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