HR: 1340h
AN: PP23B-1416    [Abstracts]
TI: Evolution in Planktonic Foraminifer Fauna and Sea Surface Temperature Variation in last 500 ky, Northern South China Sea
AU: * Zhou, Z
EM: Zhen\_Zhou@brown.edu
AF: Geological Sciences Department, Box 1846 Brown University , Providence, RI 02912 United States
AU: Clemens, S C
EM: Steven\_Clemens@brown.edu
AF: Geological Sciences Department, Box 1846 Brown University , Providence, RI 02912 United States
AU: Prell, W L
EM: Warren\_Prell@brown.edu
AF: Geological Sciences Department, Box 1846 Brown University , Providence, RI 02912 United States
AB: Site 1144 ($20\deg$3.18'N; $117\deg$25.14'E, 2037m) of Leg 184 of the Ocean Drilling Program was drilled on a sediment drift to provide a high resolution history of the South China Sea (SCS). The average sedimentation rate at this Site is $\sim$92.5 cm/ky, with the 517-meter section extending back to $\sim$1.1 Ma. We examined 280 samples from upper 300-meter that were collected at variable sampling interval corresponding to temporal intervals of 0.11$\sim$6.28 ky. Quantitative analysis reveals that the planktonic foraminifer (PF) fauna is dominated by 11 species that constitute nearly 88% of the average species population. Some species that account for smaller percent (5-10%) of the population (eg. {\it Pulleniatina obliqueloculata, Globigerinoides bulloides} etc.) appear to be dominated by glacial-interglacial scale variability while some species that account for larger percent (20-30%)of the population (eg. {\it Neogloboquadrina dutertrei, G. ruber} etc.) are dominated by higher frequency variability. A record of sea surface temperature (SST) was reconstructed for the past 500 ky using planktonic foram transfer function PF-12E. Variation of SST and some PF species share similarities with marine \delta$^{18}$O record (measured by C. B\"{u}hring {\it et al.}) indicating climatic teleconnection between high latitude of northern hemisphere and local environment. Higher frequency variability superimposed on the glacial-interglacial scale variability suggests orbital forcing at the precession frequency as well. The fragmentation index and benthic to planktonic foram ratio exhibit stronger calcium carbonate dissolution during interglacials relative to glacials, which may impact relative abundance variation patterns of several dissolution resistant species, such as {\it Globorotalia inflata} and {\it G. menardii}. Sub-orbital scale correlations are observed between SST, faunal assemblages and \delta$^{18}$O. For instance, increasing relative abundance of {\it Pulleniatina obliqueloculata} appears to be correlated to heavy \delta$^{18}$O events. In addition, we found that large decreases in winter SST are closely followed by the large scale demise or extinction of {\it G. ruber} (pink) in the SCS, for example, the event at the beginning of MIS 5 (SST dropped by $\sim$$6.5\deg$C within 1.5 ky) and the event at the end of MIS 13 (SST dropped by $\sim$$7.9\deg$C within 4.8 ky).
DE: 3344 Paleoclimatology
DE: 4243 Marginal and semienclosed seas
DE: 4267 Paleoceanography
DE: 3030 Micropaleontology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting