COMPOSITION AND AGE OF BASIC DIKES IN THE NASTENKA SITE OF THE MALO-TARYNSKOYE OROGENIC GOLD DEPOSIT (VERKHOYANSK-KOLYMA FOLDED REGION, NORTHEAST RUSSIA).

Characteristic features of the petrographic and chemical compositions as well as the age of basic dikes in the Nastenka site of the Malo-Tarynskoe orogenic gold ore deposit (MTD), located in the central part of the Yana-Kolyma metallogenic belt, northeast Russia, are considered. The dikes are composed of light greenish-gray porphyritic rocks replaced by sericite-chlorite-albite-carbonate substance with ore and epidote components, in which relics and fragments of primary igneous minerals are noted. The obtained Rb-Sr erochron dates of the dikes rocks determine their age at 162±4 Ma (I0 = 0.7128 ± 0.0002), which suggests them to be the earliest magmatic formations of the Malo-Tarynskoe deposit. The calculated formation temperature for the whole rock samples (from Ti- and Zr-geobarometers) is between 747-787 °C and 671-709 °C. Intrusion of the dikes occurred under a relatively high oxygen fugacity (ΔNiO-Ni = -0.08 – +0.83), within the nickel-nickel buffer. The genetic connection of gold mineralization with deep magmatic chambers, which are the source of basic rocks of the dike complex at the Nastenka site of the Malo-Tarynskoe orogenic gold ore deposit, is assumed. [ABSTRACT FROM AUTHOR]