Australia's continental crust examined in detail


A man recording data in a field.

A geophysicist establishing a
magnetotelluric measurement
station for continuous recording
of electric and magnetic signals
in the field.

One of the most comprehensive geophysical investigations of Australia's geological makeup ever undertaken is expected to reveal unprecedented detail of the continent's crust and upper mantle.

Called AusLAMP, the Australian Lithospheric Architecture Magnetotelluric Project is a national magnetotelluric survey aimed at identifying major structures in the crust and upper mantle, including domain boundaries, faults, shear zones, sedimentary basins, fluids and thermal structure.

AusLAMP is a national survey being undertaken by Geoscience Australia in conjunction with AuScope, the Australian National Seismic Imaging Resource (ANSIR), the State and Northern Territory geological surveys, the University of Adelaide and other partners.

The Chief of Geoscience Australia's Minerals and Natural Hazards Division, Dr Andy Barnicoat, said that AusLAMP would map the electrical conductivity structure of the Australian lithosphere in 3D through the acquisition of data at around 2800 sites across Australia.

"The AusLAMP dataset will be integrated with other national datasets, such as aeromagnetic, gravity, seismic, geochemical, temperature, and geology datasets to help develop a better understanding of the lithospheric architecture and evolution at a continental scale, which is one of the significant challenges identified in the Uncover searching the deep Earth initiative of the Australian Academy of Science," Dr Barnicoat said.

"AusLAMP aligns well with the Uncover objective and the resulting dataset will be an important Earth imaging resource for researchers as well as adding to Australia's pre-competitive geoscience data to help mining companies and explorers better define areas for potential mineral and energy exploration," Dr Barnicoat said.

The magnetotelluric data collected through AusLAMP is recorded with instruments deployed over a 55 kilometre grid spacing for about one-month and ultimately, will gather data for the whole of Australia.

Geoscience Australia and the Geological Survey of Victoria have begun collecting data in eastern Victoria under AusLAMP and the project will extend to other areas in South Australia, New South Wales and Queensland shortly.

The magnetotelluric method for gathering data is used widely for mineral, petroleum and geothermal exploration, and for crust and mantle studies. The main strengths of the method are it allows a broader range of depth investigation than other geophysical techniques and it has a greater level of sensitivity to lateral and vertical electrical conductivity variations. It is useful also for distinguishing different types of rock and helping to understand geological structures and tectonic evolution.