GEOCHEMICAL FEATURES OF TUFFISITES OF THE KRASNOVISHERSK COMPLEX, NORTHERN URALS

Abstract

The first geochemical data for tuffisites, potassic alkaline rocks of specific facies that might contribute to the elevated diamond potential of the region, are presented. The tuffisites are completely argillized, and their primary magmatic origin is verified by petrologic and mineralogic data. The geochemical features of tuffisites can be interpreted in different ways. These rocks resemble the composition of the upper continental crust in many element concentrations. However, they differ in Y, Zr, and high REE contents (in some cases) and are similar to some varieties of madupitic lamproites, particularly to low-Cr orendites in Italy, and to lamproites of the Southern Urals. This similarity is pronounced in the distribution of concentrations of major elements, REEs, and HFSE. It is suggested that some geochemical features of tuffisites are inherited from the primary magmatic rocks.