Chemical composition of magmatic rocks in a certain region and its regional geochemical characteristics

Based on a review of the available petrological and petrochemical data on magmatic rocks in a certain region in China, the average chemical composition of them has been calculated, and the frequency distribution of elements in the rocks, the mineralization of rock bodies and the regional geochemical characteristics have been discussed. In response to temporal and spatial variations during the evolutionary process of magmatic activity, a systematic variation is obvious from this study in the chemical composition of magmatic rocks, the frequency distribution patterns of elements, the concentration levels of various elements and the calc-alkali index of the rocks as well as in the average atomic weight and average atomic valence. Particularly, different geochemical indicators have been established for mineralized and barren rock bodies, respectively. Crystallization-differentiation and post-magmatic metasomatism constitute the most important mechanism controlling mineralization.