Formation stages of the Kholodninskoye pyrite-polymetallic deposit ore zone

Abstract

The Kholodninskoe pyrite-polymetallic deposit (Baikal-Patom plateau, Russia) was discovered in 1968, but the questions of its genesis still remain controversial. It is assumed that the explosive activity of volcanic apparatuses of the southern part of the Baikal-Muya zone as well as underwater exhalations of the scattered spreading zone of the back-arc basin could have most likely influenced the geochemical features of amagmatic deposits of the Bodaibo and Patom zones. To investigate the influence of underwater hydrothermal activity on the geochemical features of Neoproterozoic carbonbearing sediments of the Baikal Mountain region, the Olokit zone, which is a fragment of the spreading zone of the backarc basin, was chosen. According to the geochemical parameters, the sediments of the Itykit and Ondokskaya formations hosting the Kholodninskoye deposit fall into the sedimentation area of DalnyaTaiga period paleobasins. Having compared the development of sulfide mineralization of ore objects of the Bodaibo and Olokit structural-formation zones, the authors suggest the unity of deposit formation processes within the Baikal Mountain area. The presence of framboidal pyrite indicates that the early stages of ore formation of the Kholodninskoe hydrothermal-stratiform polymetallic deposit were synchronous with sedimentation. The source of deposit ore zone enrichment with zinc lead, silver and other elements typical for low- and medium-temperature associations was a hydrothermal solution of the scattered spreading zone of back-arc basins. It is likely that the explosive and exhalation activities of the southern Baikal-Muya zone within the studied region also spread further northward, thus influencing the formation of siderochalcophilic geochemical specialization of amagmatic black shale strata of the Bodaibo and Patom zones.