AusLAMP: imaging the Australian lithosphere for resource potential, an example from northern Australia

Abstract:

Under the Exploring for the Future (EFTF) program, Geoscience Australia has significantly progressed data coverage of Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) throughout the northern Australia, including across many under-explored and covered regions. We utilise AusLAMP data as a first-order reconnaissance survey to resolve large-scale lithospheric architectures for mapping mineral prospective areas undercover. The results of AusLAMP-EFTF provide new insights of the conductivity variation and lithospheric-scale features. Highly conductive large-scale features in the lithospheric mantle are likely to map the distribution of metasomatised mantle, brought about by partial melting and hydration. Such features have been implicated as pathways for mantle-derived fluids and magmas linked to mineral deposit formation. Alternatively, significant conductivity features within the crust could be related to conductive material in subducted oceanic sedimentary basins. These highly conductive large-scale features may control the localisation of mineral deposits in the region. This is supported by a remarkable spatial coincidence of known gold and copper deposits with lower crustal and mantle conductors. The results also identify regions with similar features in several under-explored and covered areas that are now considered to be prospective for mineral discovery.

Although the mechanism and relationship between enhanced conductivity and mineralisation are unclear and an area of ongoing research, the new data contributes to the growing evidence that mineralisation occurs in regions of high conductivity at middle and lower crustal depths. These observations provide a powerful tool to identify prospective areas for mineral exploration undercover - in particular, to make predictions for iron-oxide–copper–gold and orogenic gold systems.