近2ka来东海内陆架泥质沉积物地球化学特征

Geochemical characteristics of recent 2 ka mud on the inner shelf of the East China Sea

对位于东海内陆架闽浙沿岸泥质区北部的DD2孔进行了粒度分析、AMS14C年龄测试和主元素、微量元素分析,讨论了各元素含量与粒度间的关系,采用R型因子分析探讨了它们间的组合关系。研究表明,近2ka来DD2孔绝大多数主元素和微量元素含量稳定;随粒径变细大部分元素的含量呈现增加的趋势,而Sr和SiO2的含量则呈现减少的趋势;CaO、Na2O、Hf、Zr和Ti等的含量与粒径相关性很差。因子分析的结果表明,DD2孔泥的化学组成可划分为4种组合类型:分别反映沉积物中元素分布的主要特点,样品未经洗盐前处理引起主元素和微量元素组合的变化,Zr、Hf和Nb元素富集于特定粒度组分(粉砂),及钙质生物组分的加入和早期成岩过程中元素的再分配性质等。初步分析表明,Rb、Cu、Ni、V、P、Sc、Fe2O3、Cr、K2O、Nb、Co、Th、Ti和Al2O3为DD2孔中相对不活动的元素,可以将它们与现代长江、黄河沉积物作对比,进行物源分析。Ti/Zr和Cr/Th比值指示该孔沉积物主要来自于花岗质物源区。

Based on measurement of grain-size, AMS ^14C dating, major and trace elements, relationship between elements and grain-size in Core DD2 is discussed. The results show contents of most elements change little during recent 2 ka. And contents of most elements increase, but Sr and SiO2 decrease with lessening grain-size, and poor relationship exists between CaO, Na2O, Hf, Zr, Ti and grain-size. Based on R-model factor analysis, the chemical compositions of the core can be classified into 4 groups, corresponding to main characteristics of element distribution in Core DD2, changes of major and trace elements compositions resulted from salt not being moved, Zr, Hf and Nb being rich in special grain-size （silt）, and joining of calcium carbonate biology and reaUocating of some elements during early diagenesis, respectively. It is also shown that Rb, Cu, Ni, V, P, Sc, Fe2O3, Cr, K2O, Nb, Co, Th, Ti and Al2O3 are relatively inactive in Core DD2, and its source region was dominantly granite according to Ti/Zr and Cr/Th.