Geology of the Murihiku Area

20 Geology of the Murihiku Area

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

I. M. Turnbull A. H. Allibone (compilers) BIBLIOGRAPHIC REFERENCE Turnbull, I.M.; Allibone, A.H. (compilers) 2003: Geology of the Murihiku area. Institute of Geological & Nuclear Sciences 1:250 000 geological map 20. 1 sheet and 74 p. Lower Hutt, New Zealand. Institute of Geological & Nuclear Sciences Limited.

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 0-478-09800-6

FRONT COVER

The most prominent geological feature in the Murihiku area is the Southland Syncline. The north limb, seen here looking southeast from south of Lumsden, is outlined by prominent strike ridges trending away through the Hokonui Hills. The axis of the syncline lies to the south (right) and passes under the area of cloud in the far distance. The syncline is formed in Permian to Jurassic Murihiku Supergroup sedimentary rocks, with these strike ridges in Early to Middle Triassic North Range Group. The active Hillfoot Fault separates the Hokonui Hills from the extensive Quaternary gravels of the Waimea Plains (left), underlain by Permian Maitai Group sedimentary rocks.

Photo CN43841/16: D.L. Homer ii CONTENTS

ABSTRACT ...... v QUATERNARY ...... 41 Early Quaternary deposits ...... 41 Keywords ...... v Middle Quaternary deposits ...... 41 INTRODUCTION ...... 1 Late Quaternary deposits ...... 42 OFFSHORE GEOLOGY ...... 46 THE QMAP SERIES ...... 1 The Geographic Information System ...... 1 TECTONIC HISTORY ...... 48 Data sources ...... 1 Eastern and Western provinces ...... 48 Reliability ...... 1 Mesozoic deformation within the Median Batholith .... 49 REGIONAL SETTING ...... 2 Late Cretaceous tectonics...... 49 Cenozoic tectonics and basin development...... 49 GEOMORPHOLOGY ...... 6 Quaternary tectonics ...... 50 Northern ranges and basins...... 6 Southland Syncline ...... 7 ENGINEERING GEOLOGY ...... 51 Te Anau and Waiau basins ...... 7 Paleozoic to Mesozoic rocks ...... 51 Southland and Waimea Plains...... 12 Late Cretaceous and Tertiary sedimentary rocks ...... 51 Takitimu Mountains and Longwood Range...... 12 Quaternary sediments ...... 51 Stewart Island ...... 12 Offshore physiography ...... 12 GEOLOGICAL RESOURCES ...... 52 STRATIGRAPHY ...... 14 METALLIC RESOURCES ...... 52 Hard-rock gold mineralisation ...... 52 SILURIAN TO DEVONIAN ...... 14 Alluvial gold ...... 52 Takaka terrane ...... 14 Silicon and ferrosilicon ...... 52 CARBONIFEROUS TO CRETACEOUS ...... 14 Other metallic minerals ...... 53 The Median Batholith ...... 14 NON-METALLIC RESOURCES ...... 54 Median Batholith from Longwood Range Coal ...... 54 to Ruapuke ...... 14 Peat ...... 55 Permian Brook Street terrane intrusives within the Hydrocarbons ...... 55 Median Batholith ...... 16 Aggregate ...... 55 Triassic- Jurassic intrusives ...... 16 Limestone ...... 56 Median Batholith on Stewart Island ...... 19 Silica sand ...... 56 Carboniferous ...... 19 Serpentinite ...... 56 Middle Jurassic ...... 19 Clay ...... 56 Late Jurassic to earliest Cretaceous ...... 19 Building stone and riprap ...... 56 Early Cretaceous ...... 22 Groundwater ...... 56 Plutonic rocks of Fiordland and offshore islands ...... 22 GEOLOGICAL HAZARDS ...... 57 PERMIAN TO JURASSIC ...... 23 Brook Street terrane ...... 23 Earthquakes (by G. L. Downes) ...... 57 Unassigned mélange units ...... 26 Tsunami (by G. L. Downes) ...... 60 Murihiku terrane...... 26 Landslides...... 60 Willsher Group ...... 28 Volcanic hazard ...... 62 Dun Mountain-Maitai terrane ...... 29 Subsidence due to mining...... 62 Caples terrane ...... 31 Groundwater contamination...... 62 Paterson Group ...... 33 AVAILABILITY OF QMAP DATA ...... 63 CRETACEOUS SEDIMENTARY ROCKS ...... 34 ACKNOWLEDGMENTS ...... 63 EOCENE TO PLIOCENE ...... 35 Eocene non-marine sedimentary rocks ...... 35 REFERENCES ...... 64 Oligocene to Pliocene sedimentary rocks ...... 36 Te Anau and Waiau basins (Waiau Group) ...... 36 APPENDIX 1 Winton Basin and Southland shelf ...... 36 Late Miocene to Pliocene non-marine sediments ...... 39 Nomenclature of units mapped on Stewart Island ...... 72

iii Te Puka o Taakitimu - Monkey Island

This rocky knob near Orepuki, which becomes an island at high tide, has significance to Maaori as Te Puka o Taakitimu – the anchor stone of the legendary Taakitimu waka/canoe which was wrecked in Te Waewae Bay. It is said that the waka was turned to stone as the Taakitimu Mountains, and the bailer of Taakitimu became the Hokonui Hills.

iv ABSTRACT

The Murihiku 1:250 000 geological map covers 18 000 km2 Except on Stewart Island, these basement terranes are of south Otago and Southland, in the South Island of New overlain by discontinuously preserved Cretaceous and Zealand, and includes Stewart Island (Rakiura). more extensive Eocene and younger sedimentary rocks of Topography varies from flat-topped ranges and intervening the Ohai, Nightcaps, Waiau and East Southland groups. basins in northern Southland, to prominent strike ridge The contact is the widespread Late Cretaceous to Cenozoic topography of the Kaihiku, Hokonui, and North ranges, Waipounamu Erosion Surface in northern Southland. The the jagged Takitimu Mountains, the lower bushclad fault-controlled Cenozoic Waiau Basin contains up to 5 Longwood and Twinlaw massifs, and the extensive km of marine and non-marine clastic sedimentary rocks; Southland Plains. Stewart Island has generally subdued coeval but much thinner shelf sedimentary rocks, typically bush and scrub-covered topography, with rolling hills and limestones, extend beneath the Winton and Eastern the swampy Freshwater Depression in the centre. Southland basins and the Waimea Plains. Numerous other offshore islands dot the shallow waters of Foveaux Strait and the fringes of Stewart Island. The Quaternary glaciation in Fiordland and northern Southland Waiau Basin lies in the far southwest, on the eastern edge produced large volumes of gravel which accumulated in of Fiordland. the Waimea and Southland Plains, the latter also influenced by marine sedimentation during interglacial high sea levels. The map area covers a wide range of Paleozoic to Mesozoic Cirque glaciation affected the Takitimu and probably rocks which form parts of several tectonostratigraphic Longwood ranges, and glaciers also formed on Mt Anglem terranes. The Paleozoic to Cretaceous Median Batholith and Mt Allen on Stewart Island. comprises gabbroic to granitic plutonic rocks that intrude metamorphic rocks of the Takaka terrane on Stewart Island In northern Southland, at Gore and at Orepuki, Quaternary and the Permian oceanic volcanic island arc sequence of deposits (including beach placers at Orepuki) have the Brook Street terrane in the Takitimu and Longwood produced at least 8000 kg of alluvial gold. Lode systems ranges, and at Bluff. are preserved in the volcanic rocks around the Longwood Range but few have been mined. Platinum group metals Late Permian to Jurassic Murihiku terrane sedimentary rocks have been mined and prospected for in the Longwood separate Brook Street and Dun Mountain-Maitai terranes Range. Non-metallic minerals include limestone, sub- and underlie most of the map area, thrust over Brook Street bituminous coal at Ohai, and large reserves of lignite in the terrane in the west and faulted against Dun Mountain - East Southland Group. Maitai terrane along the northeastern limb of the regional Southland Syncline. The Dun Mountain-Maitai terrane is The Murihiku map area is subject to seismic hazard from in turn faulted against the Caples terrane in the the Alpine Fault west of Fiordland, and active faults in northeastern corner of the map area. Dun Mountain - Maitai Central Otago and Western Southland, with associated terrane rocks represent an Early Permian ophiolite complex, earthquake shaking, landsliding, ground rupture, overlain by metasediments of Permian to Triassic age. The liquefaction and delta collapse. Landslides and rockfalls, Caples terrane is probably of Permian to Triassic age in the both during and independent of major rainstorms, are minor map area. but ongoing hazards. Tsunami, mine collapse and flooding are more localised hazards.

Keywords

Murihiku; Southland; Stewart Island; Invercargill; Foveaux Strait; 1:250 000 geological map; geographic information systems; digital data; bathymetry; Brook Street terrane; Caples terrane; Dun Mountain - Maitai terrane; Murihiku terrane; Takaka terrane; Median Batholith; plutons; Pegasus Group; Paterson Group; Caples Group; Maitai Group; Willsher Group; Dun Mountain Ultramafics Group; Livingstone Volcanics Group; Dun Mountain Ophiolite Belt; Brook Street Volcanics Group; Takitimu Subgroup; Productus Creek Group; Barretts Formation; Greenhills Group; Greenhills Ultramafic Complex; Bluff Intrusives; Pahia Intrusives; Holly Burn Intrusives; Tin Hut mélange; Letham Ridge mélange; Murihiku Supergroup; Kuriwao Group; North Range Group; Taringatura Group; Diamond Peak Group; Ferndale Group; Mataura Group; Park Volcanics Group; Ohai Group; Nightcaps Group; Waiau Group; Clifden Subgroup; East Southland Group; Forest Hill Formation; marine terraces; alluvial terraces; alluvial fans; moraines; till; outwash; landslides; peat swamps; sand dunes; oysters; Livingstone Fault; Hauroko Fault; Blackmount Fault; Tin Hut Fault System; Letham Ridge Thrust; Gutter Shear Zone; Hillfoot Fault; Escarpment Fault; Freshwater Fault System; Southland Syncline; Taieri - Wakatipu Synform; Quaternary tectonics; active faulting; economic geology; alluvial gold; platinum; sub-bituminous coal; lignite; Ohai Coalfield; Eastern Southland Coalfield; peat; limestone; groundwater; hydrocarbons; engineering geology; landslides; regolith; natural hazards; seismotectonic hazard; volcanic eruptions; new stratigraphic names. v 170° E 175° E

New Caledonia Basin

35° S Kaitaia 35° S 2000 m Whangarei 2000 m

Auckland

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

40° S 40° S

Australian rough Plate Nelson Wellington Wairarapa

2000 m Hikurangi T Greymouth Kaikoura 41 mm/yr Pacific Plate

Alpine Fault38 mm/yr Haast Christchurch Aoraki Chatham Rise

S Wakatipu Waitaki 45° S 45° S Fiordland

Bounty mm/yr 37 mm/yr Dunedin Trough

2000 m 0 100 200 QMAP Campbell Plateau Kilometres Puysegur Trench 165° EE Murihiku 170° E 175° E 180° E

Figure 1 Regional tectonic setting of New Zealand, showing the location of the Murihiku geological map and other QMAP sheets, major offshore features (as illustrated by the 2000 m isobath) and active faults. The Murihiku sheet lies on the Pacific Plate, east of the Alpine Fault which marks the Australian-Pacific plate boundary west of Fiordland. The relative rates and directions of plate movements are shown by the arrows.

Adapted from Anderson & Webb (1994).

vi INTRODUCTION

THE QMAP SERIES information. The maps are drawn from data stored in the QMAP Geographic Information System (GIS), a database This map is one of a national series known as QMAP built and maintained by the Institute of Geological and (Quarter-million MAP; Nathan 1993; Fig. 1), and Nuclear Sciences (GNS). The primary software used is supersedes the previous 1:250 000 geological maps of the ARC/INFO®. The QMAP database is complementary to Murihiku area which were published in the 1960s (Wood other digital data sets maintained by GNS, e.g. gravity and 1966; McKellar 1966; Watters et al. 1968). Since then, magnetic surveys, mineral resources and localities, fossil Stewart Island has been mapped in detail for the first time localities, active faults and petrological samples. (see Appendix 1), and there have been numerous detailed Background topographic data were purchased from Land onshore and offshore geological and geophysical studies Information New Zealand. of parts of the area by government, university and industry geologists. The need for geological information has The QMAP series is based on detailed geological increased as a result of the Resource Management Act, information, plotted at 1:50 000 scale on NZMS 260 series demands for geological resources, a new educational topographic base maps. These record sheets are available curriculum, and greater awareness of natural hazards and for consultation at GNS offices in Lower Hutt and Dunedin. their mitigation. In the Murihiku area, changes in land use The detailed geology has been simplified for digitising, have expanded the demand for geological information, with linework smoothed and geological units amalgamated especially on groundwater. The increase in environment- to a standard national system based on age and lithology. focused tourism, boosted by the creation of Rakiura Point data (e.g. dips and strikes) have not been simplified. National Park, has also resulted in a demand for more All point data are stored in the GIS, but only representative detailed information on local geology. structural observations are shown. The procedures for map compilation and data storage and manipulation are The geology shown on the map has been generalised for given by Rattenbury & Heron (1997). presentation at 1:250 000 scale. Rock types are shown primarily in terms of their age of deposition, eruption or Data sources intrusion. The colour of the units on the map face thus reflects their age, with overprints used to differentiate some This geological map includes data from many sources, lithologies. Letter symbols (in upper case, with a lower including published geological maps and papers, case prefix to indicate early, middle or late if appropriate) unpublished data from University theses, unpublished indicate the predominant age of the unit. Metamorphic GNS technical and map files, mining company reports, field rocks are mapped in terms of age of the parent rock (where trip guides, the New Zealand Fossil Record File (FRED), known), with overprints reflecting the degree of and GNS digital databases of geological resources and metamorphism and deformation. The last lower case letter petrological samples (GERM, PET). Field mapping of poorly (or letters) indicates either a formal lithostratigraphic unit known areas, undertaken between 1999 and 2001, ensured or the predominant lithology. A time scale showing the a more even data coverage over the map area. Landslides correlation between international and local time scales, and were mapped from air photos, with limited field checking. ages in millions of years (Ma) or thousands of years (ka) Offshore data were obtained from published and (Cooper 2004), is inside the front cover. unpublished surveys by NIWA, GNS, and the University of Otago Geology Department. Types of data sources used This accompanying text is not an exhaustive description are shown in Fig. 2; data sources used for map compilation or review of the various rock units mapped. Except for are identified by * in the references. some units on Stewart Island, names applied to geological units are those already published; the nomenclature has Reliability not been revised where anomalies are present. For more detailed information on individual rock units, specific areas, This 1:250 000 map is a regional scale map only, and should natural hazards or minerals, see the references cited not be used alone for land use planning, planning or design throughout the text. for engineering projects, earthquake risk assessment, or other work for which detailed site investigations are The Geographic Information System necessary. Some of the data sets which have been incorporated with the geological data (GERM, for example) The QMAP series uses computer methods to store, have been compiled from old or unchecked information of manipulate and present geological and topographical lesser reliability (Christie 1989).

1 1 2 5 48 59 3 6 30 57 4 40 7 8

11 39 14 9 10 12 51 49 13 28 34 29 52 35 31 36 41 32

16 15

54 44 17 53 37 43 18 42 50 58 51

27 26 25 33 38

20 24,47 19

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23 55

21 Student theses 46

Published papers

Published 1:250 000 map sheets

Student theses Published papers 1. Hall 1989 14. Boles 1971 27. Mossman 1970 39. Landis et al. 1999 52. Cawood 1987 2. Kirby 1989 15. Forsyth 1992 28. Morton 1979 40. Coombs 1950 53. Macpherson 1938 3. Pringle 1975 16. Banks 1977 29. Griffin 1970 41. Mortimer et al. 1999a 54. Campbell & Force 1973 4. Scott 1974 17. Rombouts 1994 30. Clough 1987 42. Cahill 1995 55. Bishop & Mildenhall 1994 5. G. Hyden 1979 18. Macfarlane 1973 31. Ryder-Turner 1977 43. Price & Sinton 1978 56. Allibone 1991 6. Meder 1963 19. Waddell 1971 32. Ritchie 1977 44. Willett & Wellman 1940 7. McOnie 1969 20. Allibone 1986 33. Holden 1993 45. Allibone & Allibone 1991 Published 1:250 000 8. Houghton 1977 21. Peden 1988 34. Stenhouse 2002 46. Allibone & Tulloch 1997 map sheets 9. Griffith 1983 22. Frewin 1987 35. Bishop 1962 47. Watters 1978a 57. McKellar 1966 10. Willsman 1990 23. Cook 1984 36. Becker 1973 48. Cawood 1986 58. Watters et al. 1968 11. Begg 1981 24. Webster 1981 37. Simpson 2002 49. McIntosh et al. 1990 59. Wood 1966 12. Gass 1998 25. Graham 1977 38. Bosel 1981 50. Campbell et al. 2001 13. Arafin 1982 26. Elder 1994 51. Coombs et al. 1992

Figure 2 Types of geological data sources used in compiling the Murihiku map. Over 150 sources are represented; details of individual sources can be obtained from the references, where they are indicated by an asterisk.

REGIONAL SETTING of the active Australian-Pacific plate boundary which in southern New Zealand is the Alpine Fault, west of The Murihiku geological map area extends from eastern Fiordland (Fig. 1). The Pacific Plate beneath Murihiku is Fiordland to the Pacific coastline at the Catlins, and south largely composed of fault-bounded terranes of regional across Foveaux Strait to Stewart Island and its offshore extent with different geological histories – the Paleozoic to islands. The area lies entirely within the Pacific Plate, east Mesozoic Takaka, Brook Street, Dun Mountain-Maitai, 2 60 70 76 79 80 98 86 61 99 77 87 81 72 100 77 92 101 106

71 82 73 63 89 65 102 62 87 88 78 83 64 90 103 79 80 97 67 68 87 104 105 91 66 84 87 93 74

94 107 95

96 69

85 71

Other published maps

Reports

Unpublished maps

Other published maps 60. McKellar 1973 71. Isaac & Lindqvist 1990 80. Thomson & Read 1996 89. Mutch 1960 100. Isaac & Lindqvist 1978 61. Mutch 1964 72. Marshall 1918 81. Stewart & Glassey 1993 90. Harrington & Wood 1947 101. McPherson 1973 62. Wood 1969 82. Glassey et al. 1996 91. Mutch 1967 102. Watters 1947a 63. Bowen 1964 Reports 83. Liggett 1979 92. Chandler 1964 103. Watters 1947b 64. Turnbull 1992 73. Patchell 2002 84. Liggett 1972 93. Wood 1965b 104. Speden 1957 65. McKellar 1968 74. Mutch 1976 85. Purdie 1970 94. Bluck 1998 105. Speden 1958 66. Lindqvist 1992 75. Watters 1994 95. Wood & Hitt 1964a 106. McKellar & Mutch 1967 67. Wood 1956 76. Ritchie 1994 Unpublished maps 96. Wood & Hitt 1964b 107. Liggett 1973a 68. McIntosh 1992 77. Beanland & Berryman 1986 86. Carter & Norris 1980 97. Liggett 1973b 69. Speden 1971 78. Mutch 1977 87. Willett 1939 98. Healey 1938 70. Mortimer 1993a 79. Bishop & Macfarlane 1984 88. Willett 1950 99. Wood 1965a

Murihiku and Caples terranes – which were amalgamated Range. The terranes, and the Median Batholith, were along the margin of Gondwana during the Mesozoic overlain by Cretaceous to Cenozoic sedimentary rocks (Fig. 3). During and after terrane amalgamation, Brook which are now thin or absent over much of the map area Street and Takaka terrane rocks were intruded by the but thicker within the Te Anau and Waiau basins. Median Batholith which is represented in the map area by Quaternary deposits are widespread and include the the plutonic rocks of Stewart Island and the Longwood extensive gravels of the Waimea and Southland Plains. 3 SEDIMENTARY ANDD VOLCANIC ROCKS

Northland and Eastst Coast allochthons Morrinsville-Manaiaa Hill-Waioeka assemblageg (Waipa Supergroup)p)

Torlesse composite Eastern terrane (eastern NZ) Hunua-Bay of Islandsndsds terrane Pahau Caples terrane Rakaia P

rovince Dun Mountain - Maitaiaitaiitai terrane ovince Murihiku terrane Brook Street terraneranenee

Province

Western

ovince Takakakaka terrane estern Bullerler terrane

PLUTONICNICIC ROCKSKSS

Medianedian Batholithh Karamea,aramea, Paparoaroaa and Hohonuohonu batholithsthss

METAMORPHICORPHICRPHIC ROCKSOCKSCKSSAND AND TECTONICNICICC OVERPRINTSRPRINTSRINTSINTSTS

EskkHead andWhakatane hakataneakatanekatanene mé langesg

Haastaastst Schist Gneissneissss N

200 km

EFAULT N

ALPI

Murihiku

Figure 3 Pre-Cenozoic basement rocks of New Zealand, subdivided into tectonostratigraphic terranes; the extent of the Northland and East Coast allochthons is also shown. Chrystalls Beach Complex (Coombs et al. 2000) is shown here as part of the Caples terrane. Pale yellow (inset) shows covering Cenozoic sediments.

Adapted from Mortimer 2004 4 TAKITIMU NORTHERN RANGES MOUNTAINS AND BASINS

WAIMEA BASIN TE ANAU SOUTHLAND

PLAINS

MURIHIKU l WAIAU u t ESCARPMENT h

BASIN a O

r R e i

t v

i e r A p SYNCLINE a r i m LONGWOOD r

a R e

R i v

RANGE R v i

e SOUTHLAND u R r a

a PLAINS W

a r

F M o v e a u x S t r a i t

STEWART ISLAND

Figure 4 Shaded topographic relief model of the Murihiku map area, derived from 20 m contour data supplied by Land Information New Zealand, and illuminated from the northeast. North- to northeast-trending ranges and basins in the northeast of the map area are separated from the northwest-trending strike ridges of the Southland Syncline by the Murihiku Escarpment.

5 GEOMORPHOLOGY (McSaveney & Hancox 1996; Turnbull 2000) is present only in the Black Umbrella Range. The Murihiku map area includes several distinct physiographic regions (Fig. 4), which are controlled by The flat surfaces of the ranges, and the downlands beside underlying geology and influenced by erosion and late the Clutha River in the northeast of the map area, are Cenozoic tectonics. inherited from the Cretaceous to Cenozoic Otago Peneplain or Waipounamu Erosion Surface (WES) (LeMasurier & Northern ranges and basins Landis 1996; Youngson & Landis 1997). This broadly planar surface originally extended across much of the South The northern edge of the map sheet, between the Clutha Island and beyond. It has a complex fluvio-marine origin, and Mataura rivers, lies at the southern limit of the Central and is of early to mid Cenozoic age in the map area. The Otago region of tilted fault block ranges separated by fault- surface can be used as a structural marker for determining angle depressions. Ranges up to 1500 m in elevation Late Cenozoic deformation, such as folding and vertical include the Blue Mountains (Fig. 5) and the Black Umbrella fault displacement (Fig. 6). Range (Fig. 6). The ranges generally trend north to northeast, with some trending northwest. Most range front The southern ends of the Mataura, Black Umbrella and faults are Late Cenozoic in age, and the Blue Mountain Blue Mountains ranges are cut by the antecedent gorges No 1 Fault is active (Beanland & Berryman 1986). The fault of the Mataura, Waikaka, and Pomahaka rivers (Fig.7), blocks comprise massive to weakly foliated Caples Group formed during initial uplift of the ranges in Late Pliocene to sandstone and semischist. The blocks become lower Quaternary time. Extensive high terraces lie between these southward as the northeast-trending fault systems die out major valleys, with flights of lower terraces and fans near toward the Murihiku Escarpment. In the map area, large the modern flood plains of these rivers. The upper eastern scale landsliding typical of Central Otago range fronts slopes of the Black Umbrella Range contain small cirques of glacial origin, strongly modified by landsliding.

Figure 5 The Blue Mountains and adjacent Tapanui depression, looking south. The range front fault (Blue Mountain No 1 Fault) has active traces, although none are visible in this picture. The Blue Mountains form one of the southernmost fault blocks in the northeast-trending Otago range and basin province. The Murihiku Escarpment, parallel to the trend of the Southland Syncline, lies in the distance. Photo CN43993/9: D.L.Homer 6 Southland Syncline Te Anau and Waiau basins

The most conspicuous and well-known geomorphic feature The western margin of the Murihiku map area, between within the Murihiku map area is the Southland Syncline Fiordland and the Takitimu Mountains and Longwood (see front cover). Alternating harder sandstone and softer Range, includes parts of the Te Anau and Waiau basins. mudstone have been eroded to form strike ridges, which These depressions have existed since middle Cenozoic define the north limb of the syncline from the Catlins coast time, and are controlled by subsidence along the northeast- northwest through the Kaihiku, Hokonui, North and trending Moonlight Fault System. Both are infilled with Taringatura ranges. The syncline ends abruptly at the Cenozoic sedimentary rocks (Turnbull & Uruski 1993), Murihiku Escarpment, the geomorphic expression of the within which sandstone and limestone units form Hillfoot Fault (Fig. 4). In the Catlins, these strike ridges, prominent strike ridges. The Cenozoic sedimentary rocks crossed by northeast-trending faults, joints and lineaments, are overlain by extensive flights of Quaternary terraces, form a trellised landscape. Strike ridges are a less obvious deposited by the Waiau River draining the former Te Anau- feature of the landscape on the south limb, but form Manapouri piedmont glacier and other Fiordland glaciers. prominent bluffs in the southwestern Hokonui Hills and Moraines are not extensively preserved within these basins the Venlaw Forest, and define subsidiary folds (Fig. 8). in the Murihiku map area. Extensive alluvial fans extend Strike ridge topography is less well-developed on the west from the Takitimu Mountains into the basins. western limb in the foothills of the Takitimu Mountains (Fig. 9).

800 1100 800 700 e 1200 100 1000 900 300 g 600 700 n 800 700 2 a 4 00 600 00 1100 R T 400 500 AI a E 400 l 1000 900 R 300 l I 300 300 700 e -

r W 300 600 b A 400 m 500 500 K 200 600 A 500 U 400 T 300 100 Waikaia k I c P 500

a 500 U l 800 4 300 0

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200 Y Blue Mountains N 200 F 500 O R Mataura River 600 M 100 900 800 L 400 I Tapanui 700 200 V 500 300 IN 600 G 500 400 S TO 200 NE 300 F AU LT 400 100 300 Clutha River 200

200

100 200 Gore

HILLFOOT FAULT

100 Waipounamu Erosion Surface (WES) WES eroded along fault scarps and in gorges 100 WES concealed by Cenozoic sediments

fault fold in foliation contour on WES (100 m interval)

Figure 6 Structure contours on the Waipounamu Erosion Surface (WES), north of the Hillfoot Fault in the eastern part of the Murihiku map area. Major faults and folds in foliation are shown.

7 Figure 7 The Pomahaka River forms an antecedent gorge cutting through the southern Blue Mountains, seen here looking north-northwest. The higher flat-topped surfaces in the middle distance are underlain by Gore Piedmont Gravels of Early Quaternary age. The forested area to the right is underlain by Caples Group rocks, separated from Livingstone Volcanics Group (centre) by the northwest-trending Livingstone Fault (arrowed).

Photo CN43913/10: D.L.Homer

Figure 8 Ridges underlain by steeply dipping Jurassic sandstone and conglomerate strike inland from the Catlins coast near Teahimate Bay, on a subsidiary fold of the southern limb of the Southland Syncline. Gold has been mined from the Teahimate beach sands. Photo CN27259/18: D.L. Homer 8 Figure 9 Looking north along the Takitimu Mountains (left), which rise to 2000 m west of the upper Wairaki valley (foreground). The mountains are formed of resistant Permian Takitimu Subgroup volcanic rocks; less resistant Late Permian Productus Creek Group and Mesozoic Murihiku Supergroup sedimentary rocks form lower and less rugged country. Murihiku Supergroup rocks underlie Mt Hamilton, the isolated peak on the skyline right of centre.

Photo CN43782: D.L. Homer

Figure 10 The Southland Plains, seen here looking north over the mouth of Waimatuku Stream west of Invercargill, are underlain by Quaternary gravels of both alluvial and marine origin. An extensive 20 m marine bench (of OI stage 5 age) is truncated by a younger (6000 yr) sea cliff (arrowed) inland from the present coastline. Alluvial sediments from the Oreti River and other streams merge imperceptibly onto the OI stage 5 marine bench from the north. Wind-blown dunes trend diagonally across the back-beach lagoons in the foreground. Photo CN43805/8: D.L. Homer 9 Figure 11 Mt Hamilton, at the northern end of the Takitimu Mountains, is underlain by a thick sequence of Murihiku Supergroup sedimentary rocks. In this view to the south, bedding can be seen cutting across the west face of the peak. Faults of the Tin Hut Fault System (right foreground) separate Mt Hamilton from the main Takitimu Mountains.

Figure 12 Port Pegasus and southern Stewart Island, looking to the west. The prominent domes of Bald Cone (B), Gog (G) and Magog (M) rise above the drowned valley system occupied by Port Pegasus, and are formed of the particularly quartz-rich granitic Gog Pluton. Denser vegetation grows on the adjacent granodioritic Easy Pluton.

Photo CN43767: D.L. Homer 10 Figure 13 The lower Freshwater valley on Stewart Island is filled by a sand plain which extends from Paterson Inlet (distant), west to the Ruggedy Mountains. Longitudinal dune ridges overlie the sand plain. Thomsons Ridge (upper left) lies along the northern side of the Freshwater Fault System; the southern edge of the fault system lies along the hills to the south, and beyond to the south side of Paterson Inlet.

