GEOCHEMICAL CHARACTERISTICS OF UPPER PRECAMBRIAN STRATA IN NORTHERN ANHUI

In this paper,the average chemical compositions of various rocks and formations occurring in the upper Precambrian of northern Anhui are calculated by use of a vast amount of chemical and spectral data from the sections and compared with the crustal clarke values.According to the chemical compositions,the sections are chemically divided using the optimal partitioning method of ordered samples, and thus association laws of the elements in various rocks and formations are derived. The element contents are used to make Q-and R-mode cluster and factor analyses.The geochemical evolution trends of the elements in various formations are discussed in the light of the vertical distribution law of the elements and their contents in the strata,and sedimentary environments in different time are analysed using the contents and ratios of the facies-indicating elements.