Precambrian lithospheric structure in East Antarctica controls Phanerozoic basin forming and Gondwana breakup geometry

• Main Authors: Aitken, A., Li, L., Kulessa, B., Schroeder, D., Jordan, T., Whittaker, J., Anandakrishnan, S., Dawson, E., Wiens, D., Eisen, O., Siegert, M.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Antarctic; Australian Antarctic Basin; Australian-Antarctic Basin; East Antarctica; George V Fracture Zone; Kerguelen; Antarc*; Antarctica
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5018491

East Antarctica is the keystone to Gondwana and is fundamental to the understanding of continental breakup and the distribution of continents since the Jurassic, with further implications for the formation of today’s oceans and ice sheets and evolution of climate. Analysis of multiple geophysical datasets in East Antarctica, including radio-echo sounding, potential fields and seismic datasets have revealed the distribution of sedimentary basins within East Antarctica. Differences in the morphology and orientation of sedimentary basins define lithospheric domains separated by basement-dominated regions. The basement highs are defined by multiscale linear features evident in gravity, bed topography and seismic tomography models. These boundaries, we suggest, indicate the margins of former continental blocks that were assembled in the Precambrian to form East Antarctica. Rheological contrasts at block margins controlled later deformation during Phanerozoic extension. First, the formation of variably-oriented sedimentary basins in the Devonian to Triassic is consistent with reactivation of prior architecture and the distribution of major basin-dominated regions is indicative of differences in lithospheric rheology and composition - warmer and compositionally more fertile lithosphere is prone to subsidence. Second, the basement highs are aligned with key features of Gondwana breakup in the Jurassic to Eocene including the Africa-Madagascar-Sri Lanka triple junction, the Kerguelen Plateau, the George V fracture zone of Australian-Antarctic basin and the Macquarie Ridge. We suggest that the differential lithospheric structure of East Antarctica including mantle, crust and basins led to the localisation of these features and fundamentally controlled the geometry of Gondwana breakup.