Rb-Sr isochron dating of late paleozoic epithermal ore-forming processes: A case study of the Kairagach gold deposit, Kurama ore district, Central Tien Shan

The paper reports Rb-Sr isotopic data obtained by the authors on ore-hosting rocks from the Kairagach epithermal Au-Ag deposit in the Kurama ore district in the Central Tien Shan, Uzbekistan. The influence of mineralizing hydrothermal solutions on the host volcanic rocks of andesite-dacite composition and the metasomatic alterations of these rocks are proved to have been resulted in with the homogenization of the Sr isotopic composition, i.e., its equalization between various modes of Sr occurrence. This offers additional possibilities of the application of the Rb-Sr isochron method in dating hydrothermal processes. The application of Rb-Sr isotopic methods in studying samples from the Kairagach deposit allowed the authors to obtain dates whose reliability corresponds to isochron one (291 ± 3 Ma) or is very close to it (290 ± 6 Ma). The data thus obtained provide good reasons to believe that the corresponding epithermal mineral deposits in the Kurama ore district (Kairagach, Kochbulak, and others) were genetically related to and simultaneous with the emplacement subvolcanic porphyry intrusions.