) mm/yr (years before interval (years) (Mw) per rupture present) (m) Waimea Fault - 0.2 - - 7.1 – 7.5 Alpine (Wairau) Fault 7 4 - 5 >1000 1000 - 2300 7.3 – 7.7 Alpine Fault (Haupiri-Tophouse) 3 2.4 - 12 1600 - 1670 500 7.1 – 7.5 Awatere Fault (northern) 5.5 - 7.5 7.7 158 690 - 1500 7.5 Awatere Fault (southern) - 8 522 - 597 1900 - 4000 7.5 Clarence Fault (northern) ~7 4 - 7 - 1500 7.7 Clarence Fault (southern) 7 4 - 8 - 1080 - Kekerengu Fault 5.5 5 - 10 - 730 7.2 Jordan Thrust 2 - 4 1.3 - 2.5 (vertical), - 1200 7.1 0 - 3.4 (horizontal) Hope Fault (Conway-offshore) - 11 - 35 168 120 - 300 7.6 Hope Fault (1888 rupture) 1.5 - 2.6 14 ± 3 100 120 7.2 Hanmer Fault 1 - 3 1-2 <10000 1000 6.9 Kakapo Fault - 4.4 - 8.4 <10000 500 7.3 Esk Fault - - - 5000 - 10000 7.0 Hundalee Fault 1 - 2 0.4 - 1.5 <10000 800 - 5000 7.0 Kaiwara Fault - 0.5 <10000 2000 - 5000 7.1 Omihi Fault - 1 <10000 - 6.7 Balmoral Fault 2 - 6 1 - 2 1495 - 1925 5000 - 10000 -

57 Figure 61

(a) The Hope Fault at Glynn Wye ruptured in 1888 and evidence from offset moraines indicates that lateral movements of 1.5 to 2.6 m have occurred approximately every 120 years on average. The Hope Fault here (centre) tracks towards Hanmer Basin (top centre). Photo CN3602/26: D.L. Homer.

(b) Geologist Alexander McKay visited the Hope Fault at Glynn Wye soon after it ruptured, noting the dextral displacement marked by the 2.4 m offset of this fence. His inference that faults could have significant and repeated lateral movement was an idea that was not supported by the wider geological community until many decades later. Photo: A. McKay.

damage including landslides, ground cracking, liquefaction area (D.J. Dowrick, unpublished data.). The 1948 M6.4 and differential settlement (Eiby 1980; Grapes & others Waiau earthquake caused minor structural damage, 1998). Ground damage may have occurred as far south as principally in and between the settlements of Hanmer and northern Canterbury. The 1848 earthquake also caused Waiau (Downes 1995). considerable damage in the then lightly populated town of Wellington. Parts of the Kaikoura map area have also been subjected to strong shaking from large earthquakes whose epicentres Forty years later, the Kaikoura map area was strongly lie outside the area. The 1855 M8.1 Wairarapa earthquake shaken by the 1888 M7.0–7.3 North Canterbury earthquake, that ruptured the Wairarapa Fault in the southern North which ruptured a 30 ± 5 km segment of the Hope Fault west Island (Grapes & Downes 1997) caused subsidence in the of Hanmer Springs. Up to 2.6 m horizontal displacement on lower Wairau valley. Intensities of MM5 and above were the fault was recorded at the time (Fig 61a,b). Many cob experienced over a large part of the Kaikoura map area and and stone buildings were badly damaged or destroyed the maximum intensity of MM8, possibly MM9, occurred (MM9) in the Hope valley and on the Hanmer Plain in a from the lower Awatere valley to Kekerengu and Cape relatively narrow zone parallel to the fault (Cowan 1991). Campbell. Damage to household contents (MM6) extended as far as Kaikoura and the West Coast. Landslides and ground The 1929 M7.0 Arthur’s Pass and 1929 M7.7 Buller damage occurred in the highest intensity areas. Other earthquakes ruptured the Poulter Fault (Berryman & damaging earthquakes centred in the Kaikoura map area Villamor 2004) and the White Creek Fault (Fyfe 1929) include the 1901 M6.9 Cheviot earthquake which caused respectively. Both these earthquakes occurred in sparsely considerable damage to buildings in the Cheviot area, with populated areas outside the Kaikoura map area. intensities of MM8–9 occurring along a 30–40 km strip Nevertheless, the Buller earthquake was responsible for from Domett to Conway Flat (D.J. Dowrick, unpublished 15 deaths, the majority of which were caused by landslides data). The 1922 M6.4 Motunau earthquake, on the (Henderson 1937). A large part of the Kaikoura map area afternoon of Christmas Day, brought down large numbers was shaken with intensities of MM6 or more. Northwestern of chimneys from Cheviot to Rangiora (Downes 1995), parts of the area experienced intensities of MM8, resulting reaching a maximum intensity of MM8 in the Motunau in considerable structural and environmental damage and 58 Table 2. Mean return periods for earthquake shaking intensity for the towns of Murchison, Hanmer Springs, Culverden and Kaikoura, derived from unpublished data of W.D. Smith using the seismicity model of Stirling & others (2002).

