Age and Problem of the Genesis of the Kutyn Gold Deposit, Khabarovsk Krai.

For the first time, the U–Pb and Rb–Sr age of granodiorites of the Birandzhinskii massif, with which the gold mineralization of the Kutyn deposit in Khabarovsk krai is spatially connected, has been determined. Isotope–geochronological data show good convergence: the concordant U–Pb age of zircon is 90.7 ± 1.7 million years (SIMS), and the Rb–Sr age of the rock shaft and minerals is 92.7 ± 0.4 million years. Low εNd(t) values (about –0.8) and high primary ⁸⁷Sr/⁸⁶Sr ratios (0.7051–0.7053) relative to the parameters of the depleted mantle suggest that granodiorites were formed with the participation of the continental crust. The formation of the Birandzhinskii massif coincides with the second stage of the development of the Khingan–Okhotsk volcano-plutonic belt. The Rb–Sr age of gold-bearing quartz–carbonate–sericite metasomatites of the Kutyn deposit is 79.3 ± 0.5 million years. The obtained isotope–geochronological data indicate a time gap (about 10–12 million years) between the crystallization of granodiorites and the formation of metasomatites, which suggests the allometasomatic nature of gold mineralization. [ABSTRACT FROM AUTHOR]