HR: 0800h
AN: PP11B-0518    [Abstracts]
TI: Planktic Foraminifer Fauna and SST Variations of the Eastern Equatorial Pacific During MIS 1- 6 and MIS 13-15 (ODP Site 1240)
AU: * Yu, P
EM: menardii@mail2000.com.tw
AF: Institute of Applied Geosciences, National Taiwan Ocean University, 2, Pei-Ning RD, Keelung, 20224, Taiwan
AU: Lin, Y
AF: Department of Marine Environmental Informatics, National Taiwan Ocean University, 2, Pei- Ning RD, Keelung, 20224, Taiwan
AU: Chen, M
EM: mtchen@mail.ntou.edu.tw
AF: Institute of Applied Geosciences, National Taiwan Ocean University, 2, Pei-Ning RD, Keelung, 20224, Taiwan
AB: Numerous mechanisms have been proposed to be responsible for the mid-Brunhes transition (MBT) (0.4-0.5 Ma), whereas how well these mechanisms explain tropical Pacific climate during the MBT remains unclear. To address the MBT paleocenaographic change in surface tropical Pacific, here we conduct high-resolution planktic foraminifer fauna and sea surface temperature (SST) analyses by using cores from ODP Site 1240 (eastern equatorial Pacific). Our study focuses on two intervals: Marine Isotope Stage (MIS) 13-15 and MIS 1-6. The planktic foraminifer analysis suggests that relatively higher abundance of Globorotalia menardii (+G. tumida), and lower abundances of Globigerina bulloides and G. inflata in MIS 13-15 in comparing those in MIS 1-6. Our fauna- based SST estimates also indicate that relatively higher SST by ~2 degree Celsius and smaller variation in MIS 13-15 than MIS1-6. The different fauna and SST patterns in MIS 13-15 and 1-6 suggests different hydrographic conditions and also possibly different mechanisms driving the hydrographic changes. Furthermore, comparing our record with a planktic foraminifer fauna record from the Caribbean Sea (ODP Site 999A) (Martinez et al., 2007), where surface ocean conditions are interpreted to be more influenced by seasonal upwelling plumes and/or eddy-mediated entrainment in MIS 14, we postulate that a large-scale climatic shifting that may involve a migration of Intertropical Convergence Zone and a change of trade wind patterns in the tropical Pacific is responsible for the contrasting surface ocean hydrographies. It is probable that further works to compare our records more globally for the MBT will result thorough evaluation on other processes such as the amplification by tropical ocean-atmosphere interaction and/or changes in the Atlantic thermohaline circulation that may also affect tropical Pacific cooling.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4954 Sea surface temperature
DE: 4964 Upwelling (4279)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting