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Antarctic Science

Table of Contents - 1995 - Volume 7, Issue 02  


Papers—Earth Sciences and Glaciology

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

J.L. Smellie a1 and I.L. Millar a1a2
a1 British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
a2 British Antarctic Survey, NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK

Article author query
smellie j   [PubMed][Google Scholar] 
millar i   [PubMed][Google Scholar] 

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.

(Received August 12 1993)
(Accepted November 7 1994)


Key Words: Antarctica; basement; K-Ar ages; metamorphism; Trinity Peninsula Group; deposition.

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