Photo CN44055/15: D.L. Homer

11 Southland and Waimea Plains Stewart Island

Over half the onshore part of the Murihiku map area The topography of much of Stewart Island is dominated consists of flat to gently rolling terrain between the by a gently east-sloping plateau that rises from c. 20 m Aparima, Oreti, and Mataura rivers, known as the Southland above sea level at the east coast to between 400 and 500 m and Waimea Plains (Figs 4, 10). The terrain comprises elevation midway across the island. This gently sloping Quaternary alluvial plains and terraces built of gravel surface may be a stripped peneplain, an inference derived from the Paleozoic and Mesozoic rocks of the river supported by the deep weathering typical of the catchments. The older terraces are mantled with wind- underlying rocks. Isolated peaks such as Mt blown loess and have been subtly dissected. Younger Anglem (980 m), Mt Allen (750 m) and the Tin Range surfaces are flat with well-preserved meanders and low (640 m) may represent remnant Cretaceous hills that have terraces. Terrace and paleodrainage systems are complex, survived Cenozoic erosion. The Freshwater and Rakeahua as there has been considerable channel switching in river systems dissect the east-sloping surface. During response to aggradation, stream capture, and local higher interglacial sea levels, inundation of the Freshwater tectonism. valley west to Mason Bay may have divided Stewart Island into two or three separate islands. Marine benches and paleoshorelines are present parallel to the modern coast (Fig. 10; see also Figs 36, 37). The Steep cliffs reflecting active marine erosion characterise benches formed during interglacial high sea levels, with much of the west coast, interrupted by beaches such as subsequent tectonic uplift increasing to the west. A marine Mason Bay (see back cover). Beaches are backed by large bench is also conspicuous east from Riverton, cut off from sand dunes that extend into the scrub- and bush-covered the present coastline by a younger sea cliff (Fig. 10), and hinterland, reflecting the strong prevailing westerly winds. extends intermittently eastwards. Older paleoshorelines The east coast, in contrast, is dominated by the drowned further inland are indistinct, being partly obscured by peat valleys of Paterson Inlet, Port Adventure, Lords River and mounds up to 10 m high and many hectares in extent. Port Pegasus (Fig. 12). The drowned valleys, the easterly slope of the topography, and the generally eastward Takitimu Mountains and Longwood Range drainage direction are consistent with gentle tilting of the island towards the east, probably during the late Cenozoic. Dominating the landscape in the west of the Murihiku map area are the Takitimu Mountains (Fig. 9) and Longwood Extensive sand plain deposits form gently east-dipping Range. The Takitimu Mountains consist of deeply eroded flights of terraces throughout the Freshwater River Permian Brook Street terrane volcanic rocks uplifted catchment (Fig. 13). These terraces are overlain by between the Moonlight Fault System, which follows the longitudinal and parabolic dune fields that have modern Waiau valley, and the Tin Hut Fault System in the Wairaki analogues at Mason and Doughboy bays, where dunes and upper Aparima valleys. As these bounding faults are are actively advancing eastward under the prevailing active, the Takitimu Mountains are probably still rising. westerly winds. Extensive modern and fossil peat swamps The range was extensively glaciated during the Quaternary, are interbedded with the dune fields and sand terraces. and cirques, U-shaped valleys and down-valley outwash Evidence of Quaternary glaciation is preserved at Mt Allen plains are well developed. The volcanic rocks are jointed (Allibone & Wilson 1997), and cirques and moraines are and prone to frost shattering, so steep prograding fan common features of the Mt Anglem massif (Fig. 14). surfaces and active screes are extensively developed (see Fig. 38). Offshore physiography

Mt Hamilton (Fig. 11) is a fault-controlled massif separated Foveaux Strait from Te Waewae Bay east to Slope Point in from the main Takitimu Mountains by the active Tin Hut the Catlins is a shallow seaway with a relatively flat floor Fault System, and is still rising, with tilted Quaternary draped in gravel and sand and punctuated by hard rock surfaces on its northern flank (Force et al. 1970). Mt knobs, some of which reach the surface as islands, rocks Hamilton is underlain by Triassic sedimentary rocks of the and intertidal reefs (Cullen 1967). Areas of sandy to Murihiku Supergroup, forming one of the thickest gravelly bottom host the world famous Bluff oyster banks continuous sections of Murihiku rocks in New Zealand. (Cullen 1962). At the western entrance of the strait, the sea floor remains shallow (Fig. 4) to the head of the Solander Twinlaw and Woodlaw hills south of Ohai, and the lower Trough, beyond the mapped area. The sea floor deepens Riverton peninsula, are also fault-controlled uplifted blocks rapidly west of Stewart Island into the Solander Trough. of Permian volcanics. As they have not been glaciated At the east end of the strait, there is some relief on the sea and the rocks are typically deeply weathered, their profiles floor to depths of 40-50 m but the slope does not steepen are much more rounded than the Takitimu Mountains. The until east of Ruapuke Island. Southeast of Stewart Island Longwood Range, underlain by deeply weathered the sea floor is irregular and may be a continuation of the Paleozoic to Mesozoic plutonic rocks, may have been exhumed erosion surface studded with granite hills seen glaciated, but no glacial erosional features remain. onshore (Figs 4, 12).

12 Figure 14 The Mt Anglem massif on Stewart Island, with well-developed cirque topography, moraine ridges (dashed lines) and a glacial tarn (foreground). Jointing in quartz monzodiorite of the North Arm Pluton dips subvertically above the tarn. Photo CN2715/17: D.L. Homer

13 STRATIGRAPHY

The Murihiku map area includes significant areas of many CARBONIFEROUS TO CRETACEOUS of New Zealand’s major Paleozoic to Mesozoic “basement” rock units and, in particular, the Permian to Jurassic clastic The Median Batholith sedimentary rocks. Late Cretaceous to Cenozoic “cover” sedimentary rocks occur in the fault-controlled Te Anau Plutonic rocks in Fiordland, in the Longwood Range, at and Waiau basins and beneath the Southland Plains. Pahia Point and Bluff, beneath Foveaux Strait, and on Fluvioglacial and alluvial deposits of Quaternary age are Stewart Island are part of the Median Batholith (Mortimer widely preserved, mainly in basins and lowlands. et al. 1999b). Eastern parts of the batholith have previously been interpreted as a zone of dismembered fault-bounded Sedimentary and volcanic basement rocks are primarily volcanic arc fragments with likely allochthonous subdivided into tectonostratigraphic terranes (Figs 3, 15; relationships to both the Eastern and Western Provinces, Bradshaw 1993; Mortimer et al. 1999b). Within each terrane and referred to as the Median Tectonic Zone (Bradshaw the rocks are described in terms of their age and lithology, 1993; Kimbrough et al. 1992; Kimbrough et al. 1994; Muir related to traditional lithostratigraphic units at formation et al. 1998). or group level. Several terranes have been affected by regional metamorphic and structural events and schistose The batholith was formed between the Late Devonian rocks are also subdivided in terms of their textural (c. 380 Ma) and mid Cretaceous (c. 100 Ma) along the paleo- development. In the west the terranes have been intruded Pacific margin of Gondwana (Mortimer et al. 1999b) with by, or are dominated by, plutonic rocks of the Median the intrusion of several distinct suites of I, S and A-type Batholith. Where plutonic rocks are a minor part of a terrane granitoids at different times (e.g. Tulloch 1983, 1988; Muir they are described under that terrane. Median Batholith et al. 1998). Paterson Group volcanic and sedimentary plutonic rocks are described in order of age, subdivided rocks on Stewart Island are likely to be coeval with into plutons and intrusive complexes but only allocated to plutonism in the Median Batholith and were regarded as petrogenetic suites where these are known. Much of the part of the Median Batholith by Mortimer et al. (1999b). mapping and subdivision of Stewart Island basement rocks is new and is based on work by Allibone & Tulloch (see Numerous plutons have been mapped on Stewart Island Appendix 1). (Fig. 17) and in the Longwood Range. They are inferred to represent single or several closely related intrusions of SILURIAN TO DEVONIAN magma that form contiguous mappable bodies, except where dismembered by younger plutons. Units such as the Takaka terrane Bungaree, East Ruggedy and Pahia Intrusives comprise numerous small plutons, plugs and dikes that generally Metasediments of the Pegasus Group (SDp) (Watters et al. cannot be shown separately at 1:250 000 scale, or which 1968; Henley & Higgins 1977) form rafts, xenolith screens have not been mapped to a level where boundaries between and narrow elongate belts associated with Median individual bodies have been established. Suite and source Batholith plutons on Stewart Island. The group consists affinities of plutons are discussed where applicable. of micaceous schist rich in biotite and muscovite, quartzofeldspathic psammitic schist, laminated Median Batholith from Longwood Range to Ruapuke metaquartzites with traces of biotite and pyrite, calcareous psammitic schists rich in Ca-plagioclase, amphibole and Permian to Jurassic plutonic rocks on the mainland lying clinozoisite, and hornblende-biotite amphibolites. west and south of the Brook Street Volcanic Group from Micaceous schists commonly contain minor sillimanite but the Longwood Range to Bluff are included in the Median garnet and cordierite are both rare. Primary sedimentary Batholith (Mortimer et al. 1999a, 1999b; Fig. 18A). These features have been destroyed by deformation and intrusives are divided into an older Permian to Triassic metamorphism, although transposed lithologic layering is suite of mafic to ultramafic rocks, and younger Triassic to still present (Fig. 16). In the Kopeka River catchment, Jurassic mafic, intermediate and felsic plutons (Mortimer Pegasus Group rocks are pervasively intruded by dikes et al. 1999b). The older intrusives represent the roots of from the adjacent Blaikies Pluton (shown by an overprint). the adjacent Brook Street terrane volcanic arc while the younger suite was emplaced after accretion of the Brook At least three phases of ductile deformation and Street terrane arc to the margin of Gondwana (Mortimer metamorphism have affected the Pegasus Group (Williams et al. 1999a, 1999b). 1934b; Henley & Higgins 1977; Watters 1978b; Allibone & Tulloch 1997; Tulloch 2003). The earliest predates The Longwood - Pahia Point area has been investigated emplacement of granitoid rocks at 344 ± 2 Ma while later by Wood (1966), Challis & Lauder (1977), Price & Sinton phases occurred between c. 344-305 Ma and during (1978), Bignall (1987), Rombouts (1994) and others. movement on the Gutter Shear Zone between c. 128- Previous work has been summarised and supplemented 120 Ma (Fig. 17). The youngest detrital zircons from the with isotopic data by Mortimer et al. (1999a), with several Pegasus Group, dated by single-crystal U-Pb TIMS new plutons and intrusive units described. The Bluff (Walker et al. 1998), are 420 Ma, suggesting a maximum Intrusives have been intensively studied by Service (1937), Late Silurian to Devonian sedimentation age and Harrington & McKellar (1956), Watters et al. (1968), correlation with Takaka terrane. Mossman (1970, 1973), Graham (1977), Bosel (1981), O’Loughlin (1998) and Spandler et al. (2000). 14 L

e L t h iv a i T n m

h g

r s R u to System s i Moonlight Fault d n t e g F e ault

H illfo ot Fa ult

FWFS

E N

20 km

Tectonostratigraphic unit Lithostratigraphic unit

Caples terrane Caples Group Terrane boundary and Maitai Group Dun Mountain - other major faults Livingstone Volcanics Group Maitai terrane Dun Mountain Ultramafics Group Late Cretaceous to Recent sediments Murihiku terrane Murihiku Supergroup (see Fig. 23) Productus Creek Group Brook Street Volcanics Group Brook Street terrane (Takitimu Subgroup) Greenhills Group Brook Street terrane intrusives Many plutons (see Figs 17 and 18), Median Batholith including some in Brook Street terrane Takaka terrane Pegasus Group

Figure 15 Major fault systems, and basement tectonostratigraphic units of the Murihiku area related to their lithostratigraphic framework. FWFS - Freshwater Fault System; E - Escarpment Fault; G - Gutter Shear Zone. 15 Permian Brook Street terrane intrusives within the The Bluff Intrusives (Ybz) include the layered Greenhills Median Batholith Ultramafic Complex (Mossman 1970, 1973) which intrudes the Permian metasedimentary Greenhills Group. The In the Longwood Range, Permian intrusives form two large ultramafic complex has a concentrically zoned dunite- plutons: Pourakino Trondhjemite (Ybj) and Hekeia wehrlite core more than 750 m thick, surrounded by an Gabbro (YTh) (Cowden et al. 1990; Mortimer et al. 1999a). upper olivine clinopyroxenite portion 650 m thick, and an Trondhjemite dikes and a small stock intrude adjacent outer gabbroic ring dike system. The zoned core has well- Takitimu Subgroup rocks, which are altered to hornfels. developed cumulate layering, modified by magma flow and The trondhjemite may be a composite earliest to Middle mixing. Cogenetic dunite, wehrlite, gabbro, anorthosite, Permian unit, intruded between 292 Ma (Mortimer et al. trondhjemite, and hornblende pegmatite dikes, and younger 1999a) and 261 Ma (Tulloch et al. 1999). Hekeia Gabbro basalt and ankaramite dikes cut the complex. Associated also intrudes Takitimu Subgroup. It includes gabbro, gabbro and norite (Fig. 18B), and diorite, granodiorite and olivine gabbro, norite, troctolite, and anorthosite. A dioritic quartz diorite occur at Bluff itself. Similar norite, tonalite, phase is differentiated in places and cumulate textures and diorite with inclusions of hornfels and tonalite outcrop occur locally. On the coast between Pahia Point and on Ruapuke Island (Webster 1981). Bluff Intrusives are Riverton, Brook Street intrusive rocks include the informal dated at 265 Ma (Middle Permian) (U-Pb TIMS age; Colac granite (eTc) and Oraka diorite (eTo) units (Bignall Kimbrough et al. 1992). 1987; Mortimer et al. 1999a). Isotopic data show these Permian intrusives to be petrologically primitive, with no Triassic- Jurassic intrusives crustal contamination, and genetically related to Brook Street terrane island arc rocks. Ar-Ar spectra from Hekeia Mesozoic intermediate to silicic plutonic rocks are more Gabbro suggest minimum cooling ages of 249-245 Ma widespread than Brook Street intrusives, and form the (latest Permian to earliest Triassic) (Mortimer et al. 1999a). western side of the Longwood Range and much of the

Figure 16 Raft of Pegasus Group metasediments within Kaninihi Pluton quartz monzodiorite at South West Cape, Stewart Island, showing pervasive folding of lithologic layering. Lithologies include quartz-muscovite schist and amphibolite. 16 Paterson Group Richards Pt Porphyry ------Separation Point Forked Pluton Bungaree and East Ruggedy Intrusives Freshwater NE Pluton episodes. Modified after Tulloch (2001, Tulloch episodes. Modified after Rollers Pluton Euchre Pluton Big Glory Pluton Neck Granodiorite Cow & Calf Gabbro Median/Darran Smoky Pluton Saddle Pluton Codfish Granite Tarpaulin Pluton Ruggedy Granite North Arm Pluton South West Arm Pluton Rakeahua Pluton Freds Camp Pluton ca. 340-345 Ma ca. 125 Ma ca. 130 Ma ca. 140 Ma ca. 152 Ma ca. 167 Ma ca. 168 Ma ca. 308-294 Ma Plutons north of the Escarpment Fault Foliation development, shearing north of Freshwater valley-- Gabbro dikes Ridge Foulwind Kaninihi Pluton Mason Bay Pluton Adventure South Pluton Tobin ------

Campsite Pluton

Kopeka South Pluton Suites Gog Pluton Tikotatahi Pluton microdiorite dikes Lords Pluton Easy Pluton Walkers Pluton Table Hill Orthogneiss Upper Kopeka Pluton Knob Pluton Deceit Pluton Blaikies Pluton Pegasus Group Upper Rakeahua Pluton Doughboy Pluton Escarpment Pluton Ridge Orthogneiss Folding, foliation development, amphibolite facies metamorphism------Plutons south of the Escarpment Fault Movement on the Freshwater Fault System ------Movement on the Escarpment Fault Development of the Gutter Shear Zone------Tight to isoclinal recumbent folding,development, foliation amphibolite facies metamorphism------Age ranges and geochemical suite affinities of plutons within the Median Batholith on Stewart Island, related to major tectonic of plutons within the Median Batholith on Stewart Age ranges and geochemical suite affinities ca. 305 Ma ca. 340-345 Ma ca 420-345 Ma ca. 105-110 Ma ca. 116 Ma ca. 128-116 Ma ca. 127-120 Ma ca. 145 Ma Figure 17 2003), Tulloch & Kimbrough (in press), and unpublished information. Uncoloured boxes denote plutons not assigned to any suite. 17 coast from Pahia Point to Colac Bay (Challis & Lauder 1977; is composed of layered gabbro with numerous mafic dikes Price & Sinton 1978; Mortimer et al. 1999a). Mafic (Bignall 1987) and although undated is included in the intrusions along the coast are termed Pahia Intrusives Pahia Intrusives. Diorite, quartz diorite and granite are (Challis & Lauder 1977). Holly Burn Intrusives (Thb) present along the Pahia Point coast (Challis & Lauder 1977; (Mortimer et al. 1999a) in the western Longwoods include Price & Sinton 1978; Bignall 1987) (Fig. 18C). The informal diorite, mela- and leuco-diorite, quartz monzodiorite, units Boat Harbour diorite and Ruahine granite are granodiorite and rare monzogranite and syenogranite, and differentiated (Mortimer et al. 1999a). Mesozoic intrusives the informal Austin quartz monzodiorite along the coast of the Median Batholith are not known at Bluff. Late (Bignall 1987; Mortimer et al. 1999a). Larger areas of diorite Triassic tonalite, quartz monzonite and diorite (lTq) occur and quartz diorite are differentiated. On the western margin on Ruapuke Island, where they have been dated by Rb-Sr of the Holly Burn Intrusives, steeply west-dipping foliation (Devereux et al. 1968; Webster 1981). outlined by quartz, biotite and epidote defines the Grindstone Gneiss (shown by an overprint) (Wood 1969; Holly Burn Intrusives and coastal equivalents range in Mortimer et al. 1999a). age from Middle Triassic to earliest Jurassic, and the Pahia Intrusives are slightly younger (Devereux et al. 1968; Pahia Intrusives (Jpi) include layered gabbronorite, norite Kimbrough et al. 1994; Mortimer et al. 1999a; Tulloch and hornblende gabbros, and minor peridotite, with et al. 1999) based on a variety of dating methods. These cumulate layering (Price & Sinton 1978). Layering was Triassic - Jurassic Median Batholith rocks are isotopically accompanied by flow and deformation and is highly more evolved than the Permian Brook Street plutons they irregular. Orbicular texture is rarely developed. Centre Island intrude.

Brook Street Brook Street TAKITIMU MOUNTAINS intrusives Volcanics Group

Mackinnon Peak Intrusives LONGWOOD RANGE to COLAC BAY

TRIASSIC BLUFF and RUAPUKE Oraka Colac diorite granite Hekeia Gabbro Productus Creek Group Granodiorite, diorite Bluff Intrusives quartz diorite, diorite PERMIAN White Hill (includes Norite and Intrusives Takitimu Subgroup Pourakino Greenhills gabbro Brook Street Trondhjemite Ultramafic Dunite Greenhills Volcanics Group Complex) and other Group ultramafics

B C

Figure 18 (A) Nomenclature of Brook Street terrane plutonic rocks (included in the Median Batholith) in relation to Brook Street Volcanics, Productus Creek and Greenhills groups in the Murihiku map area, from Bluff to the Longwood Range. Units in italics are informal. (B) Norite on the foreshore at Bluff. Bluff norite has been extensively used for dimension stone, as well as for reclamation work in Bluff Harbour. (C) Diorite of the Pahia Intrusives at Monkey Island near Pahia Point. 18 Median Batholith on Stewart Island and granite comprise the Knob and Kopeka South plutons. Aligned K-feldspar megacrysts (Fig. 19B), tabular xenoliths The plutonic rocks that comprise c. 90% of the Stewart of Pegasus Group schist, and zones of compositional Island basement were previously mapped as the granitoid- banding define fabrics in many parts of the Knob Pluton dominated Rakeahua Granite in southern and western which are related to both magma flow and later ductile Stewart Island, and the diorite-dominated Anglem Complex deformation. in northeastern Stewart Island. Both units were inferred to comprise numerous individual intrusions (Watters et al. Tulloch et al. (2003) assigned the Ruggedy Granite to the 1968). Subsequent mapping has delineated many of the dominantly I-type Tobin Suite and cited the Ridge plutons initially included in these (superseded) units, and Orthogneiss as the type pluton of the S-type Ridge Suite. each is briefly described below in order from oldest to The alkaline nature of the Freds Camp, Big Glory and Forked youngest. Field relationships and radiometric dates have Creek plutons suggests correlation with the A-type been used to determine the ages of different plutons. Foulwind Suite (Tulloch et al. 2003). The c. 305 Ma U-Pb Radiometric dating indicates that the various plutons that monazite age of the Knob Pluton also suggests correlation comprise the Median Batholith on Stewart Island were with the A-type Foulwind Suite, although the peraluminous emplaced between c. 344 and 105 Ma (Tulloch 2003). Dikes and potassic nature of this intrusion distinguishes it from of diorite and gabbro, whose age is unknown, are other members of that suite. Suite affinities have not been intercalated with Pegasus Group schist and orthogneiss assigned to the other Carboniferous plutons. within the Gutter Shear Zone. These dikes form a diffuse swarm that extends for about 35 km along strike between Middle Jurassic the catchments of Doughboy Creek and the Lords River. Cretaceous deformation between c. 130 and 100 Ma resulted Middle Jurassic rocks form about 22% of the Median in development of the Gutter Shear Zone, Escarpment Fault Batholith on Stewart Island and include the Rakeahua and Freshwater Fault System within the Median Batholith (mJk) (c. 169-166 Ma), South West Arm (mJs) (c. 167 Ma), on Stewart Island (Allibone & Tulloch 1997; Tulloch 2003) and Euchre (eJe) plutons. The Euchre Pluton is assigned (Fig. 17). Cataclasis along some faults within the Freshwater a Middle Jurassic age on the basis of its geochemical Fault System may have occurred during the Cenozoic. similarity to the South West Arm Pluton. The Rakeahua Pluton (Allibone & Tulloch 1997) includes gabbro, Carboniferous anorthosite, diorite, a late quartz monzodiorite phase, and minor dolerite. A particularly large body of layered Carboniferous intrusive rocks comprise c. 12% of the anorthosite and gabbro within the Rakeahua Pluton forms Median Batholith on Stewart Island. Individual plutons the prominent Mt Rakeahua. The South West Arm (Allibone include the Ridge Orthogneiss (eCr) (344 ± 2 Ma), Ruggedy & Tulloch 1997) and Euchre plutons comprise relatively Granite (eCg) (342 ± 2 Ma), Table Hill Orthogneiss (eCt) homogenous biotite granodiorite and granite. K-feldspar (c. 340 Ma), Knob Pluton (Cmk) (305 ± 10 Ma), the Freds megacrysts occur locally within the South West Arm Pluton Camp (lCf) (294 ± 5 Ma), Big Glory (lCb) and Forked but are absent from the finer grained Euchre Pluton. (lCk) plutons (308-294 Ma) (Allibone 1991; Allibone & Tulloch 1997; Tulloch 2003) and the Neck Granodiorite Late Jurassic to earliest Cretaceous (eCn) (c. 340 Ma; T.R. Ireland and N.J.D. Cook pers. comm. 2003). The undated Adventure South Orthogneiss (Þv) Late Jurassic and earliest Cretaceous rocks emplaced and Kopeka South Pluton (Þk) may also be Paleozoic in between c. 145 and 130 Ma form about 28% of the Median age (Tulloch 2003). Batholith on Stewart Island. Principal units include the Codfish Granite (lJc) (c. 152 Ma), Saddle (eKx) and Deceit The Ridge (Fig. 19A), and Adventure South orthogneisses (mJd) plutons (c. 145 Ma), Bungaree (eKa) and East comprise foliated, locally K-feldspar megacrystic biotite Ruggedy (eKy) Intrusives (c. 140-130 Ma), North Arm and granodiorite and subordinate granite, while the Table Hill Rollers plutons (eKn, eKz) (c. 132-130 Ma), Richards Point Orthogneiss comprises foliated and often lineated biotite Porphyry (eKr) (c. 130 Ma), Tarpaulin Pluton (eKt) ± muscovite-bearing granite and leucogranite. These (c. 125 Ma), and Freshwater Northeast (eKf) and Smoky gneissic intrusions form tabular bodies intercalated with (eKs) plutons (less than c. 130 Ma). each other and with Pegasus Group schist in central and southern Stewart Island. The Ridge Orthogneiss also forms North of the Freshwater Fault System a progression from isolated blocks within and between younger plutons south dominantly mafic (Saddle Pluton) through intermediate of the Gutter Shear Zone. Massive equigranular granite (Bungaree and East Ruggedy Intrusives, North Arm and and granodiorite dominate the Ruggedy Granite and Neck Rollers plutons) to granitoid plutonism (Tarpaulin, Granodiorite respectively, with deformation restricted to Freshwater Northeast and Smoky plutons) is apparent those parts of both plutons within and adjacent to the during Late Jurassic to earliest Cretaceous time. The Saddle Freshwater Fault System. The Freds Camp, Big Glory and Pluton (Frewin 1987; Tulloch 2001) comprises gabbro and Forked plutons comprise massive quartz monzonite, diorite, with minor dunite and norite (Fig. 19C), and includes syenogranite, granite and alkali feldspar granite with gabbro at Cow and Calf Point (Watters et al. 1968). These variable amounts of biotite. Variably foliated, distinctly mafic rocks form Little Mt Anglem, The Paps, and the peraluminous biotite ± muscovite ± garnet granodiorite northeastern slopes of Mt Anglem. The Bungaree and East 19 A B

C D

E F pegmatite dike transposed contact

m Table Hill Orthogneiss

100

– intrusive

10 – 100 m contact Pegasus Group Ridge Orthogneiss leucogranite dike

Figure 19 Typical Median Batholith rocks on Stewart Island

(A) Foliated potassium-feldspar megacrystic Ridge Orthogneiss within the Gutter Shear Zone, cut by an Upper Rakeahua Pluton leucogranite dike, on Adams Hill.

(B) Aligned megacrysts of potassium feldspar in the Knob Pluton at the mouth of Seal Creek, southeast coast of Stewart Island.

(D) Compositional banding and associated foliation (schlieren), probably related to magma flow, in the Doughboy Pluton on the west face of Mt Allen.

(E) Rafts of coarse biotite leucogranite and smaller amphibolite xenoliths in the Mason Bay Pluton at the south end of Little Hellfire Beach.

(F) Schematic view of field relationships in the Gutter Shear Zone. Intercalated layers of Pegasus Group, Table Hill Orthogneiss and Ridge Orthogneiss are cut by a swarm of aplite, leucogranite and pegmatite dikes associated with the Upper Rakeahua, Campsite and Lords plutons. Dike rocks may form up to 50% of outcrops and dominate float within the dike swarm, giving a false impression of bedrock geology.

20 Ruggedy Intrusives comprise numerous small plutons and Northeast and Smoky plutons. The intense foliation dikes of diorite, quartz monzodiorite and granodiorite with developed in southern parts of the North Arm and Tarpaulin subordinate granite, gabbro, and amphibolite (Waddell plutons, and in the East Ruggedy Intrusives on the northern 1971; Frewin 1987). Similar diorite, quartz monzodiorite and side of the Freshwater valley, marks the northern edge of granodiorite form the large North Arm and smaller Rollers the Freshwater Fault System. (Frewin 1987) plutons. Dioritic rocks of the Bungaree Intrusives and North Arm Pluton form the summit region South of the Freshwater Fault System, Late Jurassic-Early of Mt Anglem. The Tarpaulin (Cook 1987, 1988) and Cretaceous plutonism is represented by the Codfish Freshwater Northeast plutons comprise biotite granodiorite Granite, Deceit Pluton, and Richards Point Porphyry. The and granite, while the more aluminous Smoky Pluton Codfish Granite comprises massive biotite granite in which comprises biotite-muscovite ± garnet granodiorite and primary magmatic minerals are extensively retrogressed to granite. Both the Freshwater Northeast and Smoky plutons chlorite, sericite and epidote. The Deceit Pluton comprises intrude the c. 130-132 Ma North Arm Pluton. massive unfoliated, biotite ± muscovite granodiorite, granite and leucogranite. The granodioritic Richards Point A widespread but not pervasive foliation is developed in Porphyry (Allibone 1991) is characterised by a prominent the North Arm, Tarpaulin and Saddle plutons, and in older chilled margin indicating emplacement at a shallow depth. rocks within the Bungaree and East Ruggedy Intrusives. No suite affinity has been assigned to any of these rocks, This foliation is cut by younger plutons within the Bungaree although their age is similar to rocks included in the Darran and East Ruggedy Intrusives and by the Freshwater Suite of Fiordland by Muir et al. (1998).

A B

Figure 20 Deformation fabrics associated with major Stewart Island faults.

(A) Strongly foliated diorite and quartz monzodiorite of the Walkers Pluton within the Gutter Shear Zone at the Ernest Islands.

