New geophysical data from Antarctica’s Ross Embayment reveal the
structure and subglacial geology of extended continental crust beneath
the Ross Ice Shelf. We use airborne magnetic data from the ROSETTA-Ice
Project to locate the contact between magnetic basement and overlying
sediments. We delineate a broad, segmented basement high with thin
(0-500m) non-magnetic sedimentary cover which trends northward into the
Ross Sea’s Central High. Before subsiding in the Oligocene, this feature
likely facilitated early glaciation in the region and subsequently acted
as a pinning point and ice flow divide. Flanking the high are wide
sedimentary basins, up to 3700m deep, which parallel the Ross Sea basins
and likely formed during Cretaceous-Neogene intracontinental extension.
NW-SE basins beneath the Siple Coast grounding zone, by contrast, are
narrow, deep, and elongate. They suggest tectonic divergence upon active
faults that may localize geothermal heat and/or groundwater flow, both
important components of the subglacial system.