Permian-Triassic Transantarctic basin

Abstract

The Permian-Triassic Transantarctic basin, which occupied the Panthalassan margin of the East Antarctic craton, including the present Transantarctic and Ellsworth Mountains, evolved above a mid-Paleozoic passive continental margin basement through the following stages: (1) Carboniferous/Permian extension, (2) late Early Permian back-arc basin, (3) Late Permian and Triassic foreland basin, and (4) Jurassic extension and tholeiitic volcanism. A mid-Paleozoic (Devonian) wedge of coastal-to-shallow marine quartzose sandstone developed on the eroded roots of the Late Cambrian-Early Ordovician Ross orogen. A lacuna in EastAntarctica during the Carboniferous was followed by the inception of Gondwanan deposition in a wide Carboniferous/Permian extensional basin. Volcanic detritus at the base of the late Early Permian post-glacial marine(?) shale and sandstone sequence in the Ellsworth Mountains is the first sign of a volcanic arc and subduction along the Panthalassan margin. A similar but much thinner non-volcaniclastic sequence accumulated in the Transantarctic Mountains. The introduction of abundant volcanic detritus to the cratonic side of the basin and a 180° paleocurrent reversal in the Late Permian in the Beardmore Glacier area are the earliest indicators of tectonism along the outer margin of the basin and the inception of a foreland basin that accumulated thick Late Permian and Triassic braided stream deposits of mixed volcanic and cratonic provenance. The Permian sequences in the Ellsworth and Pensacola Mountains were folded in the Triassic. The foreland basin was succeeded in the Early Jurassic by extension and initial silicic and then tholeiitic volcanism that led to the breakup of Gondwanaland.

Middle Triassic Paleosols and paleoclimate of Antarctica

“…The Beacon Supergroup in southern Victoria Land is an undeformed backarc sequence (Collinson 1990;Collinson et al 1994). In the Allan Hills (Fig.…”

“…In Gabites (1985) and sedimentary setting is from Collinson et al (1994), Zwartz and Woolfe (1996), and Woolfe et al (1996). (Scotese 1994); 71ЊS with the pole offshore from the central Transantarctic Mountains (Barrett 1991); and 73ЊS with the pole in central New South Wales, Australia .…”

An Early Permian, paleopolar, postglacial, river-dominated deltaic succession in the Mackellar–Fairchild formations at Turnabout Ridge, Central Transantarctic Mountains, Antarctica

“…2) appears to approximate the northern limit and closed end of the seaway, based on an abundance of sand-rich deposits found there and evidence for the pinch-out of the Mackellar Fm in the area (Elliot, 1975;Collinson et al, 1994;Miller and Isbell, 2010). (Barrett et al, 1986;Collinson et al, 1994). The type section of the Mackellar Fm is located 9 km north of Mount Mackellar (Fig.…”

“…2, 3) (Elliot, 1975;Collinson et al, 1994;Miller and Isbell, 2010). As the Permian glaciers retreated from the Ellsworth Mountain area toward the BGR (Figs 2, 3), which was located closer to the paleo-pole Powell and Li, 1994), a seaway, located at ~80 S paleolatitude, advanced into the newly formed, trough-shaped basin (Lindsay, 1970;Elliot, 1975;Collinson et al, 1994;Miller and Isbell, 2010). The southern limit of the sea is difficult to identify due to loss of outcrop below the polar plateau (Elliot, 1975;Miller and Isbell, 2010).…”

“…2B) (Barrett et al, 1986). In the CTAM the Mackellar Fm is typically 60-150 m thick and is thought to be Early Permian (Sakmarian) in age based on palynomorphs and a commonly gradational contact with underlying glacial deposits of the Pagoda Fm (Masood at al., 1994;Collinson et al, 1994). The northwestern-most known exposure of the Mackellar Fm is in the Holyoake Range north of the Nimrod Glacier (Figs.…”