Reevaluation of the timing and extent of late Paleozoic glaciation in Gondwana: Role of the Transantarctic Mountains

Evidence from Antarctica indicates that a 2000-km-long section of the Transantarctic Mountains-including Victoria Land, the Darwin Glacier region, and the central Transantarctic Mountains-was not located near the center of an enormous Carboniferous to Early Permian ice sheet, as depicted in many paleogeographic reconstructions. Weathering profiles and soft-sediment deformation immediately below the preglacial (pre-Permian) unconformity suggest an absence of ice cover during the Carboniferous; otherwise, multiple glacial cycles would have destroyed these features. The occurrence of glaciotectonlite, massive and stratified diamictite, thrust sheets, sandstones containing dewatering structures, and lonestone-bearing shales in southern Victoria Land and the Darwin Glacier region indicate that Permian sedimentation occurred in ice-marginal, periglacial, and/or glaciomarine settings. No evidence was found that indicates the Transantarctic Mountains were near a glacial spreading center during the late Paleozoic. Although these findings do not negate Carboniferous glaciation in Antarctica, they do indicate that Gondwanan glaciation was less widespread, and, therefore, that glacially driven changes to other Earth systems (i.e., glacioeustatic fluctuations, climate) were much smaller than previously hypothesized.