CARBONIFEROUS HIGH PALEO-LATITUDE INVERTEBRATE PALEOECOLOGY OF PATAGONIA DURING THE LATE PALEOZOIC ICE AGE

The Late Paleozoic Ice Age (LPIA), spanning from 345-260 Ma, was an environmentally dynamic time characterized by high southern latitude glaciation. Much of the previous paleoecological research on the LPIA has focused on low paleo-latitude regions or ‘far-field’ regions, revealing evidence for increased faunal turnover and mass extinction. However, there is still little research on high paleo-latitude invertebrate paleocommunities, so it is largely unknown if these ‘near-field’ organisms responded similarly to ‘far-field’ organisms. We propose that ice proximal paleocommunities of a Carboniferous basin in western Gondwana are characterized by decreased diversity and taxonomic richness compared to those distally located during glacial episodes. Our research aims to quantify the paleoecology of some near-field paleocommunities in Patagonia during the height of the LPIA.

We examined the Tepuel-Genoa Basin in the western region of Patagonia, Argentina. Strata in the Pampa de Tepuel Formation contain evidence for glacial influence and an abundant invertebrate fossil record. We measured 400 meters over 2.5 kilometers and evaluated and quantified the sedimentology and paleoecology of the lower and middle Pampa de Tepuel Formation.

Preliminary observations of the two sections of the Pampa de Tepuel Formation illustrate two different glaciomarine environments with corresponding ecological responses. The middle section of the Pampa de Tepuel contains course-grained clasts that suggest a more proximal position to glaciers. We interpret a diamictite in the lower section of the Pampa de Tepuel as the result of a debris flow that was distal to glaciers. Paleocommunities of the lower Pampa de Tepuel contain higher taxonomic diversity and larger body sizes compared to the middle Pampa de Tepuel. We propose that the proximity to glaciers and the associated changes in salinity and sedimentation affected marine invertebrate paleoecology during the LPIA.