【摘要】 中更新世气候转型在南海浮游有孔虫、氧同位素和其它生物记录上主要反映在900 ka BP前后发生高频率变化,特别是指示表层水骤然降温。北部冬季表层水温从24~25℃降至17~28℃,而南部也从26~27℃降至23~24℃。总的降温趋势与开放西太平洋一致,直接反映了西太平洋暖池在900 ka BP之后M IS22期间有明显的减弱。表层水大幅度降温还发生在后继的M IS20、18、16几大冰期,说明主要冰期旋回周期由41 ka转变为100 ka经历了长达400 ka的过渡时期,并且冬季风增强也在过渡时期的后半段最明显。南海南北生物组合和1δ8O值的差异,突出了中更新世气候转型期边缘海区南北气候梯度反差和冬季风在冰期增强的讯号。结论是:生态环境系统反应总体表现与冰期旋回一致的同时,还包含了独特的地区性系统演变特征。但是,南海—西太平洋地区在0.9 Ma BP前后表层海水盐度因东亚冬季风和海平面下降的定量变化,以及这些变化对气候转型时期海—气耦合过程和生态环境系统的影响,尚缺乏足够的资料和证据。更多还原

【Abstract】 Paleoecological responses to mid-Pleistocene climate transition at about 900 ka in the south China sea(SCS) were mainly reflected by high-frequency fluctuations in planktonic foraminifer,isotopic,and other biological-environmental records that indicated a sudden decrease in sea surface temperature.Winter SST declined from 24~25℃ to 17~28℃ in the northern SCS and from 26~27℃ to 23~24℃ in the southern SCS.In parallel to the general trend in the open western Pacific,these results indicated considerable weakening of the Western Pacific Warm Pool at ~900 ka,during MIS22.Large-scale SST decreases also occurred during the subsequent glacial periods MIS 20,18,and 16,indicating a transitional period of up to 400 ka during the transition of dominant glacial cyclicities from 41 ka to 100 ka.It was not until the later part of this transition did the winter monsoon become significantly strengthened.Paleobiological and isotopic differences between the northern and southern SCS enhanced the signals of N-S climate gradient contrasts and strengthening of winter monsoons during glacial periods in this marginal sea.Therefore,responses of the paleoecological-environmental system to mid-Pleistocene climate transition included not only parallel changes with glacial cycles but also some unique regional characteristics.However,changes in sea surface salinity at and since ~900 ka in responding to monsoon variability and low sea level,as well their impact on sea-air interaction and the evolution of paleoecological-environmental system in the SCS-western Pacific region,remain unclear.更多还原