Mean return period (years) Intensity Murchison Hanmer Culverden Kaikoura Springs MM6 or greater 8 8 9 9

MM7 or greater 34 21 25 35

MM8 or greater 230 53 100 120

MM9 or greater 2400 170 1000 410

extensive landsliding (Hancox & others 2002). The 1968 Tsunami M7.1 Inangahua earthquake was less extensive in its strong ground shaking effects, and the maximum intensity in the Coastal flooding and damage caused by tsunami are Kaikoura map area was probably MM7 (Downes 1995). possible along the entire coastline of the map area as well as the lower reaches of rivers. The coastal town of Kaikoura A re-evaluation of seismic hazard in New Zealand by and adjacent coastal communities are at risk. Large tsunami Stirling & others (2001, 2002) uses models of the likely of more than 4 m are life-threatening, and can be very ground acceleration at any one place, based on historical damaging to structures. Even small tsunami can cause earthquakes and the Late Quaternary geological and active erosion and create problems - for example, the strong faulting record. The highest levels of Peak Ground currents generated affect boats at anchor. The impact of a Acceleration (PGA) in the map area, corresponding to the tsunami depends on the size of the energy source and its most severe shaking and damage, are predicted along the distance from the coastline, the propagation path of the western Hope Fault. The mean return periods for specific tsunami and the morphology of the coast and the adjoining intensity levels of earthquake-induced ground shaking seabed. It is difficult to predict the impact accurately. vary significantly across the area, the return period decreasing (i.e. earthquakes occurring more frequently) In historical times the coastline has not been strongly towards the Hope Fault (Table 2). affected by tsunami generated by earthquakes at distant locations, such as South America. Locally generated The consequences of a large, shallow earthquake in or tsunami, potentially caused by near-shore fault rupture or adjacent to the Kaikoura map area will be strong ground submarine landsliding, pose a greater threat. The tsunami shaking, multiple aftershocks, shaking-induced slope caused by the 1855 M8.1 Wairarapa earthquake is the instability, and possible surface fault rupture. Fault rupture largest known local source tsunami to have occurred is known to have occurred within the last 500 years on the historically in the Kaikoura map area. The tsunami was Hope and Awatere faults (Table 1; Fig 61). The recurrence observed throughout Cook Strait area and along the Kapiti interval on individual faults in the Kaikoura map area is and northeastern Marlborough coasts (Grapes & Downes between 120 and many tens of thousands of years. 1997). Near the Clarence River mouth, the tsunami inundated parts of the coastline to several tens of metres inland and During an earthquake the felt ground shaking intensities deposited boats above high-tide mark. Submarine will vary considerably depending on ground surface slumping, particularly into the Kaikoura Canyon, has the conditions and on distance from the focus of the potential to generate a large tsunami that would arrive earthquake. Unconsolidated water-saturated sediments, onshore with minimal or no warning. such as swamp deposits, estuarine mud, marine sand and gravel, and landfill, will amplify shaking compared with Locally generated tsunami are a cause for concern as wave hard competent basement rocks nearby. The towns of heights may be large enough to be damaging and life- Murchison, Hanmer Springs and Culverden are built on threatening, possibly catastrophic, and travel times are young Quaternary deposits, and it is likely that parts of generally too short for Civil Defence warnings. The public these urban areas will show some shaking amplification, should treat strong earthquake shaking as a signal to leave as Murchison did in the 1929 earthquake (Suggate & Wood coastal locations and move inland. Similarly unusual 1979). Surface rupture along a fault could result in ground changes in sea behaviour (sudden rise or withdrawal), displacements of several metres both horizontally and possibly accompanied by roaring from the sea, could also vertically. Such offsets would disrupt all services, such as signal the imminent arrival of a tsunami and the coastal roads, railways, water, and power and telephone cables. area should be evacuated.

