南海北部晚第四纪高分辨率浮游氧同位素地层学及其古气候信息  

Late Quaternary High Resolution Monsoon Records in Planktonic Stable Isotopes from Northern South China Sea

作　　者：葛黄敏[1] 李前裕[1,2] 成鑫荣[1] 郑洪波[1] 贺娟[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]澳大利亚阿德莱得大学地球与环境科学学院

出　　处：《地球科学（中国地质大学学报）》2010年第4期515-525,共11页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(No.40321603);国家重点基础研究发展计划"973"项目(No.2007CB815900)

摘　　要：对南海北部MD05-2904孔45m的连续沉积物中提取的浮游有孔虫Globigerinoides ruber(白色)进行稳定同位素分析,得到晚MIS8以来(时间跨度257ka,平均时间分辨率228a)的高分辨率沉积记录,δ18O和δ13C的频谱分析显示了强烈的岁差(23.4ka、19.8ka)、半岁差(11.7ka、9.9ka)周期.MD05-2904孔MIS24时间段的氧同位素记录了格陵兰冰心中发现的Dansgaard/Oeschger和Heinrich事件.与葫芦洞石笋记录及南海邻区浮游有孔虫氧同位素记录的对比显示了受季风控制的区域因素,如降雨、河流输入导致的盐度变化等对表层海水组成的影响.氧同位素在MIS3、MIS6的早期以及MIS7.4偏轻;而在MIS5.5偏重,这种现象解释为降雨量和蒸发量共同作用的结果.而末次冰盛期高达6570cm/ka的沉积速率反映了低海平面时孔位离岸距离缩短带来丰富的沉积物源.Oxygen and carbon stable isotope records （with an average time resolution of - 228 a） were obtained from Core MD05-2904 （19°27. 32＇, 116°15.15＇, water depth 2 066 m）, using the mixed-layer dwelling planktonic foraminifer Globigerinoides tuber （white）. The 45 m core spans from end of MIS 8 to the Holocene, representing the sediment record of the last 257 a. Strong precession periods （23. 4 ka and 19. 8 ka） were found from spectral analysis of both δ^18O and δ^13C records, following with semi-precession cycles （11.7 ka and 9. 9 ka）. The high resolution δ^18O record of MD05-2904 reveals nearly all the Dansgaard/Oeschger and Heinrich events during MIS 2-4, as defined in the Greenland ice core record. A better correlation between MI）05-2904 planktonic δ^18O, the Hulu stalagmite δ^18O record and previously published planktonic δ^18O records from the suggests that the planktonic δ^18O record is influenced by monsoon-dominated regional factors, such as rainfall and river discharge related salinity changes. Lighter δ^18O values in early MIS 3, early MIS 6 and MIS 7. 4, and heavier values in MIS 5.5 are due to changes in precipitation and evaporation affected by monsoon. Sedimentation rates increased to 65 - 70 cm/ka in LGM, indicating more sediments when the site location was closer to the river mouth during glacial at lower sea level.

关 键 词：氧同位素 地层学 短期气候事件 东亚季风 MD05—2904 南海北部. 

分 类 号：P736.22[天文地球—海洋地质]