Late Devonian and Early Carboniferous glacial records of South America

Abstract

Three glacial episodes are identifi ed in Upper Devonian and Mississippian strata in South America using sedimentologic, stratigraphic, paleontological, bore hole, and outcrop data. The fi rst 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. Biostratigraphically, these strata correspond to the Biostratigraphically, these strata correspond to the Retispora lepidophyta–Indotriradites explanata or LE Zone and the Retispora lepidophyta–Verrucosisporites nitidus or LN Zone. Spore zones of Western Europe. The second glacial episode occurred during the late middle to early late Tour naisian and is recorded in the subsurface of the Solimoes Basin (Jurua and Jandiatuba subbasins) of northwestern Brazil and possibly in Bolivia and Argentina. The third glacial episode is of late Visean age and is currently identifi ed 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 infl uenced 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.