Petrogeochemical Zoning of Mesozoic Volcanic Rocks of the Ore Fields of Gold and Polymetallic Deposits of Eastern Transbaikalia

Abstract

Transverse petrogeochemical zoning in the location of volcaniс rocks of the Shadaronsii (J_2‒3) and Mulinskii (J_2‒3) groups typical of volcanic arcs has been revealed in Eastern Transbaikalia. Volcanic rocks of the tholeiitic and calc-alkaline series occur in the frontal zone of the volcanic arc and in the suture zone of the Mongol–Okhotsk Suture (MOS); volcanic rocks of the calc-alkaline series occur in the rear zone of the MOS. The volcanic rocks of the frontal and rear parts differ in their petrogeochemical composition, in the degree of iron oxidation, and in the distribution of REEs. These differences are typical of volcanic arcs in the zones of transition from the ocean to the continent. Vulcanoplutonic structures of the frontal zone of MOS produce gold mineralization; the rear zone of MOS produces polymetallic mineralization.