Unveiling basement provinces hidden beneath the Pensacola Pole Basin region in East Antarctica

Abstract:

A long-lived (580?-460 Ma) Andean-style convergent margin formed in response to subduction of Proto-Pacific oceanic lithosphere leading to the emplacement of magmatic arc magmatism, which is exposed along the much younger Transantarctic Mountains. Thrusting, deformation and metamorphism are the hallmarks of the Ross Orogen (RO) in addition to the arc (Goodge et al., 2020). Despite the wealth of knowledge on the RO, the location, evolution and structure of the boundary between the composite Precambrian Mawson Craton and the orogen is much less well understood, particularly in the South Pole (SP) region.

Here we combine aerogeophysical datasets collected within the European Space Agency funded PolarGAP project with vintage data and satellite gravity and satellite magnetic data to investigate the SP sector of the RO and provide the key missing link with exposures of Precambrian basement in the Southern and Eastern terranes of the Shackleton Range (SR). Prominent aeromagnetic anomalies trace the subglacial extent of arc-related rocks of the RO. Both circular and linear anomalies are imaged. The latter are interpreted as linear ribbons of back-arc crust buried beneath the Pensacola-Pole Basin (PPB).

Different magnetic patterns reveal the extent of inferred Paleo to Mesoproterozoic rocks of the South Pole Province (assigned to the Mawson Craton), while prominent linear Grenvillian(?) age belts are imaged in the composite Recovery Province sandwiched between the PPB and SR. In addition to several enhanced magnetic and gravity images, we present depth to source and preliminary 2D magnetic and gravity models crossing the RO and its boundaries with these newly imaged Precambrian provinces to shed new light into the crustal architecture of this frontier region.