3D resistivity models of the Delamerian Orogen, southeast Australia, from AusLAMP

Here we present 3D resistivity models of the lithosphere beneath an area of southeast Australia, derived from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP). AusLAMP aims to collect long period magnetotelluric (MT) sites in a 55 km spaced array across Australia. With most of southeast Australia complete, we are now armed with a tool to understand the architecture of the entire lithosphere across large areas. The AusLAMP data presented here were collected by several organisations. Geoscience Australia (GA), the Geological Survey of South Australia, the Geological Survey of New South Wales, the Geological Survey of Victoria, and the University of Adelaide all contributed staff and/or funding for collection of the data; AuScope and GA contributed instrumentation. Our resistivity models from these data encompass the Paleo-Mesoproterozoic Curnamona Province, the Neoproterozoic Flinders Ranges, and the Cambrian Delamerian Orogen, encompassing eastern South Australia and western New South Wales and western Victoria. The Delamerian Orogen marks the transition along the eastern margin of Proterozoic Australia from a passive to an active continental margin, and has potential for a range of mineral systems. The Curnamona Province is also prospective, with strong similarities and a large mantle conductivity anomaly joining it to the Gawler Craton, which hosts a world-class IOCG belt. Preliminary resistivity models indicate a highly conductive crust in the Curnamona Province. Within the Delamerian Orogen, the lithosphere is mostly resistive, with isolated conductive anomalies from around 10 km down to the lower lithosphere. The Murray Basin that hinders mineral exploration over the southern parts of the Delamerian Orogen is imaged as a widespread shallow conductor. Subduction-related crustal enrichment during the Delamerian Orogeny, identified by xenolith and seismic studies of eastern South Australia has, in part, been overprinted by the signature of recent volcanism in the form of the Newer Volcanic Province (NVP). The NVP, previously imaged by MT in Victoria, is now imaged in its full onshore extent. The new resistivity models will enable us to identify lithospheric scale structures and test tectonic models about the evolution of southeast Australia. Presented to the American Geophysical Union (AGU) conference 9 – 13 December 2019, San Francisco (https://www.agu.org/fall-meeting-2019)