近 2 ka来东海内陆架泥质沉积物地球化学特征

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、 AMS 14C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 2 ka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.

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

Based on measurement of grain-size, AMS 14C dating, major and t ra ce elements, relationship between elements and grain-size in Core DD2 is discu ssed. The results show contents of most elements change little during recent 2 k a. And contents of most elements increase, but Sr and SiO2 decrease with lesseni ng 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 t he core can be classified into 4 groups, corresponding to main characteristics o f element distribution in Core DD2, changes of major and trace elements composit ions resulted from salt not being moved, Zr, Hf and Nb being rich in special gra in-size (silt), and joining of calcium carbonate biology and reallocating of s ome 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 an d Cr/Th.