Airborne Geophysical Characteristics of the Gamburtsev Subglacial Mountains, East Antarctica: Implications for Crustal Architecture and Uplift Mechanism

Seated in the middle of East Antarctic Craton, the Gamburtsev Subglacial Mountains (GSM) are completely buried by the East Antarctic Ice Sheet and are one of the most enigmatic tectonic features on the earth. The mountain ranges are underlain by 50-60 km thick crust and over 200 km thick seismically fast Precambrian lithosphere that has been well preserved during Phanerozoic collision. Potential field features reveal the subglacial major fault systems that segment the GSM into three distinct geophysical domains: GSM Northern, Central and Southern domains. These domains may reflect the segments of an inferred early Neoproterozoic accretionary orogen, which may have been reactivated during Pan-African collisional events linked to Gondwana assembly. Combined with the passive seismic points, the depth to magnetic and gravity interfaces (Curie and Moho) and 3D density inversion, 2D geophysical models are carried out to unveil the detailed crustal architecture of the GSM. Distinct magnetic anomalies correspond to older Paleoproterozoic crust of the Lambert Terrane, north of the Gamburtsev Suture. The Southern Domain may represent an extension of the South Pole Province, an inferred Mesoproterozoic igneous province. Magnetic modelling provides support for the existence of inferred basement uplift and flower structures. The upper crustal architecture may be dominated by south verging thrust faults in the Northern Domain and north verging thrust faults in the Southern Central Domain. Gravity models present a dense lower crustal root beneath the northern GSM domains along the Gamburtsev Suture, where the crust is over 58 km thick, reflecting widespread magmatic underplating. There are three Grenvillian orogenic belts in Eastern Antarctica: (1) the Maud belt, (2) the Rayner belt, and (3) the Wilkes belt. By compiling airborne geophysical data and satellite potential data over the GSM and these belts, it can be found that the GSM and the Maud belt may potentially be linked together during the inferred Grenvillian accretionary tectonic phase. However, they appear to be affected and separated during Pan-African along the Trans East Antarctic Shear Zone.