The c. 1000–900 Ma and c. 550–500 Ma tectonothermal events in the Prince Charles Mountains–Prydz Bay region, East Antarctica, and their relations to supercontinent evolution
Xiaochun Liu, Yue Zhao, Jianmin Hu, 2013. "The c. 1000–900 Ma and c. 550–500 Ma tectonothermal events in the Prince Charles Mountains–Prydz Bay region, East Antarctica, and their relations to supercontinent evolution", Antarctica and Supercontinent Evolution, S. L. Harley, I. C. W. Fitzsimons, Y. Zhao
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The Prince Charles Mountains (PCM)–Prydz Bay region in East Antarctica experienced the late Mesoproterozoic/early Neoproterozoic (c. 1000–900 Ma) and late Neoproterozoic/Cambrian (c. 550–500 Ma) tectonothermal events. The late Mesoproterozoic/early Neoproterozoic tectonothermal event dominates the Rayner Complex and spreads over the main part of the Prydz Belt. This event includes two episodes (or stages) of metamorphism accompanying the intrusion of syn- to post-orogenic granitoids at c. 1000–960 Ma and c. 940–900 Ma. The c. 1000–960 Ma metamorphism in the northern PCM and Mawson Coast records medium- to low-pressure granulite facies conditions accompanied by a near-isobaric cooling path, whereas the c. 940–900 Ma metamorphism in Kemp Land reaches relatively higher P–T conditions followed by a near-isothermal decompression or decompressive cooling path. The late Mesoproterozoic/early Neoproterozoic orogeny (i.e. the Rayner orogeny) involved a long-lived (c. 1380–1020 Ma) magmatic accretion along continental/oceanic arcs and a protracted or two-stage collision of the Indian craton with a portion of East Antarctica, forming the Indian–Antarctic continental block independent of the Rodinia supercontinent. The late Neoproterozoic/Cambrian tectonothermal event pervasively overprinted on both Archaean–Proterozoic basements and cover sequences in the Prydz Belt. Except for high-pressure granulite boulders from the Grove Mountains, the metamorphism of most rocks records medium-pressure granulite facies conditions with a clockwise P–T path. In contrast, this event is lower grade (greenschist–amphibolite facies) and localized in the PCM. Regionally, the late Neoproterozoic/Cambrian tectonothermal event seems to have developed on the southeastern margin of the Indo-Antarctic continental block, suggesting that the major suture should be located southeastwards of the presently exposed Prydz Belt. The precise dating for different rock types reveals that the late Neoproterozoic/Cambrian orogeny (i.e. the Prydz orogeny) commenced at c. 570 Ma and lasted until c. 490 Ma, which is roughly contemporaneous with the late collisional stage of the Brasiliano/Pan-African orogenic systems in Gondwanaland. Therefore, the final assembly of the Gondwana supercontinent may have been completed by the collision of a number of cratonic blocks during the same time period.
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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.