HR: 13:45h
AN: PP52B-01    [PDF]
TI: Applicability of Modern Benthic Foraminiferal Based Paleoproductivity Estimates to the Neogene Record: A Case Study from the South China Sea
AU: * Kuhnt, W
EM: wk@gpi.uni-kiel.de
AF: Dept. of Geosciences, Christian-Albrechts-Universitaet, Olshausenstr. 40, Kiel, 24118 Germany
AU: Holbourn, A
EM: ah@gpi.uni-kiel.de
AF: Dept. of Geosciences, Christian-Albrechts-Universitaet, Olshausenstr. 40, Kiel, 24118 Germany
AU: Hess, S
AF: Centre of marine Environmental Sciences, Bremen University, Klagenfurterstr., Bremen, 28359 Germany
AU: Jian, Z
AF: Laboratory of Marine Geology, Tongji University, Tongji, Shanghai, 200092 China
AB: We investigate the applicability of modern benthic foraminiferal based paleoproductivity proxies to fossil assemblages in the South China Sea. This western Pacific marginal basin has a 30 Myr continuous pelagic sediment record and minimal carbonate dissolution, and thus provides ideal boundary conditions for such a test. We relate the composition of modern and Pleistocene to Oligocene benthic foraminiferal assemblages to satellite derived primary productivity estimates, geochemical productivity proxies and multispecies infaunal and epifaunal carbon isotope values in surface samples and piston cores from several RV Sonne cruises and from ODP Leg 184. In our core top samples, we observe a strong correlation of living and dead benthic foraminiferal density, diversity indices, and assemblage composition with carbon flux at the seafloor. These carbon-flux related faunal trends are also apparent in the fossil record, however, their general applicability to fossil assemblages are restricted by major evolutionary changes such as the middle Miocene evolution of the modern oligotrophic deep sea benthic foraminiferal fauna and the mid-Pleistocene extinction of deep water benthic foraminifers (the "Stilostomella extinction" at approx. 0.8 Ma). Our investigation shows that the use of benthic foraminiferal test accumulation rates, diversity patterns, and abundances of index species provides relatively robust tools for estimating relative carbon flux rates, even for Oligocene and Miocene assemblages. However, a straightforward application of carbon-flux transfer functions based on multivariate analyses of assemblage composition appears restricted to benthic foraminiferal assemblages that post-date the Mid-Pleistocene Revolution. Improved understanding of the paleoecology of extinct infaunal high carbon flux indicators may offer the possibility to extend this type of approach to the entire Neogene.
DE: 3030 Micropaleontology
DE: 4267 Paleoceanography
DE: 4804 Benthic processes/benthos
DE: 4806 Carbon cycling
DE: 4815 Ecosystems, structure and dynamics
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting