Mapping the basement of South Australia: BACK TO BASICS

Transcription

1 Mapping the basement of South Australia: BACK TO BASICS David Giles Centre for Mineral Exploration Under Cover School of Earth and Environmental Sciences The University of Adelaide The accountants perception Risk: Its mostly covered! Air Sheep food Dirt 1

2 The explorers perception Opportunity: Its mostly covered! Blue Sky Sampling Medium Host to ore Size, distribution and clustering in the South Australian IOCG province? 2

3 To build confidence and mitigate risk we must: continue to focus on the basics incrementally build knowledge of the geologic fundamentals map (geophysics) and sample (drilling) maximise the value of drilling THERE ARE NO SHORT CUTS The CMXUC is a collaborative research initiative between PIRSA and the University of Adelaide Established in 2005 with $1.2 million seed funding under the PACE scheme Our aim is to facilitate mineral discovery by defining and implementing the next generation of mineral exploration science Major focus is to understand and penetrate the veneer of weathered rock and alluvium that covers much of the prospective rocks of Australia 3

4 SCIENCES ENGINEERING Earth & Env Sciences ASP Civil & Env Engineering EB Mine Rehab Geology & Geophysics Petroleum G&G Petroleum Eng. Mining Engineering CMXUC Resources related research and training at University of Adelaide PIRSA Exploration Industry Structure GEOLOGY AND GEOPHYSICS UNIVERSITY OF ADELAIDE, 2007 Record undergraduate numbers ~230 1 st years in 2007, >20 hons Lots of post-graduate students (30-ish ish) Record numbers of post-doctoral fellows New staff appointments: Steve Hill, Galen Halverson Continuing Australian Research Council success -33 Discovery Grants, 1 Infrastructure Grant and 1 Linkage Grant funded for 2007 Well-equipped, equipped, cutting-edge analytical equipment Increased collaboration with industry and PIRSA 4

5 Director: David Giles Tectonics and Metallogeny David Giles, Guillaume Backe (CMXUC) Caroline Forbes (CMXUC-PIRSA) John Foden,, Martin Hand, Karin Barovich,, Andreas Schmidt-Mumm (UA, CERG) Geophysical Exploration Graham Baines (CMXUC) Graham Heinson,, Kate Selway (UA) Regolith and Landscape Evolution Steve Hill (UA, CRC LEME) Themes & People CMXUC Highlights of Year 1 Full time staff from 0 to 4 Integration with University of Adelaide staff and research groups CRC LEME, CERG $600K, ARC Linkage grant success with G.Heinson Heinson,, K.Selway Research with: Barrick,, BHPB, Teck Cominco, Heathgate, Hillgrove, Maximus, Oxiana,, Dominion, Adelaide Resources PACE proposal West Gawler Craton NCRIS seismic proposal North Gawler Craton Highlights 5

6 PROJECTS SA Focus Geographic and thematic spread Projects with tangible benefit to mineral exploration Direct research links with explorers and PIRSA The key to discovery is ground selection Ground selection is about Geologic Fundamentals First we need to establish if the geologic fundamentals are permissive (or even compelling) for a certain style of mineralisation? We need to map it and sample it In areas of cover we map the basement using geophysics,, we sample the basement by drilling 6

7 As explorers and researchers we must maximise the value of our geophysical and drill hole data Unsuccessful Drill hole PETROPHYSICS Geophysical interpretation alteration petrology geochronology structure/met tectonic setting Mineral systems regional associations Drillholes extracted from PIRSA SARIG website Yellow intersected basement Blue did not 7

8 Most holes are less than 200m Dark Blue <20m Light Blue m Yellow m Orange m Red >500m South Australian Craton marginal terranes project 3D crustal architecture from geophysics 4D evolution of the South Australian Craton In collaboration with PIRSA and Monash University Graham Baines Projects 8

9 Guillaume Backe Neoproterozoic Basins 3D crustal architecture, basin analysis and metallogeny,, depth and nature of basement In collaboration with PIRSA Projects 9

10 Caroline Forbes Mount Woods - Prominent Hill Tectonics and exploration models 3D architecture of the Gawler Craton In collaboration with Oxiana Projects 10

11 footwall thrusts Gawler Basin Southern Southern Overthrust Overthrust Mt Woods Inlier (Flottmann and Hand, 1999) Fowler Belt, Tectonics and Ni-potential PACE funded drilling and ground geophysics Breaking new ground in poorly explored terrane Projects 11

12 Tectonic framework for the Fowler Belt Barton Block: 2km 5km Thomas et al., in review, PreC Research 12

13 The importance of PETROPHYSICS the critical link between geology and geophysics (also geologists and geophysicists ists) constrains geophysical interpretations and inversions petrophysical properties can be measured in the field and predicted by modeling (including metamorphism and fluid/rock interactions) essential component for 3D map of the South Australian crust and its mineral systems HEMATITE 1% MAGNETITE 2% DENSITY > 2.7g/cm 3 13

14 At present we have no central repository for petrophysical data companies tend to collect them in an ad hoc way focus is on mineralised rocks, but background rocks are just as important Much forward modeling is conducted by inspired guesswork, many inversions are conducted with little or no geologic constraints THE PETROPHYSICAL ATLAS OF SOUTH AUSTRALIA medium term goal of the CMXUC and PIRSA all major rock types, including altered rocks and mineralisation handbook for geophysical modeling and target generation Requires collaboration of companies in possession of important petrophysical databases 14

15 To build confidence and mitigate risk we must: continue to focus on the basics incrementally build knowledge of the geologic fundamentals map (geophysics) and sample (drilling) maximise the value of drilling (inc. PETROPHYSICS) THERE ARE NO SHORT CUTS 15