The paper presents new isotope geochronological data for several mineral deposits, ore occurrences, and related igneous bodies (plutons and dikes) in the Verkhoyansk–Kolyma folded area, eastern Yakutia. Twenty-one 40Ar/39Ar mica and four U–Pb zircon dates provide the first age constraints on key metallogenic units in the area. The dating results allow correlation between tectonic, magmatic, and metallogenic events. The sampled mineral deposits within the Adycha–Taryn fault zone in the southeastern Verkhoyansk–Chersky orogen apparently formed at the Jurassic–Cretaceous boundary during the final phase of the collision between the Siberian (North Asian) craton and the Kolyma–Omolon microcontinent (Kupol’noe deposit and the early metallogenic pulse of the Malotarynskoe deposit, ~ 143–144 Ma) and in the latest Early Cretaceous, in the beginning of the orogen collapse (Tallalakh and Dora-Pil’ deposits and the Malotarynskoe late metallogenic pulse, ~ 126 Ma). According to the suggested new classification of metallogenic units, these deposits belong to the Late Jurassic–Early Cretaceous Yana–Kolyma metallogenic belt. The Kyuchus deposit (~ 106 Ma), the Deputatsky ore cluster (~ 106–113 Ma), and the Khotoidokh deposit (~ 116 Ma) in the northern Verkhoyansk–Kolyma folded area belong to the North Verkhoyansk metallogenic belt. Their origin was associated with accretional and collisional processes that produced the Novosibirsk–Chukotka orogen in the middle Cretaceous. The Mangazeya ore cluster (~ 100 Ma, Early–Late Cretaceous boundary) in the southwestern end of the North Tirekhtyakh magmatic transverse belt belongs to the West Verkhoyansk metallogenic belt. The Nezhdaninskoe, Zaderzhnoe, Kurum, and Kuta deposits of the South Verkhoyansk area (~ 125–120 and ~ 100–95 Ma) can be joined into a single Verkhoyansk–Okhotsk metallogenic belt. The belt resulted from accretion and collision along the East Asian active continental margin and the related formation of the South Verkhoyansk orogen in the Early Cretaceous.

We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochronological investigations of mafic, intermediate, and felsic igneous rocks from dikes in the Yana–Kolyma gold belt of the Verkhoyansk–Kolyma folded area (northeastern Asia). The dikes of the Vyun deposit and the Shumniy occurrence intruding Mesozoic terrigenous rocks of the Kular–Nera and Polousniy–Debin terranes were examined in detail. The dikes had diverse mineralogical and petrographic compositions including trachybasalts, andesites, trachyandesites, dacites, and granodiorites. The rocks showed significant similarities in distributions of REE, and their concentrations of most HFSEs were close to the intermediate ones between ocean islands basalts and enriched middle ocean ridge basalts. We propose that the subduction that was ongoing during the collision of the Kolyma–Omolon superterrane with Siberia led to melting in the asthenospheric wedge and in the lithosphere, which formed a mixed source for the dike systems from both an enriched and a depleted mantle source. The U–Pb SHRIMP-II dates obtained for the dikes corresponded to the Late Jurassic interval of 151–145 Ma. We present a geodynamic model for the northeastern margin of the Siberian Craton for the Tithonian age of the Late Jurassic.

