HR: 0800h
AN: PP41C-0682    [Abstracts]
TI: North Atlantic Glacial-Interglacial Ostracode Faunal Patterns through the Mid-Pleistocene Transition at ODP Site 980 and 982
AU: * Warner, J S
EM: warner@rohan.sdsu.edu
AF: Department of Geological Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, 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 92182, United States
AB: Glacial-interglacial cycles through the Mid-Pleistocene Transition (MPT; 1.2 to 0.6 Ma) are characterized by a frequency decrease from 41 to 100 kyr and an amplitude increase via more extreme glaciations. This major transition has been the focal point of much North Atlantic paleoceanographic and micropaleontological research, yet little is know about North Atlantic deep-ocean benthic ostracode faunas through the MPT. One might predict such glacial-interglacial cycles to affect ostracode assemblages, yet North Atlantic ODP Sites 980 (1,145 m) and 982 (2,168 m) reveal no major or consistent changes in ostracode accumulation rates, resampled (abundance- corrected) richness, or taxon percent abundances, with the exception of an increase in ostracode accumulation rates late in the MPT at the deeper Site 980. This ostracode faunal stability is consistent with Raymo et al.'s (2004) interpretation of relatively stable North Atlantic thermohaline circulation through the MPT based on carbon-isotope depth-profiles. However, this ostracode faunal stability stands in stark contrast to other North Atlantic ostracode studies of the latest Pleistocene (Didie and Bauch, 2000) and Late Pliocene (Cronin et al., 1996), which show strong faunal variations in response to presumed oscillations in surface export production and intermediate water ventilation associated with glacial-interglacial cycles. Late in the MPT interval (0.8 to 0.6 Ma), benthic foraminifera experience a major decline and preferential extinction of infaunal taxa at Site 980 and 982 (Kawagata et al., 2002). Coeval ostracode assemblages show no comparable taxonomic loss through this enhanced extinction interval, but ostracode accumulation rates do markedly increase at the deeper Site 980. Such differential biotic response under presumably stable benthic environmental conditions remains difficult to reconcile with current paleoceanographic data.
DE: 4804 Benthic processes, benthos (0408)
DE: 4926 Glacial
DE: 4936 Interglacial
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting