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1 CPD Hour
Yilgarn Gold Exploration Targeting Atlas Project Part 2: District-scale targeting: the transition from predictive to detective approaches will be presented by Dr Walter Witt for the Centre for Exploration Targeting.
Part 2 of the YETA Project assesses both predictive criteria and detective criteria for targeting gold in bedrock units in different districts of the Yilgarn Craton. Based on spatial analyses, the most useful predictive criteria are fault density, proximity to fault bends, preferred orientation ranges of “rheological contacts” and Mafic Group intrusions. At higher metamorphic grades, fold axes and boudins are important. Maps of down-hole gold highlight flow paths of the gold-bearing ore fluid and validate published models relating fluid flow to heterogeneous stress distribution. Arsenic distribution is partially decoupled from gold, suggesting two compositionally distinct ore fluids may have been involved. Qualitative assessments of detective targeting criteria show that contrasting hydrothermal cells can be distinguished using pathfinder elements, spectral characteristics of white mica or albite- versus muscovite-rich alteration. Juxtaposed oxidised and reduced hydrothermal fluids in gold districts can alternatively be interpreted as the geochemical expression of a longstanding structural model for gold. Other equally or more useful detective criteria include white mica intensity, a cumulative chalcophile index (e.g. W+Mo+Bi+As+Sb) and the rare alkali index [(Rb+Cs)/Th]N.
Dr Walter Witt is the principal of The Walter Witt Experience, a contract and consulting geologist business. He worked for the Geological Survey of Western Australia before embarking on a consulting career. Walter has worked in Western Australia, Papua New Guinea, China, Africa and Peru, and has extensive experience and skills including regional mapping and structural/tectonic interpretation; economic geology and recognition and interpretation of hydrothermal alteration systems.
Woolnough Lecture Theatre (1.07), Geography and Geology Building, University of Western Australia, 35 Stirling Hwy, Crawley 6009
Pay parking is available along Fairway (approx. $1.50 per hour)
You are invited to join CET staff and other attendees afterwards for refreshments provided by the UWA SEG Student Chapter in the Resource Room, Robert Street Building.
