PALEOECOLOGY OF GLACIAL AND NON GLACIAL CARBONIFEROUS FAUNAS DURING THE LATE PALEOZIOC ICE AGE IN PATAGONIA

The Late Paleozoic Ice Age records the only icehouse to greenhouse transition in Earth’s history that involved complex life. Biotic responses from low-paleolatitude (far-field) marine faunas far from ice centers have been recognized and used as a global proxy, but the biotic responses in high-paleolatitude (near-field) regions close to Gondwanan ice centers have received much less attention. We tested the hypothesis that paleocommunities within and proximal to glaciated environments differed ecologically from paleocommunities distal to glacial influence. This study focused on the paleoecology of the Tepuel Basin located in central Patagonia, Argentina in order to determine how conditions during the LPIA influenced marine paleoecology in a near-field region. Quantitative stratigraphic and paleontological analysis were performed on stratigraphic sections near the base of the Pampa de Tepuel Formation. Results from this study show that bivalve and crinoid populations dominated these paleocommunities, accounting for over 60% of the total organisms present, while brachiopods remained absent in all shell beds near the base of the formation. While this distribution is rather uncharacteristic of Paleozoic communities, climatic variations and glacial influences have most likely had an effect on community variation. There was also an increase in euryhaline organisms near the base of the formation as opposed to shell beds sampled higher stratigraphically. This uneven distribution throughout the Pampa de Tepuel formation could be indicative of the waxing and waning of glaciers during this dynamic ice age. It is important to understand the LPIA and its affects on paleoecology in order to understand how present-day climate change could affect modern ecological patterns.