(B) Strongly foliated granitoid rocks derived from either Southwest Arm Pluton or Tikotatahi Pluton within the Escarpment Fault at Port Adventure. 21 Early Cretaceous effects of both magma flow and subsequent post- crystallisation ductile shear. Peraluminous S-type Plutons emplaced between c. 125 and 105 Ma comprise granitoids elsewhere in New Zealand are Paleozoic in about 38% of the Median Batholith on Stewart Island and age and these two plutons have no known correlatives. only occur south of the Escarpment Fault. Four generations 4. The Gog (eKg) (c. 105 Ma), Lords (eKl) , Campsite of intrusions are recognised within this time span; the (eKc), and Upper Rakeahua (eKu) plutons comprise second and fourth generations in particular are probably fine-grained leucocratic biotite granodiorite and granite part of the Separation Point Suite. Pluton definitions are with subordinate quartz monzodiorite, leucogranite, given in the Appendix. The plutons include, from oldest to pegmatite and aplite, with related dikes (Fig. 19F) youngest: (Allibone & Tulloch 1997; Tulloch & Kimbrough in 1. The dioritic to quartz monzodioritic Walkers Pluton press). No sharp contact exists between the Gog and (eKw) (c. 127-120 Ma) (Peden 1988; Tulloch 2003) and more mafic Kaninihi Pluton (eKk), suggesting that the the heterogeneous quartz monzodioritic-granodioritic two plutons are closely related, with the former Escarpment Pluton (eKv) (c. 126 Ma). Foliations in representing the evolved core of the latter. The both plutons are inferred to have formed during extensive swarm of related aplite, leucogranite and movement on the adjacent Gutter Shear Zone (Fig. 20A) pegmatite dikes (outlined on the map face), and and Escarpment Fault (Fig. 20B). similarities between these four plutons, imply that they 2. The Easy (eKe) (c. 128 Ma), Tikotatahi (eKi) and are apophyses of a major body that underlies much of Doughboy (eKd) (Fig. 19D) plutons comprise texturally southern and central Stewart Island. similar hornblende, biotite quartz monzodiorite and granodiorite with minor granite (Peden 1988) and may Plutonic rocks of Fiordland and offshore islands represent apophyses of a single larger body. Rafts of diorite and gabbro occur within the Easy Pluton at Port Biotite granodiorite and biotite-hornblende tonalite (eKh) Pegasus (Þd). Field relationships and geochemical data form much of Paddock Hill at the northwest corner of the suggest the Mason Bay Pluton (eKm) (Allibone 1991) map, and are overlain by Cenozoic sedimentary rocks along is related to these three plutons. It includes biotite the Hauroko Fault (Carter et al. 1982) and toward Lake quartz monzodiorite, biotite granodiorite and granite Manapouri (cf. Wood 1966). A c. 500 m2 area of massive plus numerous amphibolite rafts (Fig. 19E). epidotised diorite (eKh), cut by a fine-grained amphibolite 3. The Blaikies (eKb) (c. 116 Ma) and Upper Kopeka dike, underlies Cenozoic rocks along the Blackmount Fault (eKp) plutons largely comprise peraluminous biotite ± (Carter & Norris 1980) and is inferred to be an outlier of muscovite ± garnet granite and granodiorite, Fiordland basement rocks. These rocks are undated, and mineralogically distinct from other mid Cretaceous are tentatively included in the Median Batholith. plutons on Stewart Island (Allibone & Tulloch 1997; Tulloch 2003). Muscovite and garnet are particularly Some of the numerous islands off Stewart Island and in common in the southern part of the Blaikies Pluton Foveaux Strait have not been visited because of access which contains numerous rafts of Pegasus Group difficulties, and are mapped as undifferentiated Median schist. Foliation development is inferred to reflect the Batholith (Þu).

22 PERMIAN TO JURASSIC As well as Permian plutonic rocks, described above under the Median Batholith, the Brook Street terrane includes Brook Street terrane several other lithostratigraphic units. The oldest is the Brook Street Volcanics Group, which in the map area is In the Murihiku map area the Brook Street terrane forms represented by the Early Permian Takitimu Subgroup. The the Takitimu Mountains, the eastern Longwood Range, Early to Late Permian Productus Creek Group rests the Riverton and Bluff peninsulas, some of the islands and conformably on the Takitimu Subgroup. Jurassic Barretts reefs in northern Foveaux Strait, and underlies much of the Formation unconformably overlies both units. Permian southern Southland Plains. The terrane is intruded in places Greenhills Group metasediments and Bluff Intrusives by the Median Batholith, and in the eastern Takitimu represent the Brook Street terrane at Bluff. Mountains it is overthrust by the Murihiku terrane (Landis et al. 1999).

20 km A B

Letham Ridge Thrust PRODUCTUS CREEK GROUP Caravan Formation

15 Elbow Formation *

Maclean Peaks Formation *

10 Heartbreak Formation

Chimney Peaks Formation *

TAKITIMU SUBGROUP 5

Brunel Formation *

0 (Base not seen) Breccia C Conglomerate

Sandstone

Mudstone C Pillow lava

Andesite

Basalt

Rhyodacite

Tuff

Figure 21

(A) Composite stratigraphic column through the Takitimu Subgroup in the Takitimu Mountains, after Houghton (1981) and Landis et al. (1999). Formations indicated by * are not differentiated on the map. (B) Pillow lava of the Takitimu Subgroup in a quarry on Twinlaw. (C) Volcanic breccia cut by dikes within Takitimu Subgroup at Riverton. Photo CN44044/10: D.L. Homer 23 In the central Takitimu Mountains the Takitimu Subgroup The Productus Creek Group (Ypg) lies east of the Takitimu (Ybt) consists of an eastward-younging homoclinal Mountains within a structurally complex area. It has been sequence (Mutch 1964; Houghton 1981), striking N-S and redefined by Landis et al. (1999), following earlier work by dipping vertically. To the south and north the strike Mutch (1972), Force (1975) and Waterhouse (1982, 1998) changes, although some of the central Takitimu formations among many others. The Group rests conformably on the can still be recognised. Takitimu Subgroup is Caravan Formation and comprises the Mangarewa predominantly volcaniclastic and includes mudstone, Formation and Glendale Limestone (not differentiated at sandstone, conglomerate and breccia, and subordinate 1:250 000 scale). Mangarewa Formation includes richly basaltic, rhyolitic, and andesitic flows and pillow lavas fossiliferous limestone (Fig. 22), pebbly conglomerate, (Houghton 1977, 1981, 1982, 1985; Houghton & Landis volcaniclastic sandstone and mudstone. Lenses of 1989; Landis et al. 1999). It is subdivided into 6 formations conglomerate occur at the top of the formation. The (Fig. 21A). Only the predominantly volcanic Heartbreak overlying Glendale Limestone comprises atomodesmatinid Formation (Ybt) (Houghton 1981) of microgabbro, basaltic limestone with minor bioturbated sandy, tuffaceous and rocks, pillow lava and volcaniclastic breccia, and the muddy horizons. Productus Creek Group sedimentary youngest Caravan Formation (Ybt) (Willsman 1990; Landis rocks are dated as latest Early to early Late Permian, based et al. 1999) of volcanic breccia with distinctive ankaramitic on macrofossil evidence (Waterhouse 1998; Landis et al. dikes and tuffs, are differentiated on the map face. The 1999). Leaves of the Gondwanan fern Glossopteris ampla rocks are folded about steeply to gently plunging axes in are preserved in Mangarewa Formation (Mildenhall 1970) the south (Nebel 2003) and are gently southeast-dipping and basal Glendale Limestone (H.J. Campbell, pers. comm.). in the north (Pringle 1975; Scott 1974). The rocks contain zeolite and prehnite-pumpellyite facies mineral assemblages The Takitimu Subgroup is intruded by gabbro, diorite, (Houghton 1982). microgabbro and microdiorite of the White Hill Intrusives (Ybl; Houghton 1981), and andesitic and microdioritic dikes Undifferentiated Takitimu Subgroup, comprising flow of the Mackinnon Peak Intrusives (mTm; Houghton 1987). rocks, dikes, pillow lavas (Fig. 21B, C) and intercalated Larger monzodiorite and olivine monzodiorite dikes up to sedimentary rocks including breccias, conglomerates, 5 km long (Wether Hill Dikes) (Douglas 1997; Willsman sandstones and tuffs, forms Woodlaw and Twinlaw, the 1990; Landis et al. 1999) and minor sills intrude both eastern Longwood Range, and the hills west from Riverton. Takitimu Subgroup and Productus Creek Group. White Bedding in these areas strikes generally north to northwest Hill intrusions are concordant, increasing in thickness with and is gently folded (Harrington & Wood 1947; Macfarlane stratigraphic depth toward the west; they are altered and 1973; Banks 1977). Takitimu Subgroup rocks at the crosscut by younger granophyric phases and by basaltic confluence of the Makarewa and Oreti rivers (Wood 1966) dikes, and are inferred to overlap in age with the final stages comprise altered and veined basalt and andesite flows of Takitimu Subgroup volcanism. Mackinnon Peak (Watters 1961). The Takitimu Subgroup is interpreted to Intrusives are considerably younger (Middle Triassic; be the remains of a calc-alkaline volcanic arc and adjacent Houghton 1987). None of these intrusives are contiguous sedimentary basins (Houghton & Landis 1989; Landis et with the Median Batholith. al. 1999), deposited by subaerial and submarine arc volcanism with closely associated turbidite sedimentation. Barretts Formation (Jub), mapped by Landis et al. (1999) Macrofossils in the Takitimu Subgroup are Early Permian in the upper Wairaki River, unconformably overlies Takitimu in age (Waterhouse 1958, 1964). Subgroup, Productus Creek Group, and various intrusives

Figure 22 Productus Creek Group limestone in a branch of the Waterloo Burn, northern Takitimu Mountains, immediately below the Letham Ridge Thrust. Slightly deformed macrofossils are visible; the outcrop is veined with calcite. Field of view is 0.5 m across. 24 and is included within the Brook Street terrane. This several metres in diameter, include granitoids, basaltic to formation replaces numerous conglomeratic units andesitic volcanics, and rare limestone. The matrix is previously assigned to Productus Creek Group and zeolitised (Landis et al. 1999). The formation is a fluvial Murihiku Supergroup (Landis et al. 1999). Barretts unit deposited on an irregular paleotopography; it has been Formation is dominated by quartzofeldspathic to dated as Early to Middle Jurassic from pollens and molluscs volcaniclastic sandstone, with coarse conglomerate and (Landis et al. 1999). Plutonic clasts within it range in age minor tuff, coal and mudstone. Conglomerate clasts, up to from Jurassic to Triassic (c. 180 to 237 ± 3 Ma; Tulloch et al. 1999).

QMAP

Dunedin

QMAP

Murihiku

NZ stage

Late Kh

mJn mJm # Kt New Haven Mataura mJc mJf Middle Catlins# Ferndale

eJd eJg Jurassic Hu

Glenomaru# Diamond Early Ha Peak

Bo lTs lTt

Bw u Warepan Bm

Murihiku Supergroup Taringatura Late Br

Gk Kaihikuan u mTs mTn Ge North

Triassic

Middle Range Gm Gn u

Early YDm Yu Kuriwao

Late

Permian lTs code on map face

Middle Kuriwao group name # Superseded group name Warepan mapped stage u Unconformity

Figure 23 Subdivision of the Murihiku Supergroup, after H.J. Campbell et al. (2003). Note that the map units used for QMAP Murihiku supersede those used on the adjacent Dunedin QMAP sheet (Bishop & Turnbull 1996). New Zealand stage names are given in full on the time scale (inside front cover). 25 The Greenhills Group (Yg) is generally attributed to the of central and eastern Southland, and the area from the Brook Street terrane and consists of interbedded Mataura River east to the Catlins coast, are underlain by volcaniclastic breccia, dolerite, spilitic tuff, sandstone and Murihiku terrane. The northern contact with the Dun rare limestone adjacent to the Bluff Intrusives at Mokomoko Mountain - Maitai terrane is the Hillfoot Fault. In the west Inlet near Greenhills (Service 1937). Macrofossils from the terrane is thrust over Brook Street terrane (Landis et Mokomoko Inlet indicate a late Early Permian age al. 1999). Rocks within the Murihiku terrane form the (Mossman & Force 1969). The Mokomoko rocks are of lithostratigraphic Murihiku Supergroup (Campbell & prehnite-pumpellyite facies. Higher grade hornblende Coombs 1966; H.J. Campbell et al. 2003). The Supergroup hornfels, garnet hornfels and hornblende and hornblende- comprises 6 groups (Fig. 23), most of which include pyroxene bearing schist at Bluff, together with basalt, numerous formations (generally not differentiated on the keratophyre, altered diorite, albite-actinolite schist, and map face). Murihiku Supergroup rocks are also involved granite from Tiwai Point, are included in the Greenhills in the Tin Hut mélange in the Wairaki River area (Landis et Group (Mossman 1970). Similar volcaniclastic rocks occur al. 1999). The map area includes the type sections for the on Ruapuke Island (Webster 1981) and also form Dog following local biostratigraphic units of Triassic age: the Island. The foliation and shearing seen in the higher grade Gore and Balfour series, and the Malakovian, Etalian, Greenhills Group rocks may be related to the deformational Kaihikuan, Oretian, Otamitan, Warepan and Otapirian event that produced the Grindstone Gneiss in the stages. Mapping of Jurassic strata for this map was Longwood Range (see above). completed prior to Hudson’s (2003) revision of the Ururoan and Temaikan local stages. Unassigned mélange units Kuriwao Group (Yu) forms inliers south of Wyndham on In the upper Wairaki River area (see Fig. 9), Landis et al. the south side of the Southland Syncline (Campbell et al. (1999) re-assigned several formations previously included 2001) and near Pukerau on the north limb (Wood 1956), in the Productus Creek Group (sensu Mutch 1972) to two both overlain by Triassic North Range Group. The tectonic units, the Tin Hut and Hawtel - Coral Bluff Wyndham inlier consists of volcaniclastic sandstone, rare mélanges. Another unit, the Wairaki Breccia, occurs as granule conglomerate and several limestone bands (Yul), fault-bounded slices of pebbly andesitic breccia (too small the lowest including rare tuff. Plant and atomodesmatinid to map at 1:250 000) containing a rich Late Permian fragments are scattered throughout. The fault-bounded macrofauna (Landis et al. 1999). Kuriwao inlier consists of blue-grey sandstone containing atomodesmatinid fragments, limestone, and conglomerate Hawtel - Coral Bluff mélange (Yer) is composed of blocks (Wood 1956). The Wyndham sequence is ca. 850 m thick; of black mudstone, sandstone and limestone in a highly the base is not seen and the top is unconformably overlain sheared grey calcareous mudstone. The blocks are by North Range Group. Although of Permian age and pervasively disrupted, and veined by zeolites and calcite. unconformably overlain by North Range Group The limestone contains conspicuous corals and is distinct sedimentary rocks, lithostratigraphic and petrographic from those of the Glendale and Mangarewa formations in evidence supports inclusion of the Kuriwao Group within being rich in bryozoans rather than atomodesmatinids. The Murihiku Supergroup (Campbell et al. 2001; H.J. Campbell macrofaunas in the Hawtel - Coral Bluff mélange are of et al. 2003). early Late Permian age, and the mélange is inferred to result from tectonic deformation of olistostromes. Both Hawtel - The North Range Group (mTn) (Coombs 1950; Campbell Coral Bluff mélange and Wairaki Breccia lie along the & Coombs 1966; H.J. Campbell et al. 2003) includes rocks Letham Ridge Thrust, which separates Murihiku terrane previously assigned to Malakoff Hill and North Etal groups, from underlying Brook Street terrane. Early and Middle and ranges in age from Early to Middle Triassic. Equivalent Triassic fossils occur in both sandstone and limestone strata to the east of the Murihiku map area were mapped as blocks in the Tin Hut mélange (eTt) in the upper Wairaki Middle Triassic (mTs) by Bishop & Turnbull (1996), where River (Landis et al. 1999). The mélange consists of sheared, the older North Range Group strata are probably excised zeolitised and veined volcaniclastic sandstone with blocks by the Hillfoot Fault. The group consists of up to 3500 m of limestone and conglomerate. It lies along the Tin Hut of well-bedded siltstone and fine sandstone (Fig. 24A), Fault System (see Fig. 45), and is probably derived from with subordinate vitric and lithic tuff, tuffaceous Murihiku Supergroup. The mélange was probably sandstone, and minor shellbeds and volcanic conglomerate emplaced during Late Cretaceous to Cenozoic faulting (Coombs 1950; Mutch 1964; Boles 1974; Begg 1981). North (Landis et al. 1999). of Ohai and at Mt Hamilton, siltstone is the dominant lithology; sandstone becomes more abundant to the east. Murihiku terrane The oldest North Range rocks are unfossiliferous, but macrofossils and shellbeds become more abundant upward The Murihiku terrane consists of Permian to Jurassic (Begg 1981). Although six formations were defined within volcaniclastic sedimentary rocks in the Southland, the group in the Hokonui Hills by Boles (1974), with Northwest Otago, Nelson, and Auckland - Waikato areas. probable equivalents in the upper Wairaki River and at Mt In the map area, the terrane extends from the northern Hamilton, only the Stag Stream Siltstone is mapped at Takitimu Mountains south to Ohai, and throughout the 1:250 000 scale. Taringatura Hills, North Range, and Hokonui Hills. Much 26 A

Figure 24 Murihiku Supergroup lithologies. (A) North Range Group thick-bedded sandstone and thin-bedded siltstone on the north limb of the Southland Syncline, on State Highway 6 in the western Hokonui Hills. (B) Monotis shellbed within Taringatura Group in Dipton Stream, Taringatura Hills. Photo: H.J. Campbell (C) Mudstone and siltstone in the Ferndale Group east of Wyndham. (D) Conglomerate of the Ferndale Group east of Tokanui. Clasts are harder than the zeolitised matrix, and conglomerates are preferentially quarried for road metal. (E) Silicified logs and stumps of the fossilised forest at Curio Bay occur on an intertidal platform of flat-lying Jurassic sediments of the Ferndale Group. Photo CN34670: D.L. Homer

27 The Taringatura Group (lTt) (Coombs 1950) overlies North Murihiku Supergroup sedimentary rocks were deposited in Range Group unconformably and consists of up to 5400 m a very long-lived back-arc or possibly fore-arc basin, of predominantly tuffaceous sandstone, with abundant adjacent to an active volcanic island arc marginal to conglomerate, tuff and siltstone. McKellar (1968) and Boles Gondwana. A wide range of environments is represented, (1974) erected several formations within the group in the from submarine fans with typical turbidite deposits and Hokonui Hills, as did Force & Campbell (1974) on the channel-filling conglomerates, through outer and inner shelf, western limb of the Southland Syncline. Equivalent rocks to deltaic and non-marine at the top, where conglomerates to the east were mapped as undifferentiated Late Triassic become more common (Fig. 25) (Carter 1979; Carter et al. sedimentary rocks (lTs) by Bishop & Turnbull (1996). 1978; Ballance & Campbell 1993; Noda et al. 2002). Taringatura Group rocks also occur in the Catlins and north Paleocurrent and petrological data imply southwest to of Wyndham (Campbell et al. 1987; Campbell et al. 2001). northeast sediment transport (Carter 1979; Ballance & Fossils are widespread (Fig. 24B) and indicate an age range Campbell 1993; Pole 2001; Thorn 2001; Noda et al. 2002; of Middle to Late Triassic. Conglomerates are conspicuous, Roser et al. 2002), although a possible northeasterly-derived and the appearance of granitic clasts in conglomerates, component has also been suggested (Boles 1974). along with distinctive Kaihikuan faunas, marks the base of Regionally extensive unconformities (Fig. 25) and the group. The Kaihikuan and Warepan stages have been disconformities occur within the supergroup and mapped separately (mTt, lTt) where possible; Kaihikuan sedimentary (formation) boundaries may be slightly time- strata include conglomerate horizons. The depositional transgressive. Provenance changed from basaltic - andesitic environment of the Taringatura Group was probably shallow in the Late Permian to highly felsic (rhyolitic) in the Middle marine, and local and regional unconformities are known. to Late Triassic; an upper continental crust (granitic) Rocks containing Warepan faunas, for example, are locally component was significant from Middle Triassic to Jurassic absent but in other places are up to 400 m thick (Campbell time (Roser et al. 2002). Contemporaneous andesitic to 1959). rhyolitic volcanism is indicated by widespread tuffs and tuffaceous sandstones, especially in the Triassic, but lavas Diamond Peak Group (eJd) was introduced by Wood (1956) are only known from two areas. for up to 1300 m of predominantly coarse tuffaceous sandstone, with minor mudstone and arkosic tuffaceous Shallow intrusive rocks, extrusive volcanics, and some sandstone, that conformably overlies Taringatura Group. sedimentary rocks of Triassic – Jurassic age, the Park Conglomerate horizons are prominent in places. McKellar Volcanics Group (TJp) (Coombs et al. 1992) are intercalated (1968) described the group in the Hokonui Hills as with Murihiku Supergroup north of Ohai and southeast of consisting of blue-grey fossiliferous mudstone with minor Wyndham. Several areally restricted formations have been sandstone, coarsening upward into sandstone and thin defined (Coombs et al. 1992). Park Volcanics Group includes but continuous conglomerate, in turn overlain by coarse porphyritic two-pyroxene andesite, trachydacite and sandstone. Marine shelf and slope environments are rhyodacite, conglomerate, and autobrecciated trachydacitic represented. Macrofaunas are of Early Jurassic age. extrusives including ignimbrite. All are modified by low- grade zeolite facies metamorphism with albitisation of Ferndale Group (mJf) (Wood 1956) conformably overlies feldspars and assemblages of laumontite, pumpellyite, Diamond Peak Group and marks the incoming of shallow celadonite and chlorite. These rocks have medium to high- water, near-shore conditions. Sandstones predominate, potassium andesitic chemistry, suggestive of back-arc or with cross bedding, abundant plant material and scarce intra-arc settings. They were largely intruded at very marine macrofossils, and mudstone units are also mapped shallow depths, although some are extrusive (cf. Grindley (Fig. 24C). Discontinuous but locally thick conglomerate et al. 1980). The volcanics have been dated by Rb-Sr and includes the distinctive McPhee Cove Conglomerate K-Ar methods as Late Triassic to Early Jurassic (Gabites (Speden 1971). In the Waikawa area, fluvial environments 1983; Coombs et al. 1992). are indicated by conglomerate (Fig. 24D) and repeated fining-upward cycles (Noda et al. 2002). The Curio Bay Willsher Group fossil forest (Fig. 24E) grew on a fluvial plain subject to flash flooding, adjacent to volcanic hills (Pole 2001; Thorn A zone of sedimentary rocks characterised by laminated 2001). Ferndale Group macrofaunas indicate an early siltstone and volcaniclastic sandstone, of Early to Late Middle Jurassic age. Triassic age, lies north of the Hillfoot Fault at the northeastern margin of the map area and has recently been Mataura Group (mJm) sedimentary rocks overlie Ferndale redefined as Willsher Group (mTw). It was previously Group conformably and are of late Middle Jurassic age, the mapped as the Kaka Point fold belt (Coombs et al. 1976) or youngest preserved in the Murihiku Supergroup in the Structural Belt (Bishop & Turnbull 1996). It has been mapped area (H.J. Campbell et al. 2003). Mataura Group divided into numerous formations, based on a coastal was described by Wood (1956) as consisting of tuffaceous section further east (J.D. Campbell et al. 2003). Inland arkose, blue-grey siltstone, feldspathic sandstone and minor exposure is poor and the group is mapped here as but persistent conglomerate. Plant fossils and fragments undifferentiated, although some conglomerate units can are common; tuffs are rare compared with older sequences. be traced.

28 Willsher Group is dominated by thick sequences of Dun Mountain-Maitai terrane laminated siltstone to very fine-grained sandstone, with conspicuous tuffs and common calcareous concretions. The Dun Mountain-Maitai terrane comprises two major Conglomerates are up to several hundred metres thick, units. The Dun Mountain Ophiolite Belt, comprising Dun with clasts ranging from andesite and felsic tuff to tonalite, Mountain Ultramafics and Livingstone Volcanics groups, gabbro and granitoids. The group is structurally complex represents a slice of Early Permian oceanic crust. The on the coast and probably inland, and is inferred to be overlying sedimentary Maitai Group was deposited on fault-bounded. The metamorphic grade is zeolite facies, these mafic igneous rocks (Coombs et al. 1976). In the although lower than the adjacent Murihiku Supergroup. A Murihiku map area the terrane is extensively disrupted, rich macrofauna indicates an age range from Early Triassic thinner, and less well-exposed than in the adjacent area of into the earliest Late Triassic. In spite of intense study, its northwest Otago (Coombs et al. 1976; cf. Turnbull 2000). terrane affinities are still uncertain; it may be a lower grade A conspicuous magnetic anomaly associated with the equivalent of the Murihiku Supergroup (Campbell et al. ophiolite belt delineates its position between areas of 2003), a Maitai Group equivalent (Bishop & Turnbull 1996), outcrop (Woodward & Hatherton 1975). The Murihiku or a separate terrane. segment of the ophiolite belt has almost no ultramafic rocks,

20 km

Southland Syncline Form lines Unconformable contacts

Conglomerate units Tuffaceous units Mataura Group Ferndale Group Murihiku Diamond Peak Group Supergroup Taringatura Group North Range Group Kuriwao Group

Figure 25 Murihiku Supergroup within the map area, showing distribution of conglomerate and tuffaceous units, and unconformities. Form lines are drawn on strike ridges and represent bedding.

29 and an increasing quartz and potassium feldspar content subgroup and several formations. Because of structural eastward suggests that it may not be derived from typical complexity, faulting and poor exposure, thicknesses of oceanic crust. U-Pb TIMS dating of rocks from the ophiolite individual units are unknown; the group is up to 6500 m belt gives ages spanning 275-285 Ma (Early Permian; thick (Campbell & Owen 2003). Equivalent units are mapped Kimbrough et al. 1992). from northern Southland to the Alpine Fault, reappearing in Nelson, where most of the formations were named (Landis The Dun Mountain Ultramafics Group forms two areas 1974). within the map sheet. Northeast of Mossburn, sheared serpentinite includes blocks of gabbro and peridotite The basal Upukerora Formation (Ymu), a distinctive (Coleman 1966; G. Hyden 1979) in a fault-bounded mélange coarse red and green volcaniclastic breccia with a hematised (Yds). A larger area of outcrop, lacking serpentinite, forms sandy matrix, occurs only as thin, mostly fault-bounded the Otama Complex (Coombs et al. 1976), northeast of the slivers in the Lintley Range (Cawood 1986). In one outcrop, Mataura River between Riversdale and Waikaka. The vesicular spilite is interbedded with breccia. Upukerora complex includes tonalite, albite granite, granophyre, Formation clasts are derived from the adjacent Livingstone norite, two-pyroxene olivine gabbro and hornblende gabbro Volcanics Group. Wooded Peak Limestone, normally (Yda), and rare anorthosite (McPherson 1973). The rocks overlying Upukerora Formation, is apparently absent from are extensively brecciated and inter-faulted with the Murihiku map area. Tramway Sandstone (Ymt) consists Livingstone Volcanics Group (Coombs et al. 1976). of well-bedded grey fossiliferous sandstone and siltstone, rare atomodesmatinid limestone, and distinctive lenses of The Livingstone Volcanics Group comprises spilitic and volcaniclastic breccia. It underlies much of the Lintley keratophyric volcanics, dikes, dolerite, and volcaniclastic Range near Lumsden (Cawood 1986) and is also present sedimentary rocks. In the Lintley Range northeast of northwest of Mossburn (G. Hyden 1979).Tramway Lumsden, the group was subdivided by Cawood (1986) Sandstone rests either on Upukerora Formation, or on into mafic and silicic igneous associations, dominated by Livingstone Volcanics Group. Blocks of keratophyre and spilite (Yl) and quartz keratophyre and plagiogranite (Ylq) plagiogranite within Tramway Sandstone at Lumsden are respectively. Small areas of undifferentiated Livingstone inferred to be olistoliths (Cawood 1986), and breccia lenses Volcanics Group form isolated knobs on the Five Rivers resemble Upukerora Formation. The Little Ben Sandstone Plain. In the Otama area, the group includes extensively (Tml) conformably overlies Tramway Sandstone and is brecciated keratophyre, quartz keratophyre and dominated by distinctive green or rarely red, hard, fine- to keratophyric breccia but spilite is rare (Coombs et al. 1976). coarse-grained volcaniclastic sandstone. The formation is Locally, diorite and tonalite with some trondhjemite (Ylp) unfossiliferous, and contains characteristic yellow-green are differentiated (McPherson 1973). North of Waipahi the and red mudstone chips. Minor siltstone, volcaniclastic group is faulted into Maitai Group (Wood 1956; Coombs conglomerate (Tml) and breccia units were recorded by et al. 1976; Cawood 1987) and includes spilite, basalt, Cawood (1987). East of Gore, Little Ben Sandstone is keratophyre and quartz keratophyre, and rare plagiogranite. massive to graded, grey or red, less commonly green Shearing, brecciation, and mylonitic contacts with the volcaniclastic sandstone, typically with red hematitic Maitai Group are common (Coombs et al. 1976; Cawood mudstone chips (Cawood 1987). Rare volcaniclastic 1987). The Livingstone Fault separates spilite from Caples conglomerate, and interbedded grey sandstone with black, terrane in the southern Blue Mountains (Stenhouse 2002; rather than red/green mudstone is present east of Clinton. see Fig. 7). The overlying Greville Formation (Tmg) at both Lumsden and Clinton consists of laminated to thin-bedded grey Both the Dun Mountain Ultramafics and Livingstone quartzofeldspathic sandstone and mudstone, with rare Volcanics groups have a complex metamorphic history tuffs. Volcaniclastic sandstone and rare conglomerate and (Coombs et al. 1976); they are of pumpellyite-actinolite, redeposited atomodesmatinid limestone occur near Clinton prehnite-pumpellyite and zeolite facies. Brecciation and (Cawood 1987) but not at Lumsden. The overlying Waiua mélange formation are likely to be early deformational Formation (Tmw) differs from the Greville Formation in the processes, but the infaulting of Dun Mountain ophiolites red or reddish-purple colour of finer grained beds. At into Maitai Group is thought to be related to obduction Clinton it contains interbedded volcaniclastic sandstone and terrane amalgamation in Cretaceous time. and pebble conglomerate. Rare atomodesmatinid limestone lenses are entirely redeposited (Cawood 1987; Campbell & Maitai Group rocks unconformably overlie, or are faulted Owen 2003). Little Ben, Greville and Waiua formations are against, Livingstone Volcanics Group. They are exposed poorly exposed east of Clinton, and contacts are inferred northwest of Mossburn, and form a semi-continuous strip to be faulted. along the western Lintley Range (McOnie 1969; Cawood 1986). Poorly exposed Maitai Group is mapped adjacent to The Stephens Subgroup (Tms) of the Maitai Group Murihiku Supergroup from Mossburn southeast to Gore. conformably overlies Waiua Formation northwest of It underlies the rolling hills of Kaiwera between the Hillfoot Mossburn (Hyden et al. 1982) but has not been recognised Fault and the Livingstone Fault, from east of Gore to southeast of Lumsden. It consists of thick-bedded grey- Balclutha (Bishop 1965; Cawood 1987; Bishop & Turnbull green sandstone and subordinate red siltstone and 1996). The group consists of well-bedded sedimentary intraformational breccia, with a conspicuous ridge-forming rocks of low metamorphic grade, subdivided into one conglomerate toward the top. Stephens Subgroup is of 30 Early Triassic age; Permian macrofossils in a quarry north Caples terrane of the Oreti River are from an allochthonous block within the conglomerate (Hyden et al. 1982; Campbell & The northeastern part of the Murihiku map area is underlain Owen 2003). by rocks of the Caples terrane, with non-schistose sandstone and mudstone adjacent to the Livingstone Fault Undifferentiated, poorly exposed Maitai Group (YTm) in the west grading northeast into semischists of the Haast rocks north of the Hillfoot Fault between Gore and Schist. The Caples terrane is a volcaniclastic sequence, Mossburn consist of siltstone and thinly laminated predominantly andesitic but with more felsic material in sandstone, and resemble both Greville and Waiua the east (Chrystalls Beach Complex of Coombs et al. 2000). formations. Conglomerate containing pebbles and cobbles In the type area of northwest Otago, the Caples terrane of sandstone, granite and diorite is exposed south of includes the Caples Group of several formations, as Lumsden. McKay (1892) noted red mudstone, possibly summarised by Turnbull (2000). In the Murihiku map area, Waiua Formation, beneath Cenozoic coal measures in a formations have not been established although several drillhole on the Waimea Plains near Riversdale. lithologic units, particularly characteristic red and green sandstone with red and green mud flakes, have been Most of the Maitai Group has been metamorphosed to mapped. Caples terrane rocks are subdivided in terms of zeolite and prehnite-pumpellyite facies (Cawood 1986, their foliation development (see text box). The semischist 1987), but lawsonite, present in northwest Otago and zones on the map face differ slightly from those in the Nelson, has not been recognised in the map area. The adjacent Dunedin QMAP sheet (Bishop & Turnbull 1996), metamorphic grade is lower than in the adjacent Dun because of revision of the textural zonation system Mountain Ophiolite Belt rocks, and similar to that of the (Turnbull et al. 2001). Caples (prehnite-pumpellyite) and Murihiku (zeolite) terranes. The depositional settings of the Maitai Group Most of the Caples Group (Yc) in the Murihiku map area is ranged from initial fault-bounded basins, to a complex of undifferentiated and consists of massive to thickly bedded submarine fans in a large elongate basin (Landis 1980; fine- to medium-grained grey sandstone with thin Aitchison & Landis 1990). The group is largely disrupted black mudstone interbeds. More uniformly volcaniclastic in origin, with subordinate silicic volcanic bedded, often graded, sandstone and mudstone are less and metamorphic debris in the Tramway Formation. The common. age of the Maitai Group is constrained by macrofossils, including ammonoids, as Late Permian to Early Triassic; Large areas in Tomagalak Stream, northeast of Lumsden, the Permian - Triassic boundary lies at the base of the are underlain by massive to metre-bedded dark green Little Ben Sandstone (Campbell & Owen 2003). and/or red sandstone with subordinate red and green

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.

