Heterogeneity in the lithosphere and deeper mantle of the Mawson-Casey region, and its Tectonic Setting within East Antarctica.

Abstract:

The extensive region of East Antarctica between Mawson and Casey stations encompasses a sector of known lithospheric boundaries in the Lambert Glacier sector, and a region which is generally assumed to be a less segmented part of East Antarctica between Davis and Casey stations. A deployment of, mostly co-located, GPS and seismic stations at 9 locations in this region commenced in the 2016/17 summer season and is pending an upgrade of key sites for ongoing recording.

Studies modelling the interactions between the solid Earth and cryosphere, in glacial isostatic adjustment, have shown the merit of approaches that make use of a 3D Earth structure. While West Antarctica and parts of central Antarctica have much improved constraints on the heterogeneity of the deep Earth through recent geophysical studies, much of East Antarctica is less-well constrained. We use the new seismic data to improve constraints on structure and rheology in a region with high uncertainty in many of the observations and ice sheet models that constrain the contribution of the overlying ice sheet to sea level rise.

In this contribution, the seismic results from the above stations, relatively close to the coast, are brought together with insights regarding the interior of the continent from a previous multivariate study, and a plate reconstruction, to construct the likely variation of physical properties in the lithosphere and asthenosphere in this region. It is likely that the Davis-Casey region is more variable than previously thought as we find both observed, and probable, heterogeneity in the deep Earth across this sector. We make use of newly written software for data synthesis in 3D, and volumetric visualisations in our analyses. We aim to make our results available to the interdisciplinary community, including ice sheet modellers, in the near future.