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New K-Ar isotopic ages of schists from Nordenskjöld Coast, Antarctic Peninsula: oldest part of the Trinity Peninsula Group?

Published online by Cambridge University Press:  12 May 2004

J.L. Smellie
Affiliation:
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
I.L. Millar
Affiliation:
British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK British Antarctic Survey, NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK

Abstract

K-Ar whole-rock dating of five samples of quartz-mica schist from the Nordenskjöld Coast, eastern Graham Land, provides the first unequivocal evidence of pre-Triassic (> 249 ± 7 Ma) deposition of a sequence regarded as part of the Trinity Peninsula Group (TPG). A maximum age range of latest Carboniferous (< c. 300 Ma)–Permian for deposition of the Nordenskjöld Coast sequence is indicated, and a polymetamorphic, polydeformational history for the TPG in northern Graham Land. However, the possibility exists that the rocks dated here from the Nordenskjöld Coast are part of a hitherto-unrecognized metamorphic basement unrelated to and older than the mainly Triassic TPG outcrops farther north. The new ages confirm the existence of a previously poorly-defined regional metamorphic event in the Antarctic Peninsula at about 245–250 Ma ago.

Type
Papers—Earth Sciences and Glaciology
Copyright
© Antarctic Science Ltd 1995

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