ARMADILLO, EGIDIO

Blankenship, Donald

CRISPINI, LAURA

Ferraccioli, Fausto

Laeufer, Andreas

Lisker, Frank

Ruppel, Antonia

Siegert, Martin

Young, Duncan

English

Egidio Armadillo

Fausto Ferraccioli

Laura Crispini

Andreas Laeufer

Antonia Ruppel

Duncan Young

Donald Blankenship

Frank Lisker

Martin Siegert

Archivio istituzionale della ricerca - Università di Genova

Geophysical Research AbstractsVol. 21, EGU2019-4367-4, 2019EGU General Assembly 2019© Author(s) 2019. CC Attribution 4.0 license.Rifting in East Antarctica: new views from the Rennick Graben andWilkes Subglacial BasinEgidio Armadillo (1), Fausto Ferraccioli (2), Laura Crispini (1), Andreas Laeufer (3), Antonia Ruppel (3),Duncan Young (4), Donald Blankenship (4), Frank Lisker (5), and Martin Siegert (6)(1) Universita’ di Genova, DISTAV, Genova, Italy (egidio@dipteris.unige.it), (2) NERC, British Antarctic Survey, Geology &Geophysics, Cambridge, UK (ffe@bas.ac.uk), (3) BGR Federal Institute for Geosciences and Natural Resources, Hannover,Germany (Andreas.Laeufer@bgr.de), (4) University of Texas, Institute of Geophysics, Austin, USA (blank@ig.utexas.edu),(5) University of Bremen, Germany (flisker@uni-bremen.de), (6) Imperial College London, The Grantham Institute forClimate Change, London, UK (m.siegert@imperial.ac.uk)Multiple continental rifting stages are known to have affected the Phanerozoic West Antarctic lithospherethroughout the Cretaceous and Cenozoic, leading to the formation of one of the largest continental rift systemson Earth- the West Antarctic Rift System (WARS). However, much less is known regarding both the extent andinfluence of inferred extensional and transtensional processes within the Precambrian lithosphere of the EastAntarctic craton, which may have heralded and potentially even followed the separation of East Antarctica fromAustralia, as part of Gondwana breakup.Two major topographic basins are known in the Victoria Land segment of the Transantarctic Mountains(TAM) and its ice covered hinterland: the Rennick Graben (RG) and the Wilkes Subglacial Basin (WSB). The RGhas been interpreted either as an extensive left lateral Cretaceous(?) pull-apart basin linked to the developmentof the early WARS, or as a more localised Cenozoic right-lateral basin un-connected to the WARS itself. TheWSB is instead often depicted as an intracratonic flexural basin related to the Cenozoic uplift of the TAM, aninterpretation that broadly matches the results of recent flexural modelling in this part of East Antarctica (Paxmanet al., 2019- JGR). However, our interpretations of aeromagnetic and topographic data indicate that extensionaland transtensional processes also affected the rigid cratonic lithosphere in the WSB -at least at upper crustal level.Here we present results from a new project (REGGAE) that aims to re-investigate the architecture and evo-lution of the RG and evaluate its potential linkages with the WSB by analysing aeromagnetic, aerogravity andland-gravity and bedrock topography data together with new structural and thermochronology constraints in theVictoria Land segment of the TAM. We show that enhanced aeromagnetic and isostatic residual gravity mapsprovide tantalising new geophysical views of the RG and several distinct sub-basins within the WSB. Here weinterpret these sub-basins within the WSB as upper crustal grabens and pull-apart basins, whose topography wassignificantly modified by the superposition of glacial erosion. The new geophysical images reveal the spatialextent of part of a Jurassic tholeiitic Large Igneous Province within the RG and WSB and also help define theinherited structural architecture and the Ross-age and Precambrian basement provinces underlying the two basinsrespectively.Our geophysical interpretation leads us to hypothesise that the RG is kinematically connected with boththe western edge of the WARS and the eastern margin of the WSB, possibly in Cenozoic and Cretaceous timesrespectively. However, gravity inversions demonstrate that neither the RG nor the WSB exhibit comparablythin crust or lithosphere as observed within the WARS, suggesting that the more rigid Precambrian lithosphereresponded markedly differently to the evolution of the regional Mesozoic and Cenozoic stress field. Additionally,potential field images confirm that both the RG and the WSB were un-affected by voluminuous rift-relatedCenozoic alkaline magmatism and thick post-Jurassic sedimentary infill is also presently lacking, in stark contrastto the deep Ross Sea Rift basins within the WARS.

Rifting in East Antarctica: new views from the Rennick Graben and Wilkes Subglacial Basin

https://iris.unige.it/bitstream/11567/970740/2/EGU2019-4367-4.pdf

Rifting in East Antarctica: new views from the Rennick Graben and Wilkes Subglacial Basin

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Archivio istituzionale della ricerca - Università di Genova