Antarctic Science

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Antarctic Science (2009), 21:633-641 Cambridge University Press
Copyright © Antarctic Science Ltd 2009
doi:10.1017/S0954102009990320

Earth Sciences

Zircon U-Pb dating of Mesozoic volcanic and tectonic events in north-west Palmer Land and south-west Graham Land, Antarctica


P.T. Leata1 c1, M.J. Flowerdewa1, T.R. Rileya1, M.J. Whitehousea2, J.H. Scarrowa3 and I.L. Millara4

a1 British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK
a2 Swedish Museum of Natural History, Box 50007, S-104 05 Stockholm, Sweden
a3 Department of Mineralogy and Petrology, University of Granada, Campus Fuente Nueva Granada 18002, Spain
a4 NERC Isotope Geosciences Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK
Article author query
leat pt [PubMed]  [Google Scholar]
flowerdew mj [PubMed]  [Google Scholar]
riley tr [PubMed]  [Google Scholar]
whitehouse mj [PubMed]  [Google Scholar]
scarrow jh [PubMed]  [Google Scholar]
millar il [PubMed]  [Google Scholar]

Abstract

New whole rock Rb-Sr and zircon U-Pb geochronological data and Sm-Nd isotopic data are presented from the central magmatic arc domain of the Antarctic Peninsula in the area of north-west Palmer Land and south-west Graham Land, Rb-Sr isochrons indicate an age of 169 ± 6 Ma for basement orthogneisses and 132 ± 9 to 71 ± 9 Ma for plutons. A U-Pb age of 183 ± 2.1 Ma, with no detectable inheritance, on zircons from an orthogneiss from Cape Berteaux provides the first reliable age for the orthogneisses, which are interpreted as metamorphosed silicic volcanic rocks, and Sm-Nd data indicate derivation in a mature volcanic arc. The age indicates they may be correlatives of the Jurassic ‘Chon Aike’ volcanism of the eastern Antarctic Peninsula. A U-Pb zircon age of 107 ± 1.7 Ma on a terrestrial volcanic sequence overlying an uncomformity strongly suggests a mid-Cretaceous age for the extensive volcanic cover of north-west Palmer Land that was previously thought to be Jurassic. The unconformity is interpreted to have been a result of compressional uplift related to the Palmer Land event. This is the first date for the event in the western part of the central magmatic arc terrane of the Antarctic Peninsula.

(Received November 14 2008)

(Accepted June 18 2009)

(Online publication August 03 2009)

Key wordsAntarctic Peninsula; geochronology; magmatic arc; orthogneiss; Palmer Land event; terrane accretion

Correspondence:

c1 ptle@bas.ac.uk


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