Broad Basement Structures Under Antarctica’s Ross Ice Shelf Revealed from Aeromagnetic Data

Abstract:

Deconvolution of aeromagnetic data from the ROSETTA-Ice project estimates the top of the magnetic sources in the crust beneath the Ross Ice Shelf (RIS). These magnetics source depths represent the top of crystalline basement. The basement surface reveals large scale features that we interpret as sediment filled structural troughs and basement highs formed during opening of the West Antarctica Rift System. Basement features in the Ross Sea that have been identified from marine seismic surveys and DSDP drilling, namely the Eastern Basin, Central High, Central Trough, Coulman High, and Victoria Land Basin, all appear to have southern components extending under the RIS. Several sedimentary basins in the Ross Sea have associated free-air gravity highs, and this trend is consistent under the RIS. The Central High spatially coincides with the tectonic boundary between West Antarctica and East Antarctica and separates two sectors that have contrasting densities and seabed depths (Tinto et al. 2019). The gravity-derived bathymetry model for the eastern RIS region shows areas of shallow seabed that may inhibit ocean circulation to critical grounding zones of the RIS along the Siple Coast. In aid of accurate modeling of ocean circulation, this basement surface can be used to refine the bathymetry model further by introducing crustal density variations across the sediment-basement interface. Future work will investigate the resulting differences in the bathymetry model with the inclusion of the basement surface.