地学前缘 ›› 2011, Vol. 18 ›› Issue (1): 56-62.

• 论文 • 上一篇    下一篇

大陆地壳中元素地球化学分异指数排序模式

岑况,陈媛   

  1. 地质过程与矿产资源国家重点实验室; 中国地质大学(北京) 地球科学与资源学院, 北京 100083
  • 收稿日期:2010-05-12 修回日期:2010-12-17 出版日期:2011-01-15 发布日期:2011-01-15
  • 作者简介:岑况(1953—),男,教授,博士生导师,从事地球化学的教学与研究工作。E-mail: cenkuang@cugb.edu.cn
  • 基金资助:

    地质过程与矿产资源国家重点实验室项目

The ordering mode of geochemical differentiation index of elements in continental crust.

  1. State Key Laboratory of Geological Processes and Mineral Resources; School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
  • Received:2010-05-12 Revised:2010-12-17 Online:2011-01-15 Published:2011-01-15

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摘要：

 深入分析了元素相容性、元素两相间的分配系数与壳幔元素地球化学分异间的关系,建立壳幔元素地球化学分异模型,提出不相容元素在地壳富集与壳幔岩石部分熔融过程相关的观点。收集并整理了原始地幔、地壳各层圈60余种元素的平均化学成分。以壳幔元素的地球化学分异理论模型为依据,计算得到壳幔元素地球化学分异强度指数,并分析了元素分异指数与元素相容性的关系。根据分异指数数值大小由高到低排序得到大陆地壳元素地球化学分异强度的序列。最左边元素为正强分异元素,即强不相容元素,富集于大陆上地壳;最右边为负强分异元素,即强相容元素,在大陆上地壳相对贫化。分异指数值靠近1的元素在地壳的富集和贫化不明显,属于过渡型。根据该序列提出元素地球化学一种新的分类法,分布于序列左边的正强分异元素为亲地壳元素类,分布于序列右边的负强分异元素为亲地幔元素,处于两者之间的元素成为亲地壳亲地幔的过渡元素,并在周期表中列出了各类元素的位置。新划分的三大类元素在周期表中呈现有规律的分布。

关键词: 壳幔元素分异, 理论模型, 分异强度序列, 亲地壳元素, 亲地幔元素

Abstract:

 This paper analyzes the compatibility of elements and the correlation between element partition coefficient in two phases and geochemical differentiation of elements in crust and mantle. On the basis of predecessors research, a geochemical differentiation model of elements in crust and mantle is developed, and the relationship between enrichment mechanism of numerous incompatible elements in the crust and the process of partial melting of rocks is proposed. We collected and collated average chemical composition of 60 kinds of elements in primary mantle and every layer of crust. On the basis of the theoretical model of geochemical differentiation of elements in crust and mantle, we have calculated the differentiation intensity index and analyzed its relation to the compatibility. Logarithm values of these indexes are arranged from high to low to make up a sequence of geochemical differentiation intensity of elements in the upper crust: at the left side of the sequence are strongly positive differentiation elements, namely strongly incompatible elements, enriched in the continental crust; at the right are strongly negative differentiation elements, namely strongly compatible elements, relatively depleted in the continental upper crust; the enrichment or depletion of elements whose differentiation index value are close to 1 is not obvious in the crust and they are called transition elements. According to this sequence, we propose a new geochemical classification of elements: strongly positive differentiation elements distributed in the left of the sequence are crustphilic; strongly negative differentiation elements distributed in the right of the sequence are mantlephilic; elements located in the middle of the sequence are crustphilicmantlephilic transition elements. The element positions and the law of their distribution in the periodic table of elements according to above categories, the variation of differentiation intensity index and its relationship with the properties of corresponding elements in the periodic table of elements are analyzed in this paper.

Key words:  differentiation of crust and mantle elements, theoretical model, differentiation intensity sequence, crustphilic elements, mantlephilic elements

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