HR: 1330h
AN: PP32A-0280    [PDF]
TI: Paleoceanographic Change off Central Japan Since the Last 150 ka Recorded in an IMAGES Core.
AU: * Oba, T
EM: oba-tad@ees.hokudai.ac.jp
AB: A long core (45.82 m length) was recovered from 2,224 m water depths off the central Japan during the IMAGES cruise in 2001. A multi-disciplinary study was carried out on this core by analyzing the following: color, grain size, mineral composition, paleomagnetism, d18O, d13C Opal, CaCO3, species of diatoms, coccolithophorids, radiolaria, planktonic foraminifera and benthic foraminifera, CaCO3 preservation, Uk37O, TOC, C/N, d13CTOC, d15NTOC, biomakers and pollen. The following main results were obtained. The d18O curve of benthic foraminifera is very similar to the standard oxygen isotope curve, suggesting continuous deposition over the last 150 ka. All warm water indices yielded by the four microfossil assemblages (diatoms, coccolith, radiolaria, planktonic foraminifera) show temperature decreases during the MIS 2 and 6, and increases during the MIS 5, although their correlation coefficients with each other are not always high (between 0.5 and 0,6). The Alkenon and oxygen isotope-derived temperature s (19?C) at the core top agree with the modern SST in this region. The isotope SST at the MIS 2 and 6 were 12-13?C, which are seen today about 4.5 degree latitude north than the core site. Similar migrations in SST are inferred from the coiling ratio of Neogloboquadrina pachyderma. The C/N ratio, d13CTOC and d15NTOC indicate that the TOC is mainly of marine origin, although terrestrial origin slightly increases during the MIS 6. The curve of the warm pollen index is similar to the d18O curve of G. bulloides, except for the MIS 6 and 5e when the land temperature changes inferred from the pollen curve precede the d18O curve. Variabilites in detritus transport and onland vegetation suggest higher precipitation on the central Japan during MIS 1 and the later half of MIS 5. Highest precipitation occurring during MIS 5 is attributed to be increased temperature contrast between air and sea surface due to significant drop of air temperature along the Pacific margin of the central Japan.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 4283 Water masses
DE: 4870 Stable isotopes
DE: 9355 Pacific Ocean
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting