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Anatectic reworking and differentiation of continental crust along the active margin of Gondwana: a zircon Hf–O perspective from West Antarctica

By
Chris Yakymchuk
Chris Yakymchuk
1
Laboratory For Crustal Petrology, Department of Geology, University of Maryland, College Park, Maryland 20742, USA
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Christine S. Siddoway
Christine S. Siddoway
2
Department of Geology, The Colorado College, Colorado Springs, Colorado 80903, USA
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C. Mark Fanning
C. Mark Fanning
3
Research School of Earth Sciences, The Australian National University, Mills Road, Canberra, ACT 0200, Australia
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Rory Mcfadden
Rory Mcfadden
4
Department of Geological Sciences, Salem State University, Salem, Massachusetts 01970, USA
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Fawna J. Korhonen
Fawna J. Korhonen
5
Geological Survey of Western Australia, East Perth WA 6004, Australia
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Michael Brown
Michael Brown
1
Laboratory For Crustal Petrology, Department of Geology, University of Maryland, College Park, Maryland 20742, USA
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Published:
January 01, 2013

Abstract

The Fosdick migmatite–granite complex of West Antarctica preserves evidence of two crustal differentiation events along a segment of the former active margin of Gondwana, one in the Devonian–Carboniferous and another in the Cretaceous. The Hf–O isotope composition of zircons from Devonian–Carboniferous granites is explained by mixing of material from two crustal sources represented by the high-grade metamorphosed equivalents of a Lower Palaeozoic turbidite sequence and a Devonian calc-alkaline plutonic suite, consistent with an interpretation that the Devonian–Carboniferous granites record crustal reworking without input from a more juvenile source. The Hf–O isotope composition of zircons from Cretaceous granites reflects those same two sources, together with a contribution from a more juvenile source that is most evident in the detachment-hosted, youngest granites. The relatively non-radiogenic ɛHf isotope characteristics of zircons from the Fosdick complex granites are similar those from the Permo-Triassic granites from the Antarctic Peninsula. However, the Fosdick complex granites contrast with coeval granites in other localities along and across the former active margin of Gondwana, including the Tasmanides of Australia and the Western Province of New Zealand, where the wider range of more radiogenic ɛHf values of zircon suggests that crustal growth through the addition of juvenile material plays a larger role in granite genesis. These new results highlight prominent arc-parallel and arc-normal variations in the mechanisms and timing of crustal reworking v. crustal growth along the former active margin of Gondwana.

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Figs S1 and S2 are available at http://www.geolsoc.org.uk/SUP18625

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Contents

Geological Society, London, Special Publications

Antarctica and Supercontinent Evolution

S. L. Harley
S. L. Harley
University of Edinburgh, UK
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I. C. W. Fitzsimons
I. C. W. Fitzsimons
Curtin University of Technology, Australia
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Y. Zhao
Y. Zhao
CAGS, China
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Geological Society of London
Volume
383
ISBN electronic:
9781862396470
Publication date:
January 01, 2013

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