History of the Ross Sea region during the deposition of the Beacon Supergroup 400 - 180 million years ago

Abstract The Beacon Supergroup is the generally flat-lying sedimentary sequence about 2½km thick that rests unconformably on Ordovician and older rocks of the East Antarctic craton. In the Ross Sea region exposure is almost entirely limited to the Transantarctic Mountains, though Devonian rocks are now known from Marie Byrd Land. The history of the region is summarised on five palaeogeographic maps using a chronology based on palynomorphs but with help from several other fossil groups and the simple lithostratigraphy. However, the time-transgressive nature of the stratigraphy is recognised from the appearance of volcanic debris in the Permian at successively higher levels down the palaeoslope. The persistent feature of sedimentation during Beacon times is the development of elongate sedimentary basins sited along the present Transantarctic Mountains. Then the eastern Ross Sea and Marie Byrd Land were similar in elevation to the East Antarctic craton on the other side of the Beacon basins, from which it is...