The Geology and Prospectivity of the Wangaratta 1:250 000 Map Sheet Area
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VIMP Report 46 The geology and prospectivity of the Wangaratta 1:250 000 map sheet area S. Maher, A.H.M. VandenBerg, P.A. McDonald and P. Sapurmas November, 1997 Bibliographic Reference: MAHER, S., VANDENBERG, A.H.M., MCDONALD P.A. AND SAPURMAS P., 1997. The geology and prospectivity of the Wangaratta 1:250 000 map sheet area. Victorian Initiative for Minerals and Petroleum Report 46. Department of Natural Resources and Environment. © Crown (State of Victoria) Copyright 1997 Geological Survey of Victoria ISSN 1323 4536 ISBN 0 7306 9425 9 This report and folded map may be purchased from: Business Centre, Department of Natural Resources & Environment, Ground Floor, 115 Victoria Parade, Fitzroy, Victoria 3065 For further technical information, contact: General Manager, Geological Survey of Victoria, P O Box 500, East Melbourne, Victoria 3002 Authorship and acknowledgements: Major contributors: Economic Geology—S. Maher and P. Sapurmas, Geology—A. VandenBerg, Geophysics—P. McDonald, Prospectivity—S. Maher and P. McDonald. Osprey Gold NL and Warren Jay Holdings P/L generously gave permission to publish information from confidential Exploration Licence reports. Digital terrain model data from GSV and GEODATA DEM-9S. Copyright, Commonwealth of Australia, AUSLIG Figures were produced by D. Jansen. Editing was by A.H.M. VandenBerg, R. Buckley, A. Willocks and P.J. O'Shea. Formatting was by G. Ellis. 4 GEOLOGY AND PROSPECTIVITY - WANGARATTA Contents Abstract 7 1 Introduction 8 2 Geophysics 10 2.1 Summary 10 2.2 Previous geophysics 10 2.3 VIMP/NGMA survey details 10 VIMP specifications 10 NGMA specifications 13 2.4 Products 13 3 Structural framework 15 4 Geological history 16 4.1 Summary 16 4.2 Lachlan Fold Belt 16 4.3 Late Palaeozoic and Mesozoic epi-cratonic sedimentation 17 4.4 Late Cretaceous break-up of Gondwana (ca 95–65 Ma) 17 5 Sedimentary and volcanic rock units 19 5.1 Cambrian 19 5.2 Ordovician (–Silurian?) 20 Hotham beds 20 5.3 Silurian—Omeo Metamorphic Complex 21 5.4 Silurian–Lower Devonian—Melbourne "Trough" 21 5.5 Devonian volcanics and sediments 22 Violet Town Caldera 22 Wabonga Caldera: Tolmie Igneous Complex 22 5.6 Upper Devonian–Carboniferous(?) Mansfield Group 23 5.7 Carboniferous–Permian 24 Boorhaman Conglomerate 24 Urana Formation 25 5.8 Tertiary 25 "Tp"—White Hills Gravel? 25 Renmark Group 25 Older Volcanics 25 Calivil Formation 26 Newer Volcanics 26 Shepparton Formation 26 5.9 Quaternary sediments 27 Alluvium (Qra) 27 Colluvium, gully alluvium (Qrc) 27 Swamp deposits (Qrm) 27 Dune deposits (Qo) 27 6 Intrusive rocks 29 6.1 Granites 29 Yackandandah Batholith 31 Pilot Range Batholith 32 Warby Range Batholith 33 Subsurface granites 34 Granite ages 35 6.2 Dykes 35 7 Economic geology 36 7.1 History of mining 36 7.2 Mineral production 39 7.3 Gold deposits 41 GEOLOGY AND PROSPECTIVITY - WANGARATTA 5 Placer gold deposits 42 Orogenic gold deposits 46 7.4 Antimony-?gold deposits in the Tolmie Igneous Complex 52 7.5 VHMS and epigenetic gold deposits in Cambrian greenstones 52 7.6 Granite-hosted tin deposits 52 7.8 Porphyry molybdenite deposits 53 7.9 Porphyry gold-copper deposits 54 7.10 Copper deposits in the Mansfield Group 54 7.11 Placer diamond occurrences 55 7.12 Coal 56 7.13 Non-metallics 57 Construction materials 57 Feldspar 57 Gemstones 58 Fluorite 58 Calcite 58 Wollastonite 58 Quartz crystals 59 Talc 59 Phosphate 59 Dimension stone 59 8 Soil and stream sediment geochemistry 61 9 Mineral resource potential and prospectivity 66 Orogenic gold 66 Placer gold 66 Thermal aureole gold 67 VHMS and epigenetic gold deposits in Cambrian greenstones 67 Antimony-?gold deposits in the Tolmie Igneous Complex 67 Porphyry gold-copper-molybdenite deposits 67 Copper deposits in the Mansfield Group 67 Diamond deposits 67 Coal 68 Industrial minerals 68 References 69 Appendix 1 77 Status of VIMP airborne surveys 77 Appendix 2 77 VIMP Survey specifications and data processing 78 NGMA Survey specifications and data processing 79 Appendix 3 81 VIMP Products 81 NGMA Products 81 Victorian Initiative for Minerals and Petroleum (VIMP) report series 83 List of figures 1 Airborne surveys and detailed geological mapping, Wangaratta 1:250 000 map area 10 2 Total magnetic intensity image 1:500 000 (Back pocket) 3 Radiometric RGB image 1:500 000 (Back pocket) 4 Digital terrain model image 1:500 000 (Back pocket) 5 1:500 000 simplified geology, Wangaratta 1:250 000 map area. (Back pocket) 6 Geology, mineral resources and tenements, Wangaratta 1:250 000 map area (Back pocket) 7 Mineral resources within the Wangaratta 1:250 000 map area 38 8 Primary, alluvial and total goldfield production. 41 9 Annual goldfield production. 