The regional geologic setting of the Adycha-Taryn metallogenic zone, one of the areas most productive for noble-metal mineralization in northeastern Russia, is discussed. The intricate metallogenic history of the zone and the prolonged geodynamic activity of its ore-hosting structures are documented. Different types of mineralization, such as hydrothermal-metamorphogenic, gold-bismuth, gold-quartz, gold-antimony, and silver-antimony, are described. New data on the isotopic compositions of oxygen in quartz, sulfur in sulfides, and oxygen and carbon in carbonates from different mineralization types are presented. The early metamorphogenic quartz beyond the ore zones has δ¹⁸O = + 20.1 ± 2.0‰. At the gold-bismuth deposits, the δ¹⁸O values of quartz are within the narrow range of + 12.5 ± 0.4‰. Quartz from the gold-quartz mineralization shows much wider variation in δ¹⁸O values, from + 14.2 to + 19.5‰. A similar range (δ¹⁸O = + 16.1 to + 19.2‰) is observed for the gold-antimony mineralization. Cryptograined quartz from the silver-antimony mineralization is enriched in light oxygen isotopes (δ¹⁸O = -3.2 to + 4.7‰). The following δ³⁴S values (‰) have been established in sulfides of mineralization of different types: gold-bismuth -3.7 to -2.2 (Apy) and -6.7 to -6.8 (Py); gold-quartz -2.1 to + 2.4 (Apy), -6.6 to + 5.4 (Py), and -6.1 to + 4.2 (St); gold-antimony -2.0 to + 1.6 (Apy), -3.5 to + 2.1 (Py), and -5.3 to + 0.2 (St); and silver-antimony -2.0 to -1.9 (Apy), -2.2 ± 0.1 (Py), and -5.7 to -5.6 (St). The δ¹³C and δ¹⁸O values are contrasting in the studied types of mineralization, varying respectively from -6.9 to -5.9‰ and from + 2.1 to + 5.7‰ (gold-bismuth), from -9.1 to -6.1‰ and from + 12.4 to 18.7‰ (gold-quartz), from -12.1 to -9.5‰ and from + 15.0 to + 16.3‰ (gold-antimony), from -11.6 to -11.1‰ and from + 1.5 to + 4.7‰ (silver-antimony). Metamorphogenic calcites are rich in both heavy C (-1.1 to -1.7‰) and heavy O (+ 20.3 to + 20.5‰) isotopes. Microthermometric study and crush-leach analysis of fluid inclusions have revealed differences in the composition of ore-forming fluids and formation conditions for different types of mineralization. The isotopic compositions of O, C, and S of mineral-forming fluids suggest a significant input of magmatic fluids to the formation of gold-bismuth and gold-antimony deposits, the contribution of metamorphic fluids increases at gold-quartz deposits, and meteoric water is involved in the formation of silver-antimony deposits.

At the orogenic gold deposits of the Yana–Kolyma metallogenic belt (northeast Russia) both Au–quartz-sulfide mineralization with native gold and disseminated sulfide mineralization with invisible Au developed. The textural and mineralogical-geochemical features, isotope-geochemical characteristics of gold-bearing sulfides from proximal metasomatites, and possible forms of Au occurrence in pyrite and arsenopyrite have been studied using electron microprobe, atomic absorption, LA-ICP-MS trace element, isotope analysis, and computed microtomography. Four generations of pyrite (Py1, diagenetic; Py2, metamorphic; Py3, metasomatic; Py4, veined) and two generations of arsenopyrite (Apy1, metasomatic; Apy2, veined) have been identified at the Khangalas deposit. In the proximal metasomatites, the most common are Py3 and Apy1. Studying their chemical composition makes it possible to identify the features of the distribution patterns of typochemical trace elements in pyrite and arsenopyrite, and to establish the nature of the relationship between Au and these elements. In Py3 and Apy1, structurally bound (solid solution) Au⁺ prevails, isomorphically entering the crystal lattice or its defects. Isotope characteristics of hydrothermal sulfides (δ³⁴S = −2.0 to −0.6‰) indicate that mantle/magmatic sulfur was involved in the formation of the deposit, though the participation of sulfur from the host rocks of the Verkhoyansk clastic complex cannot be ruled out. The Khangalas deposit has much in common with other gold deposits of the Yana–Kolyma metallogenic belt, and from this point of view, the results obtained will help to better reveal their gold potential and understand their origin.

Detailed structural study of ore zones and deformations in host rocks reveals the multistage tectonic evolution of the Malo-Taryn ore field. Gold–quartz mineralization is confined to the interstratal and longitudinal thrust faults, where vein–stringer bodies are systematically oriented relative to the structures of the thrust stage. Antimony mineralization is superposed on gold–quartz mineralization in the same structures, being associated with veins formed during the shear stage of deformations. It is determined that the types of mineralization were formed in the following sequence: gold–bismuth, low-sulfide gold–quartz, berthierite–antimonite, and silver–antimony. Data on mineral assemblages and typomorphic features of minerals are reported. The isotope composition of minerals, temperature conditions, and composition of orebearing fluids are studied. It is established that the same minerals ascribed to different types of mineralization sharply differ in typomorphic features, which is caused by the different composition and genesis of the hydrothermal fluids. The superposition of different types of mineralization on one another within repeatedly activated tectonic structures that were fluid-permeable for a long time is an important indication of large-scale deposits.