31 mudstone (Ycy), identical to Kays Creek Formation mapped direction of schistosity in rocks of t.z. IIA or IIB (Fig. 26). further north (Turnbull 2000). Similar red and green The trace of the axial plane is offset in places by Cenozoic sandstone and siltstone occurs in the lower Clutha valley faults. Kink folds in schistosity are also commonly (Becker 1973), and in the Clinton - Pomahaka area where it associated with Cenozoic faults. Mesoscopic folds in was named Watties Sandstone by Cawood (1987). Cawood bedding occur throughout the Caples terrane, with axial speculated that it was either a separate unit (terrane) or plane schistosity in the more foliated parts, but no part of the Maitai Group, but on the basis of geochemistry, macroscopic folds in bedding have been mapped. including trace elements, Stenhouse (2002) has included it Transposition of bedding increases with increasing in the Caples Group. metamorphic and textural grade, from prehnite-pumpellyite facies, t.z. I adjacent to the Livingstone Fault to t.z. III, A belt of rocks 1 to 5 km wide adjacent to the Livingstone pumpellyite-actinolite facies in the northeastern corner of Fault in the Lintley Range and the southern Blue Mountains the map area. is less indurated and deformed, and more varied, than typical Caples Group and includes black and red mudstone The Chrystalls Beach Complex (Coombs et al. 2000) is units up to 100 m thick (Yci), decimetre-bedded graded characterised by broken formation with volcanic and sandstone sequences in the Blue Mountains (Stenhouse radiolarian chert fragments, and geochemistry intermediate 2002), and massive grey sandstone. In the Lintley Range, between “typical” Caples and Torlesse terranes. In the laminated siltstone with plant fragments is interbedded map area the presence of Chrystalls Beach Complex is with mudstone. Minor Caples lithologies include based on a geochemical analysis from near Tuapeka metavolcanic rocks forming greenschist bands (Ycg) with Mouth; no structural or lithologic contact has yet been rare chert (Yct) (Clough 1987), and granule to pebble mapped bounding the Chrystalls Beach Complex and it is conglomerate (Ycc) (Becker 1973). included in the Caples terrane.

An enigmatic regional fold in foliation in the Caples terrane, Caples terrane rocks mainly accumlated in submarine fans the Taieri-Wakatipu Synform (Mortimer & Johnston 1990; in depositional settings ranging from trench slope, to Mortimer 1993a), trends northwest across the map area. trench-slope basins, and possibly trench floor (see The synform hinge is marked by a gentle change in dip summary in Turnbull 2000). Mélanges and zones of broken

Figure 26 Gently south-dipping foliation in t.z. IIA semischist of the Caples terrane defines the northern limb of the Taieri-Wakatipu Synform in the Black Umbrella Mountains. The valley of the Argyle Burn follows the Argyle Fault, in the foreground. Photo CN43910/3: D.L. Homer 32 formation may have formed during subduction-related coarser grained volcaniclastic rocks include dacite and accretion. No fossils are known from the map area. rhyolite with subordinate granitoid material and rare schist. Elsewhere, the Caples Group includes redeposited Permian The widespread occurrence of granitoid detritus, coupled limestone blocks (Turnbull 1979; Ford et al. 1999), detrital with the calc-alkaline geochemistry and predominance of zircons of Triassic age (Adams et al. 2001), and Middle felsic material, imply that the Paterson Group formed in an Triassic radiolaria in the Chrystalls Beach Complex active continental margin setting (Allibone 1991). (Coombs et al. 2000). A Late Permian to Triassic age is inferred for the Caples terrane in the Murihiku area. The Foliation is widely developed in the Paterson Group, Caples terrane was metamorphosed during Early Jurassic particularly within and adjacent to the Freshwater Fault to Cretaceous time (Graham & Mortimer 1992). Little et al. System and northern splays of the Escarpment Fault. (1999) suggested that metamorphism peaked at Greenschist facies metamorphic assemblages characterise c. 170-180 Ma (Middle Jurassic), followed at 135 Ma (Early the majority of Paterson Group rocks — chlorite zone in Cretaceous) by rapid uplift and cooling. the Freshwater valley and Paterson Inlet, and biotite zone at West Ruggedy and in the hills northeast of Little Hellfire. Paterson Group Lower amphibolite facies contact metamorphic assemblages occur in the vicinity of intrusive contacts with the Codfish Paterson Group (eJp) comprises andesitic, dacitic and Granite, Richards Point Porphyry and larger felsic porphyry rhyolitic volcanic, volcaniclastic, tuffaceous and related dikes (Allibone 1991). sedimentary rocks (Fig. 27) in the West Ruggedy, Freshwater valley, Paterson Inlet, and Little Hellfire areas U-Pb TIMS zircon dating of a stratigraphically concordant of Stewart Island (Watters et al. 1968; Waddell 1971; Cook banded rhyolite flow within the Paterson Group at The 1984; Allibone 1991). Smaller fault-bounded slices of Neck gave an age of 146 ± 2 Ma (Kimbrough et al. 1994), Paterson Group occur on the west coast of Stewart Island while TIMS zircon dating of a rhyolite tuff at Abrahams between Waituna Bay and the northern end of the Bay gave an age of c. 142 Ma (Tulloch 2003). The Paterson Ruggedy Mountains, and at the eastern end of Codfish Group is thus latest Jurassic in age, similar to the older Island (Allibone 1986; Allibone & Allibone 1991; Watters parts of the adjacent Bungaree Intrusives. Codfish Granite 1994). Paterson Group may be part of a volcanic- intruding Paterson Group south of Richards Point has an sedimentary sequence which formed the “cover” to the age of c. 152 Ma, suggesting that western, andesitic parts Median Batholith, but is still considered to be “basement” may be about 10 Ma older than other parts of the Paterson beneath Cretaceous and Cenozoic sedimentary sequences. Group. U-Pb TIMS zircon dating of a granitoid clast within the Paterson Group at Abrahams Bay gave an age of The coastal section between Little Hellfire and Richards c. 340 Ma (Tulloch 2003), similar to some of the older Point is dominated by andesitic flows, whereas other parts granitoids in the adjacent basement and implying a relatively of the Paterson Group are dominated by dacitic and rhyolitic local provenance for the group. volcaniclastic and related sedimentary rocks. Clasts in the

Figure 27 Coarse tuff (left) and tuffaceous siltstone (right) of the volcaniclastic Paterson Group at West Ruggedy Beach on northwest Stewart Island (see back cover). 33 CRETACEOUS SEDIMENTARY ROCKS Coal Measures, not differentiated). Ohai Group outliers in the upper Wairaki River consist of basal conglomerate Conglomerate, sandstone, mudstone and coal of the Ohai overlain by sandstone and carbonaceous mudstone Group (lKo) are mapped in the Ohai depression (Bowen (Landis et al. 1999). The Ohai Group is overlain 1964) (Fig. 28), and as outliers in the upper Wairaki River unconformably by the Eocene Nightcaps Group (see (Landis et al. 1999). From seismic data, Cretaceous below). sedimentary rocks, possibly Ohai Group equivalents, are inferred beneath the Waiau Basin (Turnbull & Uruski 1993). The Ohai Group was deposited in a fault-controlled fluvial The Group has been intensively investigated by mapping, basin or basins, with ongoing tectonism indicated by facies drilling and geophysical prospecting in the Ohai Coalfield and thickness changes (Sykes 1989). Pollen indicates a (Bowen 1964; Bowman et al. 1987). Sykes (1988) and latest Cretaceous age (Raine in Turnbull & Uruski 1993). Turnbull & Uruski (1993) interpreted the depositional and tectonic environments. Coarse, thick-bedded sandy conglomerate and minor sandstone (lKc) form Black Rock, off Stewart Island, Ohai Group consists of up to 50 m of basal sandstone, (Tulloch 1998) and two islands known as The Sisters carbonaceous mudstone, and impure coal (Wairio (Fig. 29) (Fleming & Watters 1974). Bedding dips east on Formation, not differentiated) resting unconformably on Black Rock, and NNW on The Sisters toward a fault Murihiku Supergroup, Takitimu Subgroup or (locally) adjacent to the coast of Stewart Island. Clasts are Barretts Formation (Bowen 1964; Landis et al. 1999). The subangular to well rounded and match lithologies on basal sequence is overlain by up to 120 m of New Brighton Stewart Island (Fleming & Watters 1974), although rare Conglomerate (lKo). Clasts are derived from Takitimu volcanic clasts occur on Black Rock (Tulloch 1998). The Subgroup and Murihiku Supergroup and include Median Sisters conglomerate matrix is zeolitised. No datable Batholith plutonics. Conformably overlying the material has been recovered, and these conglomerates are conglomerate are up to 210 m of interbedded sandstone, inferred to be of Late Cretaceous to possibly Cenozoic carbonaceous mudstone, and sub-bituminous coal (Morley age.

Figure 28 The town of Ohai in the down-faulted Ohai depression. Twinlaw and Woodlaw hills lie beyond (upper right) with the Longwood Range in the far right distance. Coal seams in the Late Cretaceous Ohai Group are worked in open cast and underground mines north of the town. Photo CN43931/2: D.L. Homer 34 Figure 29 Northwest-dipping conglomerate of inferred Late Cretaceous age forming the northernmost of The Sisters islands east of Port Pegasus, southeastern Stewart Island.

EOCENE TO PLIOCENE 1940). Beaumont Coal Measures are conformably overlain by up to 350 m of Orauea Mudstone (Eno), a lacustrine to Eocene to Pliocene sedimentary rocks once blanketed lagoonal carbonaceous mudstone with rare graded much of the Murihiku map area, resting unconformably on sandstone interbeds. Orauea Mudstone is overlain by older rocks. A sequence over 8 km thick is preserved in the Oligocene Waiau Group, but the contact has not been seen. central Waiau and Te Anau basins, partly exposed around The Nightcaps Group reflects regional subsidence and the deformed basin margins (Turnbull & Uruski 1993). The formation of an extensive fluvial then lacustrine system sequence is thinner to the east (e.g. F. Hyden 1979, 1980; over much of western Southland (Turnbull & Uruski 1993). Isaac & Lindqvist 1990; Cahill 1995) and largely concealed beneath the gravels of the Waimea and Southland plains, The Eocene Mako Coal Measures (Em) formation is with outcrops on river banks and in stream beds. Limestone preserved along the southwestern side of the Hokonui strike ridges protrude through the gravels, and limestone Hills (Rout 1947; McKellar 1968). It rests unconformably quarries are a feature of the Southland landscape (Fig. 30). on Murihiku Supergroup and consists of about 20 m of Cenozoic sedimentary rocks are mapped in several groups; silty mudstone, claystone and sandstone overlain by lithostratigraphic nomenclature of the various formations 15-20 m of sandstone with thin seams of sub-bituminous and groups is summarised in Fig. 31. coal.

Eocene non-marine sedimentary rocks Eocene lignite measures (Elm) are poorly exposed in a shallow basin in the lower Pomahaka Valley west of Nightcaps Group (En) overlies fresh to slightly weathered Clydevale (Liggett 1979). Mapping and drilling confirm a basement rocks on the margins of the the Takitimu maximum preserved thickness of 20 m. The unit consists Mountains and is intermittently exposed around the of lignite, white to brown variably carbonaceous clay, and Longwood Range. It is inferred to extend beneath the rare fine-grained sand. It rests on leached Caples terrane western Winton Basin (Cahill 1995). Two formations are basement and is unconformably overlain by Early mapped. The basal Beaumont Coal Measures (Enb), up to Quaternary Clydevale Gravel. Tiny remnants of quartz 250 m thick, include arkosic sandstone in channelled and sandstone and mudstone (lEh), in places silica-cemented, cross-bedded units, subordinate carbonaceous mudstone, are preserved adjacent to the Tuapeka Fault Zone, and are rare coal seams and, at Orepuki, oil shale (Willett & Wellman correlated with the Hogburn Formation of Central Otago. 35 Oligocene to Pliocene sedimentary rocks Miocene McIvor Formation (Mwv), was probably derived from the westward-prograding limestone-dominated Thick Oligocene to Pliocene marine sedimentary rocks are Clifden Subgroup (Turnbull & Uruski 1993). In the preserved in the deep Te Anau and Waiau basins in southeast of the Waiau Basin around the Longwood western Southland. Thinner sequences are present in Range, shallow marine facies overlying basement include central and eastern Southland. Sedimentary rocks in the conglomerate, fossiliferous sandstone, limestone and southern Te Anau Basin are zeolitised (Landis 1974) but mudstone of the Waihoaka Formation (Owk), limestone zeolitisation is less apparent in the Waiau Basin. There are (Oul, Mul); and conglomerate and sandstone (Oc) in the numerous folds within the Cenozoic rocks, and basin Pourakino Valley and near Otautau (Harrington & Wood margins are complexly faulted (Carter & Norris 1980; Isaac 1947; Forsyth 1992). & Lindqvist 1990). The Clifden Subgroup of the Waiau Group represents the Te Anau and Waiau basins (Waiau Group) western part of a shallow marine shelf which covered much of Southland in the Late Oligocene to Middle Miocene At the northern end of the Takitimu Mountains in the Te (F. Hyden 1979, 1980), extending into the Waiau Basin Anau Basin, Eocene Nightcaps Group is conformably through the tectonically-controlled Ohai depression. overlain by undifferentiated lower Waiau Group rocks Clifden Subgroup includes several formations and the type (eOw) comprising graded sandstone with olistostromes, localities of several New Zealand stages (Fig. 32A) and is channelised breccia and conglomerate and local limestone, described in detail by Wood (1969). Two informal overlain by graded sandstone and mudstone (Carter & subdivisions are mapped: a lower Clifden Subgroup (Mwc) Norris 1977a; Turnbull & Uruski 1993; Turnbull 2000). The of basal sandstone overlain by pebbly conglomeratic older sandstone and conglomerate is locally derived from limestone (Hyden 1980), and thick limestone of the Forest Takitimu Subgroup and the younger graded sandstone Hill Formation (Ouf) (Fig. 32B); and an upper Clifden from Fiordland granitoids. Lower Waiau Group thins out Subgroup (Mwc) of laminated siltstone and mudstone, locally and the overlying Waicoe Formation, of massive, shellbeds, massive fossiliferous bioturbated sandstone, sometimes concretionary calcareous mudstone (Oww), and locally lignite at the top of the sequence. rests on Nightcaps Group (or possibly basement, east of Mt Hamilton). Waicoe Formation hosts numerous other The Clifden Subgroup is unconformably overlain by further named formations in the Waiau Basin; it encloses graded Waiau Group rocks, including massive shallow marine limestone beds (Muf) of a submarine fan sequence in the sandstone with minor shellbeds (Late Miocene Rowallan upper Aparima River (Mutch 1972). A tiny but important Sandstone, Mwa; Turnbull & Uruski 1995). Overlying outcrop of Tunnel Burn Formation limestone (lOw), at Rowallan Sandstone is the very shallow marine Pliocene the foot of Paddock Hill west of the Hauroko Fault (Carter Te Waewae Formation (^wt) (Turnbull & Uruski 1995), et al. 1982), represents a condensed shelf sequence on the composed of laminated siltstone, cross-bedded sandstone margin of the Te Anau Basin (Norris & Turnbull 1993; and local shellbeds and conglomerate, forming the cliffs Turnbull & Uruski 1993). behind Te Waewae Bay. Orepuki Formation (^Qa) is slightly younger, very shallow to marginal marine and Southwest of the Takitimu Mountains, the Blackmount possibly fluvial sandstone, lignite, and conglomerate, in Fault separates two further Waiau Group sequences of paleovalleys and dissected high terraces on the southern predominantly submarine fan sediments (Carter & Norris Longwood Range near Orepuki (Willett & Wellman 1940; 1977a, 1977b, 1980; Turnbull & Uruski 1993, 1995) (Fig. 31). Willett 1946a; Wood 1969). West of the fault, near Monowai in the southernmost Te Anau Basin, Miocene graded sandstone and mudstone of Winton Basin and Southland shelf the Borland Formation (Mwb) overlie Waicoe Formation. Borland Formation is overlain by northward-derived Middle East of the Takitimu Mountains and Longwood Range, Miocene conglomerate and sandstone of the Monowai Cenozoic subsidence was less than along the Moonlight Formation (Mwm), succeeded in turn by graded sandstone Fault System and sedimentary rocks are thinner, although and mudstone and rare conglomerate of the Duncraigen the Winton Basin is up to 2800 m deep (Cahill 1995). Basal Formation (Mwd) submarine fan. Eocene non-marine sedimentary rocks are overlain by massive calcareous mudstone of the Oligocene Winton East of the Blackmount Fault, a westerly-derived submarine Hill Formation (Owh), the lateral equivalent of the Waicoe fan sequence (Blackmount Formation, Owb) with a locally- Formation. The Winton Hill Formation lenses out beneath derived basal dioritic breccia (Ligar Breccia) rests on the Eastern Southland Coalfield (Isaac & Lindqvist 1990). dioritic basement and grades up through thick-bedded lithic It is overlain by the Chatton Formation (part of the East sandstone into graded sandstone and mudstone, and then Southland Group; see below) and then by distinctive into Waicoe Formation. An easterly-derived Oligocene scarp-forming bioclastic bryozoan limestone of the Late redeposited graded limestone - mudstone facies, Oligocene to Early Miocene Forest Hill Formation (see Figs Birchwood Formation (Owi) (Arafin 1982) is enclosed 30, 31, 32B). Forest Hill Formation commonly has a basal within Waicoe Formation mudstone west of Ohai. A conglomeratic facies (not mapped) (F. Hyden 1979, 1980). younger easterly-derived submarine fan of graded In the Winton Basin, neither Forest Hill nor Winton Hill limestone beds isolated within Waicoe mudstone, the formations are assigned to any group. Non-marine East 36 Southland Group rocks overlie Forest Hill Formation west Formation (Mep), between the Blue Mountains and a of Forest Hill (Isaac & Lindqvist 1990). basement high northeast of Gore, consists of interbedded fossiliferous claystone, sandstone, lignite and The East Southland Group (Isaac & Lindqvist 1990) carbonaceous mudstone. It was deposited in a Late underlies the area east of the Oreti River, and the Waimea Oligocene-Early Miocene estuary. Plains and basins north of Gore, and is time-equivalent to both Chatton and Forest Hill formations. The group The Gore Lignite Measures (Meg) contain economically consists of discontinuous basal marine and estuarine facies significant lignite deposits in eastern Southland, hosting (Chatton and Pomahaka formations), conformably overlain numerous seams up to 18 m thick. Oil shale occurs in the (and in places underlain) by non-marine Gore Lignite Waikaia Valley (Wood 1966). Three lithofacies were Measures. differentiated by Isaac & Lindqvist (1990): a lower sandstone-dominated unit, a middle unit hosting thick coal Chatton Formation (Mec) as mapped includes the Castle seams (Fig. 33), and an upper sandstone-siltstone- Downs Formation of Hyden (1980), following Isaac & carbonaceous mudstone unit with little coal. The Gore Lindqvist (1990). It consists of up to 150 m of fossiliferous Lignite Measures were deposited in lower coastal plain, sandy limestone and variably glauconitic sandstone, delta plain and alluvial plain environments, in a representing inner to mid-shelf environments. In the west progradational setting. On Landslip Hill the quartz gravel it overlies Winton Hill Formation; elsewhere it either and sand facies are silica-cemented and form extensive overlies basement, or rests on and interfingers with East horizons (Wood 1956; Lindqvist 1990); scattered boulders Southland Group coal measures. At Bluff, Chatton of very hard, silica- and limonite-cemented quartz sand Formation rests unconformably on basement and is locally and gravel in the Kaihiku Range, on the southern Blue derived, conglomeratic and cemented by authigenic Mountains, and in the Waipahi district are inferred to be zeolites (Bosel & Coombs 1984). Chatton Formation varies equivalents. Scattered silcrete boulders in the Millers Flat in age from Late Oligocene in the north to late Early basin (mMm; Wood 1966) are correlated with the equivalent Miocene in the south (Isaac & Lindqvist 1990). Pomahaka Miocene Manuherikia Group of Central Otago.

Figure 30 Quarries in Oligocene to Miocene Forest Hill Formation limestone, at Castle Rock north of Winton. LImestone is down-faulted into Triassic rocks in the axis of the Southland Syncline. The North Range lies beyond, to the north. The active Castle Rock Fault lies parallel to the line of pine trees (arrowed) in the centre middle distance.

Photo CN43901/21: D.L. Homer 37

E Wyndham Mep

limestone

Mec Meg Meg Gore MegMec Gore Lignite Measures Mep Chatton Fmn Pomahaka Fmn Mul OulOuf limestone Owh Forest Hill Fmn Oc Winton Hill Fmn Em conglomerate Mako Coal Measures area. Not to scale. Mec Mec Owh Basin Meg East Southland Group ungrouped

Em inton Wi Mec En Meg Meg Mul Ouf Mec Oc En Owh Winton

Oul Orepuki

SCOTTS GAP FAULT Owh Range

lKo Ohai Longwood Qa lKo Owk En Ouf Mwc Eno Oww Enb Owi Ouf Mwc

Enb Eno Clifden Muf Oww Oww Mwv lKo New Brighton Conglomerate

En Eno Orauea Mudstone Enb Beaumont Coal Measures lKo Ohai Group (undifferentiated) Oww Basin En En Mwc Mwc Oww Mountains Oww Takitimu Group Oww Oww eOw En

Nightcaps Ohai Group Mwa Waiau

Owb Blackmount Owb

Mwa aa Basin Waiau

FAULT

aiuBasin B iau Wa enuBasin TeAnau

Basin BLACKMOUNT Mwm p Mwb Mwd

Oww eAnau Te lOw (undifferentiated) c Oww Ouf Forest Hill Fmn

Qawt Orepuki Fmn Te Waewae Fmn p Prospect Fmn

lOw

FAULT Broken fence diagram illustrating lithostratigraphic nomenclature of Cretaceous and Cenozoic sedimentary rocks in the Murihiku

MwaMw Rowallan Sandstone Clifden Subgroup MufMwv limestone Oww McIvor Fmn Owi Waicoe Fmn Owk Birchwood Fmn Owb Waihoaka Fmn Blackmount Fmn P MwdMwm Duncraigen Fmn MonowaiMwb Fmn Oww Borland Fmn lOw Waicoe Fmn eOw Tunnel Burn Fmn Waiau Group

adc Hill Paddock HAUROKO W Waiau Group Figure 31 38 Figure 32

(A) The type locality of the Clifden Subgroup at Clifden, western Southland, extends along the southern bank of the Waiau River from the Clifden bridge (centre left) upstream into the trees (right centre). This is also the type locality for the Southland Series, and for the Clifdenian, Waiauan, Lillburnian and Altonian stages.

(B) Forest Hill Formation limestone on the banks of the Waiau River at Clifden.

