The 3D crustal structure of the Wilkes Subglacial Basin, East
Antarctica, based on joint inversion of gravity and magnetic data using
variation of information
Abstract
Direct geological information in Antarctica is limited to ice free
regions along the coast, high mountain ranges or isolated nunataks.
Therefore, indirect methods are required to reveal subglacial geology
and heterogeneities in crustal properties, which are critical steps
towards interpreting geological history. We present a 3D crustal model
of density and susceptibility distribution in the Wilkes Subglacial
Basin and the Transantarctic Mountains (TAM) based on joint inversion of
airborne gravity and magnetic data. The applied “variation of
information” technique enforces a coupling between gravity and magnetic
sources to give an enhanced inversion result. Our model reveals a
large-scale body located in the interior of the Wilkes Subglacial Basin
interpreted as a batholithic intrusive structure, as well as a linear
dense body at the margin of the Terre Adélie Craton. Density and
susceptibility relationships are used to inform the interpretation of
petrophysical properties and the reconstruction of the origin of those
crustal blocks. The petrophysical relationship indicates that the
postulated batholitic intrusion is granitic, but independent from the
Granite Harbour Igneous Complex previous described in the TAM area.
Emplacement of a large volume of intrusive granites can potentially
elevate local geothermal heat flow significantly. Finally, we present a
tectonic evolution sketch based on the inversion results, which includes
development of a passive continental margin with seaward dipping basalt
horizons and magmatic underplating followed by two distinct intrusion
events in the Wilkes Subglacial Basin with Pan-African ages (700 - 551
Ma) and Ross ages (550 - 450 Ma).