East Antarctic rifting triggers uplift of the Gamburtsev Mountains

Abstract

The Gamburtsev Subglacial Mountains are the least understood tectonic feature on Earth, because they are completely hidden beneath the East Antarctic Ice Sheet. Their high elevation and youthful Alpine topography, combined with their location on the East Antarctic craton, creates a paradox that has puzzled researchers since the mountains were discovered in 1958. The preservation of Alpine topography in the Gamburtsevs may reflect extremely low long-term erosion rates beneath the ice sheet, but the mountains' origin remains problematic. Here we present the first comprehensive view of the crustal architecture and uplift mechanisms for the Gamburtsevs, derived from radar, gravity and magnetic data. The geophysical data define a 2,500-km-long rift system in East Antarctica surrounding the Gamburtsevs, and a thick crustal root beneath the range. We propose that the root formed during the Proterozoic assembly of interior East Antarctica (possibly about 1 Gyr ago), was preserved as in some old orogens and was rejuvenated during much later Permian (roughly 250 Myr ago) and Cretaceous (roughly 100 Myr ago) rifting. Much like East Africa, the interior of East Antarctica is a mosaic of Precambrian provinces affected by rifting processes. Our models show that the combination of rift-flank uplift, root buoyancy and the isostatic response to fluvial and glacial erosion explains the high elevation and relief of the Gamburtsevs. The evolution of the Gamburtsevs demonstrates that rifting and preserved orogenic roots can produce broad regions of high topography in continental interiors without significantly modifying the underlying Precambrian lithosphere.

Exploring the Recovery Lakes region and interior Dronning Maud Land, East Antarctica, with airborne gravity, magnetic and radar measurements

“…It can be seen that the ice stream is >3 km deep here, with a sharp border to higher subglacial terrain towards the southern side of the ice stream. The gravity signatures and bedrock maps of Figure 7 also show SW-NE-striking features, probably associated with subglacial fault systems (Paxman et al 2017), and also a highland-like subglacial region to the east of Recovery Lakes, towards the Gamburtsev Subglacial Mountains region (Ferraccioli et al 2011;Paxman et al 2016). The SW-NE-striking features also show up in the magnetic data in Figure 9.…”

Electrical structure beneath Schirmacher Oasis, East Antarctica: a magnetotelluric study

“…Regional plume-related dynamics in the deep lithosphere have been postulated as the dominant trigger for this thermal activity, with a possible contributing influence from the adjacent West Antarctic Block, a process that has also been invoked in earlier studies to account for the regional uplift in East Antarctica such as in the GamburtsevÁVostok areas (Studinger et al 2003;Bell et al 2006). However, a recent study by Ferraccioli et al (2011) negated this hypothesis and interpreted the feature to be a compositional Airy compensation. Continental flood basalts are known from western Dronning Maud Land and the Transantarctic Mountains which are regarded as manifestations of the KarooÁ Maud mantle super-plume activities at about 180 Mya (e.g., Bormann & Fritzsche 1995), which enabled subsequent Gondwanaland break-up (e.g., Storey 1995;Raval & Veeraswamy 2003).…”

Antarctica and supercontinent evolution: historical perspectives, recent advances and unresolved issues

“…6b). This proposed path also corresponds with the eastern branch of the East Antarctic Rift System (Figs 2 & 6) (Ferraccioli et al 2011), a prominent subglacial topographical feature that has a western branch in the Lambert Graben and is likely to follow older geological boundaries. Although Fitzsimons (2003) favoured a Pan-African age for this structure, there is evidence for metamorphism and magmatism at 1090-1060, 800-650 and 550-500 Ma in the Pinjarra Orogen of Western Australia (Fig.…”