Provenance and Porosity analysis of the Greymouth Basin, New Zealand. A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geology in the University of Canterbury by Ryan David Steadman University of Canterbury 2017 Frontispiece View of 12 Mile Beach "It is widely acknowledged that the high level of geological complexity inherent at Greymouth is considerably greater than that normally experienced in most producing coalfields elsewhere" (Bowman, Caffyn, Duff, 1984). Contents Contents ....................................................................................................................... List of Table and Figures .............................................................................................. Acknowledgements .................................................................................................... 1 Abstract ...................................................................................................................... 2 Chapter 1 Introduction ............................................................................................... 3 1.1 Introduction ................................................................................................... 3 1.2 Geological History and Basin Formation ....................................................... 6 1.3 Economic Geology ........................................................................................ 8 1.4 Geologic Setting ............................................................................................ 9 1.5 Lithological Summary .................................................................................. 13 1.6 Controversies .............................................................................................. 14 1.7 Aims of this Work ........................................................................................ 16 Chapter 2 Methods .................................................................................................. 17 2.1 Sedimentary Description ............................................................................. 17 2.1.1 Sample Locations ................................................................................. 17 2.1.2 Measured Section ................................................................................. 20 2.1.3 Descriptions of Individual Outcrops and Cores ..................................... 21 2.2 Conglomerate Clast Provenance ................................................................ 21 2.2.1 Sampling in the Field and Core ............................................................ 21 2.2.2 Clast Counts ......................................................................................... 22 2.2.3 Petrographic Identification .................................................................... 23 2.2.4 Igneous Clast Geochemistry ................................................................. 24 2.3 Sandstone Provenance ............................................................................... 26 2.3.1 Sampling in the Field and Core ............................................................ 26 2.3.2 Thin Section Creation ........................................................................... 27 2.3.3 Feldspar Staining .................................................................................. 27 2.3.4 Point Counting ...................................................................................... 28 2.4 Mudstone Provenance ................................................................................ 30 2.4.1 Sampling ............................................................................................... 30 2.4.2 Geochemistry ....................................................................................... 31 2.5 Sandstone Porosity ..................................................................................... 33 2.5.1 Sample Selection .................................................................................. 33 2.5.2 Blue Epoxy Stain .................................................................................. 34 2.5.3 Point Counting ...................................................................................... 34 Chapter 3 Stratigraphy ............................................................................................ 35 3.1 Lithostratigraphy .......................................................................................... 36 3.1.1 Basement ............................................................................................. 36 3.1.2 Greenland Group .................................................................................. 36 3.1.3 Granites ................................................................................................ 37 3.1.4 The Charleston Metamorphic Group .................................................... 37 3.1.5 Pororari Group ...................................................................................... 38 3.1.6 Paparoa Coal Measures and Paleocene Brunner ................................ 39 3.1.7 Jay Formation ....................................................................................... 39 3.1.8 Ford Formation ..................................................................................... 40 3.1.9 Morgan Formation ................................................................................ 41 3.1.10 Waiomo Formation ............................................................................ 42 3.1.11 Rewanui Formation ........................................................................... 42 3.1.12 Goldlight Formation ........................................................................... 44 3.1.13 Dunollie Formation ............................................................................ 45 3.1.14 Brunner Formation ............................................................................ 46 3.2 Sedimentology of Sample Localities ........................................................... 46 3.2.1 12 Mile Beach Section .......................................................................... 47 3.2.2 Core logs .............................................................................................. 54 3.2.3 DH 634 ................................................................................................. 54 3.2.4 DH 660 ................................................................................................. 55 3.2.5 DH 632 ................................................................................................. 57 3.2.6 DH 649 ................................................................................................. 58 3.2.7 DH 620 ................................................................................................. 59 3.3 Stratigraphic Analysis .................................................................................. 64 Chapter 4 Provenance Analysis .............................................................................. 67 4.1 Conglomerate Provenance ......................................................................... 68 4.1.1 Clast Counts ......................................................................................... 77 4.1.2 Granite and Basaltic Clast Geochemical Analysis ................................ 84 4.1.3 Weathering ........................................................................................... 99 4.2 Sandstone Provenance ............................................................................. 101 4.2.1 Sandstone Point Counts ..................................................................... 110 4.2.2 Point Count Analysis .......................................................................... 113 4.2.3 Sandstone Tectonic Setting ................................................................ 117 4.3 Mudstone Geochemical Analysis and Provenance ................................... 119 4.4 Conglomerate Provenance ....................................................................... 121 4.5 Sandstone Provenance ............................................................................. 124 4.6 Mudstone provenance ............................................................................... 127 4.7 Conclusion ................................................................................................ 127 Chapter 5 Morgan Volcanic Conglomerate ........................................................... 128 5.1 Clasts Encountered ................................................................................... 129 5.2 Clast Count ............................................................................................... 133 5.3 Geochemical Analysis ............................................................................... 135 5.3.1 Major Element Analysis ...................................................................... 135 5.3.2 Trace Element Analysis ...................................................................... 137 5.4 Comparison of basalt clasts in Rewanui Formation conglomerates to Morgan Volcanic Conglomerate clasts ............................................................................ 139 5.5 Tectonic Setting ........................................................................................ 141 Chapter 6 Reservoir Capability ............................................................................. 144 6.1 Methods ...................................................................................................