Photo CN44048/22: D.L. Homer

Palynology indicates the Gore Lignite Measures are of eversion of the Te Anau Basin along the Livingstone and Late Oligocene to Early Miocene age (Pocknall & other faults (Turnbull & Uruski 1993; Manville 1996). Mildenhall 1984), although the youngest measures may be Middle Miocene (Isaac & Lindqvist 1990). Pebbly Hill Gravels (M^q) consists of up to 150 m of Late Miocene to Pliocene sandy pebbly quartz conglomerate Late Miocene to Pliocene non-marine sediments with a clayey matrix, interbedded with rare claystone, quartz sand and lignite. The unit appears to overlie Gore Lignite In the Te Anau Basin, the Waiau Group marine sequence is Measures unconformably near Gore (Wood 1956), where truncated by the Late Miocene to Pliocene Prospect McKellar (1968) called it Waimumu Quartz Gravel. Similar Formation (^p) (Fig. 34), preserved in the core of the quartz and quartz-lithic gravel and sand north of Gore, Monowai Syncline north of Blackmount (Carter & Norris inferred to be slightly younger, were named Waikaka Quartz 1977a). The formation consists of clast-supported Gravels by Wood (1978). Pliocene lignite offshore in conglomerate with subordinate cross-bedded sandstone. Toetoes Bay (Wood 1966), and quartz sand and lignite in Apart from local Takitimu Subgroup and Fiordland input, drillholes southeast of Invercargill (Mutch 1975), may be Prospect Formation is largely derived from the Caples laterally equivalent to the Pebbly Hill Gravels. terrane, reflecting Late Miocene to Pliocene uplift and 39 Figure 33 Weathered woody lignite in the Gore Lignite Measures of the East Southland Group in the Goodwin mine, near Waimumu. Photo: M.J. Isaac

Figure 34 Steeply dipping Late Miocene to Pliocene Prospect Formation gravels, largely derived from sandstones of the Caples terrane, in the axis of the Monowai Syncline at Redcliff Stream. 40 QUATERNARY Deeply weathered gravels (eQa) forming dissected terrace surfaces near Ohai include plutonic, volcanic and The widespread Quaternary deposits of the Murihiku map greywacke clasts and are almost completely weathered. area rest unconformably on older units, and have been They may represent deposits of a proto-Waiau River flowing subdivided using both geomorphology and lithology. east through the Ohai depression and into the Aparima They have been given a variety of formation names in the catchment (see below). Small terrace remnants underlain past (e.g Wood 1966; McKellar 1968). On the map, deposits by deeply to moderately weathered gravels in the lower are coded by age expressed in terms of their assessed Waiau valley are also mapped as Early Quaternary, but are Oxygen Isotope (OI) stage, prefixed by “Q”, with a letter probably younger than the Ohai gravels. code and overprint for their depositional environment. Radiometric age control is lacking for most deposits, Middle Quaternary deposits although McIntosh et al. (1990) and Berger et al. (2002) have used luminescence and tephrochronology to date Middle Quaternary glacial and fluvioglacial deposits are alluvial terrace sequences in the Mataura valley. preserved in the Waiau catchment. Weathered, sandy to Radiocarbon dates are available for some younger deposits, bouldery, Fiordland-derived till (mQt) occurs on Paddock particularly on Stewart Island; nevertheless most age Hill. Glacial outwash gravel (mQa) up to 100 m thick, with assessments are based on geomorphic correlation with some interbedded till and ice-contact deposits, underlies dated sequences, degree of weathering and preservation high terrace remnants between Redcliff Creek and of landforms, and by “counting back” through glacial Blackmount (Fitzharris 1967; Carter & Norris 1980). Outwash events. Although deposits are assigned a “best guess” OI is also mapped south of Monowai, and forms more stage (e.g. Q4a) on the map face, the ages recorded in the extensive terraces east of the Waiau River above Clifden. GIS database reflect any uncertainty (e.g. Q2-6). Deposits The gravels are weathered, sandy, pebbly to bouldery, of unknown age are mapped as undifferentiated Quaternary planar to cross-bedded, and overlain by up to 3 m of loess. (uQa). These include alluvium on Stewart Island and Slightly to moderately weathered, Fiordland- and locally- alluvial fans in numerous places. derived outwash gravel also underlies terraces northeast of Mt Hamilton. Associated contemporaneous fan Early Quaternary deposits remnants (mQa) are dominated by Murihiku Supergroup debris from nearby Mt Hamilton. The Maitland and Clydevale - Pomahaka areas are underlain by Gore Piedmont Gravel (eQa) and Clydevale High, loess-covered terrace remnants on the Waimea Plains Gravel (eQa) (Wood 1956; Liggett 1979; Barrell & Glassey and in the Waikaia valley are underlain by moderately to 1994b). No type localities or formal definitions have been strongly weathered sandstone-dominated (Caples-derived) introduced for these units and neither has been dated. gravels (mQa). On the eastern Southland Plains, the Middle Both lie in structural depressions and form a broad rolling Quaternary Kamahi Terrace (Wood 1966; Mutch 1975) to flat landscape (see Fig.7). The gravels are deeply which extends from Gore to Invercargill, was deposited by weathered with clasts of quartz, greywacke, argillite, a proto-Mataura River and has a well-developed fan semischist and schist; lithic clasts are usually intensely morphology with an apex at Gore. The Kamahi surface is weathered. Gore Piedmont Gravel is gently deformed mantled by sand dunes and loess and underlain by against the Dunsdale Fault System. Both units are weathered greywacke-quartz sandy gravels up to 50 m interpreted as probably Early Quaternary alluvial plain thick. Locally-derived fans (mQa) grade onto the surface deposits from the proto-Waikaka, Pomahaka and Clutha west of Gore. A dissected fan of very similar weathered rivers; Clydevale Gravel remnants extend as far as Balclutha alluvial gravels (Fig. 35) of inferred Middle Quaternary age (Barrell et al. 1998). Undifferentiated Early Quaternary lies adjacent to the lower Aparima River. Remnant terraces deposits (eQa) underlying very high terrace remnants of weathered greywacke-schist gravel, and gently sloping adjacent to the Clutha River (Thomson & Read 1996) are fan surfaces (mQa) with a very thin veneer of gravel, are younger than the adjacent Clydevale Gravel. mapped along the Clutha River from Millers Flat to

Figure 35 Deeply weathered gravels, composed of sandstone and volcanic clasts, in a road cut south of Otautau. Similar brown to orange-weathered gravels of Middle Quaternary age underlie many fan surfaces in Southland, including the extensive Kamahi Terrace of the eastern Southland Plains. 41 Clydevale (Thomson & Read 1996) ; they are inferred to be Waiau valley, Q6a deposits are mostly eroded and only Middle Quaternary in age. narrow terrace treads remain, above a more extensive OI stage 4 aggradational terrace surface. Q6a terraces in the On the north side of the Freshwater valley, Stewart Island, Clutha are also eroded (see above). a sequence of locally derived basal gravel overlain by cross-bedded sand and variably carbonaceous silt (mQa) Alluvial fans (Q6a) building out from the Blue Mountains, rests on granitic basement and underlies an extensive Late the Taringatura Hills and the hills north of Ohai are dated Quaternary sand plain. Palynology indicates an Early to on the basis of profiling onto major catchment terrace Middle Quaternary age (Mildenhall 2003). sequences. The fans merge onto wider, flatter alluvial terraces with no distinctive fan morphology. The fan Q8 gravels are generally sandier or siltier than the better sorted gravels of the major rivers. Till inferred to date from OI stage 8 (Q8t) is mapped on Paddock Hill, with remnants of moderately weathered glacial Late Quaternary deposits outwash gravel terraces (Q8a) mapped south of Paddock Hill, near Redcliff Creek, and along the southern margin of Q5 the Takitimu Mountains. On the eastern side of the Waiau catchment, extensive alluvial fans (Q8a) derived from the A flat-topped marginal marine bench (Q5b) is intermittently screes of the Takitimu Mountains have built out over older preserved along the coast from west of the Waiau River terraces and moraines. (Fig. 37) to east of the Mataura River, decreasing in height from 25-60 m ASL in the west, to 12-25 m at Riverton and 5- OI stage 8 terraces mapped in the Mataura catchment, 7 m in the east. The bench is underlain by gravel and sand, following McIntosh et al. (1990) and Berger et al. (2002), with peat in places, resting on a flat to undulating erosion are underlain by moderately weathered greywacke gravels surface cut in both Cenozoic sedimentary rocks and older with subordinate quartz, and overlain by loess. McIntosh basement rocks. It is overlain by dunes at Waipapa Point. et al. (1990) and McIntosh et al. (1998) attributed these East of Invercargill the bench is obscured by thick mounds terraces to an ancestral “Lumsden River”, when the Oreti of peat formed over both the deposits and the marine cliff River flowed east from Lumsden rather than south as it behind it. Marginal marine deposits on the bench can be does now (Fig. 36). Terraces mapped as Q8a in the lower distinguished from nearby (possibly coeval) fluvial gravels Mataura and Oreti catchments may be degradational by their plane-parallel or inland-dipping tabular cross surfaces eroded into older (mQa) gravels. bedding, rather than trough cross bedding, and by containing a higher proportion of reworked quartz gravel Q7 (Liggett 1976). These marginal marine deposits are inferred to date from OI stage 5 (70 - 130 ka), with an intermediate Flat to gently rolling and dissected surfaces (Q7b) between step (Fig. 37) representing a fluctuation in sea level during 20 and 40 m ASL northeast of Riverton, around Orepuki, this interglacial period. and west of the Waiau River at about 100 m ASL, are interpreted to be of marginal marine origin and assigned to Q4 OI stage 7 (185 - 248 ka). The coastline east from the Mataura River is backed by terraces a few metres to tens of metres Fiordland-derived fresh bouldery sandy till (Q4t) forms wide, at heights of 7 - 9 m ASL. These inferred OI stage 7 hummocky ground in the upper Waiau River adjacent to marine benches are overlain by up to 4 m of loess the Mararoa weir (McKellar 1973). A down-valley outwash comprising several horizons, and underlain by weathered gravel train (Q4a) forms the widest terraces preserved along and iron-stained, locally derived gravels. the Waiau River, including the extensive flats north and south of Clifden. Several degradational terrace surfaces OI stage 7 terraces at 10-20 m ASL with an up-river slope of have been cut into these gravels. 4° were mapped near Balclutha by Barrell et al. (1998). This profile projects up the Clutha River to meet OI stage Terrace gravels (Q4a) are preserved throughout the 6 terraces mapped down-valley by Thomson & Read (1996). Aparima, Oreti, Mataura and Clutha catchments. The The apparent mis-match between the alluvial terraces and gravels are relatively fresh and greywacke-dominated; the the marine surfaces mapped at the coast may indicate that proportion of Fiordland material decreases away from the the alluvial terraces are slightly older than shown, and Waiau catchment and schist, quartz and semischist debris have been partly stripped of gravel (perhaps by marine increases toward the Clutha catchment. In the lower incursions up the Clutha River). Mataura valley, the gravels underlie loess dated by thermo- luminescence as being older than 44 ka ±3 ka (Berger et al. Q6 2002). Loess dunes (Q4e) are mapped north of Gore (McIntosh et al. 1990). The Waiau and upper Oreti catchments contain outwash gravel terraces consisting of Fiordland-derived rocks Fan gravels (Q4a) derived from local ranges, mapped south (Q6a). The associated till occurs north of the map area, in of Ohai and beside the Blue Mountains, are assigned to OI the southern Te Anau Basin (McKellar 1973). In the lower stage 4 on the basis of down-valley profiling and their 42 Oreti 1 Oreti 2

"Lumsden River"Mataura

Hillfoot Fault Oreti Waiau 1

Waiau

Aparima 2

Aparima 1

Aparima

Makarewa

Mataura

Invercargill

Coastline N Present-day rivers Shorelines: Q7 20 km Q5

Figure 36 Southland Plains Quaternary paleogeography, showing present-day river systems and inferred paleodrainage, together with inferred paleoshorelines behind marine terrace remnants. There has been considerable channel switching of the major rivers throughout the Quaternary. The Waiau River may have drained via Ohai into the Aparima in the Early Quaternary (Waiau 1). In the late Middle Quaternary the upper Oreti River (Oreti 1) drained south into the Aparima catchment at Mossburn. Diversion of the Oreti 1 stream to the east (to its present position) was probably influenced by movement on active faults near Mossburn (see Figs 40 and 44). Drainage from the Five Rivers plain (and possibly the upper Mataura) flowed east into the present-day Mataura (Oreti 2) - the “Lumsden River” (McIntosh et al. 1990, 1998). The Aparima and upper Oreti rivers combined formed the wide plains between the two present-day river channels, and drained southeast into the present-day lower Oreti (Aparima 1). Probable stream capture saw this Aparima-Oreti river drain through a limestone ridge southeast of Otautau to reach the sea at Waimatuku (Aparima 2) (see Fig. 10). The lower Oreti, north of Winton, may have captured the east-flowing Oreti (the “Lumsden River”) south of Lumsden to bring it into its present route. The present-day Aparima River, minus the upper Oreti, was probably captured by a stream draining from the Otautau area to Riverton. During the Middle Quaternary the lower Mataura River built an extensive fan from Gore into the Makarewa and lower Oreti catchments.

43 Figure 37 Raised marine benches (Q5b) west of the Waiau River are underlain by gravel and sand. The prominent dark line (left centre and upward) is a former sea cliff inferred to date from a minor sea level fluctuation during OI stage 5. Gold was concentrated in beach sand at the foot of this cliff, and was sluiced in the Tunnel Claim; sludge channels (dark gullies) run from the old cliff to the modern cliff above the beach ridges behind the modern shoreline. The mouth of the Waiau River is in the distance, marked by a boulder bar. Photo CN44029/24: D.L. Homer

height relative to younger deposits. These gravels are Q2 generally sandier and siltier than the better sorted gravels of the major rivers; their ages are poorly constrained. Probable OI stage 2 tills occur throughout the Takitimu Mountains, but some may be older and as there is no age Q3 control, they are mapped as undifferentiated till (uQt).

The only deposits of this age are laminated and cross- Fresh sandy pebbly to bouldery glacial outwash (Q2a) bedded sands and silts in the upper Waiau River (Q3a) forms inner terraces above the modern flood plain in the (McKellar 1973). This unit was deposited on a sand plain, Waiau River, but its associated till is only preserved north probably associated with a pro-glacial stream system. of the Murihiku map area. Q2 outwash derived from the 44 Monowai glacier forms wide terraces west of Blackmount, carbonaceous mud may be interbedded. Several terrace but no till from the OI stage 2 advance is known (Fitzharris levels may be present. Alluvial fans (Q1a) with clearly 1967). defined radial drainage and steeper slopes grade downstream onto terraces. Fans are composed of locally OI stage 2 alluvial and fan deposits (Q2a) are widespread derived, commonly angular gravel, and may include debris in most catchments. Many are probably of wider age range flows as well as stream deposits. than OI stage 2. A large area of Q2a alluvium between the Oreti and Aparima rivers northwest of Winton was Sand dune deposits deposited following channel switching of the Aparima River into the Oreti (see Fig. 36). Dune fields (Q1d) occur on the mainland, along the south coast, and on Stewart Island. The mainland dunes are well On Stewart Island, parallel-laminated sand underlies much preserved behind modern sandy beaches such as Oreti of the Freshwater valley, and forms terraces along the west Beach and east of Waipapa Point. Some dune fields may coast between the Ruggedy Mountains and Mason Bay. predate OI stage 1, and have since been remobilised. Most Radiocarbon ages of 24 802 ± 196 years and > 48 000 years are longitudinal dunes, with shore-parallel back-beach have been obtained from peat within this sand. Field dune ridges closer to the coast. Active dune fields are relationships suggest this sand covers a wide age range indicated by a red overprint. and consequently it is mapped as Late Quaternary (lQ). Peat within the sand at Little Hellfire has a cold climate Dunes are widely preserved behind bays and beaches on Last Glaciation palynoflora (Mildenhall 2003). The sand the western coast of Stewart Island. Bishop & Mildenhall terraces along the west coast include breccia lenses and (1994) reported radiocarbon ages of 7-10 000 yrs from peat beds derived from the adjacent granite basement (Bishop (including a fossil forest) beneath the Mason Bay dune & Mildenhall 1994). Longitudinal and parabolic dunes in field. Liggett (1973c) reported, but did not map, widespread the Freshwater valley overlie fluvial sands of Late dune sands overlying Kamahi Terrace gravels (mQa) Quaternary age (see above), and although undated are northeast from Invercargill, up to 35 km inland from the likely to be OI stage 2 (Q2d). Winds from both westerly present coastline. Silcrete boulder ventifacts around Gorge and easterly quarters are indicated by the dune patterns Road (probably derived from silica-cemented sand within (F.J. Brook, pers. comm. 2002; see Fig. 13). the Gore Lignite Measures) have been faceted by these wind-blown sands. Holocene deposits Peat deposits Cirque moraines Significant areas of the Southland Plains are covered by Cirque morphology is widely preserved in the Takitimu fibrous to woody peat deposits (Q1a) (Fig. 39), some of Mountains, and there are small cirques on Mt Allen which form mounds above the surrounding terraces; the (Allibone & Wilson 1997) and Mt Anglem on Stewart Island base of these thick peats is probably older than OI stage 1. (see Fig. 14). Most cirques date from OI stage 4 and earlier The Awarua Plains east of Invercargill in particular have glacial events, but are commonly floored or fronted by well-developed and actively growing peat mires, and the bouldery angular till (Q1t), typically with well preserved peat beneath the Awarua deposit is at least 15 m thick. terminal moraine topography. In the Takitimu Mountains, Some peat swamps are ponded behind gravel barriers, or successive moraine loops are preserved in some cirques limestone bands such as the Isla Bank - Otautau ridge. In and some occur well down-valley from their headwaters. the Blue and Takitimu Mountains, peat swamps are still In the absence of radiometric dating, these are mapped as forming in poorly drained valley heads and on ridges, undifferentiated Quaternary till (uQt). impounded by vegetation in string bogs. Peat is widespread on Stewart Island, forming paleosols within Scree fluvial and dune sands, underlying large areas in the Freshwater valley, and accumulating over much of the On Mt Hamilton and in the Takitimu Mountains, scree and island beneath modern vegetation. slopewash derived from Brook Street and Murihiku terrane rocks is extensive enough to be shown on the map (Q1s; Landslide deposits Fig. 38). Most scree is reactivated from deposits formed during Quaternary glacial periods when vegetation cover Landslides are most common in areas underlain by Caples was suppressed, and may be up to 50 m thick. Scree Group semischist in the north of the map area, influenced deposits commonly grade downslope into fan and alluvial by unfavourably oriented joint and foliation surfaces. Only deposits. those over 1 km2 in area are shown on the map, by an overprint. Smaller landslides occur within Murihiku Alluvial terraces and fans Supergroup rocks, mainly as bedding plane dip slope failures in steeply dipping interbedded sandstone- Alluvium (Q1a) infills most valleys and underlies modern mudstone units. Minor landslides affect areas of Winton flood plains, and consists of locally derived, often bouldery, Hill and Waicoe formation mudstones. Although landslides unconsolidated gravel, sand, and mud; peat and in the semischist were probably initiated at various times 45 Figure 38 Looking southward from the central Takitimu Mountains to Telford Peak (centre). The extensive partly vegetated scree slopes are developed on Permian volcanic rocks of the Takitimu Subgroup.

during the Early Quaternary (McSaveney et al. 1988) and underlying rocks, and debris from small landslides and so predate OI stage 1, many are still partly active. solifluction lobes.

Beach deposits Loess is widespread throughout Southland up to 300 m ASL, and has been extensively investigated by Bruce (1973, An extensive area of beach gravel (Q1b) with well- 1984), McIntosh (1992, 1994), McIntosh et al. (1988,1990) developed ridges underlies the Tiwai peninsula east of and Berger et al. (2002). Loesses have been dated using Bluff. An area of gravel with ridge topography beside the tephra (volcanic glass) (Eden et al. 1992) and luminescence, lower Oreti River is also mapped as a beach deposit. Some and date back to at least 350 ka (Berger et al. 2002). In beach sands preserved behind modern beaches along the some localities up to four loess sheets are preserved, Catlins coast are large enough to be shown; generally separated by paleosols (Berger et al. 2002), in a sequence modern beach sands (Q1b) are quite narrow and grade up to 6 m thick (Bruce 1973). Loess dune fields mapped by into dune fields above high water mark. McIntosh et al. (1990) north of Gore reflect strong westerly wind reworking older loess deposits, some as old as 250 000 Deposits of human origin years. Loess dunes are also reported from the older terraces in the Blackmount region by Carter & Norris (1980). Tailings (Q1n) from gold dredging operations are Although a significant landforming lithology, loess is too widespread in the Waikaia and Waikaka catchments. Smaller variable in thickness and in outcrop to be shown on the areas (not mapped) occur at Waimumu, west of Gore. 1:250 000 geological map, although the loess dunes north Tailings also infill valleys between Round Hill and Orepuki, of Gore are shown. west of Riverton. Parts of Bluff Harbour consist of land reclaimed (Q1n) during port expansion in the 1950s (Wood OFFSHORE GEOLOGY 1958) and 1960s. The submarine geology and surficial sediments of Foveaux Unmapped surficial materials Strait have been described by Cullen (1967) and Cullen & Gibb (1965). Information on the deeper sedimentary rocks Surficial materials, or regolith, include loess, weathered and structures came from a seismic reflection profile in rock, and soils. While important in interpreting the eastern Foveaux Strait (Mortimer et al.2002). Turnbull & underlying geology, and significant for human activities Uruski (1993) re-interpreted oil company seismic data from such as agriculture and construction, they are too thin, the Solander Basin, in the western approaches to the Strait. diffuse, and complex to be shown on the map. On flat to Eastern Foveaux Strait and part of the shelf offshore from gently sloping older Quaternary surfaces in Central Otago Stewart Island lie within the Great South Basin, described and in northern Southland, the regolith is dominated by by Cook et al. (1999). The basement geology of Foveaux silty loess which, where remobilised on steeper slopes, Strait can be inferred from regional geophysical data grades into loess colluvium. Elsewhere and on higher and (Woodward & Hatherton 1975) supplemented by steeper slopes, the regolith is predominantly slopewash information from the scattered islands.Offshore basement and locally derived scree, weathered material derived from southeast of the Catlins is assumed to be Murihiku 46 Figure 39 Strip mining of a Sphagnum-dominated peat swamp east of Winton; much of this peat is exported for horticultural uses. The peat has formed a raised mound over alluvial gravels, which show subdued terrace edge morphology (upper right). Photo CN43917/19: D.L. Homer

Supergroup, following Cook et al. (1999) and Mortimer et In western Foveaux Strait, Turnbull & Uruski (1993) mapped al. (2002). Murihiku rocks thin to the southwest, up to 2 km of younger Cenozoic mud-dominated overlapping Brook Street terrane on an inferred thrust sedimentary rocks lying unconformably on basement. The contact - the extension of the Letham Ridge Thrust (cf. youngest are Pliocene, the offshore equivalent of the Te Landis et al. 1999) (see cross-section A-A’). The Brook Waewae Formation. Thicker sequences further west are Street - Median Batholith contact, inferred to be intrusive, as old as Eocene. Sediment distribution was partly lies beneath northern Foveaux Strait just south of Ruapuke controlled by faults linking the Freshwater Fault System Island, where Median Batholith rocks are exposed. Mafic to onshore faults west of Te Waewae Bay (Turnbull & plutonics of the Median Batholith underlie central Te Uruski 1993). Waewae Bay, off the Waiau River mouth (Bishop et al. 1992). Central Foveaux Strait is shallow and swept by strong bottom currents, and the surficial sediments are sand- and Mid Cretaceous to Miocene sedimentary rocks gravel-dominated especially in the northwest. Rocky sea unconformably overlie basement southeast of Foveaux floor topography extends north from the Ruggedy Islands, Strait (Cook et al. 1999). Only thickness contours and between Ruapuke Island and Waipapa Point east of (isopachs) estimated from seismic data are shown on the Bluff (Cullen 1967; Cullen & Gibb 1965). Pliocene lignite map. The Great South Basin sequence includes basal and fossiliferous Miocene rocks have been dredged from breccia and conglomerate, Late Cretaceous sandy and near Bluff and off Stewart Island respectively (Watters et carbonaceous fluvial rocks and overlying latest Cretaceous al. 1968), implying the local presence of a thin cover of coastal and shallow marine rocks. Sedimentary basins were Cenozoic sediment. On the sea floor, shellbeds are dominant controlled, in part, by a series of northwest and northeast- in places, particularly further offshore in deeper water trending faults, possibly including reactivated extensions (Cullen & Gibb 1965). In the Strait itself, some shellbeds of the onshore Freshwater Fault System. are derived from the commercially important Bluff oyster, Ostrea chilensis, which lives only in areas of fine sandy gravel (Cullen 1962).

47 TECTONIC HISTORY

Eastern and Western provinces: Gondwana and Rocks of the Murihiku terrane were thrust across the allochthonous accreted terranes eastern margin of the Brook Street terrane (including the Middle Jurassic Barretts Formation), on the Letham Ridge Basement rocks of the Murihiku map area span the Thrust during the Middle to Late Jurassic (c. 160-140 Ma) boundary between continental Paleozoic crust with (Landis et al. 1999). Accretion of the Murihiku terrane Gondwana affinities (Western Province) and late Paleozoic along the Letham Ridge Thrust therefore post-dates to Mesozoic volcano-sedimentary terranes (Eastern accretion of the Brook Street terrane to the Western Province) accreted to the margin of Gondwana during the Province (Gondwana) by c. 70-100 Ma. Ongoing plutonism Mesozoic. The boundary between Eastern and Western in the Median Batholith further to the west did not extend provinces has been referred to as the Median Tectonic eastwards into the Murihiku or eastern Brook Street Line or Median Tectonic Zone (e.g. Bradshaw 1993) and is terranes, even after docking with the Western Province. one of the fundamental structures in the pre-Cretaceous This may reflect an absence of thicker continental crust basement of New Zealand. Plutonic rocks of the Median beneath the Eastern Province terranes (Mortimer et al. 2002) Batholith are inferred to span and stitch this boundary suitable for generating granitoid plutonic rocks. The (Mortimer et al. 1999b). In the Murihiku map area the Letham Ridge Thrust probably continues southeast boundary between Eastern and Western provinces is beneath beneath the Murihiku Supergroup into eastern largely concealed by Cenozoic sedimentary rocks or lies Foveaux Strait where Late Permian rocks (Kuriwao Group) beneath Foveaux Strait. Cenozoic tectonism has also locally may be relatively thick (see Mortimer et al. 2002, and cross- obscured earlier relationships between basement terranes section A-A’). Numerous unconformities adjacent to along the Eastern-Western Province boundary. Kuriwao Group could, however, imply proximity to a more tectonically active margin of the Murihiku sedimentary Paleozoic Pegasus Group schists on Stewart Island are the basin. oldest rocks in the Murihiku map area and represent dispersed fragments of Western Province Takaka terrane The steep north-dipping Hillfoot Fault separates the basement, which formed at or near the Paleozoic Pacific Murihiku and Dun Mountain-Maitai terranes (Bishop & margin of Gondwana. Eastern Province volcanic and Turnbull 1996; Mortimer et al. 2002). An active trace has sedimentary terranes, characterised by relatively low been identified along this fault, although the presence of metamorphic grades, formed in a variety of subduction- overlying gently dipping Eocene to Miocene rocks related settings along or distant from the margin of indicates only minor movement on this terrane boundary Gondwana. These settings include an intra-oceanic since the early-mid Cenozoic. Juxtaposition of the Murihiku volcanic arc and related sedimentary basins (Brook Street and Dun Mountain-Maitai terranes along the Hillfoot Fault terrane), a 2000 km long arc-flanking basin (Murihiku is likely to have been during the Cretaceous. The insertion terrane), and trench and trench slope environments (Caples of the Willsher Group (a suspect terrane) along the terrane). The Dun Mountain-Maitai terrane represents a boundary between Murihiku and Dun Mountain-Maitai slice of ophiolitic oceanic crust, unconformably overlain terranes also probably occurred during this phase of by Maitai Group forearc basin sedimentary rocks. movement. Formation of the Southland Syncline also dates from the Cretaceous, although in the north adjacent to Mt Accretion of the Eastern Province terranes to the Western Hamilton it has been tightened during Cenozoic folding. Province is the result of prolonged convergent tectonics along the New Zealand segment of the paleo-Pacific margin The boundary between the Dun Mountain-Maitai and of Gondwana. Triassic to Cretaceous I-type dioritoid- Caples terranes is marked by the steeply north-dipping granitoid plutonism within the Median Batholith, along Livingstone Fault (Coombs et al. 1976; Cawood 1986). and west of the contact between Eastern and Western Dismemberment of the Dun Mountain-Maitai terrane within provinces, is another important consequence of this the wider Livingstone Fault System - possibly including convergence. strike-slip movement of hundreds of kilometres (Cawood 1986, 1987) - reflects transport along this terrane boundary. In the Longwood Range, Middle Triassic to Early Jurassic Cooling ages of c. 135 Ma in the Caples terrane may reflect plutonic rocks of the Median Batholith intrude older Brook uplift at the time of accretion onto the Dun Mountain- Street terrane plutonic rocks, and accretion of the older Maitai terrane (Little et al. 1999). Formation of the parts of the Median Batholith and Brook Street terrane regionally extensive Taieri-Wakatipu synform may also be onto Gondwana took place around 230-245 Ma (Mortimer related to metamorphism and subsequent uplift of the et al. 1999a). Further evidence is provided by the presence Caples terrane. Late Cretaceous sedimentary rocks overlie of clastic material from both the Brook Street terrane and the Livingstone Fault near the Otago coast (Bishop & the Median Batholith in Middle to Late Jurassic Turnbull 1996) and indicate juxtaposition of the Caples conglomerates of both Southland and Nelson (Tulloch et and Dun Mountain-Maitai terranes prior to c. 90 Ma. al. 1999). Cenozoic uplift inferred along the Livingstone Fault to the north (Turnbull 2000) does not appear to have occurred in the Murihiku map area.

48 Mesozoic deformation within the Median Batholith beneath the Waiau Basin controlled sedimentation in half- graben (e.g Sykes 1989; Turnbull & Uruski 1993). A major The Median Batholith on Stewart Island is cut by the Gutter fault which separates plutonic rocks from conglomerates Shear Zone, Escarpment Fault, and Freshwater Fault on the southeast coast of Stewart Island, east of Port System. Gneissic rocks in the Longwood Range and Pegasus, may mark the northwestern margin of the Great strongly foliated metasediments near Bluff indicate that South Basin. Mesozoic deformation also occurred in these parts of the Median Batholith. Cenozoic tectonics and basin development

The 2-5 km wide Gutter Shear Zone affects units older than A period of tectonic quiescence in southwestern New c. 120 Ma but is cut by plutons younger than c. 116 Ma, Zealand in the Paleocene was followed by Middle Eocene constraining the timing of deformation to c. 118 Ma. opening of fault-controlled basins. These basins formed Western Province Takaka terrane (Pegasus Group) rocks in response to regional extension propagating northward are restricted to the area within and south of the Gutter along the Moonlight Fault System (Fig. 15) from the Shear Zone. Paleozoic granitoids within and south of the Solander Basin (Norris & Turnbull 1993; Turnbull & Uruski Gutter Shear Zone have been affected by multiple phases 1993). In contrast, rifting continued in the Great South of ductile deformation, whereas those to the north are Basin with deposition of thick clastic Paleocene sedimentary undeformed, except along the Freshwater Fault System. rocks (Cook et al. 1999). Extension, rapid subsidence and sedimentation continued into the Late Oligocene in The Escarpment Fault in central and northern Stewart Western Southland. Island cuts granitoids older than 120-110 Ma, but is itself cut by rare dikes that were probably emplaced between Initiation of the Alpine Fault in the Early Miocene changed about 110 and 105 Ma. Rocks to the south of the the tectonic setting to convergent strike-slip, resulting in Escarpment Fault all have Ar-Ar cooling ages of c. 100 Ma basin eversion in the Waiau and Te Anau basins. Fiordland whereas those to the north have cooling ages comparable moved northeast relative to the Longwood and Takitimu with their emplacement ages. Lineations indicate that rocks ranges in the Middle Miocene, reactivating the Moonlight south of the Escarpment Fault were thrust across those to and northern Livingstone fault systems, the northwest the north and east at c. 110-100 Ma (Allibone & Tulloch extension of the Freshwater Fault System in Foveaux Strait, 1997; Spell et al. 1999). and faults surrounding the Takitimu Mountains.

