Tectonic Evolution and Structural Control of Dikes-Hosted Orogenic Gold Deposits in The Yana-Kolyma Collision Orogen, Eastern Siberia: Insights from Terranes of the Eastern Margins of the Siberian Craton

The Yana-Kolyma collision orogen is one of world-class gold economic belts, where the large gold deposits are localized, mainly in the Upper Paleozoic and Lower Mesozoic clastic rocks. Dikes-hosted orogenic gold deposits have been to a lesser extent, but they are important for analyzing the structural control of mineralization within the framework of the tectonic evolution of the host orogen. Orogenic gold deposits of the Vyun ore field are hosted in Titonian mafic and felsic dike, but they have no genetic connection with dikes. The late formation of deposits leads to the fact that previously reactivated polydeformed structures turn out to be mineralized. Study of the structural control of mineralization is also complicated by superimposed late tectonic events. Based on the analysis of collected field materials, the paper presents the results of the study of deformation structures of the Vyun ore field within the framework of the Mesozoic evolution history throughout the geological time of the eastern convergent margin of the Siberian craton. Four stages of deformations are identified. The pre-mineralization deformations, metamorphic and magmatic events share a common NE-SW shortening (D1), which is related to the subduction of the Oymyakon oceanic slab and collision of the Kolyma-Omolon superterrane from the eastern margin of the Siberian Craton. These deformations are characterized by multiphase history of superposition of several tectonic events under conditions of compression and progressive deformations (D1/1 and D1/2). Ore mineralization was formed at the end of compression in the same stress field (D1/2). Its structural control is determined by reactivation of older dikes and faults. Dikes are areas of heterogeneous stress and heterogeneous strain, being favorable for the concentration of ore fluids. The metallogenic time of formation of the gold mineralization is synchronous to the tectonic event likely reflects the final stages of the Kolyma–Omolon microcontinent – Siberian Craton collision of the Valanginian during crustal thickening. The main impulse of Au mineralization coincided with a slowdown in convergence. Postmineralization tectonic regime was related to the Aptian-Late Cretaceous tectonic transition from compression to transpression. Transpressional tectonics was determined accordingly by W-E (D2) and N-S (D3) stress fields caused by several accretion events in the Cretaceous on the northern and eastern margins of Siberia. D4 tension strains are caused by the opening of the Eurasian Oceanic basin in the Arctic in the Paleocene. The obtained results of the relation between polydeformed structures and associated mineralization have important implications to contribute to a proper understanding of the structural control of orogenic gold deposits and their relationship to the evolution of the host orogen and the conceptual exploration targeting orogenic gold deposits in Phanerozoic terranes of craton margins.