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 2 1 /2km 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 concluded that major changes in crustal thickness are required since the Late Triassic to achieve the present geography.Research areas that are potentially rewarding include the development of a magnetic stratigraphy and polar wander curve, which have been complicated by overprinting from the Jurassic dolerites, and study of the sedimentology and palaeontology of the Devonian sequence to determine environment of deposition. The Beacon also provides an unusual opportunity to study diagenesis of sandstone that has experienced high temperatures at a shallow depth.

Viscous flow lobes in central Taylor Valley, Antarctica: Origin as remnant buried glacial ice

“…Environmental conditions in the coastal thaw zone favor active-layer cryoturbation, solifluction, and thermokarst degradation of buried ice Hall and Denton, 2000), whereas those in the upland stable zone foster dry active layers, typically ≤15 cm thick, preservation of multi-million-year old ashfall deposits, and bedrock erosion rates as low as 5-20 cm Myr −1 (Sugden et al, 1995;Summerfield et al, 1999;Marchant et al, 2002;Balco and Shuster, 2009). The little-studied (from a geomorphic perspective) inland mixed zone occurs at the transition between these two end member zones sandstones, siltstones, and conglomerates) (Barrett, 1981). Thick intrusive sills of Jurassic-age Ferrar Dolerite intrude all of these rocks (Elliot and Fleming, 2004).…”

Degradation of glacial deposits quantified with cosmogenic nuclides, Quartermain Mountains, Antarctica

“…Bedrock in the valleys consists of Devonian-Triassic sandstones of the Beacon Supergroup and Jurassic sills and dikes of the Ferrar Dolerite (Barrett, 1981). The general climate of the area is a hyper-arid, cold-polar desert.…”

Magnetostratigraphic chronology of a late Eocene to early Miocene glacimarine succession from the Victoria Land Basin, Ross Sea, Antarctica

“…The TAM succession comprises granitic and metamorphic basement (Gunn and Warren, 1962), which is separated from the overlying flat-lying Devonian to Triassic continental sediments of the Beacon Supergroup by an unconformity known as the Kukri erosion surface (Barrett, 1981). The Beacon Supergroup is extensively intruded by the Jurassic Ferrar Supergroup (Harrington, 1958).…”