Pangea Rifting Shaped the East Antarctic Landscape

Maritati, Alessandro1, Danišík, Dr Martin2, Halpin, Dr Jacqueline1, Whittaker, Dr Joanne1, Aitken, Dr Alan3

1Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, TAS 7001, Australia, 2John de Laeter Centre/The Institute for Geoscience Research, Curtin University, Perth, WA 6845, Australia, 3School of Earth Sciences, University of Western Australia, Perth, WA 6009, Australia

East Antarctica remains one of the few continental regions on Earth where an understanding of the origin and causal processes responsible for topographic relief is largely missing. Low‐temperature thermochronology studies of exposed Precambrian basement revealed discrete episodes of cooling and denudation during the Paleozoic–Mesozoic; however, the significance of these thermal events and their relationship to topography across the continental interior remains unclear. In this contribution, we present a model for the origin of topography of interior East Antarctica which seeks to establish a link between Paleozoic–Mesozoic AFT and AHe cooling ages and continent‐scale geodynamic processes. We use new zircon and apatite (U‐Th)/He thermochronology from Precambrian basement outcrops to determine the timing, magnitude, and style of Phanerozoic cooling of the Bunger Hills region, a poorly exposed section of East Antarctic basement across the large-scale domain of Indo-Antarctica and Australo-Antarctica. Thermal history modelling results indicate that Precambrian basement in the Bunger Hills region experienced a distinct cooling episode during the Late Paleozoic–Triassic, which we relate to ~2–4 km of regional exhumation associated with intracontinental rifting, followed by a second episode of localized cooling and ≤1 km exhumation during the Late Jurassic–Cretaceous separation of India from East Gondwana. Late Paleozoic–Triassic cooling and exhumation in the Bunger Hills region is consistent with the timing and magnitude of rift‐related cooling and exhumation reported in the Lambert Rift and George V Land, suggesting a single denudational system driven by Pangea‐wide extension. We propose that this event had a profound impact on the formation of topographic relief of East Antarctica via the exhumation of large sections of basement and the formation of vast intracontinental sedimentary deposits across the East Antarctic interior. By contrast, extension associated with the Jurassic–Cretaceous breakup of East Gondwana did not provide an equally widespread denudational response across the East Antarctic interior. The topographic framework formed during the Paleozoic–Mesozoic had a significant impact on the long‐term landscape evolution of East Antarctica and provided a template for Cenozoic erosion on the continent.


Biography

I am a PhD candidate at the University of Tasmania with a strong focus on petrology, geochronology and geochemistry. My current research activity focuses on integrating multiple geoscientific datasets at different scales to gain insights into the crustal architecture and tectonic evolution of East Antarctica.

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