南海第四纪海水Sr同位素组成演化

QUATERNARY Sr ISOTOPIC RECORDS OF THE SEAWATER IN THE SOUTH CHINA SEA

本文分析了南海ＮＳ９０－１０３孔沉积物中浮游有孔虫Ｓｒ同位素组成，获得南海２４０ｋａ以来海水￣８７Ｓｒ／￣８６Ｓｒ演化曲线。结果表明，２４０ｋａ以来南海海水￣８７Ｓｒ／￣８６Ｓｒ比值呈较大幅度的脉动式波动，幅度一般在±０．００００７０以上；南海的半封闭性，高Ｓｒ通量和高￣Ｓｒ／￣８６Ｓｒ比值的河流输入以及南海较高的沉积速率导致了这种大幅度脉动式海水Ｓｒ同位素变化。

r isotopic compositions from the planktonic foraminifera of Core NS90-103,drilledat the South China Sea,show the variation of ￣87Sr/￣86Sr ratios of the seawater. From240ka B.P. to present,the ￣87Sr/￣86Sr ratios sharply oscillated in large amplitudes,usuallyover ±0.000070.This“impulsing”oscillation may result from the semiclose environmentof the South China Sea,the river input with high Sr fluxes and high ￣87Sr/￣86Sr ratios andthe high sedimentation rates of the deposits in the South China Sea.