OXYGEN ISOTOPE CHARACTERISTIC AND PALEOCEANOGRAPHIC VARIATIONS OF THE WESTERN PACIFIC WARM POOL SINCE PLIOCENE

As the global climate engine,the western Pacific warm pool is the hot issue concerning paleoceanography and paleoclimate research. Through the planktonic foraminifera oxygen isotope from ODP 130 at site 807A,we established the Astronomical Timescale for the past 4.5 Ma.The time resolution is better than 2~3 ka.We studied the depth of thermocline and the upper water column structure variation by the oxygen isotope changes of surface genus and sublayer genus of plantonic foraminifera.Combined with frequence analysis and cross frequence analysis with Earch Trace Parameter(ETP),we studied the evolution of western Pacific warm pool since Pliocene,especially during the stage of ice sheet formation at North Pool, and its response to earch orbit changes, that provided a scientific foundation for global climate evolution.