Past 360 Kyr Paleoenvironment In Central West Pacific Warm Pool

Western Pacific Warm Pool, an average 28℃isotherm as the boundary, is theregion of the world's most intense air-sea exchange, but also is the gathering place ofmany important water masses and ocean currents. Changes in the WPWP influencethe climate change of Asia, Pacific and even global and the formation of someimportant natural disasters. It is one of the sources of climate anomalies. Revealingthe variation rule of the WPWP is very significant to understanding the global climatechange. In order to understand the paleoenviroment evolution of the WPWP, weselected in the core 97322-4 (00 o 01.7321 'S, 159 o 14.6625' E, water depth: 2362m)located in Ontong Java platform in the core of the WPWP as the researching materialsto analyse theδ18O,δ13C of planktonic foraminifera G. ruber and N. dutertrei and theforaminiferal assemblages and compare with the results of previous studies. Finally,we rebuilt the paleoenvironmental evolution course of the WPWP since 360ka andfilled the gaps of lower research resolution in this area.By oxygen isotope analysis, 97322-4 reached MIS10 period, with fourglacial-interglacial cycles. That the rate of change in sub-surface water wassignificantly higher than the surface water indicated that the subsurface water is moresensitive to changes in the environment and water temperature changes is more severe,which suggested that the WPWP environmental changes mostly occurred in thesub-surface water. Planktonic foraminiferalδ¹³C minimum events in fourdeglaciation may reflect the impact of the Subantarctic Mode Water (SAMW) andAntarctic Intermediate Water (AAIW) on the low-latitude tropical sea. This event proved the 13C minimum events in deglaciation is universal in the tropical Pacific, but also provided further evidence for the Antarctic influence to the tropics.Subsurface water's carbon isotope , benthic foraminiferal abundance, U + B(%)qualitatively reflected the paleoproductivity change process of the hole 97322-4, which indicating that the glacial has high productivity and the interglacial has the low productivity. Its driving mechanism may be controlled by the ENSO-like alteration of the thermocline depth.The structure of upper water in 97322-4 didn't present the glacial-interglacial cycle characteristics. Changes can be divided into two stages: MIS10-MIS7, in this phase the thermocline was shallower; after MIS7, the thermocline showing a deeper trend.The fluctuations of planktonic community composition in 97322-4 hole were more frequent, but did not strictly follow the glacial - interglacial cycles. Precession and semiprecession cycle were more common, indicating that the abundance of foraminifera in the area were influenced by the tropical driving. The slope and the eccentricity cycles are also reflected in the area, suggesting that the high latitudes also played the role of driver.