Ductile shearing associated with the Freshwater Fault In contrast to Western Southland, the area east of the System affects rocks as young as c. 125 Ma, indicating Moonlight Fault System and the Takitimu Mountains that deformation occurred after this time. Cataclasis along remained relatively tectonically stable throughout the early some Freshwater faults post-dates foliation development Cenozoic, with formation of the Waipounamu Erosion (Allibone 1991) and may be Cenozoic. Fault-bounded slices Surface across southern New Zealand (LeMasurier & of granitoid rocks and Paterson Group volcanic rocks were Landis 1996), followed by coal measure deposition in imbricated during reverse movement in the Cretaceous shallow basins. Eocene to Oligocene subsidence in the and/or Cenozoic. Winton Basin was probably controlled by reactivation of Late Cretaceous faults extending east from Ohai (Cahill The Early to mid-Cretaceous movement histories on these 1995). Local more rapid subsidence continued in the major structures indicate that deformation within the Winton Basin into the Late Miocene, and maximum regional Median Batholith is not simply an extension of Triassic subsidence is marked by an Early Miocene marine and Jurassic tectonism associated with accretion of the transgression (Chatton Formation) which reached inland Brook Street and Murihiku terranes to the Western to Waikaia. Province. In the Late Miocene to Pliocene, the Northern Southland Late Cretaceous tectonics ranges were uplifted in response to shortening east of the Alpine Fault. Intermontane basins developed and gravel Following terrane accretion, cessation of Median Batholith units (Prospect Formation and Pebbly Hill Gravels) plutonism and internal deformation, and a period of uplift accumulated, with continuing uplift into the Quaternary and erosion (the Rangitata Orogeny), New Zealand rifted resulting in the younger Gore Piedmont and Clydevale from Antarctica and then from Australia. In the Murihiku gravels. Infaulting of middle Cenozoic sedimentary rocks map area rifting was accompanied by opening of the Great into the already tilted Southland Syncline ranges on South and Western Southland sedimentary basins northeast-trending faults also dates from the Late Miocene (Turnbull & Uruski 1993; Cook et al. 1999). Cretaceous to Pliocene, as does probable southeasterly-directed sedimentary rocks associated with rifting are the oldest overthrusting along the Dunsdale Fault System (Hatherton preserved in these basins: the Ohai Group in western 1979) and its northern extensions (Isaac & Lindqvist 1990). Southland, and the Hoiho Group in the Great South Basin. Most of the present-day topography of Murihiku was Northeast- and northwest-trending faults at Ohai and probably formed by the end of the Pliocene.

49 Quaternary tectonics east of the Takitimu Mountains on the Tin Hut Fault (Landis et al. 1999), is probably also related to Fiordland motion. The western side of the Murihiku map area is currently The northeast- and northwest-trending Quaternary fault being deformed, as Fiordland moves northeastward in traces within the Hokonui and Taringatura ranges relation to the area east of the Waiau River in response to (including the Hillfoot Fault), and a fault which deforms oblique compression within the Pacific Plate southeast of terraces at Mossburn, may represent adjustment of these the Alpine Fault (see Fig. 3). Much of this motion is areas in response to bending of the Southland Syncline. presumed to be along the Moonlight Fault System, where Late Quaternary fault scarps on the Blue Mountains and strike-slip movement has been inferred from earthquakes Spylaw faults represent the compressive regime covering (Anderson et al. 1993). Quaternary fault traces occur along much of Central Otago, where block faulting along this system, including one beneath the Mararoa Weir northeast-trending faults is widespread (Jackson et al. abutments (R.M. Carter, pers. comm.) on an extension of 1996). The Clifton Fault and an active fault northeast of the Hauroko Fault. Shortening across faults southwest of Mossburn (Fig. 40) are inferred to be splinters of the the Takitimu Mountains, and sinistral strike-slip movement Livingstone Fault System (Fig. 15).

Figure 40 The trace of an active fault northeast of Mossburn. The trace (arrowed) is downthrown to the east by about 2 metres, and extends from the Acton Stream in the north (top) to the braided Oreti River (bottom). The photograph dates from 1957; although more recent aerial photos exist, they do not show the trace as clearly because of the effects of cultivation. NZ Aerial Mapping vertical air photo 2525/23, survey SN 1020 50 ENGINEERING GEOLOGY

This section provides generalised information to assist significant rock defect only in fine-grained lithologies. In geotechnical investigations and hazard assessments, but t.z. IIA and IIB semischists rock strength decreases with is not a substitute for detailed site investigations. Potential increasing foliation development, and in t.z III schist difficulties with some rock types are highlighted. foliation is a major rock defect. Landslide debris in semischist and schist terrain is predominantly weak with little internal strength, but larger landslides shown on the Paleozoic to Mesozoic rocks map face are extremely variable in their engineering properties. They range from large intact blocks separated Plutonic rocks exposed on the coast and on headlands by shear zones, to internally chaotic masses. such as Pahia Point are strong, hard and fresh, but inland in the Longwood Range they are typically very weathered. The zeolite content of Murihiku Supergroup sedimentary Joints are generally widely spaced (0.5-5 m). Gneissic rocks induces rapid weathering and breakdown of clasts foliation is normally not a significant pervasive defect. and fresh surfaces, even in hard freshly quarried material. Weathering within the Longwood Range may extend to at Jointing is very close in mudstones. Sandstones are less least 10 m below the surface and the most weathered rocks closely jointed (0.1-0.5 m) and normally these rocks are are extremely weak, prone to slipping and rilling in fresh relatively strong and can support steep batters, although exposures. small block falls may be promoted by closer jointing. Conglomerates, often preferentially quarried as they Brook Street terrane volcanics and volcaniclastic contain hard clasts, are easily fractured around clasts and sedimentary rocks in the Takitimu Mountains are hard and tend not to perform well in steep batters. fresh on steep faces, but on more gentle terrain are prone to frost-shattering which exploits pervasive close jointing. Late Cretaceous and Tertiary sedimentary rocks In lower-lying areas such as north of Ohai they tend to weather readily to weak soft clayey soils. Zeolite alteration The wide lithological variation in these rocks is reflected makes Brook Street terrane rocks vulnerable to by their range of rock strengths and properties. disintegration when crushed. On Twinlaw and Woodlaw, Sandstones are usually hard when fresh; jointing is variably Brook Street terrane rocks are deeply weathered although spaced (0.1-2 m). Mudstones of the Waicoe and Winton fresh, strong material can be quarried below the weathering Hill formations are prone to landsliding and may cause zone (see Fig. 21B). Coastal exposures at Riverton are engineering difficulties in road batters. Forest Hill very fresh and hard. Formation and Clifden Subgroup limestones are hard, generally widely jointed rocks which are strong and can Paleozoic rocks in the Greenhills to Bluff area are generally support large cliffs (see Fig. 32B). Sandstones within the very strong and hard, capable of supporting steep faces Ohai and Nightcaps groups are generally strong and widely and providing large blocks. Deep weathering may be jointed, but coals and carbonaceous mudstones (such as present in old gullies and beneath vegetation cover on the Orauea Mudstone) are more clay-rich and weaker. Slope flatter slopes. On Stewart Island, the plutonic rocks around stability may be a problem in mine batters where Oban are variably weathered and range from extremely weak, carbonaceous mudstone is abundant. Claystone and to very strong and hard when fresh. Rock strength is siltstone in the Mako and Gore coal measures are soft, influenced by jointing, topography and degree of weak rocks and can be unstable on steeper slopes, weathering more than by rock type. especially when wet. The large landslide at Landslip Hill has failed in Gore Lignite Measures beneath a hard, strong Volcanic and plutonic rocks within the Dun Mountain silcrete cap. Pebbly Hill Gravels and quartz gravels within Ophiolite Belt north of Mossburn, in the Lintley Range East Southland Group are poorly consolidated weak soils. and around Otama tend to be hard and relatively fresh but are closely jointed. Serpentinite north of Mossburn is a Quaternary sediments very weak rock, but contains hard “knockers” of gabbro and diorite. Maitai Group sedimentary rocks range from Gravel and sand in Quaternary moraines, outwash plains, strong to extremely weak, the strength diminishing with alluvial terraces and fans are loose, weak sediments. decreasing grain size, and increased weathering and Schistose or non-schistose clasts in Caples-derived cleavage development. Sandstones are generally closely gravels are harder and less prone to weathering than clasts jointed (0.1-0.5 m); although large faces in mudstones of in gravels derived from Murihiku or Dun Mountain-Maitai Greville and Waiua formations may stand steeply, surface terrane rocks. Gravels of the Waiau catchment are rich in fretting is common. hard, strong Fiordland-derived plutonic rocks, and a minor Fiordland-derived component is also present in the upper Caples terrane sandstones are strong, hard, variably jointed Oreti catchment. Aparima gravels have a significant rocks. Slopes cut in fresh rock are generally stable, component of relatively hard Brook Street terrane although rock falls may occur on very steep faces. Rock volcanics. Regolith, including extremely weathered rock, strength decreases with increasing weathering, but closely loess and loess colluvium, is a weak rock or soil, and is spaced joints are more significant defects. Bedding is a vulnerable to shallow landsliding on steeper slopes.

51 GEOLOGICAL RESOURCES

The Murihiku map area contains a wide variety of Alluvial gold geological resources, the most economically significant being gold, sub-bituminous coal and lignite, aggregate, There are many alluvial gold occurrences in the Murihiku limestone, and peat. Mining for alluvial gold was map sheet, including beaches from the Waiau River to the widespread in the late 19th and early 20th centuries, but few Catlins coast, and placer deposits in the sediments of the hard-rock deposits were found or exploited. Coal mining Mataura and Clutha rivers and their tributaries (Fig. 41) was initially on a small scale from many scattered pits and developed into a major industry at Ohai in the 1940s to Gold at the Tunnel Claim west of the Waiau River (Fig. 37; 1960s, but has since declined. Lignite has been mined for Wood 1969), and at Orepuki and Round Hill (Macpherson many years from Eastern Southland and in the Waikaia 1938) was recovered from beach deposits on raised marine and Pomahaka areas. Considerable reserves of lignite were benches and from streams reworking them. At Round Hill, delineated in Eastern Southland following a comprehensive gold was mined from Early Quaternary sediments and exploration programme in the 1980s (Isaac & Lindqvist weathered alluvium, with a total production of 2488 kg 1990). Some alluvial gold mines are still operating, and from the Round Hill Gold Company alone (Lindqvist et al. prospecting for gold and platinum continues. Aggregate 1994). The Arethusa (Longwood) Nugget reputedly and limestone quarrying is ongoing and large reserves are weighed 36 ounces (1.02 kg). The source for this gold may available. have been mineralisation in Takitimu Group rocks of the adjacent Longwood Range. Some gold is also present in The economic geology of the map area has most recently the Waiau River, where a dredge once operated south of been described by Doole et al. (1989) and Lindqvist et al. Blackmount (Hall-Jones 1982). Dredging and sluicing of (1994), based on Geological Resource Map of New Zealand numerous beach placer deposits further east, from Fortrose data; this section summarises and updates those reports. to Haldane, produced some very fine-grained gold Past production figures are given by Williams (1974), Doole (Lindqvist et al. 1994). Although prospected in the 1990s et al. (1989) and Lindqvist et al. (1994); more recent annual (MacDonell 1992) there is no current mining. production statistics are available from the Ministry of Economic Development. Hall-Jones (1982) gave histories Sluicing and dredging operations recovered gold along of many of the goldfields. the Waikaia and Waikaka rivers from their headwaters downstream to the Mataura River, and on the Waimumu METALLIC RESOURCES and Charlton alluvial goldfields near Gore. The gold was derived from lodes in the Otago schists, reworked into Hard-rock gold mineralisation Miocene and younger quartzose gravels, and then into Late Quaternary alluvium. Mining began in the late 1800s, Most known gold lodes within the Murihiku map area are but records are incomplete and regional assessments do in the Longwood Range. Several lodes were discovered in not give total production, although it was probably several the 1870s and 1880s adjacent to the contact between thousands of kilograms. The Waimumu field alone Takitimu Subgroup and Median Batholith intrusive rocks. produced 570 kg (Mutch & Baker 1989). The King Solomon Gold occurs in both altered plutonic and volcanic rocks. Mine east of Waikaia produced 605 kg of gold from Ore crushing batteries were erected on the Arethusa and underground workings in infaulted fluvial and fan gravels. Printz’s reefs but the mining was short-lived (Hall-Jones Some of the gold in the older alluvial deposits is quite 1982) and although only 1.5 kg are recorded as having coarse, and intergrown with quartz (Falconer 1987; Clough been produced, output was probably much greater. More & Craw 1989; Craw 1992). Prospecting continues, with recent exploration in the Longwood Range has identified several small alluvial mines operating (Fig. 42). several gold anomalies (Nicholson et al. 1988) in both the Pourakino and Orauea catchments. Traces of gold have Alluvial gold was panned and sluiced from creeks that been reported from the Dun Mountain Ophiolite Belt near drain both the eastern and western sides of the Tin Range Otama, as well as a gold-bearing quartz lode, but there is on Stewart Island (McKay 1890; Williams 1934a; Howard no evidence of significant mineralisation (see Lindqvist et 1940). Minor amounts of alluvial gold were obtained from al. 1994). the Kopeka River and tributaries in southeastern Stewart Island (Williams & Mackie 1959). Traces of gold have also On Stewart Island gold has been reported in the northern been recorded on Waituna, West Ruggedy, Smoky, Newton Ruggedy Range and at North Red Head Point. Brittle and Port William beaches in the north of the island (Howard faulting, pyritic silicified breccia, and quartz veining with 1940). disseminated pyrite southwest of West Ruggedy Beach may be the source of the gold. Gold on Waituna Bay Silicon and ferrosilicon beach (Howard 1940) may be derived from deformed and extensively altered Ruggedy Granite and Paterson Group Quartz gravel from the Cenozoic sedimentary rocks of volcanic rocks that crop out at either end of the bay and eastern Southland has been prospected as a potential along the coast to the north. feedstock for production of silicon and ferrosilicon, partly

52 Ohai

Pomahaka

Mako

Orepuki

Alluvial goldfields Eastern Southland coalfields (Miocene) N Orepuki, Mako and Pomahaka coalfields (Eocene) Ohai Coalfield (Cretaceous)

50 km Rivers Roads

Figure 41 Coalfields and estimate areas for the Eastern Southland, Mako, Pomahaka, Orepuki and Ohai coalfields. The main alluvial gold workings in the Murihiku map area are also shown. influenced by the proximity of coal and hydroelectric power recorded some platinum values (e.g. Rossiter 1989; Cowden supplies. Sufficient quantities of quartz gravel are available et al. 1990; Ford 1999). Traces of platinum occur in the in the Pebbly Hill Gravels, and in Q5 marine terraces at Greenhills Ultramafic Complex (Spandler et al. 2000). Awarua, but the percentage of impurities inhibits their utilisation (Turnbull & Ker 1970; Hope et al. 1971). Copper occurs in mineralised breccia and shear zones as Modern and more cost-effective treatment methods may chalcopyrite, associated with pyrite and pyrrhotite, within result in a renewal of interest in this resource. granophyre and diorite of the Dun Mountain Ophiolite Belt near Otama. Extensive prospecting in the 1970s failed Other metallic minerals to locate any economic deposits (McPherson 1973; Lindqvist et al. 1994). Traces of copper are reported from Platinum was recovered as a by-product of alluvial gold the Longwood Range, the Takitimu Mountains and on mining from many claims around the Longwood Range, Stewart Island (McKay 1890; Lindqvist et al. 1994). The west of the Waiau River and as far east as the Catlins intrusive contact between Codfish Granite and Paterson (Williams 1974). The platinum ranges from very fine grains Group andesitic rocks south of Richards Point coincides up to nuggets of several ounces, and is probably derived with a zone of altered rocks that contain common pyrite from the margins of the Waiau Basin (Mitchell 1995). and traces of chalcopyrite (Allibone 1986) and which may Numerous prospecting programmes, and recent drilling of be the source of copper mineralisation noted by McKay the Hekeia Gabbro in the southern Longwood Range, have (1890) (cf. Rolston 1972). 53 Figure 42 Waikaka gold dredge working Late Miocene to Pliocene and Early Quaternary quartz gravel, south of Waikaka township (October 2002). This operation has now closed. Photo CN43866/17: D.L. Homer

Manganese as psilomelane with up to 59% Mn occurs surveyed in the 1950s and 1980s (Bowen 1964; Bowman et with barite in a lode in the southeastern Longwoods (Beck al. 1987; Sykes 1988). A detailed survey was made of the 1962) but has never been mined. Molybdenum is found in Eastern Southland Coalfield, utilising drilling, down-hole a small quartz lode in the northwestern Longwood Range logging, geological mapping and paleoenvironmental (Willett 1943). Mercury as cinnabar was reported from analysis during the 1970s and early 1980s (Isaac & Caples terrane rocks in the Waikaka area by Henderson Lindqvist 1990). Other smaller fields are covered in the (1923), with up to 12% Hg (Lindqvist et al. 1994). Tin as regional resource assessment by Lindqvist et al. (1994). cassiterite was worked on a small scale from streams around the North Arm of Port Pegasus and on the southern Tin The Ohai Coalfield lies in a east-trending structural Range on Stewart Island. A single short adit driven along depression north of Twinlaw (see Fig. 28). Faulting is a wolframite- and cassiterite-bearing quartz vein a few widespread, and the coal-bearing rocks are folded into centimetres wide within a narrow greisen zone near the numerous anticlines and synclines (Bowen 1964; Bowman summit of the Tin Range had no significant recorded et al. 1987). The coal contains 0.3-0.6% sulphur and 1-8% production (McKay 1890; Williams 1934a, 1974). ash. Seams up to 23 m thick lie within the Morley Coal Measures of the Ohai Group. Seams are lenticular and often NON-METALLIC RESOURCES split or are washed out by fluvial sand channels, and syn- depositional faulting and folding are indicated (Sykes 1988). Coal Most of the open-cast and underground mines were north of Ohai, although several pits were located nearby at The Murihiku area has extensive deposits of coal, both Nightcaps. 100-150 million tonnes (Mt) of reserves are Tertiary lignite and the higher rank Cretaceous sub- estimated to remain, down to depths of 500 m (Lindqvist et bituminous coals of the Ohai field (Fig. 41). Nearly all al. 1994). Although some coal has been mined from the known occurrences of coal have been worked to some unconformably overlying Eocene Beaumont Coal extent since the late 1800s, and several pits are still in Measures (Bowen 1964), the seams are thin (2-3 m), with operation. The Ohai Coalfield was extensively mapped and high ash, and of lesser economic interest.

54 Eastern Southland Coalfield lies between Gore, Invercargill Hydrocarbons and the Mataura River. The structure is simple with low dips, except near the Bushy Park and Hedgehope faults. The Cretaceous and Tertiary sedimentary sequences Lignites within the Gore Lignite Measures are mainly in within the Murihiku map area have been investigated by the “middle measures”; individual seams are laterally several exploration programmes and wells. The onshore persistent and typically 1-8 m thick, but locally as thick as hydrocarbon potential is discussed by Turnbull & Uruski 19 m (Croydon and Ashers Siding) (Isaac & Lindqvist 1990). (1993), Lindqvist et al. (1994) and Cahill (1995), and the Seams are low in ash (less than 10%) and sulphur (0.14- offshore by Turnbull & Uruski (1993) and Cook et al. (1999). 0.65%). Coal rank is highest in the northwest and lowest The Winton Basin has been tested by three wells, and a in the south, reflecting variation in the original depth of seismic survey in the 1980s, summarised by Cahill (1995). burial. The thickest seam at Waimumu has 42% bed Although the basin is up to 2800 m deep, with Eocene coal moisture, suggesting former burial of 810 m, whereas measures as potential souce rocks at the base, only the J T Makarewa lignite with 64% bed moisture has never been Benny-1 well, drilled in the 1960s, had hydrocarbon shows. buried deeper than 145 m. The Waiau Basin sequence, up to 5 km thick in the map Drilling programmes between 1975 and 1984 outlined area, has potential source rocks (Ohai and Nightcaps significant resources in nine areas (Isaac & Lindqvist 1990) groups) at depth, with potential reservoir rocks and (Fig. 41). The total resource at less than 200 m of cover has structural and stratigraphic traps in several places (Turnbull been estimated to be 6760 million tonnes Indicated and & Uruski 1993). One well west of the map area produced 1570 million tonnes Inferred coal-in-ground. Studies no evidence of hydrocarbons. Oil was produced from shale confirmed large scale open pit mining was technically within the Nightcaps Group at Orepuki between 1899 and feasible and the Ashers-Waituna (Kapuka) deposit was 1903 (Willett & Wellman 1940) but further extraction would identified by the Liquid Fuels Trust Board as the best site be uneconomic. This oil shale is of interest as a potential to provide feedstock for a coal to liquid fuel conversion source rock in the Waiau Basin west of Orepuki (Turnbull plant. To date the project has been judged uneconomic. & Uruski 1993). Oil shale within Gore Lignite Measures, Mining for electricity generation is being considered. south of Waikaia, was used as a fuel for gold dredges in the early 1900s. Production of methane from Ohai Group Other smaller areas of lignite are present elsewhere, for coals has been tested near Ohai, and the underground example, south of Tapanui in the Pomahaka valley, in the gasification of these higher ranking coals has some Maitland area, and in the Wendon valley. potential (Cave & Boyer 1990).

Eocene coal was mined from Beaumont Coal Measures in Oil seeping from plutonic rocks on Stewart Island may the Orepuki Coalfield (Willett 1946a). It is of sub- have travelled along faults from the hydrocarbon-bearing bituminous B rank (Wood 1969), due to significant burial sedimentary rocks of the Great South Basin to the beneath Waiau Group sedimentary rocks. The coalfield is southeast. The hydrocarbon potential of the Great South structurally complex but has not been fully investigated; Basin, tested by several wells beyond the map area, was inferred reserves of 1 Mt may exist. Scattered small deposits summarised by Cook et al. (1999). of Beaumont Coal Measures have been mined around the flanks of the Takitimu Mountains (summarised by Turnbull Aggregate & Uruski 1993). A small mine exploited the Eocene Mako Coal Measures north of Hedgehope (Rout 1947), and The Murihiku map area is relatively well endowed with although one drillhole intersected the seam during Eastern aggregate sources, except for the Catlins and Stewart Southland Coalfield exploration, the extent of reserves is Island. Most aggregate is extracted from Quaternary and unknown (Isaac & Lindqvist 1990). Eocene lignite has also Recent alluvium in river beds, or from modern or Q5 beach been worked from seams 2 to 5 m thick in several small pits gravels along the south coast. The composition of alluvium in the Pomahaka Coalfield, west of Clydevale. Drilling in varies across the map area, depending on the predominant the 1970s resulted in estimated coal-in-ground reserves of rock type in the catchment. The Pebbly Hill quartz gravel 5.4 Mt (Liggett 1979). deposits and quartz gravels near Waikaka are worked as an aggregate source and for decorative purposes. All of Peat these deposits have very large reserves which, in the case of pits working modern river beds, are replenished during Peat deposits cover significant areas of the Southland floods. Plains, and several are currently being exploited (Fig. 39). Large deposits occur southeast of Invercargill, east of Aggregate is quarried from Caples t.z. I sandstone in the Otautau, and south of Mossburn. The deposits are up to Blue Mountains. Caples semischists make poorer 15 m thick. These deposits range from fine-grained aggregate as they break down more rapidly; nevertheless, Sphagnum peats to accumulations of branches, logs and semischist is frequently quarried for base course metal for stumps. Very large reserves exist east of Invercargill, roading. Where Murihiku Supergroup sedimentary rocks although partly protected as botanical reserves. predominate, good aggregate is scarce because of pervasive

55 zeolitisation, and conglomerate horizons are often worked Lignite Measures are unlikely to have economic potential. preferentially as the clasts are commonly hard. Some Maitai Although montmorillonite and illite occur within Waicoe Group sedimentary rocks - mainly Little Ben Sandstone - and Winton Hill formation mudstones, these have never have been quarried for roading aggregate. “Rotten rock” been worked and the mudstones are unsuitable for ceramic from small quarries in weathered outcrops of most basement manufacture (Wood 1969). units is widely used throughout Southland as base course for farm roading. Bluff Intrusives and Greenhills Group Loess, suitable for brick and tile manufacture, is extremely metasediments (especially tuffs) are also worked for widespread within the map area, although the only current aggregate. The basic tuffs within the Greenhills Group are operation is for making field tiles, at Pukerau. Loess more suitable than the veined mafic intrusive rocks resources within the map area are very large. (Lindqvist et al. 1994). Aggregate on Stewart Island is in very short supply, and it has sometimes been shipped Building stone and riprap across from the mainland. The existing quarry in variably weathered diorite cannot provide aggregate of a suitable Riprap for river protection work is intermittently quarried standard and exploration is under way for a better source. from Maitai and Murihiku rocks near Mossburn, and from Dun Mountain Ophiolite Belt rocks near Otama. Large Limestone blocks of Forest Hill Formation limestone are suitable for river protection work. Norite was quarried for reclamation The Murihiku area has large reserves of Cenozoic limestone at Bluff (Watters et al. 1968) and, together with norite from suitable for agricultural use. Thin limestones within Ruapuke Island, has also been used as a building stone Permian Maitai and Kuriwao groups have been also (Hayward 1987). Hayward also records Triassic sandstone worked, but largely as a source of aggregate. Most quarries as having been used in buildings at localities across the are in Forest Hill Formation (Fig. 30) although limestone- Murihiku sheet, including Waikawa in the Catlins. However rich facies of the Chatton Formation have been worked at the zeolitic cement in these sandstones is a drawback as it Waimumu (McKellar 1968) and Balfour (Isaac & Lindqvist renders them vulnerable to weathering. 1990). Forest Hill Formation limestone is variably hard and may require blasting. Groundwater

Silica sand Groundwater is a valuable resource within the Murihiku map area, especially with increasing demand for water from Quartz sand within the Gore Lignite Measures north of the dairy industry. Lindqvist et al. (1994) summarised Invercargill, and on Landslip Hill, has been worked for actual and potential aquifers and their properties; a regional plastering sand and as an abrasive, respectively (Lindqvist map and discussion of aquifers is given by Hughes (2001). et al. 1994). The greatest yields are from aquifers within loose sandy gravels close to rivers, and from modern and raised beach Serpentinite gravels. These aquifers are unconfined and vulnerable to pollution. Groundwater is also obtained from older terrace Serpentinite, used as a magnesium source in fertiliser, was gravels, but these aquifers are limited by a high clay content formerly quarried at Black Ridge northeast of Mossburn. (Hughes 2001). Groundwater in deeper gravels is typically Serpentinite and dunite are now quarried from ultramafic contained within coarser, less clay-bound gravel in rocks at Greenhills. Reserves have not been calculated but lenticular buried channels with no connection to nearby within the Greenhills Ultramafic Complex are likely to be channels, and adjacent wells may not be tapping the same many millions of tonnes. aquifer.

Clay Cenozoic sedimentary rocks can also produce groundwater. Some quartz sands and gravels in the Eastern Southland Several sources of kaolinitic clay within the map area have Coalfield produce strongly artesian flows from depths as been worked in the past. Clay minerals are abundant in great as 200 m. Some of this groundwater is of high quality, deeply weathered granitic rocks on Stewart Island, but but in other wells it is unacceptably acidic through have not been exploited. The Ohai Group includes clays interaction with coal-bearing strata (Hughes 2001; Rosen as “seat earths” beneath coal seams, and these have 2001). The Chatton Formation, interbedded with lignite potential for ceramic use (Bowen 1964), but mining is likely measures, hosts an aquifer system near the Toetoes Bay to be difficult and the extent of the clays is unknown. coastline (Lindqvist et al. 1994). Groundwater is also Nightcaps Group clay at Waimeamea has been used for extracted from fracture systems within Forest Hill Formation brick-making (Wood 1969). Clay was mined from the (Hughes 2001), and may also be present in older, harder Pomahaka Coalfield and from Mako Coal Measures west rocks, within joints and fractures rather than in pore spaces of Hedgehope. Thin beds of kaolinitic clay within the Gore as it is in the younger rocks. Yields from such fracture systems are generally low.

56 GEOLOGICAL HAZARDS

Numerous geological hazards exist within the Murihiku e.g., local magnitude (ML), surface wave magnitude (MS), map area. They include landsliding, earthquake shaking and moment magnitude (MW). These may differ by small and liquefaction, erosion, tsunami, and groundwater amounts. MW is the most reliable, but is only available for contamination. Many of these hazards are influenced by large earthquakes. In this publication, the generic term geological factors such as rock properties and distribution, magnitude may be assumed to be ML for small and moderate and the presence and activity of faults. The hazards are earthquakes, and MW or MS for large earthquakes that have summarised here, but this map and text should not be used occurred since instrumental measures have been available. for detailed natural hazard zonation or assessment of specific sites. Recording of site-specific natural hazard The Modified Mercalli intensity scale (MM scale; see information is the responsibility of local authorities, and text box) is a 12-level descriptive scale used to rank the an awareness of the presence of major hazards, and their strength or intensity of shaking produced by an earthquake potential for recurrence, is essential for regional and district at a location. The MM intensity level is determined by planning purposes. Regional hazard assessments are given noting the effects of shaking on people, fittings, structures by Van Dissen et al. (1993) and Glassey (2002). and the environment at the place of interest and comparing them with descriptors in the scale. MM 10 is the highest Earthquakes (by G. L. Downes) MM intensity level so far reliably observed in New Zealand.

