The secular development of accretionary orogens: linking the Gondwana magmatic arc record of West Antarctica, Australia and South America

Tracking voluminous Permian volcanism of the Choiyoi Province into central Antarctica

“…248 Ma) from Marie Byrd Land have zircon Hf compositions that are generally more depleted than central Antarctica (Fig. 8) and record unambiguous evidence for a depleted mantle source (Nelson and Cottle, 2018). In summary, there is currently no evidence to support Marie Byrd Land as a likely source region for Permian zircon in central Antarctica.…”

“…At least two geologically feasible scenarios can explain the lack of juvenile Hf isotopic compositions (εHf i > +5) in central Antarctica samples. The evolved signature may result from contamination of depleted mantle melts by assimilation of enriched Cambrian (e.g., Ross Orogen) and/or Proterozoic (Grenville-aged cratonic basement) crustal reservoirs (Hagen-Peter et al, 2015;Hagen-Peter and Cottle, 2018) that are ubiquitous along the Gondwana margin (Nelson and Cottle, 2018). Alternatively, enriched compositions may have resulted from enriched lithospheric mantle melting followed by crustal assimilation.…”

“…Zircon Hf isotope compositions for crystalline basement in the Antarctic Peninsula and the adjacent crustal block of Thurston Island are limited ( Fig. 8; Flowerdew Riley et al, 2017;Nelson and Cottle, 2018). The available data suggests they both record enriched Hf isotopic compositions in the Permian-Triassic and, therefore, may have been sourced from an enriched lithospheric mantle similar to that of South America.…”

“…268 Ma Permian zircon age peak for central Antarctica and has similarly enriched zircon Hf isotope compositions (mean εHf i = +0.4 ± 0.7 [2SE]) suggesting Thurston Island as a potential source for Permian zircon from central Antarctica (Fig. 8; Nelson and Cottle, 2018). In contrast, there are no Permian magmatic rocks from Marie Byrd Land contemporaneous with the ca.…”

“…268 Ma central Antarctica Permian zircon ( Fig. 8; Pankhurst et al, 1998;Mukasa and Dalziel, 2000;Yakymchuk et al, 2013Yakymchuk et al, , 2015Nelson and Cottle, 2018). Older Permian magmatic rocks (ca.…”