Polyphase structural evolution of northern Victoria Land (Antarctica) in the light of Gondwana break-up and the development of the Australia-New Zealand-Antarctica plate fragments (ANZAPF)

Description

The Australia-New Zealand-Antarctica plate fragments (ANZAPF) evolved as consequence of break-up and fragmentation of Gondwana since the late Early Jurassic. Antarctica occupied the centre of Gondwana, and it thus holds a key position for any plate tectonic reconstruction. Northern Victoria Land (NVL) is located at the Pacific end of the Transantarctic Mountains, a high-elevation mountain chain that stretches for >3500 km from the Atlantic to the Pacific oceans across the entire Antarctic continent. The modern Transantarctic Mountains represent the uplifted western shoulder of the Cenozoic West Antarctic Rift System. The main uplift commenced around the Eocene-Oligocene boundary due to inversion of a wide mid-Jurassic to early Paleogene sedimentary basin ("Mesozoic Victoria Basin"). The basement rocks of the Transantarctic Mountains formed by orogenic processes due to subduction of the Palaeopacific Ocean beaneath East Gondwana during the ?latest Ediacaran to early Palaeozoic Ross Orogeny. This long-lasting geological history of NVL produced a highly anisotropic crust, which is very much susceptible to repeated reactivation. Here, we present multi-methodological evidence for the polyphase structural evolution of NVL after initial break-up of Gondwana in this region indicated by the ca. 180 Ma Ferrar volcanic event. A post-34 to 30 Ma old, predominantly Neogene NW-SE striking dextral strike-slip belt with local transtension and transpression has overprinted and in parts obliterated older structures and controls the present structural architecture of NVL. It may be interpreted in terms of dynamic response to intra-oceanic fracture zone arrays between Australia and Antarctica reaching into the NVL crust and extending further into the Ross Sea.

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