Sedimentological record of the late Paleozoic glaciation in Queensland, Australia

Abstract

Although much is known of the timing, geographical extent, and character of the late Paleozoic Gondwanan glaciation, its rec ord in eastern Australia is poorly resolved. Some previous investigations have asserted that large parts of Australia were covered by a cold-based continental ice sheet during the Pennsylvanian (late Carboniferous). New data from Queensland in northeast Australia reported herein, however, suggest that the glaciation there was restricted to discrete, short-lived periods, in the Namurian (315 Ma), Westphalian (311 Ma), and Sakmarian (289–293 Ma). Thick successions in three widely separated areas indicate that the glaciation was confined in each case to local (valley or mountain) glaciers and that the mainly proglacial sediments were enclosed in every case by substantial intervals of fluvial, lacustrine, and shallow-marine strata deposited under nonglacial conditions. Accordingly, we submit that the cessation of glacial sediment deposition elsewhere in Gondwana during the Pennsylvanian to earliest Permian was due to the decay of glaciers, rather than to a transition to a cold-based ice sheet or sheets, as has been previously suggested. The interpretations presented herein make a significant contribution toward constraining the size and extent of glaciation in Gondwana, which has major implications for late Paleozoic world climate and sea-level fluctuations.