Mineral resource assessment of the West Coast Region, New Zealand A.B. Christie R.G. Barker R.L. Brathwaite GNS Science Report 2010/61 November 2010 BIBLIOGRAPHIC REFERENCE Christie, A.B.; Barker, R.G. and Brathwaite, R.L. 2010. Mineral resource assessment of the West Coast Region, New Zealand, GNS Science Report 2010/61. 235 p. A.B. Christie, GNS Science, PO Box 30368, Lower Hutt 5040 R.G. Barker, Consulting Geologist, PO Box 54094, The Marina, Manukau 2144 R.L. Brathwaite, GNS Science, PO Box 30368, Lower Hutt 5040 © Institute of Geological and Nuclear Sciences Limited, 2010 ISSN 1177-2425 ISBN 978-0-478-19809-6 CONTENTS ABSTRACT ......................................................................................................................... XI 1.0 INTRODUCTION ........................................................................................................ 1 2.0 MINERAL RESOURCE ASSESSMENT FACTORS AND LIMITATIONS ................... 5 3.0 PREVIOUS WORK ..................................................................................................... 7 4.0 METHODS .................................................................................................................. 8 5.0 DATA ......................................................................................................................... 9 6.0 RESOURCE MAPS .................................................................................................... 9 7.0 SETTING .................................................................................................................. 10 7.1 Population and Infrastructure ...................................................................................... 10 7.2 Geomorphology ........................................................................................................... 11 8.0 GEOLOGY ............................................................................................................... 13 8.1 Previous Work ............................................................................................................. 13 8.2 Introduction .................................................................................................................. 13 8.3 Paleozoic to Jurassic Gondwana Rocks ..................................................................... 16 8.4 Early to Mid Cretaceous Rocks and the Mid to Late Cretaceous Gondwana Break-up . ..................................................................................................................................... 17 8.5 Late Cretaceous-Pliocene Sedimentary Basins .......................................................... 17 8.6 Middle and Late Quaternary ........................................................................................ 18 8.7 Geological Correlation with Australia .......................................................................... 18 9.0 GEOCHEMISTRY ..................................................................................................... 19 9.1 GIS Data Sets (Fig. 13-17) .......................................................................................... 19 9.2 Geochemical Interpretation ......................................................................................... 25 10.0 BULK COMMODITIES: ROCK AGGREGATE, SAND, BUILDING STONE AND LIMESTONE ........................................................................................................................ 26 10.1 Current Production ...................................................................................................... 26 10.2 Aggregate .................................................................................................................... 26 10.2.1 West Coast Deposits ..................................................................................... 32 10.2.2 Future Potential ............................................................................................. 38 10.2.3 Aggregate Exports ......................................................................................... 40 10.3 Building and Dimension Stone .................................................................................... 41 10.3.1 West Coast Deposits (Table 7) ..................................................................... 41 10.3.2 Future Potential ............................................................................................. 44 10.4 Limestone .................................................................................................................... 44 10.4.1 West Coast Deposits (Table 8 and Figure 28) .............................................. 44 10.4.2 Future Potential ............................................................................................. 48 11.0 COAL ....................................................................................................................... 52 11.1 Introduction .................................................................................................................. 52 11.2 Coal Measures and Coal Rank ................................................................................... 56 GNS Science Report 2010/61 i 11.3 Coal Resources ........................................................................................................... 57 11.4 Coalfields ..................................................................................................................... 58 11.4.1 Buller Coalfield .............................................................................................. 58 11.4.2 Inangahua Coalfield ...................................................................................... 61 11.4.3 Murchison Coalfield ....................................................................................... 61 11.4.4 Reefton Coalfield ........................................................................................... 61 11.4.5 Garvey Creek Coalfield ................................................................................. 62 11.4.6 Charleston Coalfield ...................................................................................... 62 11.4.7 Punakaiki Coalfield ........................................................................................ 62 11.4.8 Pike River Coalfield ....................................................................................... 62 11.4.9 Greymouth Coalfield ...................................................................................... 64 11.4.10 Minor Coalfields ........................................................................................... 65 11.5 Future Potential ........................................................................................................... 66 12.0 MINERAL RESOURCE ASSESSMENT OF METALLIC AND INDUSTRIAL MINERALS .......................................................................................................................... 66 12.1 Assessment Method .................................................................................................... 66 12.2 Mineral Deposit Models ............................................................................................... 67 13.0 METALLIC MINERAL DEPOSITS ............................................................................ 69 13.1 Antimony ...................................................................................................................... 69 13.1.1 Vein Sb (Figure 51) ....................................................................................... 69 13.2 Beryllium ...................................................................................................................... 72 13.2.1 Be pegmatite (Figure 52) ............................................................................... 72 13.3 Chromium .................................................................................................................... 74 13.3.1 Podiform Cr (Figure 53) ................................................................................. 74 13.4 Copper ......................................................................................................................... 78 13.4.1 Stratiform Cu (Figure 55) ............................................................................... 78 13.4.2 Vein Cu (Figure 56) ....................................................................................... 80 13.5 Gold ............................................................................................................................. 82 13.5.1 Orogenic shear zone Au - Paleozoic (Figure 58) .......................................... 83 13.5.2 Orogenic shear zone Au - Mesozoic (Figure 69) .......................................... 97 13.5.3 Orogenic Alpine Au - Cenozoic (Figure 70) ................................................ 100 13.5.4 Alkali intrusion-related Au (Figure 71) ......................................................... 102 13.5.5 Moderately reduced granite Au (Figure 72) ................................................ 104 13.5.6 Detachment-fault-related polymetallic deposits (Figure 73) ........................ 106 13.5.7 Placer Au (Figure 75-78) ............................................................................. 108 13.6 Molybdenum .............................................................................................................. 123 13.6.1 Porphyry Mo (Figure 91) ............................................................................