Chapter 1: Geologic history of the Ellsworth Mountains, West Antarctica

Abstract

The stratigraphie succession in the Ellsworth Mountains includes strata from Cambrian to Permian in age. No definite evidence of major unconformities in the Ellsworth succession is known, and it is possible that continuous deposition took place from Cambrian to Permian time.The oldest stratigraphie unit, the Heritage Group, was deposited in Middle to Late Cambrian time. More than half of the 13,000+-m-thick stratigraphie succession of the Ellsworth Mountains was deposited during this time interval. Basic igneous volcanism and tectonic activity occurred in both the source and accumulation areas throughout the deposition of this group. Shallow-marine conditions prevailed during the deposition of the overlying 3,000-m-thick Upper Cambrian to Devonian Crashsite Group. This group indicates a period of tectonic stability that continued through the remainder of Ellsworth Mountains sedimentation. Deposition of the glaciomarine Permo-Carboniferous Whiteout Conglomerate and the Permian Polarstar Formation completed the sedimentary sequence. Major deformation of the Ellsworth Mountains sedimentary succession, the Ellsworth (Gondwanide) Orogeny, took place in Late Permian or early Mesozoic time. The original location of these rocks is unclear, but they probably accumulated near the margin of East Antarctica. With the breakup of Gondwanaland, the Ellsworth Mountains, and their southern neighbors likely comprised a microplate that translated and rotated to its present position sometime in late Mesozoic or early Cenozoic time. The uplift of the mountains may have accompanied these postulated movements. The geomorphic evolution of the Ellsworth Mountains in Cretaceous and Cenozoic time includes the development of an integrated stream valley pattern and, later, valley and continental glaciation, followed by moderate déglaciation.

The Gondwana Plate margin in the Weddell Sea sector: Zircon geochronology of Upper Paleozoic (mainly Permian) strata from the Ellsworth Mountains and eastern Ellsworth Land, Antarctica

“…2) (Webers et al, 1992a). The Lower Paleozoic Heritage Group, 7.5 km thick, is entirely Cambrian and is overlain by the Crashsite Group, a thick (3 km) sequence of quartz-rich sandstones that is divided into three formations (Webers et al, 1992a). The transition beds between the two groups contain a possible Upper Cambrian fauna (Shergold and Webers, 1992), but the only other biostratigraphic age control on the Crashsite Group is confined to a Lower Devonian brachiopod fauna in the Mount Wyatt Earp Formation, the upper of the three formations (Webers et al, 1992b).…”

“…2) (Webers et al, 1992a). The Lower Paleozoic Heritage Group, 7.5 km thick, is entirely Cambrian and is overlain by the Crashsite Group, a thick (3 km) sequence of quartz-rich sandstones that is divided into three formations (Webers et al, 1992a).…”

Active layer thermal monitoring of a Dry Valley of the Ellsworth Mountains, Continental Antarctica

“…Geological formations include the Late Precambrian Minaret Group (marble), the middle to late Cambrian Heritage Group (sedimentary rocks), the upper Cambrian to Devonian Crashsite Group (predominantly quartzites), the Permo-Carboniferous Whiteout Conglomerate, and the Permian Polestar Formation (marine and terrestrial tillites) (Webers et al, 1992). At the study site, Mt.…”

Archaeocyaths from South America: review and a new record

“…The most striking similarities are those related to their glaciogenic rocks, clast lithology, glacial lithofacies and source areas, in addition to their palaeoclimatic, palaeogeographic and palaeotectonic aspects related to Permo‐Carboniferous Gondwanaland glaciation (Episode III, Veevers and Powell, ; López‐Gamundí, ). In the Ellsworth Mountains of West Antarctica, the Whiteout Conglomerate represents the Permo‐Carboniferous Gondwanaland glaciation (Webers et al ., ), and hence is the time‐stratigraphical equivalent of the formerly mentioned units.…”