Since organised European settlement began in New Earthquake occurrence in the southern South Island Zealand, no large earthquakes and very few moderate or (Fig. 43) is predominantly within a zone of seismicity along small earthquakes are known to have occurred within the the Pacific - Australian plate boundary, part of which is Murihiku map area. Seismicity has been low in recent times formed by the Alpine Fault. Deformation caused by intra- (Fig. 43). However, moderate to strong shaking with some plate collision is responsible for many earthquakes, most damage has been caused by large earthquakes originating occurring at depths down to about 160 km. The largest of outside the map area, such as the 1979 M7.3 Puysegur these earthquakes, although not originating within the Bank earthquake and the 1988 M6.7 Te Anau earthquake. Murihiku map area, can cause moderate to strong shaking within it. For example, the 1988 M6.7 Te Anau earthquake, Magnitude and Modified Mercalli intensity are frequently 57 km beneath Fiordland, caused shaking intensities of used earthquake terms. Magnitude is a means of ranking MM5 or MM6 in the map area, with intensities up to MM8 the size of earthquakes. It is calculated using instrumental closer to the epicentre. The earthquake caused a temporary records of earthquake shaking. There are various ways of interruption of power supplies to Invercargill. doing this, which result in magnitudes of different types,

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.

57 1976 M6.5 Milford Sound

1988 M6.7 Te Anau

1993 M6.8 o S Secretary

o 1979 M 7.3 Puysegur Bank

Depth<40km Intensity Depth > 40 km 4-4.9 5-6.4 6.5 + o

o E oo oo

Figure 43 Locations of earthquakes in southwestern New Zealand with magnitudes >3.5, for the period 1964 - June 2002. Some significant earthquakes are highlighted. Murihiku map area is shaded.

Large shallow earthquakes may rupture to the ground (Rhoades & Van Dissen 2000; Norris et al. 2001). Such an surface along faults. Major faults west of the Murihiku event is expected to generate felt intensities of MM6 at area include the Hollyford, Dusky and Moonlight Fault Invercargill (Glassey 2002), causing widespread contents systems, and the Alpine Fault. Of these, the Alpine Fault damage to houses and some minor structural damage. is the most active, and considered capable of producing up to magnitude M8 earthquakes. Large earthquakes While most of the deformation associated with the plate producing surface fault ruptures on the onshore part of boundary occurs near the boundary, some is being the Alpine Fault probably occur every few hundred years transferred east of Fiordland. Large active faults within (Rhoades & Van Dissen 2000; Norris et al. 2001), the last the Murihiku map area (Fig. 44) include the Hauroko Fault known being in 1717. The probability of fault rupture of (part of the larger Moonlight Fault System), the Tin Hut the southwest onshore segment of the Alpine Fault in a Fault System (Fig. 45), the Blue Mountain No 1 Fault M8 earthquake within the next 20 years is 6-14% (Beanland & Berryman 1986), and the Hillfoot Fault. Smaller 58 traces are mapped within the Hokonui Hills, in the Catlins on other parts of the faults. Physical offset on active faults (Settlement Fault of Speden 1971; Bishop & Turnbull 1996), will affect objects and the landscape on or within a few near Clinton (Clifton Fault) and on the Spylaw Fault hundred metres of the faults. Shaking will be more intense (Beanland & Berryman 1986). More detail on some of these toward faults, possibly MM9 along ruptures, and will also faults is given by Van Dissen et al. (1993), Stirling et al. be stronger in deep soft soils. The degree of damage to be (1998) and Glassey (2002). Recurrence intervals (i.e. the expected from various intensities is summarised in the text average time interval between large earthquakes, Table 1) box. range from about 600 years to 3000 years or more (Stirling et al. 2000). Other possibly active faults have been Liquefaction, the phenomenon whereby saturated soils identified, but rupture histories are known for few of these and unconsolidated sediments change from a solid to a and it has not been possible to determine whether the liquid state, is often caused by strong earthquake criteria have been met for declaring a fault to be active, ground-shaking. Liquefaction occurs at intensities of MM7 that is, evidence of movement within the last 125 000 years and higher, and may occur at distances of 100-150 km from or repeated movement within the last 500 000 years. earthquakes of magnitude M7-7.9. Ground shaking and acceleration during large earthquakes are amplified in weak, Earthquakes ranging up to magnitude M7.3 can be expected unconsolidated sediments greater than 20 m in depth, such on surface rupturing faults within the Murihiku area. as near estuaries, river flats and swamps. This amplification Earthquakes of magnitude M7 and above often generate can increase shaking intensity locally by one or two MM long duration shaking, possibly in excess of one minute. intensity levels over that experienced on nearby firm Surface rupture with vertical or horizontal offsets of ground (Van Dissen et al. 1993). The fine-grained, water- perhaps several metres, may occur on or near mapped fault saturated artificial fill at Bluff Harbour is particularly prone traces, along strike from those traces, or as new ruptures to this type of settlement (Glassey 2002).

Hauroko Spylaw Fault Fault

Tin Hut Fault System

Hillfoot Fault Blue Mountain No.1Fault

Clifton Fault

Invercargill Settlement N Fault

Landslides Active Faults

Rivers 20 km Roads

Figure 44 Known active fault traces and large landslides within the mainland Murihiku map area.

59 Table 1 Estimated return periods for earthquakes within the Murihiku map area, calculated by W. Smith from the seismicity model of Stirling et al. (2000).

Intensity Mean return period (years) Invercargill Gore Te An MM6 40 50 10 MM7 350 300 45 MM8 5000 2600 320 MM9 78000 36000 4700

In the future, the Murihiku map area can expect moderate entire eastern seaboard of New Zealand, with damage in to strong shaking from relatively frequent large to very many places. In 1877, water levels in Bluff Harbour varied large earthquakes outside the area, and from infrequent by up to 1.2 m, moving buoys and creating strong currents. moderate to large earthquakes within its boundaries. In 1960, the effects at Bluff were minor, with a rise and fall Probabilistic hazard analysis suggests that maximum peak of only 15 cm, but at Colac Bay “debris and seaweed was ground acceleration (PGA) during a 475 year period in festooned along the waterfront and water reached right up Invercargill is 10-30% g (“g” = acceleration due to gravity; to baches on the high ground” (Southland Times 25 May Stirling et al. 2000). The maximum PGA increases to the 1960). west, and PGA of 1.0 g can be expected near the Alpine Fault. Active faults within the Murihiku area with longer Tsunami generated by distant events take many hours to return periods of up to 1000 years will also produce high reach New Zealand, sufficient time for Civil Defence to PGA values, particularly on soft ground. In terms of take appropriate action. Locally generated tsunami are of shaking intensity, the mean return periods for average more concern as wave heights may be large enough to be ground for some locations within the Murihiku area are damaging and life-threatening, possibly catastrophic, and given in Table 1. travel times may be too short for Civil Defence to issue warnings. Very strong shaking is warning enough to leave Tsunami (by G. L. Downes) coastal locations and move inland. Local tsunami may persist for up to twelve hours, and distant source tsunami Coastal flooding and damage due to tsunami are possible for as much as three days. The first waves of any tsunami along the entire coastline of the Murihiku map area, are often not the largest. Wave heights are difficult to including Stewart Island, and for several kilometres up predict in advance, and may vary greatly within a short estuaries such as Jacobs River, New River and Bluff distance due to local bathymetry or topography. Harbour. Tsunami are generated by large sudden movements of the sea floor caused by local or distant Landslides earthquakes, volcanoes, or by local submarine or coastal landslides, possibly initiated by strong earthquake shaking. Landslides within the Murihiku area are most common in They can also be generated by meteorite impact. the semischist terrain in the north, and in Mesozoic and Cenozoic mudstones (Fig. 44). Semischist landslides are An uprising of the sea in the 1820s caused the deaths of slow-moving and complex failures, and a number are active, many Maori on the beach near Orepuki and affected much at least in part. Damage from further movement will of the coast (Bradley 2002). The event was almost certainly generally be restricted to local farm infrastructure. a tsunami with a local origin, suggesting that waves generated by large offshore earthquakes or submarine Landslides within Murihiku Supergroup rocks in the upper slumping could significantly affect much of the Murihiku Wairaki River and in the Catlins are dip-slope failures along coastline. mudstone beds. Small landslides (up to 1 km2) in Cenozoic sediments (Fig. 44) are mainly in Waicoe or Winton Hill In contrast, distant source tsunami have had less impact Formation mudstones; these pose only a local risk. A in the Murihiku area. The largest tsunami known were those spectacular landslide in Gore Lignite Measures on Landslip caused by very large earthquakes on the west coast of Hill (Fig. 46) records repeated movements and parts of it South America in 1868, 1877, and 1960. These produced remain active. strong water level oscillations over several days along the

60 Figure 45 The upper Wairaki River area, looking south over a prominent Holocene trace in the Tin Hut Fault System (centre) (Landis et al. 1999). Hills immediately to the left (east) of the fault are underlain by Caravan Formation, Takitimu Subgroup. Ohai township is in the far distance. Photo CN43884/22: D.L. Homer

61 Volcanic hazard mines within the Eastern Southland Coalfield or in peripheral mining areas such as Waikaka and Maitland may be at risk. Solander and Little Solander islands in western Foveaux The hazard has not been quantified; that would require Strait, beyond the map area, are the eroded remnants of an detailed examination of old mine plans together with an andesitic volcano associated with subduction of the assessment of rock strengths above old workings. Australian Plate beneath the Pacific Plate at the Puysegur Trench. There is seismic evidence for several other Groundwater contamination volcanoes nearby (Turnbull & Uruski 1993). Solander volcano is of Pleistocene age (Bishop 1986) and the others Groundwater contamination is potentially a serious hazard. are as old as Miocene. No ash deposits associated with This hazard is increasing with changes in land use, for these volcanoes have been identified in Southland, and example from sheep farming to intensive dairying. There Solander volcano is quiescent, but there remains a is evidence that agriculture, horticulture and factories are possibility of renewed volcanic activity in the vicinity of already affecting groundwater chemistry in Southland, Solander Island. Any resumption of activity would be especially in shallow aquifers, where high nitrate levels signalled by swarms of low-magnitude earthquakes and faecal coliform indicator bacteria have been found in preceding any eruption by weeks, months, or even years. bores (Hughes 2001). Localised groundwater contamination is mainly found close to such sources as Subsidence due to mining septic tanks and offal pits, and where wellhead protection is inadequate. The Edendale Aquifer, the only Southland The hazard posed by ground collapse following aquifer that has been systematically studied, has been underground mining is largely restricted to the Ohai showing elevated nitrate levels since the mid-1980s, and district, although small areas above old underground lignite pesticide residues have also been found (Hughes 2001).

Figure 46 Active landsliding in Gore Lignite Measures on Landslip Hill, north of Waipahi. Older landslides with smoother topography and degraded headscarps are visible on either side of the active landslide. The scarp is supported by silcrete within the Gore Lignite Measures (Lindqvist 1990). Photo CN44012/7: D.L. Homer 62 AVAILABILITY OF QMAP DATA ACKNOWLEDGMENTS

The geological map accompanying this booklet is based The Murihiku geological map was compiled by I.M. on information stored in the QMAP Geographic Information Turnbull (NZMS 260 sheets D43, D44, D45, E44, E45, F45, System maintained by the Institute of Geological & Nuclear F47, G44, G46, G47) and A.H. Allibone (C50, D48, D49, Sciences. The data on the map are a subset of available D50, E48, E49) with help from N. Mortimer (F44, F46 and information. Other single or multi-factor maps can be part D46), D. Thomas (E47 and part E46), P.J. Glassey, A.J. generated from the GIS as required, for example maps Tulloch, M.S. Rattenbury, S. Wilson and F.J. Brook. showing single rock types, or mineral localities in relation Unpublished geological maps of the Blackmount, western to host rocks. Other digital data sets which may be Ohai, and Taringatura Hills areas were provided by R.M integrated with the basic geology include gravity and Carter and R.J. Norris, C.J. Patchell, and the late J.D. magnetic surveys, active faults, earthquakes, landslides, Campbell respectively. C.R. Anderson, Y. Cook, E. Ladley, mineral resources and localities, fossil localities, and B. Morrison, C.J. Paterson, C. Reid, R.J. Smillie, P. petrological samples. Data can be presented for user- Stenhouse, S. Wilson, C.J. Adams, P.J. Forsyth, M. defined areas or within specified distances from roads or Falconer, J.G. Begg and H.J. Campbell helped with the coastlines. Maps can be produced at varying scales, fieldwork; Campbell and Begg also helped with the bearing in mind the scale of data capture and the paleontology. Tulloch provided radiometric and generalisation involved in digitising; maps produced at geochemical data and assisted with the interpretation of greater than 1:50 000 scale will not show accurate, detailed the Stewart Island rocks. geological information unless they are based on point data (e.g. structural information). Contributions from staff of the Geology Department, University of Otago (including D.S. Coombs and C.A. Raster image files of QMAP sheets, with digital versions Landis) are acknowledged with thanks. A.F. Cooper gave of accompanying booklet texts, are available on CD-ROM. permission to use information from theses. Image files can also be downloaded from the GNS web site http://www.gns.cri.nz. If required, QMAP series map data Helicopter support was provided by South West can also be made available in vector GIS format. Helicopters (C. Brown, D. Sutherland, W. Pratt, and the late T. Green), and fixed wing support by Wanaka The data record maps on which the digital geology is based Flightseeing (A. Woods). K. Geeson (Seaview Water Taxi), are filed in GNS offices at Dunedin and Gracefield (Lower R. Tindal (N.Z. Forest Service), and A. Gray and P. Lowen Hutt) and, although unpublished, are available for (Department of Conservation) helped with seaborne consultation. The map units and geological legends used access to Stewart Island. Coastal geology was supported on the detailed maps are based on a lithostratigraphic by R. Russ and the crew of R/V Huia. mapping philosophy, and may differ from those shown on this published QMAP sheet. The QMAP database will be D.J.A. Barrell (Quaternary geology), P.J. Glassey and G.L. maintained, and updated where new geologic mapping Downes (Hazards) contributed to the map text; digitising improves existing information. For new or additional was done by J. Arnst, B. Smith Lyttle, D. Thomas and C. geological information, for prints of this map at other scales, Thurlow. N.D. Perrin and R. Thomson helped with landslide for selected data or combinations of data sets, or for mapping and interpretation of Quaternary geology; derivative or single-factor maps based on QMAP data, bathymetric data were supplied by the National Institute please contact: of Water and Atmospheric Research and manipulated by P.G. Scadden. The map and legend were prepared for The QMAP Programme Leader publication by D.W. Heron, B. Smith Lyttle, C. Thurlow Institute of Geological and Nuclear Sciences Ltd and M. Coomer; the base map was obtained from Land P O Box 30368 Information New Zealand. Discussion and comment on Lower Hutt. all or part of the map and text from D.J.A. Barrell, H.J. Campbell, P.J. Forsyth, N. Mortimer, D.D. Ritchie and A.J. Tulloch are gratefully acknowledged. The map and text were reviewed by J.G. Begg, M.J. Isaac and M.R. Johnston.

Funding was provided by the Foundation for Research, Science and Technology, under contracts CO5809, CO5X0003 and CO5X0206.

63 REFERENCES

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64 Bradley, D. 2002: Tsunami. In Invercargill City Council Lifelines Cave, M.P.; Boyer, C.M. 1990: Natural gas from coal; Southgas Project Hazards Report. Invercargill, Invercargill City investigations at Ohai, New Zealand. Proceedings of the Council. Section 5. Pp. 1-13.+ New Zealand Petroleum Exploration Conference, Bradshaw, J.D. 1993: A review of the Median Tectonic Zone: Queenstown: 357-364. Ministry of Commerce.+ terrane boundaries and terrane amalgamation near the Median Cawood, P.A. 1986: Stratigraphic and structural relations of the Tectonic Line. New Zealand Journal of Geology and southern Dun Mountain Ophiolite Belt and enclosing strata, Geophysics 36: 117-125.+ northwestern Southland, New Zealand. New Zealand Journal Bruce, J.G. 1973: Loessial deposits in southern South Island, of Geology and Geophysics 29: 179-204.+* with a definition of Stewarts Claim Formation. 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Institute of Geological & Nuclear Sciences Carter, R.M.; Hicks, M.D.; Norris, R.J.; Turnbull, I.M. 1978: Monograph 20. 188 p. +* Sedimentation patterns in an Ancient Arc-Trench-Ocean Coombs, D.S. 1950: The geology of the northern Taringatura Basin Complex: Carboniferous to Jurassic Rangitata Orogen, Hills, Southland. Transactions of the Royal Society of New New Zealand. In Stanley, D. J.; Kelling, G. ed. Sedimentation Zealand 78: 426-448.+* in submarine canyons, fans and trenches. Stroudsburg, Coombs, D.S.; Landis, C.A.; Norris, R.J.; Sinton, J.M.; Borns, Pennsylvania, Dowden, Hutchison and Ross Inc. Pp. 340- D.J.; Craw, D. 1976: The Dun Mountain Ophiolite Belt, 361 + New Zealand, its tectonic setting, constitution, and origin, Carter, R.M.; Lindqvist, J.K.; Norris, R.J. 1982: Oligocene with special reference to the southern portion. American unconformities and nodular phosphate: hardground horizons Journal of Science 276: 561-603.+ in western Southland and northern West Coast. 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65 Cowden, A.; Ruddock, R.; Reay, A.; Nicolson, P.; Waterman, P.; Ford, P.B. 1999: Report on exploration program carried out by Banks, M.J. 1990: Platinum mineralisation potential of the ANZEX Resources within the 40304 exploration permit area, Longwood Igneous Complex, New Zealand. Mineralogy and on and about the Longwood range, Southland, New Zealand. Petrology 42: 181-195.+ New Zealand unpublished open-file mining company report Cox, S.C.; Allibone, A.H. 1995: Naming of igneous and M3696, Ministry of Economic Development, Wellington . metamorphic rock units in Antarctica: recommendation by Ford, P.B.; Lee, D.E.; Fischer, P.J. 1999: Early Permian conodonts the SCAR Working Group on Geology. Antarctic Science 7: from the Torlesse and Caples Terranes, New Zealand. 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Dam Site - Preliminary Geological argon mineral dates on intrusive rocks from the Foveaux Status Report. Institute of Geological & Nuclear Sciences Strait area. New Zealand Journal of Geology and Geophysics Client Report 35561T.10a, Institute of Geological & Nuclear 11: 1230-1235.+ Sciences, Lower Hutt.* Doole, M.H.; Watters, W.A.; Christie, A.B. 1989: Sheet QM438 Graham, I.J. 1977: Geology of Ocean Beach, Southland. BSc Port Pegasus and part Sheet QM 418 Bluff. Geological (Hons) thesis, University of Otago, Dunedin.+* Resource Map of New Zealand 1:250 000. New Zealand Graham, I.J.; Mortimer, N. 1992: Terrane characterisation and Geological Survey Report M155. 22 p.+ timing of metamorphism in the Otago Schist, New Zealand, Douglas, A. 1997: Potassic intrusions into the Takitimu Group, using Rb-Sr and K-Ar geochronology. New Zealand Journal Wether Hill. 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66 Henley, R.W.; Higgins, N.C. 1977: Geology of the granitic terrane Kimbrough, D.L.; Mattinson, J.M.; Coombs, D.S.; Landis, C.A.; of southwestern Stewart Island (Note). New Zealand Journal Johnston, M.R. 1992: Uranium-lead ages from the Dun of Geology and Geophysics 24: 333-348.+ Mountain ophiolite belt and Brook Street terrane, South Hope, J.M.; Nicholson, D.S.; Marshall, T. 1971: Feasibility study Island, New Zealand. Geological Society of America Bulletin for a silicon industry in Southland, New Zealand. Proceedings 104: 429-443.+ of the Australasian Institute of Mining and Metallurgy 240: Kimbrough, D.L.; Tulloch, A.J.; Coombs, D.S.; Landis, C.A.; 83-96.+ Johnston, M.R.; Mattinson, J.M. 1994: Uranium-lead zircon Houghton, B.F. 1977: Geology of the Takitimu Group and ages from the Median Tectonic Zone, New Zealand. New associated intrusive rocks, central Takitimu Mountains, Zealand Journal of Geology and Geophysics 37: 393-419.+ western Southland, New Zealand. 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A. 1973b: Attitudes of bedding, Southland Plains. Hyden, F.M. 1979: Mid-Tertiary temperate shelf limestones, Unpublished map, file number VF1834, Institute of Southland, New Zealand. PhD thesis, University of Otago, Geological & Nuclear Sciences, Dunedin.* Dunedin.+ Liggett, K.A. 1973c: Progress report on mapping of part of Hyden, F.M. 1980: Mass flow deposits on a mid-Tertiary Southland Plains in connection with examination of Mataura carbonate shelf, southern New Zealand. Geological Magazine Coalfield. Unpublished technical file report E46/710, Institute 117: 409-424.+ of Geological & Nuclear Sciences, Dunedin.* Hyden, G. 1979: Geology of the West Dome sector of the Dun Liggett, K.A. 1976: Notes on the Pleistocene geology of the Mountain Ophiolite Belt. PhD thesis, University of Otago, Riverton District. Unpublished technical file report E46/ Dunedin.+* 723, Institute of Geological & Nuclear Sciences, Dunedin.+* Hyden, G.; Begg, J.G.; Campbell, H.J.; Campbell, J.D. 1982: Liggett, K.A. 1979: Report on 1978 Mapping and Drilling of Permian fossils from the Countess Formation, Mossburn, Pomahaka Coalfield. New Zealand Geological Survey Report Southland. New Zealand Journal of Geology and Geophysics M72. 12 p. +* 25: 101-108.+* Lindqvist, J.K. 1990: Deposition and diagenesis of Landslip Hill Isaac, M.J.; Lindqvist, J.K. 1978: Geology of Maitland Coalfield. silcrete, Gore Lignite Measures (Miocene), New Zealand. Unpublished map, file number VF2147, Institute of New Zealand Journal of Geology and Geophysics 33: 137- Geological & Nuclear Sciences, Dunedin.* 150.+ Isaac, M.J.; Lindqvist, J.K. 1990: Geology and lignite resources Lindqvist, J. K. 1992: Study of sedimentation and erosion, of the East Southland Group, New Zealand. New Zealand Makarewa River, Southland. 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68 Muir, R.J.; Ireland, T.R.; Weaver, S.D.; Bradshaw, J.D.; Evans, Peden, R. 1988: Dynamic Metamorphism within the Rakeahua J.A.; Eby, G.N.; Shelley, D. 1998: Geochronology and Batholith, Mason and Doughboy Bay Region, Stewart Island. geochemistry of a Mesozoic magmatic arc system, Fiordland, MSc thesis, University of Otago, Dunedin.+* New Zealand. Journal of the Geological Society of London Pocknall, D.T.; Mildenhall, D.C. 1984: Late Oligocene - Middle 155: 1037-1052.+ Miocene spores and pollen from Southland, New Zealand. Mutch, A.R. 1960: S168 - The Nightcaps. Unpublished map, New Zealand Geological Survey Paleontological Bulletin 51. file number VF528, Institute of Geological & Nuclear Sciences, 120 p. + Dunedin.* Pole, M. 2001: Repeated flood events and fossil forests at Curio Mutch, A.R. 1964: Sheet S159 Morley. Geological Map of New Bay (Middle Jurassic), New Zealand. Sedimentary Geology Zealand 1:63 360. Wellington, New Zealand, Department of 144: 223-242.+ Scientific and Industrial Research. 1 sheet. +* Price, R.C.; Sinton, J.M. 1978: Geochemical Variations in a Suite Mutch, A.R. 1967: Riverton. Unpublished map, file number of Granitoids and Gabbros From Southland, New Zealand. VF351, Institute of Geological & Nuclear Sciences, Dunedin.* Contributions to Mineralogy and Petrology 67: 267-278.+* Mutch, A.R. 1972: Geology of Morley Subdivision. New Zealand Pringle, I.J. 1975: Geology of the Brown Peak - Clare Peak area, Geological Survey Bulletin 78. 104 p. + northern Takitimu Mountains, western Southland, New Mutch, A.R. 1975: Eastern Southland Coalfield. New Zealand Zealand. BSc (Hons) thesis, University of Otago, Dunedin.+* Geological Survey Report M44. 25 p. +* Purdie, B. R. 1970: Final report on the Bluff area. New Zealand Mutch, A.R. 1975: Eastern Southland Coalfield. Unpublished unpublished open-file mining company report MR31 for map, file number VF696, Institute of Geological & Nuclear McIntyre Mines NZ Ltd, Ministry of Economic Sciences, Dunedin.* Development, Wellington.* Mutch, A.R. 1976: N.Z. Forest Products Ltd Groundwater Rattenbury, M.S.; Heron, D.W. 1997: Revised Procedures and Investigation, Riverton District, Southland. Unpublished Specifications for the QMAP GIS. Institute of Geological & technical file report E46/410, Institute of Geological & Nuclear Nuclear Sciences Science Report 97/3. 52 p.+ Sciences, Dunedin.* Rhoades, D.A.; Van Dissen, R.J. 2000: Probability of Rupture Mutch, A.R. 1977: Drill holes and silicified quartz conglomerate on the Alpine Fault allowing for uncertainties. EQC Research horizons Landslip Hill - S170. Unpublished technical file Report 99/388, prepared by the Institute of Geological & report G45/334, Institute of Geological & Nuclear Sciences, Nuclear Sciences. 23 p.+ Dunedin.* Ritchie, D.D. 1977: The geology of the area east of the Waipahi Mutch, A.R.; Baker, L.A. 1989: Recent exploration and evaluation River, eastern Southland. 3rd year report, University of Otago, of detrital gold in Otago and Southland. In Kear, D. ed. Dunedin. * Mineral Deposits of New Zealand. Monograph 13. Ritchie, D. D. 1994: Regional geochemical and geological survey Australasian Institute of Mining and Metallurgy, Parkville, follow-up: Nokomai hard rock gold exploration programme. Victoria, Australia. Pp. 189-196. + New Zealand unpublished open-file mining company report Nathan, S. 1993: Revising the 1:250 000 Geological Map of New MR2031 for L & M Mining Ltd, Ministry of Economic Zealand - a discussion paper. Institute of Geological & Development, Wellington.* Nuclear Sciences Science Report 93/26. 28 p. Rolston, K.A. 1972: Reconnaissance study of Stewart Island Nathan, S.; Rattenbury, M.S.; Suggate, R.P. (compilers) 2002: Prospect. New Zealand unpublished open-file mining Geology of the Greymouth area. Institute of Geological & company report MR135 for Magellan Petroleum NZ Ltd, Nuclear Sciences 1:250 000 geological map 12. Lower Hutt, Ministry of Economic Development, Wellington.+ New Zealand. Institute of Geological & Nuclear Sciences. 1 Rombouts, M.J. 1994: Geology of the southern Longwood tops, sheet + 58 p.+ western Southland. MSc thesis, University of Otago, Nebel, O. 2003: Geology of the southern Takitimu Mountains. Dunedin.+* MSc thesis, University of Muenster, Muenster.+* Rosen, M.R. 2001: Hydrochemistry of New Zealand’s aquifers. Nicholson, P.; Inger, M.; Cowden, A. 1988: Geological and In Rosen, M. R.; White, P. A. ed. Groundwaters of New geochemical report Longwood Range project, Invercargill Zealand. Christchurch, Caxton Press, New Zealand District. New Zealand unpublished open-file mining Hydrological Society. Pp. 77-110 + company report MR1154 for Sigma Resources, Ministry of Roser, B.P.; Coombs, D.S.; Korsch, R.J.; Campbell, J.D. 2002: Economic Development, Wellington. + Whole-rock geochemical variations and evolution of the arc- Noda, A.; Takeuchi, M.; Adachi, N. 2002: Fan deltaic-to-fluvial derived Murihiku Terrane, New Zealand. Geological sedimentation of the Middle Jurassic Murihiku Terrane, Magazine 139: 665-685.+ Southland, New Zealand. New Zealand Journal of Geology Rossiter, A.G. 1989: Final report on exploration licence 33-383, and Geophysics 45: 297-312.+* Waiau Valley, Southland. New Zealand unpublished open- Norris, R.J.; Cooper, A.F.; Wright, T.; Berryman, K. 2001: Dating file mining company report MR1455 for Platinum Group of past Alpine Fault rupture in South Westland. EQC Research Metals NL, Ministry of Economic Development, Report 99/341. 70 p. + appendices.+ Wellington.+ Norris, R.J.; Turnbull, I.M. 1993: Cenozoic Basins Adjacent to Rout, M.V. 1947: Geology of the Forest Hill Survey District, an Evolving Transform Plate Boundary, Southwest New Southland. New Zealand Journal of Science and Technology Zealand. In Ballance, P. F. ed. South Pacific Sedimentary 29B: 1-9.+ Basins. Sedimentary Basins of the World. Amsterdam, Ryder-Turner, N. 1977: The Geology of the Gore-Pukerau area. Elsevier Science Publishers B.V. Pp. 251-270 + BSc (Hons) thesis, University of Otago, Dunedin.* O’Loughlin, B. 1998: Geology of the Greenhills Ultramafic Salvador, A. ed 1994: International Stratigraphic Guide (Second Complex, Bluff Peninsula. BSc (Hons) thesis, University of Edition). International Union of Geological Sciences, Otago, Dunedin.+* Trondheim, Norway, and Geological Society of America, Patchell, C.M. 2002: The Geology of Mount Linton Station, Boulder, Colorado. + Southland, New Zealand. Scale 1:21739. Unpublished map, Scott, G.L. 1974: Geology of the Gladstone Peak area, Takitimu file number VF2829, Institute of Geological & Nuclear Mountains, western Southland, New Zealand. BSc (Hons) Sciences, Dunedin. * thesis, University of Otago, Dunedin.+*

