GEOCHEMICAL CLASSIFICATION OF SILICIC IGNEOUS ROCKS OF MAJOR GEODYNAMIC ENVIRONMENTS

Abstract

A large body of published geochemical data on the Phanerozoic granitoids of within-plate, collision, and subduction environments was used to revise the universally accepted methods for the determination of the geodynamic setting of granitoid formation on the basis of chemical characteristics. Possible errors related to the use of particular methods were distinguished. The granitoids of the environments considered were geochemically characterized and the conclusion on their geochemical individuality was confirmed. On the basis of the discriminant analysis of available geochemical data, a set of discriminant functions was calculated for improved analytical or graphical solution of the problem of the tectonic correlation of granitoids of primary magmatic nature (volcanics of dacite-rhyolite composition and intrusive granitoids and granites containing more than 65 wt % SiO2) using the concentrations of either major elements only or major and trace elements. The proposed discriminant functions were tested on the example of Precambrian granitoids, which illustrated prospects of their use for the tectonic reconstructions of Precambrian regions.