Reaserch Of The Paleoceanography Of The Western Pacific Warm Pool During The Mid Pleistocene

Core MD06-3047, retrieved from the eastern area of Luzon island---the marginalarea of the Western Pacific Warm Pool (WPWP), were analysed on planktonicforaminiferal faunas, stable oxygen and carbon isotope of planktonic and benthicforaminifera, Mg/Ca ratios of the shell of surface,subsurface dwelling planktonicforaminifera, to fill up the vacuum on the paleoenvironment research in this region,further clarify the relationship between the Kuroshio current system and thelow-latitude tropical area (WPWP).The planktonic foraminiferal faunas in core MD06-3047have intensive tropicalcharacteristic, the warm water-favoring species dominate the faunas. There is obvious100ka and precessional periods in the variety of planktonic foraminiferal faunas, thatmeans the ice volume in high latitude and climate process in low latitude are thedrivers of the faunas in core MD06-3047.The depth of thermocline, nutricline and surface paleoproductivity in westernPhilippine Sea have obvious glacial/interglacial cycle, the thermocline and nutriclineare shallow, the surface paleoproductivity rise in glacial periods, and vise versa.The SST oscillation range of this core in glacial/interglacial exceed over6℃.The oscillation range of sub-SST is about6℃and is a little smaller than SST. That'smore than the value estimated for the SST range of open western pacific.That meansthe edge of glacial warm pool is unstable, and the MD06-3047is out of the28℃outline of the warm pool area. The globle ice volume varierty and low latitude radiation influenced the upper water thermo change. The thermo change of subsurfaceleads the suface water; the thermo variation of upper water leads the globle icevolume change.Remarkable eccentricity, precession, and half-precession periods have beenfound in depth of thermocline, nutricline, surface paleoproductivity, surface andsub-surface temperature recorded in Core MD06-3047, therefore the upper waterstructure, surface paleoproductivity and upper water temperature are influencing byhigh-latitude ice volume variation and low-latitude processes.The reside salinity of surface water in Core MD06-3047which was low inglacial periods and high in interglacial periods, indicates that surface water of WPWPwas low-salty in glacial times removing ice-volume factor, related with moreprecipitation caused by southward moving of ITCZ in glacial times.Tropical pacific west-east thermo gradient was small in glacial times and largein interglacial times from mid-Pleistocene. DOT, surface paleoproductivity andtropical pacific west-east thermo gradient, indicate that equatorial Pacific was inENSO-like variation mode since70,000ka, just like El Ni o condition in glacialperiods, and La Ni a condition in interglacial periods.