Permian glacigenic deposits in the Transantarctic Mountains, Antarctica

In Antarctica, late Paleozoic glacigenic strata occur throughout the Transantarctic, Ellsworth, and Pensacola Mountains and in the Shackleton and Heimefront Ranges. The most laterally and stratigraphic continuous exposures occur in the central Transantarctic and Darwin Mountains. These strata were deposited within two topographically expressed basins. The larger of the two basins was a trough-shaped basin that extended between the present locations of the Darwin and Amundsen Glaciers. Basement highs surrounded the basins and formed uplands onto which preglacial, glacial, and postglacial strata onlapped. An examination of late Paleozoic glacigenic units in the Darwin Mountains and the central Transantarctic Mountains reveals that Permian glacio marine sediments were deposited within the basins, and that subglacial diamictites and proximal glaciomarine sediments were deposited along basin margins. This is in marked contrast to earlier reports that identified glacigenic strata in the Transantarctic Mountains as the deposits of a terrestrial glacial system. On some highs, the occurrence of paleosols overlain by postglacial strata suggests that ice-free areas occurred locally along basin margins. A correlation of fossil spores and pollen with Australian palynomorph zones suggests that the Antarctic glacigenic strata are restricted to the Lower Permian. These findings suggest that glaciation was less widespread (temporally and spatially) than previously hypothesized. It is thus unlikely that a single, massive ice sheet covered Antarctica continuously at any time during the Carboniferous and Permian.