Crustal structure of the Gamburtsev Province, East Antarctica, from airborne geophysics

The Gamburtsev Subglacial Mountains are completely buried by the East Antarctic Ice Sheet and hence are one of the most enigmatic tectonic features on Earth. The mountain range is underlain by 50-60 km thick crust and seismically fast Precambrian lithosphere, which is over 200 km thick. Here we present gravity and aeromagnetic images derived from the AGAP aerogeophysical survey, depth to magnetic source estimates and a joint forward magnetic and gravity model along an independent passive seismic line to investigate the crustal structure of the Gamburtsev Province. The magnetic and gravity images reveal three distinct geophysical domains, namely the Northern, Central and Southern Gamburtsev domains, sandwiched in between the South Pole and the Southern Lambert provinces. We interpret these domains as reflecting segments of an inferred early Neoproterozoic (ca 1 Ga) accretionary orogen, which may have been reactivated during Pan-African (ca 550 Ma) collisional events linked to Gondwana assembly. Our gravity model confirms the presence of a dense lower crustal root beneath the northern and central Gamburtsev domains, where the crust is up to 58 km thick. The magnetic modelling suggests that the upper crustal architecture is dominated by south verging thrust faults in the Northern Domain and north verging thrust faults in the Southern Central Domain. Our modelling results are a first step towards comprehending the complex 3D orogenic architecture of the Gamburtsev Province and its broader linkages with Rodinia and Gondwana supercontinent assembly in interior East Antarctica.

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