Correlation between lithospheric resistivity and gold deposits in southeast Australia: statistical and geological significance

Abstract:

Gold deposits form in a range of geodynamic settings and styles of deposition, associated with specific characteristics in fluid source and chemistry. These differences may lead to differences in the minerals that are deposited in the ascent pathway, and thus alter the physical properties that can be measured at different levels in the lithosphere. Models derived from magnetotelluric data are sensitive to lithospheric resistivity variations and have been increasingly applied to mineral exploration, with evidence emerging for a spatial association between many mineral deposits and lower crustal conductors.

Southeastern Australia has estimated resource of ~5000 t gold contained within a variety of deposit styles. A resistivity model of this region was recently published from Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) data under a collaborative project between Geoscience Australia, the Geological Survey of New South Wales, and the Geological Survey of Victoria. This showed a strong spatial correlation between lower crustal conductors and gold deposits. In this presentation we examine the statistical and geological significance of this correlation for different deposit styles. We demonstrate that there are clear differences in the resistivity expression between different styles of gold deposition. The variability may reflect differences in the fluid source chemistry and geodynamic setting of the deposits, and will have important implications for the exploration of these resources.