Mineral exploration in the St Ives area, Eastern Goldfields, using geophysical and hyperspectral data

Abstract

Recognising the imprint of invading fluids on primary geology using geophysical and hyperspectral airborne imagery can help locating sites where there may have existed suitable physicochemical contrasts able to precipitate Au. This is tested in the St Ives area of Western Australia, for regionally metamorphosed ultramafic rocks. Airborne magnetic TMI data are used to map areas enriched in magnetite, which could have developed after serpentinisation (hydration reactions). However, magnetic susceptibility often changes along strike of mapped ultramafic units. The hyperspectral data provide mineralogical links between this geophysical response and the mapped geology. That is, areas of higher magnetic response are often associated with relatively ferrous-poor silicate Mg-OH-bearing minerals. The ultramafic units are characterised by high contents of talcamphibole. Cross-cutting zones of potential Kmetasomatism can be assessed using the hyperspectral chlorite (and biotite) information and gamma radiometrics.