THE LATE PALEOZOIC ICE AGE: REVISION OF THE WESTERN GONDWANA RECORD

The late Paleozoic Ice age (LPIA) lasted ~90 million years beginning in South America and possibly Africa during the Mississippian (Visean) and ending in Australia at the end of the Middle Permian (Capitanian). New data suggest that at no time was Gondwana completely covered by ice. However, discrete glacial events, which lasted for 1 to 8 million years and separated by ice-free conditions of equal duration, shifted west to east across Gondwana. Previous reports identified that the LPIA began in western Argentina with the occurrence of 5 widely scattered events. However, recent work by the authors indicates that these events were correlative to a single glacial event, the Namurian Hoyada Verde/Guandacol glaciation. A previously unrecognized older Visean event also occurred. Alpine glaciers and ice caps characterized both the Visean and Namurian events. Small ice sheets developed farther east later in the Pennsylvanian in Brazil, eastern Argentina, and southern Africa. At that time, western Argentina was ice free. Ice flow directions derived from Asselian strata in South Africa provide evidence for initial development of ice in Antarctica. The occurrence of glacigenic strata in eastern South America, southern Africa, Antarctica, India, and Australia indicate that the greatest extent of ice occurred during the Early Permian. At that time, numerous, discontinuous glacial centers were scattered across the super continent. Following the Sakmarian, glaciation shifted to Australia where smaller ice centers continued into the middle Permian. By then, ice had disappeared from western Gondwana.