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

Abstract

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 Car- boniferous to Early Permian ice sheet, as depicted in many paleo- geographic reconstructions. Weathering profiles and soft-sediment deformation immediately below the preglacial (pre-Permian) un- conformity suggest an absence of ice cover during the Carbonif- erous; otherwise, multiple glacial cycles would have destroyed these features. The occurrence of glaciotectonite, massive and strat- ified diamictite, thrust sheets, sandstones containing dewatering structures, and lonestone-bearing shales in southern Victoria Land and the Darwin Glacier region indicate that Permian sedimenta- tion occurred in ice-marginal, periglacial, and/or glaciomarine set- tings. 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 glacia- tion was less widespread, and, therefore, that glacially driven changes to other Earth systems (i.e., glacioeustatic fluctuations, cli- mate) were much smaller than previously hypothesized.