南海北部191PC柱样沉积物中浮游有孔虫特征及其古环境意义

PLANKTONIC FORAMINIFERA IN CORE 191PC FROM THE NORTHERN SOUTH CHINA SEA AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE

通过对在南海北部陆坡采取的191PC柱状样进行氧碳同位素测试、碳酸钙含量分析以及浮游有孔虫丰度和组合分析,初步划分了191PC柱状样的地层,并据此讨论了末次冰期以来浮游有孔虫丰度和组合的变化,并利用两种浮游有孔虫古生态转换函数再造了末次冰期以来的表层海水古温度和上层水体结构的变化,且由此反映出南海北部末次冰期以来季风演化的趋势。研究表明,该柱状样底部达到氧同位素III期;末次盛冰期到冰后期,南海北部冬季表层海水温度上升5.7—5.8℃,夏季温度上升1.4℃,温跃层总体呈变深的趋势,冬季混合层深度变浅,而夏季混合层深度变深,同时,表层海水垂直温差的变化也可能反映了由末次冰期到冰后期,南海北部具有冬季风减弱而夏季风加强的趋势。

Planktonic foraminifera （PF） have been studied quantiatively for the piston core 191PC from the northern slope of the South China Sea, and PF oxygen-carbon isotopes and calcium carbonate have also been analyzed. The resuits show that the 7.20 m-long core contains a depostional history since the marine isotope stage 3 （MIS3）. The sea surface paleotemperature （SST） estimated by the transfer function FP-12E and SIMMAX-28 shows that the winter SST ascended by 5.7-5.8℃, while the summer SST ascended by 1.4℃ from the last glacial maximum （LGM） to the post-glacial period. Meanwhile the depth of thermocline （DOT） deepened gradually since MIS 3, and the mixed layer depth （MLD） shoaled in winter while deepened in summer. Such a change in MLD might indicate the trend that the winter monsoon weakened while the summer monsoon strengthened during this time.