59 ACKNOWLEDGMENTS

were prepared by P. Carthew, M.S. Rattenbury and D.B. This map was compiled by M.S. Rattenbury (part or all of Townsend. Parts or all of the map and text were reviewed NZMS 260 sheets M30, M31, M32, M33, N31), M.R. by G.H. Browne, J.S. Crampton, S.W. Edbrooke, B.D. Field, Johnston (M29, N29, N30, O29, P29, Q29) and D.B. P.J. Forsyth, C.J. Hollis, M.G. Laird, N.J. Litchfield, T.A. Townsend (M33, N32, N33, O30, O31, O32, O33, P30, P31), Little, and I.M. Turnbull. The map and text were edited by with significant contributions from C. Mazengarb (N31, P.J. Forsyth and D.W. Heron. Text layout was by P.L. O31) and M.J. Isaac (O30). Major sources of contributing Murray. M.J. Isaac checked proofs of the map and text. information were geological maps at 1:50 000, by Suggate (1984), Challis & others (1994), Johnston (1990), Reay (1993) R. Solomon of Te Runanga o Kaikoura provided the and Warren (1995). Additional data came from published historical information for the front cover and frontispiece papers, reports, bulletins, and unpublished material from photographs. the files of GNS Science, mineral exploration company reports and university theses. Funding for the QMAP: Geological Map of New Zealand project was provided by the Foundation for Research, Fieldwork during 2000–2004 concentrated on visiting Science & Technology under contract C05X0401. selected key areas and filling gaps in knowledge, especially in the greywacke rocks. Fieldwork was undertaken with The base map is sourced from Land Information New considerable assistance from B. Allan, J.G. Begg, R. Zealand. Crown copyright reserved. Jongens, J.M. Lee, B. May, T. Nash, G.A. Partington, J. H. Rattenbury. P. Sprung, D. Thomas, and I.M. Turnbull.

Aerial photograph interpretation of landslides by T.P Coote, G.D. Dellow and S.A.L. Read was compiled from the Landslide Map of New Zealand project. The offshore geology has been compiled from Field, Browne & others (1989), Field, Uruski & others (1997) and unpublished and some published data of P.M. Barnes and co-authors listed in the references. We thank the National Institute of Water AVAILABILITY OF QMAP DATA and Atmospheric Research for permission to reproduce offshore bathymetry, faults and folds from their digital records. The geological map accompanying this book is derived from information stored in the QMAP geographic The co-operation of geology department heads from information system (GIS) database maintained by GNS Victoria, Canterbury and Otago universities in allowing Science and from other GIS-compatible digital databases. access to student theses is gratefully acknowledged. The data shown on the map are a subset of the available Geological map data have been sourced from the following information. Customised single-factor and multifactor maps university theses; Adamson (1966), Allen (1962), Audru can be generated from the GIS and integrated with other (1996), Botsford (1983), Challis (1960), Clegg (2001), Cowan data sets to produce, for example, maps showing fossil or (1989), Cutten (1976), Grapes (1972), Hall (1964), Harker mineral localities in relation to specific rock types, or maps (1989), Hill (1998), Jones (1995), Kirker (1989), Kundycki showing rock types in relation to the road network. Data (1996), Lihou (1991), Lowry (1995), McLean (1986), can be presented for user-defined specific areas, for Melhuish (1988), Montague (1981), Nicol (1977), Powell irregular areas such as local authority territories, or in the (1985), Prebble (1976), Ritchie (1986), Robertson (1989), form of strip maps showing information within a specified Rose (1986), Slater (2001), Smith (2001), Stewart (1974), distance of linear features such as roads or the coastline. Stone (2001), Townsend (1996, 2001), Vickery (1994), Waters The information can be made available at any required (1988), and Worley (1995). The North Canterbury GIS scale, bearing in mind the scale of data capture and the compiled by Pettinga & Campbell (2003) contains data from generalisation involved in digitising. Maps produced at a University of Canterbury student theses including scale greater than 1:50 000 will generally not show accurate, Litchfield (1995), Mould (1992), Nicol (1991), and infill detailed geological information. The QMAP series maps mapping by A.M. Wandres. are available in GIS vector and raster digital form using standard data interchange formats. Development and maintenance of the GIS database were by D.W. Heron and M.S. Rattenbury, with digital capture For new or additional information, for prints of this map at and map production by J. Arnst, T. Browne, B. Carthew, other scales, for selected data or combinations of data D.W. Heron, B. Lukovic, M. Persaud, J.H. Rattenbury, P. sets or for derivative or single-factor maps based on QMAP Sprung, S. Tille and D.B. Townsend. Map design and digital data, please contact: cartography were by D.W. Heron and M.S. Rattenbury. QMAP Leader The text was written by M.S. Rattenbury, D.B. Townsend GNS Science and M.R. Johnston with considerable input to the P. O. Box 30 368 geological hazards section from G.L. Downes. The diagrams Lower Hutt 60 REFERENCES

