Paleoecology and sedimentology of fossil-bearing, high-latitude glaciogenic deposits in the Tepuel Basin, Patagonia, Argentina

PAULS, K.N.; FRAISER, M.L.; ISBELL, J.; PAGANI, M.A.; TABOADA, A. C.

Charlotte, North carolina

Congreso; Annual Meeting of the Geological Society of America; 2012

Geological Society of America

The glacial and non-glacial intervals of the Late Paleozoic Ice Age (LPIA) are of great interest due to their similarities with changing climate regimes during the Pleistocene. The changes and adaptations of the biota, as seen in the rock record, can serve as a proxy for understanding future trends in Earth’s climate system. Most of the known LPIA marine faunal data come from low-latitudinal regions, and thus have been used as a globalproxy. However, modern organisms in the tropics and polar regions respond differently to changing climate, and the same can be proposed for paleocommunities during the LPIA. The hypothesis of this study is that in high-paleolatitude regions, glacial and non-glacial communities were ecologically dissimilar. It is important to understand the capacity of different global climate regimes and adaptability of the fauna that lived within them.This study focuses on a high-latitude shelf edge to slope fauna from the Tepuel-Genoa Basin in Chubut Province in Patagonia, Argentina in order to better understand the responses of a high-latitude fauna to changing environmental conditions, and to develop a more robust understanding of climate change and its impacts on the biosphere. During field work, counts of six fossil beds were taken and a 200-meter stratigraphic section was measured and described. Preliminary data suggest that the composition of the paleocommunities reflectschanges in the local environment. Ostracodes are the dominant taxon in two fossil beds, which could be an indication of an influx of freshwater that created a more brackish-water environment. This biotic change also corresponds to a large sandstone unit, which has been interpreted as a slide block. This slide block, along with the change in abundance and diversity within the fossil beds, are strong indicators of changing environmentsproduced during a sea level lowstand when clastic systems reached the shelf edge. Further statistical analysis is needed to determine the significance of these changes. By continuing research on the LPIA, we may be better able to understand the fundamental factors of species and ecosystem instability because of the substantial environmental and climatic shifts that occurred.