中文摘要：

浮游有孔虫属种的分布与表层海水温度和上部水体结构的变化以及古生产力水平的高低密切相关，其壳体的地球化学特征也运载着诸多古海洋学信息。本文对南海南部TX05站（6°20.6＇N，111°16.2＇E；水深1750m）钻孔91个沉积物样品中的浮游有孔虫Globigerinioides ruber、Globigerinoides sacculifer和Pulleniatina obliquiloculata壳体进行了氧、碳稳定同位素（δ ^18O和δ ^13C）分析，结合5个AMS ^14C测年数据点和5个氧同位素年龄控制点，重建了氧同位素期（Marine Isotope Stage，简称MIS）8期（大约27万年）以来该站温跃层深度和古生产力变化的历史。结果表明，G.ruber、G.sacculifer和P.obliquiloculata壳体δ 18O记录的冰期-间冰期温跃层海水温度变化幅度大于表层海水，表层海水温差约为3.4℃、温跃层海水温差约为3.7℃。有孔虫温跃层与表层属种壳体的δ^18O差值（△δ^8O（P.obiliquloculata-G.ruber））表明温跃层整体上呈变浅的趋势，特别是自倒数第二个冰消期以来最为明显，且在间冰期时浅、冰期时深。在MIS 8来，上述所有壳体的δ 13C呈现逐渐变重的趋势，且在间冰期时相对其前一个冰期时重。3个属种壳体的碳同位素记录表明研究站位的初级生产力自表层向下逐渐增大，到水深50m左右达到最大值，再往深层则递减；其差值（△δ ^13C（G.ruber-P.obliquiloculata））、以及浮游有孔虫绝对丰度和高生产力属种的百分含量均显示古生产力水平以倒数第二个冰消期为界呈现阶段性的上升，且总体上在间冰期时较高、冰期时较低。温跃层深度和古生产力的变化可能主要与冰期-间冰期差异逐渐增大背景下的东亚冬、夏季风的强化有关。

英文摘要：

In this study, oxygen（δ ^18O）and carbon（δ ^13C）isotopes are analyzed on shells of Globigerinoides ruber, Globigerinoides sacculifer and Pulleniatina obliquiloculata from sediments of a 778cm long gravity core that was retrieved at Site TX05（6°20.6＇N, 111°16.2＇E; water depth in 1750m）in the southern South China Sea（SCS）. Absolute abundances of planktonic foraminiferal assemblages and relative abundance of some species are examined to give supplementary information. A total of 91 sediment samples were collected at 6cm intervals in the upper 260cm and at 10cm intervals from 260cm to 778cm. G. ruber is used as an indicator of surface water, G. sacculifer is considered as a deep mixed-layer dweller and P. obliquiloculata a thermocline/subsurface water dwelling species. Isotopic profiles of these species are thus jointly investigated to reconstruct evolutionary history of upper ocean thermal structure and paleoproductivity. The stratigraphy of this core is constrained by 5 AMS 14C dating points and 5 oxygen isotope stratigraphic tie points. Together with countings of planktonic foraminiferal species, these isotopic data document a ca.270-ka history of depth of thermocline（DOT）and paleoproductivity in the southern SCS since marine isotope stage（MIS）8. The results show a larger glacial-interglacial amplitude of seawater temperature variation in the thermocline than in the sea surface, indicated by δ ^18O records of G. ruber, G. sacculifer and P. obliquiloculata. The glacial-interglacial difference is ca.3.4℃ for sea surface temperature and ca.3.7℃ for thermocline temperature. Difference of shell δ 18O between surface and subsurface dwellers（△δ^ 18OO（P.obiliquloculata-G.ruber））indicates a general shoaling trend of DOT, particularly remarkable since the penultimate deglaciation, and also shows shallower DOT in interglacials and deeper DOT in glacials. δ^ 13C of all the species shows an overall increasing trend, while higher values occur in interglacials than in anteceding g