Radiometric evidence for the age of the subduction complex in the South Orkney and South Shetland Islands, West Antarctica

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Abstract
New K-Ar and Rb-Sr data are presented for the age of part of the supposed late Palaeozoic/early Mesozoic metamorphic complex in West Antarctica (here renamed the ‘Scotia metamorphic complex’). These results, together with a review of other radiometric and palaeontological evidence, fail to confirm a pre-Mesozoic age for the subduction complex in this region although rocks belonging to the albite-epidote-amphibolite facies could be as old as Permian. Blueschists and greenschists from the South Shetland Is appear to be significantly younger and were probably formed, in part at least, during Cretaceous subduction.