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 2.75 to 2.95 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 Antarctica’s crust.