Wednesday, 29 August 2007 - 10:30 AM
3.A.C-2

U-Pb zircon age from the Ultrahigh temperature metapelites, Rauer Group, east Antarctica: Implications for Grenvillian and Pan-African events Overprint

Yanbin Wang1, Laixi Tong2, and Dunyi Liu1. (1) Beijing SHRIMP center, Institute of Geology, Chinese Academy of Geological Science, Baiwanzhuang Rd, No.26,, Beijing, 100037, China, (2) Institute of Earth Sciences, Academia Sinica, China

SHRIMP U-Pb dating on zircons in an ultrahigh temperature (UHT, ~1000 °C) granulite-facies metapelite from Mather Peninsula, Rauer Group, east Antarctica, yielded two episodes zircon growth ages at ~1000 Ma, and ~530 Ma. Two episodes emplacement ages for the magmatic precursor rocks of ca. 2530 Ma and ca. 2650 Ma were derived from zircon cores. Successive zircon growth at ca. 1000 Ma to 530 Ma records a sequence of distinct, widely spaced high-temperature metamorphic and/or anatectic events related to Grenvillian and Pan-African orogenesis. This study presents the first robust geochronological evidence and new constraints on the timing of UHT metamorphic event on the Rauer Group, supporting that peak UHT metamorphic event occurred at ~1000 Ma and overprinted by the separate high-grade event at ~530 Ma. This is critical in understanding the role of the eastern Prydz Bay during the assembly of east Gondwana supercontinent.

[Manuscript]

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