Exploring lithospheric scale structure in the Southern Yilgarn Craton with 3D magnetotellurics

The electrical structure of the southern Yilgarn Craton is of interest in building an understanding of the pathways for mineralisation at the lithospheric scale. This project uses three dimensional inversion of magnetotelluric data from both broadband and long period stations to investigate an east west traverse of the South West, Youanmi and Kalgoorlie terranes of the Yilgarn Craton in Western Australia. These data are from the Southern Cross magnetotelluric survey. Previous studies in the region focussed on two dimensional modelling, however, phase tensor analysis of these data show a predominantly three dimensional subsurface that varies in strike across the profile. For this study models were produced using 26 stations, four of which contain data from an additional long period survey. The modelling highlights several conductive regions within a predominantly resistive subsurface. One large western conductor dominates the South West Terrane at depth, and a second more conductive feature is observed underneath the Kalgoorlie Terrane. These conductive regions may be associated with various mineralisation events during mantle activity prior to cratonization of the Yilgarn Craton.