PETROLOGY OF GABBRO-DOLERITES FROM NEOPROTEROZOIC DIKE SWARMS IN THE SHARYZHALGAI BLOCK WITH REFERENCE TO THE PROBLEM OF BREAKUP OF THE RODINIA SUPERCONTINENT

Abstract

Results of the detailed petrological study (including mineralogical, petrological, and geochemical characterization and isotopic dating) of Neoproterozoic dike swarms in the southern flank of the Siberian craton are employed in discussing the petrogenesis of the dike series and the environments of their origin. Variations in the composition of the gabbro-dolerites are determined to have been caused by a combination of partial melting of the magma source and the further fractional crystallization of the melts. The parental melts of the gabbro dolerites are demonstrated to have been derived within a lithospheric magmatic chamber early during the extensional stage in the inner parts of the Rodinia supercontinent.