69 Service, H. 1937: An Intrusion of Norite and Its Accompanying Tulloch, A.J. 2001: Sr-Nd isotopic test for Brook Street affinity Contact Metamorphism at Bluff, New Zealand. Transactions of rocks in NW Stewart Island and Ruapuke Island. of the Royal Society of New Zealand 67: 185-217.+* Unpublished technical file report D48/571, Institute of Simpson, B. 2002: The Murihiku - Maitai terrane boundary, Geological and Nuclear Sciences, Dunedin. + South East Otago. MSc thesis, University of Otago, Tulloch, A.J. 2003: U-Pb geochronology of plutonic rocks from Dunedin.* Stewart Island, New Zealand. Unpublished technical file Spandler, C.J.; Eggins, S.M.; Arculus, R.J.; Mavrogenes, J.A. report D48/59, Institute of Geological and Nuclear Sciences, 2000: Using melt inclusions to determine parent-magma Dunedin. + compositions of layered intrusions: Application to the Tulloch, A.J.; Kimbrough, D.L. in press: Paired plutonic belts in Greenhills Complex (New Zealand), a platinum group convergent margins and the development of high Sr/Y minerals-bearing island-arc intrusion. Geology 28: 991-994.+* magmatism: the Peninsular Ranges Batholith of California Speden, I.G. 1957: Wyndham field sheets. Unpublished maps, and the Median Batholith of New Zealand. Geological Society file numbers VF64, VF1562, Institute of Geological & Nuclear of America Special Paper 374 (Gastil volume). Sciences, Dunedin.+* Tulloch, A.J; Kimbrough, D.L.; Faure, K.; Allibone, A.H. 2003: Speden, I.G. 1971: Geology of Papatowai Subdivision, southeast Paleozoic plutonism in the New Zealand sector of Gondwana Otago. New Zealand Geological Survey Bulletin 81. 166 p. (Abstract). Ishihara Symposium, Macquarie University, July +* 2003. Geoscience Australia. Spell, T.L.; Tulloch, A.J.; Allibone, A.H.; Walker, N.W. 1999: Tulloch, A.J.; Kimbrough, D.L.; Landis, C.A.; Mortimer, N.; Assembly and breakup of the Pacific Gondwana Margin: Johnston, M.R. 1999: Relationships between the Brook Another Piece of the Puzzle from Stewart Island, New Street Terrane and Median Tectonic Zone (Median Batholith): Zealand. Eos Transactions, Fall Meeting Supplement. evidence from Jurassic conglomerates. New Zealand Journal American Geophysical Union 80 (17): F1070.+ of Geology and Geophysics 42: 279-293.+ Stenhouse, P. 2002: Terrane affinities in the southern Blue Turnbull, I.M. 1979: Stratigraphy and sedimentology of the Mountains, West Otago. BSc (Hons) thesis, University of Caples terrane of the Thomson Mountains, northern Otago, Dunedin.+* Southland, New Zealand. New Zealand Journal of Geology Stewart, D. L.; Barrell, D. J. A. 1995: Lower Clutha Power and Geophysics 22: 555-574.+ Investigations - Tuapeka Project. Geology, geomorphology Turnbull, I. M. 1992: Cretaceous and Cenozoic stratigraphic and landslide hazards of the right bank slopes, Rongahere columns from the Western Southland region. New Zealand Gorge. Institute of Geological and Nuclear Sciences Client Geological Survey Report G169. 100 p.* Report 352904.22A, Institute of Geological & Nuclear Turnbull, I.M. 2000: Geology of the Wakatipu area. Institute of Sciences, Lower Hutt.* Geological & Nuclear Sciences 1:250 000 geological map Stewart, D. L.; Glassey, P. J. 1993: Lower Clutha Power 18. Lower Hutt, Institute of Geological & Nuclear Sciences. Investigations - Tuapeka Project. Preliminary reservoir 1 sheet + 72p.+ landslide hazard assessment, Tuapeka Mouth to Beaumont. Turnbull, I.M.; Craw, D.; Mortimer, N. 2001: Textural zonations Institute of Geological and Nuclear Sciences Client Report in the Haast Schist - a reappraisal. New Zealand Journal of 1993/39, Institute of Geological & Nuclear Sciences, Lower Geology and Geophysics 42: 171-183.+ Hutt.* Turnbull, I.M.; Ker, D.S. 1970: Quartz gravels as a source for Stirling, M.; McVerry, G.; Berryman, K.; McGinty, P.; Villamor, silica in Otago and Southland. Unpublished technical file P.; Van Dissen, R.J.; Dowrick, D.; Cousins, J.; Sutherland, report QM418/334, Institute of Geological & Nuclear R. 2000: Probabilistic Seismic Hazard Assessment of New Sciences, Dunedin.+ Zealand: New Active Fault Data. Institute of Geological and Turnbull, I.M.; Lindqvist, J.K.; Norris, R.J.; Carter, R.M.; Cave, Nuclear Sciences Client Report 2000/53, Institute of M.P.; Sykes, R.; Hyden, F.M. 1989: Lithostratigraphic Geological & Nuclear Sciences,, Lower Hutt.+ nomenclature of the Cretaceous and Cenozoic sedimentary Stirling, M.W.; Wesnousky, S.G.; Berryman, K.R. 1998: rocks of Western Southland, New Zealand. New Zealand Probabilistic seismic hazard analysis of New Zealand. New Geological Survey Record 31. 55 p. + Zealand Journal of Geology and Geophysics 41: 355-375.+ Turnbull, I.M.; Uruski, C.I. 1993: Cretaceous and Cenozoic Sykes, R.1988: The Morley Coal Measures, Ohai Coalfield, sedimentary basins of Western Southland, South Island, New Southland. New Zealand Energy Research and Development Zealand. Institute of Geological and Nuclear Sciences Committee Report 170. 85 p.+ Monograph 1. 86 p. + 4 enclosures. + Sykes, R. 1989: The nature and origin of sediment intrusions in Turnbull, I.M.; Uruski, C.I. 1995: Geology of the Monowai - coal seams at Ohai, Southland. New Zealand Geological Waitutu area. Scale 1:50 000. Institute of Geological & Nuclear Survey Record 35: 109-112.+ Sciences geological map 19. Lower Hutt, Institute of Thomson, R.; Read, S.A.L. 1996: Tuapeka Hydro-electric Geological & Nuclear Sciences. 2 sheets + 68 p. + Investigations - Correlation of Quaternary alluvial terraces Van Dissen, R.J.; Lindqvist, J.K.; Turnbull, I.M. 1993: Earthquake in the Lower Clutha Valley. Institute of Geological and Nuclear hazards in the Southland Region. Institute of Geological & Sciences Client Report 35558T.10, Institute of Geological & Nuclear Sciences Client Report 1993/96, Institute of Nuclear Sciences, Lower Hutt. +* Geological & Nuclear Sciences, Lower Hutt.+* Thorn, V. 2001: Vegetation communites of a high paleolatitude Waddell, S.J. 1971: Some aspects of the geology of the northern Middle Jurassic forest in New Zealand. Palaeogeography, coast of Stewart Island, New Zealand. MSc thesis, University Palaeoclimatology, Palaeoecology 168: 273-289.+ of Otago, Dunedin.+* Tulloch, A.J. 1983: Granitoid rocks of New Zealand – a brief Walker, N.; Allibone, A.H.; Tulloch, A.J. 1998: U-Pb ages of review. Geological Society of America Memoir 15: 5-20. + detrital zircon from Pegasus Group, Stewart Island. Tulloch, A.J. 1988: Batholiths, plutons and suites: nomenclature Geological Society of New Zealand Miscellaneous Publication for granitoid rocks of Westland - Nelson. New Zealand 101A: 239.+ Journal of Geology and Geophysics 31: 505-509.+ Waterhouse, J.B. 1958: The age of the Takitimu Group, western Tulloch, A.J. 1998: The Traps, Black Rock and bits of Southern Southland. New Zealand Journal of Geology and Geophysics Stewart Island. Unpublished technical file report D50/571, 1: 604-610.+ Institute of Geological & Nuclear Sciences, Dunedin.+ 70 Waterhouse, J.B. 1964: Permian stratigraphy and faunas of New Willett, R. W. 1950: Geological map of the Waiau Survey District. Zealand. New Zealand Geological Survey Bulletin 72. Unpublished map, file number VF728, Institute of Geological 111 p.+ & Nuclear Sciences, Dunedin.* Waterhouse, J.B. 1982: New Zealand Permian brachiopod Willett, R.W.; Wellman, H.W. 1940: The oil-shale deposit of systematics, zonation and paleoecology. New Zealand Orepuki, Southland. New Zealand Journal of Science and Geological Survey Paleontological Bulletin 48. 205 p. + Technology B22: 84-99.+* Waterhouse, J.B. 1998: Permian geology of Wairaki Downs, New Williams, G.J. 1934a: The genetic significance of some tin- Zealand, and the realignment of its biozones with the tungsten lodes in Stewart Island, New Zealand. Economic international standard. Proceedings of the Royal Society of Geology 29: 411-434.+ Victoria 110: 235-345. Williams, G.J. 1934b: A granite-schist contact in Stewart Island, Watters, W. A. 1947a: S160/9 Unpublished map, file number New Zealand. Quarterly Journal of the Geological Society of VF737, Institute of Geological & Nuclear Sciences, Dunedin.* London 90: 322-350.+ Watters, W. A. 1947b: East Gore - Pukerau. Unpublished map, Williams, G.J. 1974: Economic geology of New Zealand. file number VF81, Institute of Geological & Nuclear Sciences, AUSIMM Monograph Series 4, 2nd edition. Parkville, Dunedin.* Australasian Institute of Mining and Metallurgy. 384 p.+ Watters, W.A. 1961: Petrographic notes on specimens from Oreti Williams, G.J.; Mackie, J.B. 1959: Economic minerals in Stewart - Makarewa junction. Unpublished technical file report E46/ Island. Proceedings of a mineral conference, School of Mines 572, Institute of Geological & Nuclear Sciences, Dunedin.+ and Metallurgy, University of Otago, vol. 6, paper 125.+ Watters, W.A. 1962: Hornblende-rich gabbroic rocks from Cow Willsman, A. 1990: Stratigraphy, tectonics, and provenance of and Calf Point, Stewart Island, New Zealand. Transactions rocks in the Wether Hill area, western Southland. BSc (Hons) of the Royal Society of New Zealand (Geology) 1: 279-84. + thesis, University of Otago, Dunedin.+* Watters, W.A. 1978a: Diorite and associated intrusive and Wood, B.L. 1956: The Geology of the Gore Subdivision. New metamorphic rocks between Port William and Paterson Inlet, Zealand Geological Survey Bulletin 53. 128 p. +* Stewart Island, and on Ruapuke Island. New Zealand Journal Wood, B.L. 1958: Submarine geology of Bluff Harbour. New of Geology and Geophysics 21: 423-442.* Zealand Journal of Geology and Geophysics 1: 461-9. Watters, W.A. 1978b: Stewart, Snares and Bounty Islands. In Wood, B. L. 1965a: Heriot. Unpublished map, file number VF297, Suggate, R.P.; Stevens, G.R.; Te Punga, M.T. ed. The Geology Institute of Geological & Nuclear Sciences, Dunedin.* of New Zealand. Wellington, Government Printer. Pp. 111- Wood, B. L. 1965b: Sheet S177 Invercargill. Unpublished map, 112. + file number VF1349, Institute of Geological & Nuclear Watters, W.A. 1994: Notes on rocks within the Median Tectonic Sciences, Dunedin.* Zone near Nelson City and on Stewart and Codfish islands. Wood, B.L. 1966: Sheet 24 - Invercargill. Geological map of New Institute of Geological and Nuclear Sciences Science Report Zealand 1:250 000. Wellington, New Zealand, Department 94/27. 45 p. +* of Scientific and Industrial Research. 1 sheet. +* Watters, W.; Speden, I.G.; Wood, B.L. 1968: Sheet 26 - Stewart Wood, B.L. 1969: Geology of Tuatapere Subdivision, Western Island. Geological map of New Zealand 1:250 000. Southland. New Zealand Geological Survey Bulletin 69. 161 Wellington, New Zealand, Department of Scientific and p. +* Industrial Research. 1 sheet. +* Wood, B.L. 1978: Southland and Western Central Otago. In Webster, J. 1981: Geology of Ruapuke Island. BSc (Hons) thesis, Suggate, R. P.; Stevens, G. R.; Te Punga, M. T. ed. The University of Otago, Dunedin.+* Geology of New Zealand. Wellington, Government Printer. Willett, R. W. 1939: Western Southland. Unpublished maps, file Pp. 521-529 + numbers VF728-735, Institute of Geological & Nuclear Wood, B. L.; Hitt, G. J. 1964a: Invercargill air photo interpretation. Sciences, Dunedin.* Unpublished map, file number VF1203, Institute of Willett, R.W. 1943: A molybdenite-bearing quartz lode, Waiau Geological & Nuclear Sciences, Dunedin.* Survey District, Southland. New Zealand Journal of Science Wood, B. L.; Hitt, G. J. 1964a: Woodend air photo interpretation. and Technology B25: 91.+ Unpublished map, file number VF1204, Institute of Willett, R.W. 1946a: Orepuki Coalfield, Southland. New Zealand Geological & Nuclear Sciences, Dunedin.* Journal of Science and Technology B27: 439-445 .+ Woodward, D.J.; Hatherton, T. 1975: Magnetic anomalies over Willett, R. W. 1946b: Eastern Southland Coalfield. Unpublished southern New Zealand. New Zealand Journal of Geology maps, file numbers VF466, VF612, Institute of Geological & and Geophysics 18: 62-82.+ Nuclear Sciences, Dunedin.* Youngson, J.H.; Landis, C.A. 1997: The Te Wai Pounamu Erosion Surface (field trip guide). Geological Society of New Zealand Miscellaneous Publication 91B: FT2-1 - FT2-9.+

71 APPENDIX 1

NOMENCLATURE OF UNITS MAPPED ON biotite muscovite (garnet) granite with subordinate granodiorite STEWART ISLAND Age: Middle to Late Carboniferous

Many of the names applied in this map to the intrusive rocks of Freds Camp Pluton Stewart Island have not previously been published, although Previous usage or definition: introduced by Allibone & Tulloch some have appeared in theses. Several manuscripts giving detailed (1997) descriptions of the plutonic rocks are either in preparation or in Name: from Freds Camp, on the south side of Paterson Inlet review. A brief description of the new and previously mapped Type area: coastal outcrops near Freds Camp units is given here, sufficient to formalise the nomenclature (new Content: fine- to medium-grained quartz monzonite, granite and names are underlined). The definitions generally follow alkali feldspar granite lithostratigraphic nomenclatural procedures as outlined by Age: Middle Carboniferous to Early Permian Salvador (1994), modified for plutonic rocks following arguments presented by Cox & Allibone (1995). Intrusive rocks are generally Big Glory Pluton mapped as plutons, which may comprise a variety of rocks with Previous usage or definition: not previously named different compositions and textures. However all rocks within a Name: from Big Glory Bay, on the south side of Paterson Inlet single pluton have field relationships that suggest they are derived Type area: western shoreline of Big Glory Bay from a single or several closely related batches of magma. For Content: leucocratic fine-grained biotite muscovite granite this reason, only the most homogeneous plutons have been given Age: undated but inferred to be similar to Freds Camp Pluton names that include a specific composition (such as Ruggedy Granite). The nomination of type areas rather than single outcrops Forked Pluton for the plutonic units also reflects their variable internal character. Previous usage or definition: not previously named For some units, there are no useful or appropriate geographic Name: from Forked Creek, on the south side of the Freshwater names, and the plutons are named from their general type area Valley rather than a discrete place – e.g. Freshwater Northeast, Upper Type area: tributaries of Forked Creek around Grid Ref D48/ Kopeka. 2115000/5357000 Content: a plug of alkali feldspar granite and quartz syenite Ridge Orthogneiss Age: undated but inferred to be similar to Freds Camp Pluton Previous usage or definition: introduced by Allibone & Tulloch (1997) Rakeahua Pluton Name: from informal usage, after the summit ridge of Mt Allen Previous usage or definition: the name Rakeahua Granite was and Table Hill introduced by Watters et al. (1968); Allibone (1991) recognised Type area: open tops of Table Hill and Mt Allen several discrete plutons within the original unit and suggested Content: K-feldspar megacrystic and coarse-grained equigranular the original Rakeahua Granite be renamed the Rakeahua Batholith. biotite granodiorite orthogneiss Further mapping has enabled individual plutons to be recognised Age: Early Carboniferous throughout and the Rakeahua Pluton is now applied to the original type locality, but with a different definition. The term Rakeahua Ruggedy Granite Batholith has been abandoned Previous usage or definition: introduced by Allibone (1991) Name: from Mt Rakeahua Name: from the Ruggedy Mountains Type area: Mt Rakeahua including the summit region and the Type area: Ruggedy Mountains bush-clad lower slopes Content: coarse-grained leucogranitoid ranging in composition Content: heterogeneous coarse-grained gabbro, diorite and from granite to granodiorite anorthosite (Allibone & Tulloch 1997), fine-grained diorite, Age: Early Carboniferous gabbro, biotite quartz monzodiorite and tonalite Age: Middle Jurassic Table Hill Orthogneiss Previous usage or definition: introduced by Allibone & Tulloch South West Arm Pluton (1997) Previous usage or definition: introduced by Allibone & Tulloch Name: from Table Hill, north end of the Tin Range (1997) Type area: summit and north side of Table Hill Name: from South West Arm of Paterson Inlet Content: fine- to medium-grained homogeneous leucocratic biotite Type area: shoreline of South West Arm (muscovite) granite, leucogranite and granodiorite orthogneiss Content: homogeneous medium- to coarse-grained, locally Age: Early Carboniferous megacrystic biotite granite and granodiorite Age: Middle Jurassic Neck Granodiorite Previous usage or definition: mapped by Cook (1984) but not Euchre Pluton previously named Previous usage or definition: not previously named Name: from The Neck, outer Paterson Inlet Name: from Euchre Creek on the south side of Paterson Inlet Type area: southernmost part of The Neck Type area: outcrops in Euchre Creek Content: massive medium- to coarse-grained biotite granodiorite Content: fine-grained massive homogeneous biotite granodiorite Age: Early Carboniferous and granite Age: undated but inferred to be similar to South West Arm Pluton Knob Pluton Previous usage or definition: introduced by Allibone & Tulloch Codfish Granite (1997) Previous usage or definition: introduced by Allibone (1991) and Name: from Granite Knob and Lees Knob Allibone & Allibone (1991) Type area: the south faces of Lees Knob and Granite Knob Name: from Codfish Island Content: medium- to coarse-grained and locally megacrystic Type area: western Codfish Island

72 Content: homogeneous massive medium-grained biotite granite Content: diorite forming a small pluton Age: Late Jurassic Age: undated but probably Early Cretaceous

Deceit Pluton Richards Point Porphyry Previous usage or definition: not previously named Previous usage or definition: introduced by Allibone (1991) Name: from Deceit Peaks, south of Doughboy Bay Name: from Richards Point on the northwest coast Type area: Deceit Peaks Type area: coastal outcrops on the southern side of Richards Content: medium- to coarse-grained biotite (muscovite) granite, Point with subordinate leucogranite and granodiorite Content: a plug of plagioclase-quartz-biotite-magnetite- Age: latest Jurassic porphyritic dacite and granodiorite Age: Early Cretaceous Saddle Pluton Previous usage or definition: not previously introduced, although Tarpaulin Pluton Frewin (1987) described a “Saddle Suite”. Previous usage or definition: previously named Tarpaulin Name: after Saddle Point, on the north coast of Stewart Island Metagranite by Cook (1987), here redefined to include similar west of Oban rocks on the northern coast of Paterson Inlet and Thomson Ridge Type locality: northeast coast of Stewart Island Name: from Tarpaulin Beach at The Neck Content: medium- to coarse-grained gabbro, and anorthositic Type area: Tarpaulin Beach, eastern Paterson Inlet gabbro with norite and troctolite Content: generally foliated leucocratic biotite (muscovite) granite Age: undated, but probably similar to Bungaree Intrusives, Late and granodiorite Jurassic or earliest Cretaceous Age: Early Cretaceous

Bungaree Intrusives Smoky Pluton Previous usage or definition: not previously named, although Previous usage or definition: not previously introduced, although Frewin (1987) described a “Bungaree Suite” Frewin (1987) named a “Smoky granite” Name: from Bungaree on the northeast coast of Stewart Island Name: from Smoky Beach on the north coast Type area: coastal section from Port William to Murray Type area: coastal outcrops between Smoky Beach and Long Beach including the Bungaree area Harry Bay Content: heterogeneous and locally foliated intrusions of diorite, Content: medium- to coarse-grained massive biotite muscovite quartz diorite, and quartz monzodiorite with subordinate gabbro, (garnet) granite with minor leucogranite, aplite and pegmatite granodiorite and granite Age: Late Jurassic to Early Cretaceous Age: earliest Cretaceous Freshwater Northeast Pluton Cow & Calf Gabbro Previous usage or definition: not previously named Previous usage or definition: named by Watters (1962); not shown Name: from the northern catchment of the Freshwater River on this map. Probably a correlative of the Saddle Pluton and Type area: creeks draining SSW of Mt Anglem and low hills in other small gabbro plugs within the Bungaree Intrusives the centre of the Freshwater Valley 5-6 km east of Benson Peak Name: from Cow and Calf Point southwest from Oban Content: fine- to medium-grained massive biotite granodiorite Type area: Cow and Calf Point coastal outcrops and granite with accessory muscovite in more leucocratic parts Content: hornblende pyroxene gabbro and hornblendite Age: probably Early Cretaceous Age: undated but probably Early Cretaceous Walkers Pluton East Ruggedy Intrusives Previous usage or definition: not previously defined, although Previous usage or definition: not previously named Peden (1988) mapped Walkers Hill diorite and Ernest Islands Name: from East Ruggedy beach diorite Type area: coastal outcrops from East Ruggedy to a boulder Name: from Walkers Hill southeast of Mason Bay beach 2km west of Long Harry Bay Type area: streams draining the western and southern faces of Content: numerous minor plugs, plutons and dikes of variably Walkers Hill deformed fine- to medium-grained gabbro, diorite, quartz Content: a large locally foliated heterogeneous pluton of quartz monzodiorite, granodiorite and granite, with gneiss and monzodiorite, with subordinate diorite and granodiorite amphibolite Age: Early Cretaceous Age: undated, but probably earliest Cretaceous by analogy with Bungaree Intrusives Escarpment Pluton Previous usage or definition: introduced by Allibone & Tulloch North Arm Pluton (1997) Previous usage or definition: not previously named Name: from the escarpment that forms the southern face of the Name: from North Arm of Paterson Inlet Rakeahua valley Type area: shoreline outcrops around the head of North Arm Type area: creek exposures east and west of the track up the Content: medium-grained, variably foliated quartz monzodiorite, escarpment to Table Hill with subordinate diorite, and granodiorite Content: variably foliated, medium-grained heterogeneous biotite Age: Early Cretaceous ± hornblende granodiorite and quartz monzodiorite often rich in gabbroid and dioritoid xenoliths and mafic enclaves Rollers Pluton Age: Early Cretaceous Previous usage or definition: named by Frewin (1987) and here formalised Easy Pluton Name: from Rollers Point on the northeast coast Previous usage or definition: not previously named Type area: Rollers Point Name: from Easy Harbour, southwestern coast of Stewart Island

73 Type area: coastal outcrops around Easy Harbour Type area: coastal outcrops around Broad Bay and tops south of Content: medium-grained biotite ± hornblende granodiorite and Smiths Lookout quartz monzodiorite grading to fine-grained biotite granite around Content: weakly foliated to massive biotite quartz monzodiorite, Port Pegasus tonalite and granodiorite Age: Early Cretaceous Age: undated, probably Early Cretaceous

Gog Pluton Tikotatahi Pluton Previous usage or definition: not previously named Previous usage or definition: not previously named Name: from the prominent peak Gog, west of Port Pegasus Name: from Tikotatahi Bay south of Port Adventure on the east Type area: outcrops at Fraser Peaks west of Port Pegasus coast Content: fine- to medium-grained massive granodiorite, granite Type area: coastal outcrops around Tikotatahi Bay and the and leucogranite, with K-feldspar megacrysts in places southern side of Port Adventure Age: latest Early Cretaceous Content: medium-grained biotite ± hornblende granodiorite and quartz monzodiorite, foliated near its northern margin Lords Pluton Age: Early Cretaceous Previous usage or definition: not previously named Name: from the Lords River Doughboy Pluton Type area: middle reaches of the Lords River Previous usage or definition: not previously defined, although Content: fine- to medium-grained massive quartz monzodiorite, Doughboy Bay granodiorite mapped by Peden (1988) around granodiorite, granite and leucogranite Doughboy Bay is included in the Doughboy Pluton Age: undated, but probably Early Cretaceous by comparison Name: from Doughboy Bay and Doughboy Creek with Gog Pluton Type area: outcrops along Doughboy Creek and Doughboy Bay Content: massive to weakly foliated medium-grained biotite ± Campsite Pluton hornblende granodiorite and quartz monzodiorite Previous usage or definition: introduced by Allibone & Tulloch Age: Early Cretaceous (1997) Name: from an un-named campsite beside a stream 1500m Blaikies Pluton northeast of Mt Allen, in the centre of the pluton Previous usage or definition: introduced by Allibone & Tulloch Type area: headwaters of the Kopeka River immediately east of (1997) Mt Allen Name: from Blaikies Creek southeast of the Tin Range Content: fine- to medium-grained massive quartz monzodiorite, Type area: upper reaches of Blaikies Creek and adjacent open granodiorite, granite and leucogranite tops southeast of Blaikies Hill Age: undated, but probably Early Cretaceous by comparison Content: variably foliated medium- to coarse-grained biotite ± with Gog Pluton muscovite ± garnet granite, subordinate granodiorite and minor tonalite Upper Rakeahua Pluton Age: Early Cretaceous Previous usage or definition: not previously named Name: from the upper reaches of the Rakeahua River Upper Kopeka Pluton Type area: upper reaches of the southwest branch of the Rakeahua Previous usage or definition: not previously named River Name: from the upper Kopeka River catchment Content: fine- to medium-grained massive granite, leucogranite, Type locality: the upper Kopeka River 2 km above the Blaikies aplite and pegmatite Creek confluence Age: Early Cretaceous Content: generally unfoliated medium to coarse biotite ± muscovite ± garnet granite, subordinate granodiorite and minor Adventure South Orthogneiss tonalite Previous usage or definition: not previously named Age: undated but probably Early Cretaceous by analogy with Name: from the area south of Adventure Hill the Blaikies Pluton Type area: creeks south of Adventure Hill Content: strongly foliated fine-grained biotite granodiorite and Mason Bay Pluton granite gneiss Previous usage or definition: introduced by Allibone (1991) Age: undated; constrained from field relationships as post-Early Name: after Mason Bay Carboniferous and pre-Early Cretaceous Type area: outcrops in sand dunes around the northern half of Mason Bay and adjacent streams Kopeka South Pluton Content: variably foliated heterogeneous quartz monzodiorite, Previous usage or definition: not previously named granodiorite and granite often containing amphibolite xenoliths Name: from the south side of the Kopeka River and rafts Type area: outcrops in the hills south of the upper Kopeka River Age: Early Cretaceous Content: foliated fine- to medium-grained biotite garnet granite and granodiorite Kanihinihi Pluton Age: undated, Paleozoic to Cretaceous Previous usage or definition: not previously named Name: from Kanihinihi Point, at the southwest side of Broad Bay

74 This map and text illustrate the geology of the Murihiku area, extending from the lower Clutha River across Southland to the Waiau basin on the fringes of southern Fiordland, and south to Stewart Island (Rakiura). Onshore geology is mapped at a scale of 1:250 000; offshore bathymetry and major structural elements are also shown. Geological information has been obtained from published and unpublished mapping by Institute geologists, from work by University of Otago and mining company geologists, and from various computer data bases. All data are held in a Geographic Information System and are available in digital format on request. The accompanying text summarises the regional geology and tectonic development, as well as the economic and engineering geology of the area.

The map area is mostly underlain by Paleozoic and Mesozoic sedimentary rocks of the Murihiku Supergroup, exemplified in the Southland Syncline. Permian igneous rocks, including volcanics and plutonics, form the Takitimu and Longwood ranges on the western margin of the sheet, and Paleozoic to Cretaceous granitic to gabbroic rocks dominate Stewart Island. Cenozoic marine and nonmarine sediments underlie the Te Anau and Waiau basins, and also form extensive coal measures beneath the Southland and Waimea Plains. Quaternary sediments are dominated by the wide gravel plains of the Aparima, Oreti, and Mataura catchments, and, on Stewart Island, the dune fields of the Freshwater Depression. The Murihiku area, especially the western side, includes several major active fault systems. Earthquakes and tsunami are the major geological hazards.

The Ruggedy Mountains in northwestern Stewart Island. The Carboniferous Ruggedy Granite forms the conspicuous outcrops; infaulted slivers of Paterson Group lie within the granite at West Ruggedy Beach (left foreground) and in Waituna Bay (centre right). The Freshwater valley (left) is underlain by laminated sand, reworked from dunes blown up from the Ruggedy and Waituna beaches, and from Mason Bay (upper right). The gently sloping surface in the far distance is probably an exhumed Cretaceous peneplain. Photo CN43963/10: D.L. Homer

ISBN 0-478-09800-6