EGU21-1825, updated on 03 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Some evidence for a wide fan-shaped extension of the East Antarctic plate at the Mesozoic-Cenozoic transition

Egidio Armadillo1, Daniele Rizzello2, Pietro Balbi1, Davide Scafidi1, Andrea Zunino3, Fausto Ferraccioli4,5, Guy Paxman6, Alessandro Ghirotto1, and Martin Siegert7
Egidio Armadillo et al.
  • 1Università di Genova, DISTAV, Genova, Italy (
  • 2Tellus sas, Italy
  • 3ETH Zurich, Switzerland
  • 4Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy
  • 5British Antarctic Survey, BAS, Cambridge, UK
  • 6Lamont-Doherty Earth Observatory, Columbia University, New York, USA
  • 7Grantham Institute and Department of Earth Science and Engineering, Imperial College, London, UK

The Transantarctic Mountains (TAM) separate the Mesozoic to recent West Antarctic rift system (WARS) from a wide and depressed triangular sector of East Antarctica spanning from 100° E to 160° E in longitude and from the Oates, George V and Adelie coastlines to 85° S in latitude. The sub-ice bedrock of this sector shows a basin and range style topography comprising two major basins of continental proportions -the Wilkes Basin and the Aurora Basin complex- and many smaller basins such as the Adventure, Concordia, Aurora and Vostok trenches. Most of these basins and trenches exhibit a triangular shape with the acutest angle pointing approximatively to a single pole towards the South, giving a fan shaped pattern of significant dimensions. We name here this region as the East Antarctic Fan shaped Basin Province (EAFBP). To the West, this province is limited by the intraplate Gamburtsev Mountains (GM).

Origins and inter-relationships between these four fundamental Antarctic tectonic units (WARS, TAM, EAFBP, GM) are still poorly understood and strongly debated. In the EAFBP, very little is known about the mechanism generating the basins, their formation time, whether they are all coeval and if and how they relate to Australia basins before Antarctica-Australia rifting. Present genetic hypotheses for some of the basins span from continental rifting to a purely flexural origin or a combination of the two. Also, post-tectonic erosional and depositional processes may have had a significant impact on the present-day topographic configuration.

Here we investigate the possibility that the EAFBP is the result of a single genetic mechanism: a wide fan-shaped intra-continental extension around a pivot point at about 135° E, 85° S that occurred at the Mesozoic-Cenozoic transition. We discuss evidence from the sub-ice topography and potential field airborne and satellite data.

We have used international community-based Antarctic compilations in public domain, including BedMachine (Morlighem et al., 2020), AntGG (Scheinert et al., 2016) and ADMAP 2.0 (Golynsky et al., 2018). We have applied image segmentation techniques to the rebounded sub-ice topography to automatically trace the first order shape of the sub-ice basins. Then we have fitted the edges of the basins by maximum circles and we have estimated the best Euler pole identified by their intersection. Potential field anomalies have been taken into account in order to enlighten major discontinuities not revealed by the sub-ice topography.

Software simulations of the EAFBP opening in the frame of global plate tectonics reconstructions indicate that it may be inserted in the frame of the later phase of the Antarctica-Australia rifting, giving constraints on timing that allow us to date the EAFBP opening at the Mesozoic-Cenozoic transition.

The reconnaissance of the EAFBP as the result of a continental-scale fan-shaped extension may have deep implications on global and regional tectonics plate reconstructions, plate deformation assumptions and new tectonic evolutionary models of WARS, TAM and GM.

How to cite: Armadillo, E., Rizzello, D., Balbi, P., Scafidi, D., Zunino, A., Ferraccioli, F., Paxman, G., Ghirotto, A., and Siegert, M.: Some evidence for a wide fan-shaped extension of the East Antarctic plate at the Mesozoic-Cenozoic transition, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1825,, 2021.