Variations of primary productivity in the western Philippine Sea in the past 260000 years:evidence from coccolith

Primary productivity data of the Core MD06-3047 (17°00.44′N, 124°47.93′E, 2510m water depth) from the International Marine Global Change Study Program (IMAGES) is presented in this paper. The core is taken from the Benham Rise of West Philippine Sea. Coccolith records revealed considerable glacial-interglacial changes of paleoproductivity in the west Philippine Sea over the past 260 ka. The recently published research data of the core made this study possible to reveal the forcing mechanisms of the glacial-interglacial variations in primary productivity. During the period of 260~80 ka, the abundance of F. profunda and primary productivity shows a similar variation trend with the tropical eastern-western Pacific sea surface temperature gradient (ΔSST). The lower ΔSST in the glacial intervals indicate that tropical Pacific was suffered a long term El Niño-like condition, which produced relatively shallow thermocline/nutricline and high primary productivity in the western Pacific. On the contrary, the higher ΔSST in the interglacial intervals indicates a La Niña-like state in the tropical Pacific, which deepened the thermocline/nutricline and suppressed the primary productivity. From the late MIS5 to the last deglacial, we attribute the high values of productivity in the glacial interval and low values in the interglacial intervals to the Eastern Asian winter monsoon, due to the similar trend between illite/smectite ratio and primary productivity in the core MD06-3047.