Special Paper 441: Resolving the Late Paleozoic Ice Age in Time and Space

Abstract

Three glacial episodes are identified in Upper Devonian and Mississippian strata in South America using sedimentologic, stratigraphic, paleontological, borehole, and outcrop data. The first glacial episode is of late Famennian ("Strunian") age and is interpreted from strata in basins of Brazil, Bolivia, and Peru, where ice sheets and alpine glaciers reached coastal and marine settings. Biostratigraphi-cally, these strata correspond to the Retispora lepidophyta-Indotriradites explanata or LE Zone and the Retispora lepidophyta-Verrucosisporites nitidus (LN) spore zones of Western Europe. The second glacial episode occurred during the late middle to early late Tournaisian and is recorded in the subsurface of the Solimões Basin (Juruá and Jandiatuba subbasins) of northwestern Brazil and possibly in Bolivia and Argentina. The third glacial episode is of late Visean age and is currently identified in basins of Brazil and possibly in the area of the former Acre Basin shelf, but data are poor. In Bolivia and Peru, the Ambo Group also displays glacially influenced sediments as well as strata in central western Argentina. These glacial episodes may also have occurred in Africa, but data are still scarce, and the ages of potentially coeval strata are not well constrained. Indirect evidence of these Paleozoic glacial events in Gondwana is suggested by researchers in Western Europe, Asia, and in the United States on the basis of geochemical, stratigraphic, sedimentologic, paleontologic, and eustatic data. © 2008 Geological Society of America.