New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana.

Flowerdew, M.J.; Daly, J. S.; Riley, T.R.. 2007 New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana. In: Cooper, A.K.; Raymond, C.R.; ISAES Editorial Team, ., (eds.) Antarctica: a keystone in a changing world. Online proceedings of the 10th International Symposium on Antarctic Earth Sciences, Santa Barbara, California, August 26 - September 1, 2007. U.S. Geological Survey and National Academies Press, 4pp. (U.S. Geological Survey Open File Report, 2007-1).

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Abstract/Summary

Five of six Rb-Sr muscovite mineral isochron ages from the Scotia Metamorphic Complex of the South Orkney Islands, West Antarctica, average 190 ± 4 Ma. The muscovite ages are interpreted to date foliation-formation and thus also accretion and subduction at the Gondwana margin. Coincident picrite and ferropicrite magmatism, indicative of melts from deep-seated depleted mantle, permits a causative link between accretion and the arrival of the Karoo – Ferrar – Chon Aike mantle plume in the Early Jurassic. Three biotite Rb-Sr mineral isochron ages are consistently younger and average 176 ± 5 Ma. The biotite ages may record post-metamorphic cooling or more likely retrogressive metamorphic effects during uplift.

Item Type:	Book Section
Identification Number/DOI:	10.3133/of2007-1047.srp012
Programmes:	BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Long-Term Monitoring and Survey – Geosciences Division
Additional Keywords:	Geochronology, Rb-Sr dating, South Orkney Islands
NORA Subject Terms:	Earth Sciences
Date made live:	19 Nov 2008 12:18
URI:	http://nora.nerc.ac.uk/id/eprint/4502

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