42 6 GEOLOGY AND PROSPECTIVITY - WANGARATTA 10 Gold-quartz vein orientations, Wangaratta 1:250 000 map area 48 11 Distribution of stream sediment samples analysed for gold (excluding samples analysed with the bulk cyanide leach method) 63 12 Distribution of stream sediment samples analysed for gold by bulk cyanide leaching (BCL) 63 13 Distribution of stream sediment samples not analysed for gold 64 14 Distribution of diamond indicator stream sediment samples 64 15 Distribution of soil samples analysed for gold (excluding samples analysed with the bulk cyanide leach method) 65 16 Distribution of soil samples analysed for gold by bulk cyanide leaching (BCL) 65 17 Distribution of soil samples not analysed for gold 66 18 1:500 000 TMI image showing mineral resources (Back pocket) List of tables 1 Summary of geophysical responses of non-intrusive rock units 12 2 Airborne surveys on WANGARATTA 14 3 Specifications of the WANGARATTA airborne survey 15 4 Summary of granite plutons 31 5 Production for goldfields between 1864 and 1996 42 6 Gold production from principal mines operations in the Chiltern-Rutherglen goldfield 44 7 Principal gold mining operations in the Beechworth and Eldorado goldfields 45 8 Principal dredging and sluicing operations in the southern goldfields 46 9 Major primary gold producers from each goldfield of the Dargo-Harrietville gold province 48 10 Gemstone occurrences 59 11 Status of VIMP airborne surveys 78 GEOLOGY AND PROSPECTIVITY - WANGARATTA 7 Abstract This report summarises the geology and prospectivity of the WANGARATTA 1:250 000 map area in northeastern Victoria. New airborne geophysics conducted over WANGARATTA as part of the Victorian Initiative for Minerals and Petroleum (VIMP) and National Geoscience Mapping Accord (NGMA) programs has enabled a reappraisal of the regional geology and prospectivity of the area. This has been complemented by compilations of mineral resources, mineral exploration and exploration geochemistry. Broad areas with potential to host a variety of styles of mineralisation have been outlined as a result of this reappraisal. These include: · Cainozoic placer and supergene gold deposits; · extensions to and repetitions of historic primary gold deposits; · thermal aureole gold deposits related to the Strathbogie Granite; · unrecognised sediment-hosted disseminated gold deposits; · volcanic-hosted massive sulphide and epithermal gold deposits associated with Cambrian greenstones; · stratiform base metal-uranium deposits in Upper Devonian–Lower Carboniferous basins and Ordovician Hotham Group; · tin, molybdenum and gold deposits hosted by granites; · Cainozoic placer tin deposits; · diamond deposits; · Permian coal deposits; · antimony-gold deposits associated with Upper Devonian calderas; · porphyry gold-copper-molybdenite deposits associated with high-level intrusions; and · a variety of industrial minerals. 8 GEOLOGY AND PROSPECTIVITY - WANGARATTA 1 Introduction This report summarises the geology and mineral resources of the Wangaratta 1:250 000 map area (WANGARATTA) in northeastern Victoria (Fig. 1), and includes an appraisal of new airborne geophysical data. This information is designed to aid mineral exploration and mineral resource development. It complements new airborne magnetic and radiometric data and stream sediment and soil geochemical data compiled from expired Exploration Licences covering WANGARATTA collected as part of the Victorian Initiative for Minerals and Petroleum (VIMP) program, and detailed geological maps which cover most of the northern half of WANGARATTA (Fig. 1). Mineral exploration in WANGARATTA, including details on anomalies in geochemical surveys and significant drill intersections, is summarised in Wilkie and Brookes (1997). Detailed information on the location, production and geology of mines and prospects within WANGARATTA accompanies this report in the WANGARATTA Mine Database. The database, explanatory notes and references are supplied on a 3.5 inch DOS disk in the following formats: WANGARATTA Mine Database Wangmine.mdb Microsoft Access 2.0 format Wangmine.ldb Microsoft Access 2.0 format *.txt Tab delimited ASCII text files derived from the Access Database Explanatory Notes Readme.doc Microsoft Word 6.0 format Readme.txt ASCII text file format References Referenc.doc Microsoft Word 6.0 format Referenc.txt ASCII text file format The mine database is only one layer in the GIS data set covering WANGARATTA. Other layers include geology, geochemistry (also available in ASCII text and relational database formats), magnetic and radiometric images, current and expired Exploration Licences (ELs), national parks and roads. This data set is available from the Geological Survey of Victoria. GEOLOGY AND PROSPECTIVITY - WANGARATTA 9 Figure 1 Airborne surveys and detailed geological mapping, Wangaratta 1:250 000 map area. 10 GEOLOGY AND PROSPECTIVITY - WANGARATTA