Abstract

The advantages of integrating datasets in the search for mineralization in areas characterized by subdued relief, extensive areas of transported regolith, and a semi-arid climate, are shown using direct observations (e.g. bedrock and regolith mapping, regolith geochemistry) and remotely-sensed data (e.g. airborne magnetics, gravity, Landsat TM) over a 48 000 km2 area in central Western Australia. In this area, Archaean granite and greenstones are unconformably overlain by a 5 km-thick sequence of Paleoproterozoic (c. < 1840 Ma) and Mesoproterozoic (c. 1200 Ma) sedimentary rocks, both of which are intruded by c. 1070–1400 Ma dolerites. Known mineralization comprises small lode gold deposits hosted by Archaean greenstones (e.g. <0.25 Mt @ ∼4 gt−1) and MVT-type mineralization in Paleoproterozoic stromatolitic carbonate rocks. Outcrop is sparse, with transported regolith covering about 85% of the area.

Regolith sampling and subsequent multi-element analysis has been carried out on a 4 × 4 km sampling grid over the whole area, and simultaneous measurement of gravity at each regolith sampling site has been carried out in the eastern two-thirds of the area. Integration of these data with existing gravity data, airborne magnetics, Landsat TM, and detailed bedrock mapping of selected exposures has identified seven potential areas of mineralization, including structurally controlled gold and base metal deposits associated with regional deformation, stratiform MnO and base metal mineralization, and magmatic sulfide mineralization associated with the intrusion of thick mafic sill complexes. Although regional regolith chemistry is capable of identifying all seven areas of mineralization, detailed bedrock mapping and geophysics are essential to understand the style of mineralization and to put the mineralization into a tectonic framework. The preferred tectonic model comprises the deposition of siliciclastic and chemical sedimentary rocks on a passive continental margin, followed by regional deformation, and emplacement of high-level mafic sills and dykes.

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