摘要
对采自南海深海中的两个柱样进行了分析。沉积速率分别为6.2cm·ka－1（317－82－25柱）和4．2cm·ka-1（90－37柱），均明显大于其他深海沉积速率，说明了南海这个边缘海的“放大效应”。此外，还分析了采自珠江口至外陆架的表层样，总结出从几元素在平面上的分布规律：从河口一陆架边缘～半深海，U，几含量的变化趋势均为多～少一多，Th／U比为小→大→小；而碳酸盐含量则显示出少→多→少的分布规律，即U，Th的含量与碳酸盐含量成反比，这可能是碳酸盐的所谓“稀释效应”所致。铀含量随柱样深度的变化曲线基本上与氧同位素曲线相吻合，其相关系数达0．67,证明U含量变化可能具有气候意义。Th的高含量点亦落在冷期之内。文中还探讨了水中铀的来源去向，说明了它能反映气候变化的原因。
Two core samples collected from the deep waters of the South ChinaSea were analysed. Their sedimentary rates were 6.2 cm. ka- l for column 3l7-82-25and 4.2 cm. ka- 1 for column 9O-37 separately, faster than those of other deep seasediments, which explained the 'effect of amplification' of the South China Sea as amarginal sea. Some surface samples collected from Zhuiang River mouth to the outershelf were also analysed. The plane distributive laws of U and Th were: theircontents were high→low→high from the river mouth to the shelf margin and to thehalf deep sea, Th / U ratio was small→ large→ small; while carbonates were few→more→ few. This showed that U and Th contents were in inverse proponion tocarbonate content, which might result from the 'effect of dilution' of carbonates.The change of the U-content curve with depth coincided basically with the curveof oxygen isotope, the relative coefficient was 0.67, proving that the change ofU-content in deep sea sediments might be related to the paleoclimate. The highTh-content also occurred in the cold period. The source and going direchon ofUranium in sea water was discussed and the reason why the change of U-contentpossibly had climatic significance was explained.
出处
《热带海洋》
CSCD
1997年第3期32-40,共9页
基金
中国科学院南海海洋研究所所长基金!900501
关键词
南海
沉积物
铀
钍
分布特征
古环境
U and Th isotopes, distributive characteristics, sedimentary rate, Oxygen isotope, climatic evolution
