METALLOGENIC ZONALITY OF THE DEVONIAN VOLCANOPLUTONIC BELT IN CENTRAL KAZAKHSTAN

Abstract

The article reviews metallogeny of the main development stages of the Devonian volcanoplutonic belt in Central Kazakhstan and relations of the metallogeny to magmatism and geodynamic environment. Gold quartz-vein or gold-polymetallic massive sulfide deposits are associated mainly with the earlier stage of the Devonian belt development; rare metal deposits, mainly with the middle stage; and gold quartz-vein and gold-molybdenum-copper porphyry, with the late stage. The frontal zone of the belt is characterized by a less alkaline and potassic magmatism and by more abundant copper mineralization, whereas the rear zone, in addition to copper, contains rare metal and gold mineralization. Regular changes in deposit types of the same metals were established across the strike of the belt. This feature is the most pronounced for copper. Copper and gold-pollymetallic (with copper) massive sulfide deposits and occurrences are confined to the frontal zone of the Devonian belt. Complex copper-molybdenum-gold porphyry deposits are more typical for the rear zone, whereas deposits of the copper sandstone type occur in the external part of this zone. Copper deposits of the stratiform type are confined mainly to marginal parts of back-arc structures. The late stage of the Devonian belt development is characterized by the most alkaline and high-potassic magmatism and by the most productive metallogenic potential as compared to the preceding stages.