摘要
对位于闽浙沿海岸泥质区北部的DD2孔沉积物采用激光粒度仪进行了粒度分析,采用ICP-MS进行了稀土元素质量分数测定,分析了该孔稀土元素质量分数与粒度的关系,讨论了稀土元素组成及分馏特征,并与长江、黄河沉积物进行了对比。分析表明,该孔沉积物的w(HREE)、w(LREE)均明显高于长江和黄河沉积物,并随粒度变细而增大,其中Ce的富集造成DD2孔相对更富LREE;[w(La)/w(Lu)]N、[w(La)/w(Yb)]N、[w(Gd)/w(Yb)]N的变化相对较小,且这3个参数的值略小于黄河沉积物的值,而远小于长江沉积物的值,但[w(La)/w(Sm)]N的变化大,且与长江沉积物的值更为接近。这说明该孔沉积物轻重稀土元素分馏、HREE之间的分馏均要弱于长江、黄河沉积物,特别是HREE间的分馏程度,DD2孔要弱得多;而LREE间的分馏程度,DD2孔总体上要比长江和黄河沉积物显著。DD2孔沉积物的δ(Ce)和δ(Eu)平均值分别约为0.92和0.66,即Ce为弱亏损,而Eu异常明显。黄河改道前后该区沉积物的稀土元素地球化学特征无明显变化;从稀土元素组成特征上也难以识别出其物质来源是长江还是黄河,产生这种现象的主要原因是黄河和长江沉积物REE的组成及其特征差别不大以及粒度的控制规律,其中[w(La)/w(Lu)]N、[w(La)/w(Yb)]N随粒径减小呈现出变小的趋势。
This paper analyzes the grain-size and REEs for core DD2 sediment, located at north of the mud area off Zhejiang-Fujian provinces. It also discusses the relation between grain-size and content of REEs, characteristics of REEs component and their fractionations and between the core and those of Yangtze River and Yellow River sediment. It is found that the core DD2 contains obviously a larger number of HREEs and LREEs than the Yangtze and Yellow rivers ,with the sediments increasing with the fining of grain-sizes and that its LREEs is richer than HREEs owing to enrichment of Ce. While the values of （La/Lu）N, （La/Yb）N and （Gd/Yb）N in core DD2 sediments change less with the depth, a bit less than those in the Yellow River sediment and much less than those in the Yangtze River sediment. However, value of （La/ Sm）N changes greatly with depth, and is more approximate to that in the Yangtze River than that in the Yellow River. It shows fractionations between LREEs and HREEs, and those between HREEs in core DD2 are weaker than those in the Yangtze and the Yellow rivers, especially for HREEs. However, fractionations in core DD2 sediment between LREEs are stronger than those in the Yangtze and Yellow rivers. Average values of δ（Ce） and δ（Eu）, 0.92 and 0.66 respectively, indicate that Ce is a bit depleted and Eu is strongly depleted. No obvious changes of characteristics of REEs in core DD2 sediment are discovered before/after the Yellow River＇s shifting. Therefore, it is difficult to identify the source of core DD2 sediments according to its REEs composition because of small REE difference between the Yangtze and Yellow rivers and their contents controlled by grain-size, for example, （La/Lu）N and （La/Yb）N decrease with grain-size fining.
出处
《地质科技情报》
CAS
CSCD
北大核心
2007年第3期7-12,共6页
Geological Science and Technology Information
基金
中国科学院边缘海地质重点实验室开放基金项目(MSGL0507)
国家自然科学基金项目(40576032)
中国科学院王宽诚博士后基金项目(20040921123415)
中国博士后科学基金项目(2005037177)
