Reconstruction of the early Mesozoic plate margin of Gondwana by U–Pb ages of detrital zircons from northern Victoria Land, Antarctica
Martin Elsner, Robert Schöner, Axel Gerdes, Reinhard Gaupp, 2013. "Reconstruction of the early Mesozoic plate margin of Gondwana by U–Pb ages of detrital zircons from northern Victoria Land, Antarctica", Antarctica and Supercontinent Evolution, S. L. Harley, I. C. W. Fitzsimons, Y. Zhao
Download citation file:
Detrital zircons of eight sandstone samples from the Triassic–Early Jurassic Section Peak Formation (Victoria Group, Beacon Supergroup) in northern Victoria Land, Antarctica, were investigated by U–Pb LA–ICPMS dating. The basin was flanked by the East Antarctic craton, and by a magmatic arc at the palaeo-Pacific margin of Gondwana. It accommodated sandstones ranging from quartzo-feldspathic to volcaniclastic in composition. The detrital zircon age spectra yield pronounced concentrations at c. 190–250 Ma, 500–700 Ma and 800–1200 Ma. The proportion of Triassic–Early Jurassic zircons increases from base to top of the formation, and correlates positively with the abundance of detrital volcanic rock fragments. The youngest zircon ages are close to the stratigraphic age of each sample, indicating contemporaneous magmatic activity along the active margin of Gondwana. Igneous rocks that formed during the Ross Orogeny (c. 470–545 Ma) were a minor source only, suggesting that the Ross Orogen became progressively covered by sediments as the basin expanded. Pan-African (c. 500–700 Ma) and Grenville (c. 800–1200 Ma) age zircons may have been derived from crustal sources currently covered beneath the polar ice sheet, although recycling from Cambro-Ordovician units provides an alternative explanation.
The exact results of the age analyses of all samples are presented in Tables A1 to A8 at http://www.geolsoc.org.uk/SUP18624
Figures & Tables
Antarctica and Supercontinent Evolution
Antarctica preserves a rock record that spans three and a half billion years of history and has a remarkable story to tell about the evolution of our Earth, from the hottest crustal rocks yet found in an orogenic system, to the assembly and breakup of Gondwana in the Phanerozoic. This volume highlights our improved understanding of the tectonic events that have shaped Antarctica and how these potentially relate to supercontinent assembly and fragmentation. The internal constitution of the East Antarctic Shield is assessed using information available from the basement geology and from detritus preserved as Mesozoic sediments in the Trans Antarctic Mountains. Accretionary orogenesis along the proto-Pacific margin of Antarctica is examined and the volumes of intracrustal melting compared with juvenile magma additions in these complex orogenic systems assessed. This volume demonstrates the diversity of approaches required to elucidate and understand crustal evolution and evaluate the supercontinent concept.