COCCOLITH VARIATIONS IN CENTRAL WEST PACIFIC WARM POOL AND THEIR RESPONSE TO ENVIRONMENTAL CHANGE DURING LATE QUATERNARY

The analysis of coccolith species and percentage for the past 380 ka from Site KX97321-2 of the central West Pacific Warm Pool has been carried out. The results show that the relative abundance of Florisphaera profunda increased in the last 380 ka, indicating the decline of nutricline depth and the decrease in primary productivity. The relative abundance of Gephyrocapsa spp. however, dropped in the last 380 ka. Gephyrocapsa caribbeanica was the most abundant species in the Mid-Brunhes interval as the result of the adaptive evolution to the Mid-Brunhes peculiar environment. Based on the spectrum analysis of primary productivity converted from F. profunda, 100 ka and 30 ka cycles were discovered during the last 380 ka. 20 ka cycle was found obvious in the 0~80 ka and 320~380 ka, and 40 ka cycle in the 80~320 ka.