The 3D Crustal Structure of the Wilkes Subglacial Basin, East Antarctica, Using Variation of Information Joint Inversion of Gravity and Magnetic Data.

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 toward interpreting geological history. We present a 3D crustal model of density and susceptibility distribution in the Wilkes Subglacial Basin (WSB) 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 inferred susceptibility and density, relating these quantities to the same gravity and magnetic sources to give an enhanced inversion result. Our model reveals a large body located in the interior of the WSB 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 bodies. The petrophysical relationship indicates that the postulated batholitic intrusion is granitic, but independent from the Granite Harbor Igneous Complex described previously in the TAM area. Emplacement of a large volume of intrusive granites can potentially elevate local geothermal heat flow significantly. Finally, we present a new conceptual tectonic model 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 intrusive events associated with the protracted Ross Orogen. Plain Language Summary: Most rocks in Antarctica are hidden beneath a thick ice sheet. Therefore, indirect techniques are required to reveal rock provinces within Earth's crust below the ice. Rocks simultaneously influence the gravity and magnetic fields through their physical properties (density and susceptibility). Here we use both the gravity and magnetic fields to reveal rock provinces beneath the ice and use the relationship between density and susceptibility of the rocks to interpret the distribution of granitic rocks of the Transantarctic Mountains and the Wilkes Subglacial Basin region in East Antarctica. Granitic rocks can lead to elevated heat flow due to radiogenic decay of minerals within the rock and thus influence the overlying ice sheet. Based on our subsurface model of rock provinces we speculate on the tectonic evolution of the region. Key Points: We present a new 3D crustal density and susceptibility distribution model based on joint inversion of gravity and magnetic dataDensity and susceptibility data are used to identify crustal level intrusions and the craton marginOur new conceptual tectonic model identifies a earlier intrusive event in the interior of the Wilkes Subglacial Basin, separate from those exposed in the Transantarctic Mountains [ABSTRACT FROM AUTHOR]