LATE MISSISSIPPIAN BRACHIOPOD COMMUNITY RESPONSE TO THE ONSET OF THE LATE PALEOZOIC ICE AGE, ARROW CANYON, NV

The intensification of the Late Paleozoic Ice Age during the latest Mississippian impacted marine invertebrate paleocommunities worldwide across the Mid-Carboniferous boundary, with previous studies suggesting a mass extinction due to the global shift in climate. The fossiliferous marine Paleozoic section of Arrow Canyon in southern Nevada records the history of the Late Paleozoic Ice Age and provides an ideal opportunity to study its effect on paleocommunities. The onset of the Late Paleozoic Ice Age is recorded within the uppermost Mississippian Indian Springs Formation at Arrow Canyon. The Indian Springs Formation consists of interbedded limestones, siltstones, and paleosols and represents a complex non-marine, marginal marine, and open marine depositional system that was located near the paleoequator. Fossiliferous intervals within the Indian Springs Formation occur during transgressive periods; initial observations suggest that diversity increases up-section with each transgressive interval. Further work will determine whether new brachiopod taxa that appear in each subsequent transgressive period within the Indian Springs Formation migrated from higher latitudes or if the brachiopods in these assemblages are endemic to the region; previous studies suggest that brachiopods migrated from high-latitude regions towards the tropics as vast ice sheets developed over the southern hemisphere. The results from this study will test the migration hypothesis and provide insight into the overall faunal response to the onset of the Late Paleozoic Ice Age.