A PRELIMINARY MODEL FOR THE 500 MA EVENT IN THE EAST ANTARCTIC SHIELD

Abstract

Most rocks from the East Antarctic Shield preserve structures, mineralogies and mineral compositions that record granulite facies metamorphic events during Proterozoic and Archaean times. However, there is independent evidence that the shield experienced a major tectono-thermal event during the Early Cambrian. The combined evidence suggests that a tectono-thermal event during the Cambrian may have exhumed the East Antarctic Shield and adjacent parts of Gondwana from as deep as 10-15 kilometres. Substantial basaltic underplating during a period of minor lithospheric thinning may have been responsible for this exhumation. The model is consistent with the evidence and also with the occurrence o..