南沙群岛永暑礁等8座环礁现代沉积物中Ca、Sr、Mg的特征

CONTENT CHARACTERS ABOUT Ca, Sr AND Mg IN MODERN SEDIMENTS FROM EIGHT ATOLLS OF NANSHA ISLANDS

南沙群岛永暑礁等8座环礁的现代沉积物中,不同礁体之间Ca、Sr、Mg含量变化较大;在同一个环礁的礁坪、泻湖坡和泻湖盆底等不同的地貌带中,Sr含量的变化特征最显著,它在泻湖盆底沉积物中含量最高;通过计算,Ca与Sr、文石与Sr、高镁方解石与Mg含量成正相关;Mg与Sr、文石与Mg、高镁方解石与Sr含量成负相关;Ca与Mg、Ca/Mg与粒径<0.063mm的百分含量、Ca/Mg与平均粒径（Mz）之间的相关性不显著。

The content of Ca. Sr and Mg in modern sediments vary obviously in different atolls of Nansha Islands. In three geomorphological zones, i. e. reef flat, lagoon shope, and lagoon basin floor , the content variation of Sr is most distinct and it is richest in the sediments of lagoon basin floor. The calculated restlts indicate that the contents of Ca vs Sr, aragonite vs Sr, high-Mg calcite vs Mg, are positively correlated, and Sr vs Mg, aragonite vs Mg, high-Mg calcite vs Sr are inversely correlated, and the correlations of contents of Ca vs Mg, Ca/Mg vs percentage of grain size<0.063mm, Ca/Mg vs mean grain size (Mz) are not clear.