THE QUANTITATIVE-MINERAL COMPOSITION OF GRANITOIDS AND ITS IMPORTANCE FOR PROBLEMS OF PETROLOGY AND NOMENCLATURE

Compilations of mineral compositional data from several "classical regions of granitoid" rock in the U.S.S.R. are shown on triangular diagrams with quartz, K-feldspar, and plagioclase at the apices. Names, most of which are more or less according to general usage, are applied to different fields within the diagram. It is concluded that location within the compositions of rocks diagrams from the different massives indicate relationships between compositions and certain geological features of coeval masses and also reflects such things as assimilation, hybridization, and "degree of differentiation."--R. V. Dietrich.