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62 Childerhouse, S.J.; Dawson, S.M.; Slooten, E. 1995: Abundance Crampton, J.S.; Laird, M.; Nicol, A.; Hollis, C.J.; Van Dissen, and seasonal residence of sperm whales at Kaikoura, New R.J. 1998: Geology at the northern end of the Clarence Valley, Zealand. Canadian Journal of Zoology 73: 723-731. Marlborough; a complete record spanning the Rangitata to Kaikoura orogenies. In Laird, M. ed. Geological Society of Christie, A.B. 1989: Computerised minerals bibliography users New Zealand, New Zealand Geophysical Society 1998 Joint guide. New Zealand Geological Survey Report M 161. 48 p. Annual Conference, 30 November - 3 December: field trip guides. Clayton, L. 1968: Late Pleistocene glaciations of the Waiau Geological Society of New Zealand miscellaneous publication Valleys, north Canterbury. New Zealand Journal of Geology 101B: 35 p. and Geophysics 11: 753-767. 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70 This map and text illustrate the geology of the Kaikoura area, extending east from Murchison to southern Marlborough, and south to Waikari in north Canterbury. Onshore geology is mapped at a scale of 1:250 000 while offshore the bathymetry, thick Quaternary sedimentary deposits and major structural elements are shown. Geological information has been obtained from published and unpublished mapping and research by GNS Science geologists, from work by staff and students of the University of Canterbury, Victoria University of Wellington and the University of Otago, from offshore mapping by the National Institute of Water and Atmosphere, and from mineral exploration reports. All data are held in a geographic information system and are available in digital format on request. The accompanying text summarises the geology and tectonic development, as well as the geological hazards and the economic and engineering geology of the map area. The map is part of a series initiated in 1996 which will cover the whole of New Zealand.

The map area is mostly underlain by Mesozoic greywacke rocks of the Torlesse terrane, except in the northwest where narrow fault-bounded remnants of the Buller, Takaka, Brook Street, Murihiku, Dun Mountain-Maitai and Caples terranes occur, as well as the Median Batholith and other granitic rocks. Discontinuously preserved late Early Cretaceous to Pliocene, predominantly marine sedimentary and volcanogenic rocks occur in the northwest, the east and the south of the map area. Quaternary terrestrial sediments are widespread on land, including till, loess, scree, landslide, alluvial fan and alluvial terrace deposits. Numerous active faults of the Marlborough Fault System transect the map area, marking the plate boundary zone between the Pacific and Australian tectonic plates. Several of these faults have moved in historic times contributing to the region's relatively high seismic hazard.

The highest point of the Inland Kaikoura Range is Mt Tapuae-o-Uenuku(2885 m) where the summit region is composed of erosion-resistant Cretaceous mafic igneous intrusive rocks and associated hornfelsed Pahau terrane greywacke. The active Clarence Fault separates the Inland Kaikoura Range from the distinctive Chalk Range in the middle distance, and the white screes there and in the foreground emanate from Paleogene carbonate rocks. Photo: D.B. Townsend

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