Abstract:

Relative behaviors of immobile elements during weathering are usually stable from rock to its weathered products. The stability of these relative behaviors is similar to the genetic inheritance in biology. The term of geochemical gene is proposed here to describe the stability of relative variations in contents. The geochemical gene is coded as a sequence of immobile elements. Furthermore, similarity of gene is also proposed and calculated to evaluate the degree of consistency between samples in geochemical gene. Eleven immobile elements are selected to code the geochemical gene based on their abundances in the acidic, intermediate and basic rocks in China, and the sequence of these immobile elements is Al₂O₃→SiO₂→P→Ti→La→Fe₂O₃→Th→Zr→Nb→Y→U. This geochemical gene is presented to characterize the geochemical attributes of the acidic, intermediate and basic rocks in China, and is therefore called geochemical lithogene in terminology. Geological materials with four scales sourcing from the same andesite of Xiong’er Group in western Henan Province, China are selected to test the validity of the geochemical lithogene. The results from the vertical weathering profile developed over the andesite indicate a well heredity from the fresh rock to its weathered products and a well inheritance from the top soil to its sources with different weathering degrees evaluated on WIG. The results from the lateral surficial soil profile, areal stream sediment surveys with a scale of 1:50,000 and 1:200,000 developed over the andesite outcrops indicate a well similarity among the soils and stream sediments sourced from the same parent rock in geochemical lithogene. A geochemical lithogene database may be constructed on the database of regional geochemical survey and may play an important role in the scientific fields such as basic geology, environmental survey, and forensic geochemistry.

Key words: immobile element, geochemical gene, similarity of gene, geochemical lithogene, weathering