南海深海沉积中的更新统/上新统界线及与意大利Vrica层型剖面的对比  

THE PLIOCENE/PLEISTOCENE BOUNDARY IN DEEP-SEA SEDIMENTS OF THE SOUTH CHINA SEA AND ITS COMPARISON WITH THE VRICA BOUNDARY-STRATOTYPE OF ITALY

作　　者：赵泉鸿[1] 翦知[1] 成鑫荣[1] 

机构地区：[1]同济大学海洋地质教育部重点实验室,上海200092

出　　处：《海洋地质与第四纪地质》2003年第2期65-72,共8页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金资助项目(49999560);国家重点基础研究发展规划项目(2000078502);上海市科学技术发展基金资助项目(00290710)

摘　　要：应用浮游有孔虫定量统计、底栖有孔虫氧同位素和磁性地层学等资料来确定南海ODP1148站深海沉积中的上新统/更新统(P/P)界线。氧同位素期(MIS)64和65之间的P/P界线在1148站位于井深112 75m处,计算年龄为1 805Ma,在地层对比上与Vrica层型剖面的P/P界线一致。浮游有孔虫Pulleniatinaobliquiloculata在MIS62出现以右旋壳为主的转变,计算年龄为1 76Ma,此事件和Olduvai极性亚时顶界看来是最接近P/P界线的可靠时间面。除此以外,在1148站P/P界线及其附近没有发现重大的地层学和环境变化事件。相比之下,1148站底栖δ18O值在3 05～2 53Ma期间快速变重,冬季表层海水温度下降了5℃,指示了北半球冰盖的形成。The data of planktonic foraminiferal census, benthic foraminiferal δ18O and magnetostratigraphy have been used to determine the Pliocene/Pleistocene boundary of the deepsea sediment at ODP Site 1148 in the South China Sea, and to make a comparative study with the P/P boundarystratotype at Vrica, Italy. The P/P boundary between MIS 64 and 65 is located at depth 11275 m and dated to be 1805 Ma at Site 1148, which is stratigraphically coincident with the P/P boundary at Vrica stratotype. The coiling change from the sinistral to dextral in Pulleniatina obliquiloculata is found in MIS 62 and dated to be 1.76 Ma. This event, together with the top boundary of the Olduvai subchron,may be the most reliable datum nearest the P/P boundary in the South China Sea. Except these datum levels, there is no significant event in biostratigraphy and environmental change found at or near the P/P boundary at Site 1148. Comparatively, a rapid increase in benthic δ18O occurred between 3.05 and 2.53 Ma with a 5 ℃ decrease in winter SST at Site 1148, indicating the formation of the North Hemisphere Icesheet.

关 键 词：深海沉积 剖面 更新统/上新统界线 浮游有孔虫 氧同位素 南海 

分 类 号：P736.213[天文地球—海洋地质] P736.223[天文地球—海洋科学]