New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana.
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...
Published in: | New Rb-Sr Mineral Ages Temporally Link Plume Events with Accretion at the Margin of Gondwana |
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Main Authors: | , , |
Other Authors: | , , |
Format: | Book Part |
Language: | English |
Published: |
U.S. Geological Survey and National Academies Press
2007
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Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/4502/ https://nora.nerc.ac.uk/id/eprint/4502/1/Flowerdew_et_al_2007_South_Orkney_RbSr.pdf http://pubs.usgs.gov/of/2007/1047/srp/srp012/of2007-1047srp012.pdf https://doi.org/10.3133/of2007-1047.srp012 |
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. |
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