HR: 0800h
AN: PP11A-0226    [Abstracts]
TI: Biotic Response of Tethyan Bathyal Ostracodes Across the Eocene-Oligocene Transition
AU: * Slotnick, B S
EM: bsslotnick@gmail.com
AF: Department of Geological Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92115, United States
AU: Schellenberg, S A
EM: schellenberg@geology.sdsu.edu
AF: Department of Geological Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92115, United States
AB: The fundamental global climate shift from "greenhouse" to "icehouse" conditions during the Eocene-Oligocene transition (EOT) has been variously attributed to the development of oceanic gateways, perturbations in the global carbon cycle, and variations in orbital forcing. This global climate shift is marked by the first significant Cenozoic glaciation of Antarctica and associated with a variety of faunal and floral changes in the marine and terrestrial realms. Establishing the tempo and mode of biotic changes through the EOT can provide insight on both its physico- chemical nature and biotic impact. In the deep-ocean benthic environments, ostracodes provide the only numerically significant metazoan faunal record by virtue of their highly calcified valves, and improved faunal records should provide a productive complement to more established benthic foraminiferal records. Dall'Antonia et al. (2003) found no major faunal changes in ostracode assemblages through the Global Stratotype Section and Point (GSSP) for the Eocene-Oligocene Boundary (i.e., base of the Priabonian stage) in the Massignano Quarry of Italy. However, the stratigraphic congruence of this GSSP with the globally recognized Oi-1 oxygen- isotope shift remains controversial; Van Mourik and Brinkhuis (2005) argue that Oi-1 event significantly postdates the current GSSP on the basis of dinoflagellate biostratigraphy and correlation to other isotopically well- characterized EOT sections. To further explore this issue, we are extending the existing GSSP ostracode faunal record up-section through the adjacent "Massicore" to characterize any biotic responses that may coincide with, and thereby independently test, the predicted position of the Oi-1 event. Preliminary analyses of limited samples show markedly higher ostracode abundances (i.e., valves per gram bulk sediment; insufficient constraints on sedimentation rates preclude calculation of ostracode accumulation rates) above the predicted Oi-1 event. Ongoing faunal analyses of ostracode valves per gram, resampled (abundance-corrected) richness, and community structure will assess potential biotic responses across the predicted position of the Oi-1 event and through the broader EOT.
DE: 4804 Benthic processes, benthos (0408)
DE: 4806 Carbon cycling (0428)
DE: 4944 Micropaleontology (0459, 3030)
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting