Satellite magnetic anomalies of the Antarctic Wilkes Land impact basin inferred from regional gravity and terrain data

Abstract

The GRACE gravity and subglacial terrain data of Wilkes Land are consistent with the presence of a mascon produced by giant impact perhaps at the end of the Permian. In contrast to the relatively extensive ice probing radar coverage, aeromagnetic data coverage is limited across the basin. However, Magsat, Ørsted, and CHAMP satellite magnetic observations reveal the thinned crust of the impact site to be associated with the largest satellite altitude crustal magnetic anomaly of Antarctica. The underlying region of enhanced magnetization is consistent with the GRACE gravity and BEDMAP terrain data and extends into south-central Australia in a reconstructed Gondwana. The strongly magnetized crust can reflect the impact's thermal enhancement of lower crustal viscous remanent magnetization as well as the production of positively magnetized melt rocks within the fractured crust.