Heterogeneous structure of Antarctic crust for solid-earth and cryosphere interaction research

Knowing the heterogeneous crustal structure is essential for understanding the ice dynamics, glacial isostatic adjustment (GIA) and tectonic history in Antarctica. For example, geothermal heat flux (GHF) is a major boundary condition for ice dynamics and the crust thickness and its composition (mafic or felsic) are important factors in GHF. Meanwhile, the GIA signal and its gravity response are essential for detecting mass-balance change and predicting future sea-level change. Errors in the density model used, which may be over 10%, will propagate into the gravity calculations. In this study, we use gravity inversion constrained by seismic depth estimation to recover the heterogeneous crustal structure of Antarctica, and estimate its uncertainties. Specifically, we modify by inversion the density of the uppermost mantle, the crustal density, the Moho depth, and the sedimentary cover thickness with an ensemble model with different density/geometry variation constraints. The output models indicate the most representative model of Antarctic crustal structure within the capacity of the method and current data constraints. Our preliminary results show that crustal density varies between 2.8 to 2.9 g/cm3 while the Moho depth varies between 22 km in Ross Ice Shelf and 54 km in Gamburtsev Subglacial Mountains. Low-density sedimentary basins are modelled at up to 10 km thickness beneath the ice shelf, and 3 km inland of Antarctica. Model also shows mantle density varies from 3.25 to 3.35 g/cm3. These density and thickness variations indicate likely substantial differences in crustal heat production, crustal rheology, and the expected GIA response of Antarcticas crust.