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

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 Carbo...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Smellie, J.L., Millar, I.L.
Format: Article in Journal/Newspaper
Language:unknown
Published: Cambridge University Press 1995
Subjects:
Earth Sciences
Antarctic
The Antarctic
Antarctic Peninsula
Graham Land
Trinity Peninsula
Nordenskjöld
Nordenskjöld Coast
Antarc*
Antarctic Science
Online Access:http://nora.nerc.ac.uk/id/eprint/515846/
https://doi.org/10.1017/S0954102095000253
Description
Summary: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.

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