The age and tectonic position epithermal gold mineralization Omolon Massif (North-East Asia)

Abstract

Some aspects of the genesis of industrially important Paleozoic epithermal gold deposits of the Omolon massif are considered. According to the results of Ar-Ar dating of ores, their age is 20–30 Ma younger than that of the volcanic complexes of the Kedonian volcanic belt of the Devonian, with which this mineralization is traditionally associated. For the Paleozoic continental marginal magmatism of the Omolon massif, we have identified a stage of post-subduction rifting, characterized by the formation of volcano-plutonic associations of shoshonite-latite series. The authors suppose that it was at this stage, the chronological boundaries of which are determined as 335–286 Ma, that the ores under consideration were formed. The paragenetic connection with riftogenic shoshonite-latite series explains such specific features of the Paleozoic epithermal gold mineralization of the Omolon massif, such as high gold-silver ratio, low ore sulfide content, widespread development of fluorite and tellurides, low values of the primary Sr isotope ratio (0,703–0,706).