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Mid-Cretaceous ductile deformation on the Eastern Palmer Land Shear Zone, Antarctica, and implications for timing of Mesozoic terrane collision

Published online by Cambridge University Press:  28 October 2002

ALAN P. M. VAUGHAN ,
SIMON P. KELLEY  and
BRYAN C. STOREY
ALAN P. M. VAUGHAN
Affiliation:
British Antarctic Survey, High Cross, Madingley Rd, Cambridge CB3 0ET, UK
SIMON P. KELLEY
Affiliation:
Department of Earth Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK
BRYAN C. STOREY
Affiliation:
Gateway Antarctica, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
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Abstract

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Ar–Ar dating of high-strain ductile mylonites of the Eastern Palmer Land Shear Zone in the southern Antarctic Peninsula indicates that reverse movement on the shear zone occurred in late Early Cretaceous times (Albian), and not latest Jurassic times as previously supposed. The Eastern Palmer Land Shear Zone forms a major tectonic boundary, separating suspect arc terranes from rocks of Gondwana continental affinity. The dated mylonites are developed in Lower Jurassic plutonic rocks at Mount Sullivan, eastern Palmer Land, and form part of a zone of ductile reverse deformation up to 25 km wide. Biotite from a fine-grained mafic mylonite yields an Ar–Ar cooling age of 102.8±3.3 Ma. Movement of this age on the Eastern Palmer Land Shear Zone is coeval with circum-Pacific deformation, possibly related to a mantle superplume event, and provides support for allochthonous-terrane models for the Antarctic Peninsula with accretion in post-Early Cretaceous times.

Keywords

Antarctic PeninsulaGondwanasuperplumesorogenystructural geology
Type
Research Article
Information
Geological Magazine , Volume 139 , Issue 4 , July 2002 , pp. 465 - 471
Copyright
© 2002 Cambridge University Press