Petrogeochemistry and forming conditions of the Mesozoic volcanoplutonic formations in the Baleisky ore node

Abstract

Research subject. In this research, volcanoplutonic formations (VPF) in the Baleisky ore node (BON) consisting of intrusions of the Amudzhikan-Shakhtama complex (J2-3) and comagmatic effusions of the Shadaron series (J2-3) were investigated.Methods. Investigations were carried out in the analytical center of the SB RAS Geological (Ulan-Ude). Silicate analysis was performed by the conventional method. Ore and rare elements were determined by the RFA method. Rare earth elements were detected using the ASP-AES method.Results. It was determined that VPF in the BON has a zonal structure. In the central parts of the BON, granite rods of the Amudzhikan-Shakhtama complex (J2-3) are located. Further, moving from the central BON parts towards its periphery, a belt of small intrusions of the Amudzhikan-Shakhtama complex (stocks of monzonite diorites, granodiorites, dikes of diorite porphyrites, lamprophyres) is located. The majority of gold deposits and ore occurrences are confined to this zone. The peripheral parts of the BON feature volcanogenic sedimentary deposits of the Shadaron series (J2-3). In composition, these deposits correspond to island-arc and post-col-lisional formations. It is shown that the intrusions of the Amudzhikan-Shakhtama complex correspond to high-potassium calc-alkaline series.Conclusions. It was found that the magmatic melts of the Mesozoic ore-bearing intrusions located in the Baleisky deposit area are more differentiated and located at lower depths compared to the rocks of similar composition in other BON parts.

Keywords

• baley volcanoplutonic formations
• magma chamber
• island-arc andpost-collisional environments