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 δ18O and magnetostratigraphy have been used to determine the Pliocene/Pleistocene boundary of the deepsea sediment at ODP Site 1148 in the South China Sea, and to make a comparative study with the P/P boundarystratotype at Vrica, Italy. The P/P boundary between MIS 64 and 65 is located at depth 11275 m and dated to be 1805 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 δ18O 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 Icesheet.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
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)
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
Pliocene/Pleistocene boundary
planktonic foraminifera
oxygen stable isotope
the South China Sea
