Gravity anomalies provide a tool to study crustal structure, effective elastic thickness, and
isostatic and tectonic processes. Over the last 10 years major airborne gravity surveys were flown by the
international community over several Antarctic frontiers. The longer-wavelength Antarctic gravity anomaly field
is increasingly better resolved with satellite-gravity. These recent airborne and satellite gravity datasets
provide novel perspectives on Antarctic crustal structure and geodynamic evolution.
We review results from some of these surveys over the Gamburtsev Subglacial Mountains, Dronning Maud
Land, the Wilkes Subglacial Basin, the Transantarctic Mountains and the West Antarctic Rift System and
present gravity modelling outputs of crustal thickness for these regions. We contrast these gravity results with
a seismically-derived estimation of Antarctic crustal thickness (Baranov and Morelli, 2013, Tectonophys).
Anomalously thick East Antarctic crust lies beneath the Gamburtsev Mountains and parts of Dronning Maud
Land (50-58 km). Crustal thickening may stem from the collision of a mosaic of East Antarctic crustal
provinces in Meso to Neoproterozoic times (Ferraccioli et al., 2011, Nature), or during younger Edicaran to
early Cambrian “Pan-African age” orogenic events. The preservation of such thick crust provides significant
support for the high bedrock topography in East Antarctica. Additional flexural uplift along the flanks of the
Permian to Cretaceous East Antarctic Rift System helps explain the enigmatic Gamburtsev Mountains. Lithospheric flexure along the flank of the West Antarctic Rift System (WARS) may explain the Transantarctic
Mountains (TAM), the longest and highest non-compressional mountain range on Earth. Whether the Wilkes
Subglacial Basin also developed in response to lithospheric flexure is debated. Our gravity models image
thicker crust beneath the Transantarctic Mountains (TAM) (ca 40 km thick), compared to the relatively thinner
crust (30-35 km) beneath the Wilkes Subglacial Basin (Jordan et al., 2013 Tectonophys); this is difficult to
reconcile with previous flexural model predictions. Three geodynamic processes could explain the thicker
crust beneath the TAM: i) Cambrian-Ordovician subduction and accretion along the East Antarctic craton
margin; ii) formation of a Paleozoic to Mesozoic plateau in West Antarctica that collapsed leaving behind a
region of thicker crust; iii) extensive Jurassic magmatic underplating related to Gondwana break-up.
Gravity modelling helps trace the WARS beneath the West Antarctic Ice Sheet (WAIS). The interior Ross Sea
Embayment features 25-28 km-thick crust, while parts of the Amundsen Sea Embayment (ASE) are underlain
by 19-23 km-thick crust. Narrow Cenozoic rifts may be interspersed with regions of more distributed
Cretaceous extension, explaining the anomalously thin crust and lower Te values beneath the ASE. Major
contrasts within the WARS are relevant also for the WAIS as these likely exert a key influence on geothermal
heat flux variations, which in turn influence basal melting and ice motion.
EPIC Alfred Wegener Institut