Electrical Structure of the Crust and Mantle in Southwestern Australia

Funding: This research is funded by the National Natural Science Foundation of China (42274085).

Abstract: The Yilgarn Craton in Western Australia, one of the world's oldest cratons, is rich in mineral resources and provides significant opportunities for research into geothermal energy, crustal dynamics, and mineral exploration. To investigate the electrical structure of southwestern Western Australia, we interpret magnetotelluric data using a finite element-based inversion algorithm we developed, complemented by Bouguer gravity anomaly data, and perform a detailed analysis of the crust-mantle electrical structure. We rigorously validate model sensitivity and cross-verify the inversion results with those obtained using ModEM and Bouguer gravity anomaly interpretations. Our findings identify the Darling Fault and the southern Manjimup Fault as critical structural boundaries that delineate distinct geological features in the study area. All three methods consistently reveal low-resistivity anomalies in the asthenosphere at depths shallower than 100 kilometers. By integrating these results with insights from seismology, gravity, geodynamics, and geochemistry, we suggest that significant geological activity occurs beneath the ancient crust of the Yilgarn Craton. The observed low-resistivity anomalies likely result from the influence of the Darling Fault, the southern Manjimup Fault, and early magmatic processes associated with the craton’s evolution.