Crustal architecture of central Australia from magnetotellurics

Project Investigators

Associate Professor Graham Heinson

Associate Professor Martin Hand

Doctor Kate Selway

Project details

Central Australia's crustal architecture is defined by the Palaeo- to Mesoproterozoic Arunta and Musgrave inliers which were exhumed from beneath the Neoproterozoic to Palaeozoic Amadeus, Ngalia and Georgina Basins during the intracratonic Petermann and Alice Springs Orogens. Many significant questions remain concerning central Australia's crustal architecture, including:

• Did the Musgrave and Arunta Blocks accrete laterally or vertically?
• What is the structure of the core of the Alice Springs Orogen, and therefore
• What driving forces produced the Orogen?

These questions can only be answered with deep geophysical imaging.

Magnetotellurics (MT) is an electromagnetic geophysical technique that can determine the electrical structure of the earth with little environmental impact and cost. Four MT surveys have been carried out in central Australia as part of this project. Two of the surveys are adjacent and, when linked, cross from the Arunta region, over the Amadeus Basin and into the Musgrave Block. Results from the northern survey provide support for a proposition that an exotic terrane has been accreted onto the southern margin of the Arunta region. The southern survey was designed to test models of assembly of the Arunta region and Musgrave Block. A third survey was carried out over the entire north-south extent of the Arunta region. This survey investigated the extent of fluid-rock interaction during the major intracratonic Palaeozoic Alice Springs Orogeny. The final survey extended from the central-northern Gawler Craton to the southern margin of the Musgrave Block and was designed to test models of Gawler Craton-Musgrave Block accretion.

This project was completed in August, 2006.

The findings of this project were presented to the public by Doctor Kate Selway, as part of the Fresh Science Program sponsored by the Federal and Victorian governments.