摘要
MD06-3050岩芯位于西菲律宾海吕宋岛以东本哈姆高原,利用钙质超微化石下透光带种属Florisphaera profunda占总颗石的相对丰度,恢复了中更新世以珲该海区的上层水体结构演化特征。结果显示,西菲律宾海区自1040ka以来,温跃层/营养跃层经历了由浅—深—浅—深的长周期变动,可能是由于全球碳库的长周期变化对气候系统的大规模调整所致;同时温跃层/营养跃层也具有明显的冰期-间冰期旋回性特征。温跃层变动的另一个重要特征是在中布容事件前后呈现出相反的冰期-间冰期变化趋势,认为可能是由东亚冬、夏季风强度变化引起。
Calypso core MD06- 3050 （ 15 °57. 0943＇ N, 124°46. 7747＇E, length 31.74m, water depth 2967 m） recovered during Marco Polo2 （ MD-155 ） IMAGES XIV cruise in the Benham Rise, east off Luzon Island in the Western Philippine Sea,was analyzed to study the Quaternary calcareous nannofossil records. The core is yellow silty mud with obvious black volcanic ash layers and rich in nannofossils-foraminifera oozes. Some layers were absence in MD06-3050, such as the upper part of the core（0 -6cm） , and the middle upper depth of 986 - 1002cm, but the other parts of MD06-3050 are continuous. We choose the upper 16.61m to study. The core was sampled at 2-cm intervals for planktonic foraminiferal oxygen isotope analysis. Twenty to thirty specimens of Globigerinoides tuber, a surface-dwelling species,were cut to 150 -350 um. The analytical precision is better than ±0.06‰（to PDB）. The chronostratigraphy was based on the correlation of our δ ^18 O curve to the LR04 stack records. We also got two calcareous nannofossil bioevents as age control points, the last occurrence of Pseudoemiliania lacunosa （458 ka） at 960 - 962cm and the first appearance of Emiliania huxelyi （264ka） at 516 518cm. We established stratigraphy of the oxygen isotope in the core MD06-3050 over the last 1040ka. Samples were collected at 4 - 10cm intervals. Smear slides were made directly from unprocessed samples. In each slide, forty view fields of a light microscope were grabbed by a digital camera. Each frame was analyzed by an automated system of coccolith recognition （SYRACO4.0）. Then the relative abundance of lower-photic layer coccolith species, Florisphaera profunda in total coccoliths was achieved. This proxy was used to reconstruct the dynamics of the upper water mass structure in this study. The Western Philippine Sea is one of the largest marginal sea in the Western Pacific, which is important to regulate the global climate as a heat engine and divergence centre. The study area,also as Kuroshio source region, has
出处
《第四纪研究》
CAS
CSCD
北大核心
2011年第2期216-226,共11页
Quaternary Sciences
基金
国家重点基础研究发展规划项目(973项目)(批准号:2007C13815903)
中国科学院知识创新工程项目(批准号:KZCX2-YW-221)
国家自然科学基金项目(批准号:41076030
40976026和40906038)共同资助
关键词
西菲律宾海
中更新世
温跃层变动
长周期
冰期-间冰期旋回
东亚季风
the Western Philippine Sea, mid-Pleistocene, variations in thermocline, long-term, glacial cycles, East Asian monsoon
