Age of formation of gold-sulfide-quartz veins in the Kizas ore field, Shamansky ore cluster, Western Sayan, based on 40Ar/39Ar data

DOI: 10.47765/0869-5997-2026-10014

Abstract

The Kizas ore field formed by deposits of the Early Cambrian Shaman Formation is characterized by an amagmatic structure and is notable for its anomalously high placer gold potential: over 22 tonnes of placer gold have been extracted throughout its history of

exploitation. Numerous gold occurrences are known within the field, the largest being the Troitsky Site. Gold-bearing quartz veins of varying orientations and zones of irregular vein-veinlet silicification are confined to a wide and elongated mineralized zone of pyrite-quartz-sericite-ankerite metasomatic alteration. Given the ongoing debate regarding the age of the gold mineralization and the source of the ore-forming material, as well as the spatial remoteness of the quartz vein-veinlet zones from intrusive complexes, dating of the ores and hydrothermal alteration products is a matter of importance. ⁴⁰Ar/³⁹Ar dating of sericite from the gold-bearing quartz veins has confirmed their Middle Devonian to Early Carboniferous age (391–359 Ma). Analysis of the crushed quartz samples revealed an association of gold with pyrite and chalcopyrite, and less frequently with bornite and hematite. ICP-MS analysis of the quartz veins indicated elevated concentrations of Ag, Cu, Bi, Te, and As.