Siliciclastic record of rapid denudation in response to convergent-margin orogenesis, Ross Orogen, Antarctica

Abstract

Siliciclastic rocks of the upper Byrd Group in the Transantarctic Mountains record rapid denudation and molasse deposition during Ross orogenesis along the early Paleozoic convergent margin of Gondwana. These rocks, which stratigraphically overlie Lower Cambrian Byrd carbonate deposits, are dominated by fresh detritus from proximal igneous and metamorphic sources within the Ross Orogen. Biostratigraphic evidence indicates that deposition of the siliciclastic succession is late Botomian or younger (<515 Ma). The largest modes of U-Pb and 40Ar/39Ar ages from detrital zircons and muscovites respectively in the siliciclastic molasse are Early to Middle Cambrian, but based on ages from crosscutti..