Airborne electromagnetics for regional cover thickness mapping

Roach, Ian C.1, Wong, Sebastian1, Ley-Cooper, Yusen1, Brodie, Ross C.1, Wilford, John1

 1Geoscience Australia, GPO Box 378, Canberra

Geoscience Australia applies airborne electromagnetic (AEM) surveying to map regional geology and the architecture of mineral, energy and groundwater systems. Most recently, Geoscience Australia has engaged in very large area, very wide line spacing AEM data acquisition as part of the AusAEM program. In this, we acquire ~20 km line spacing data to broadly characterise the electrical conductivity of wide swathes of Australia in the world’s largest (by area) AEM surveys.

Results from regional AEM surveys demonstrate the efficacy of the AEM method for mapping regolith and sedimentary cover over basement rocks, as well as for mapping large hydrostratigraphic systems. Data commonly also reveal conductivity features associated with potential ore host rocks and alteration systems. Airborne electromagnetic data are especially effective when interpreted in combination with other datasets including boreholes and potential fields. The AusAEM data are being combined with other data to develop 3D cover thickness and stratigraphic surface models either by manual interpretation or by using a machine learning approach.

As an example, in the Paterson Province of Western Australia, 2 km and 6 km spaced AEM lines and industry boreholes were used to develop a 3D depth to Proterozoic basement model. This, together with newer, more detailed AEM acquired by explorers, is now being used by industry as a first-pass risk reduction dataset for locating new Au, Cu and base metal resources in Neoproterozoic rocks of the Anketell Shelf under the Canning Basin. The AEM data have also been used in this area to map groundwater systems within the palaeodrainage systems, which can be used to model the sources and sinks of potash-bearing brinesa ACT 2601, Australia


Biography

Ian Roach is a senior geoscientist at Geoscience Australia. Ian’s interests are many and varied.

About the GSA

The Geological Society of Australia was established as a non-profit organisation in 1952 to promote, advance and support Earth sciences in Australia.

As a broadly based professional society that aims to represent all Earth Science disciplines, the GSA attracts a wide diversity of members working in a similarly broad range of industries.

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