Forecast-exploration model of gold deposits of the Toupugol-Khanmeishor ore cluster as a basis for identification of promising areas for geological exploration within the Malyi Ural volcano-plutonic belt in the Polar Urals

A forecast-exploration model of gold deposits of the Toupugol-Khanmeishor ore cluster was developed, which made it possible to recommend geological exploration within other promising areas of the Malyi Ural volcano-plutonic belt (VPB) in the Polar Urals. The studies have demonstrated that the Manyukuyu and Kokpela potential ore clusters of the Tan’yu-Lagorta complex ore district in the southern Malyi Ural VPB represent the most promising targets for the further prospecting for lode gold mineralization assigned to various structural-compositional subtypes of the gold-sulfide-quartz mineral type.

Strike-slip fault tectogenesis in formation of the East Sikhote-Alin volcano-plutonic belt: Structural and dynamic analysis

Study object. The role of strike-slip fault tectogenesis in magmatism of the large (North Eastern Primorye) fragment of the Eastern Sikhote-Alin volcano-plutonic belt (ESAVPB) is studied. Materials and methods. The materials of geological mapping and field geostructural thematic-line research are used. Study methods are based on the concept of the geostructural patterns being formed by lateral, namely, strike-slip movements of crustal blocks. Results. There is recognized the system of the NE-trending sinistral faults, whose activation taken place during two stages. The pre-Late-Cretaceous fold-and-strike-slip-fault (orogenic) stage is characterized by the widely developed fold system within the stratified formations covering active strike-slip faults of the pre-Mesozoic consolidated basement. By the Late Cretaceous, the strike-slip faults cut the fold system into narrow blocks, creating the preconditions for the strike-slip faults’ activation during the next destructionand-strike-slip-fault (riftogenic) stage (Late Cretaceous – Cenozoic). During the latter, the strike-slip faults were activated under transtension (strike slip with extension) with formation of volcano-tectonic extension structures (VTES) nearcrosswise the strike-slip faults. The VTES played, on the one hand, the role of magma-feeding channels. On the other hand, the extension caused preconditions for formation of the depression subsidences that accumulated large volumes of the volcanics covering and «crosslinking» the VTES, resulting in wide development of volcanic covers within the ESAVPB. Conclusion. The VTES’ opening is thereby the effect of lateral (strike-slip) displacements of continental geoblocks that is not consistent with a priori ideas of the development of the East Sikhote-Alin volcano-plutonic belt under the oceanic plates’ subduction. The resulting materials complement the formulations according to which the East Asian volcanic belt formed under the structural-and-dynamic conditions being caused by the evolution of the East Asian global strike-slip fault zone resulting from displacement of the Asian continent to the south-west under the Earth’s rotational geodynamics.

Strike-slip related tectogenesis and structure-forming flow of crustal masses of the Asia-Pacific transition zone

Research subject. This study was aimed at examining the strike-slip related tectogenesis of the Asia-Pacific transition zone (APTZ).Materials and methods. The research was based on the materials collected by the author during long-term fieldwork across the territories of Primorye, Khabarovsk Krai and, partly,Vietnam. Extensive materials on the topic of the APTZ tectogenesis published by researchers fromRussia,China andJapan were analysed. Investigations involved the study of structural and kinematic assemblages representing the forms, directions and time of crustal mass flows under the strike-slip related tectogenesis of the East Asian global strike-slip fault zone (EAGSSFZ).Results. The EAGSSFZ consists of three transit strike-slip fault systems (zones) playing the role of the APTZ basic deep fault structures. Its master system (MS) is NNE (25–30°) trending longitudinally to theAsia edge. The MS is bordered by diagonal NE 50–70° trending near-continental and meridional near-oceanic EAGSSFZ systems. The MS controls the East Asian volcano-plutonic belt (EAVPB), demarcating the APTZ into internal (near-continental) and external (near-oceanic) zones. Two stages of the strike-slip related tectogenesis were established: orogenic-constructive (Jurassic–to–Late-Cretaceous) and riftogenic-destructive (Late Cretaceous–to–Cenozoic). The riftogenic destruction broke the previously formed orogenic foldedthrust structures, thus causing the EAVPB magmatic succession from intracrustal intrusions (Early Cretaceous) to volcanics (Late-Cretaceous-to-Cenozoic). An increase in the crustal destruction during the end of Cretaceous to Cenozoic resulted in the formation of epicontinental sedimentary basins and deep-sea riftogenic depressions of marginal seas. The structure-forming flow of the APTZ crustal masses occurred in the SSW 180–250° direction being opposite and obliquely opposite towards the NNW subduction direction of oceanic plates.Conclusion. The kinematic disconformity as well as the coincidence of the continental crust flow (plate flows) with the direction of inertial-and-equator-oriented forces allowed the author to determine the structuring of the transition zone as a process independent of the geodynamics of oceanic plates and subordinate to the rotational geodynamics of the non-uniformly rotating Earth.

Selenga ore district in Western Transbaikalia: structural and mineragenetic zoning, genetic types of deposits and geodynamic settings of ore localization

Based on complex structural, geological, and mineragenetic metallogenic studies, taking into account the results of earlier subject-specific, prospecting, mapping, and exploration works, it has been established that Upper Paleozoic and Early Mesozoic tectono-magmatic structures are widely developed within the ore district. They are associated with the development of the transregional Upper Paleozoic Selenga-Vitim volcano-plutonic belt of riftogenic type as well as with the formation of the Early Mesozoic Western Transbaikalian zone of intraplate magmatism. The main commercially important mineral raw material resources of the Selenga ore district which are located in the ore clusters (the Kunaley, Kizhinga, Cheremshanka-Oshurkovo, Tashir etal.) and beyond their bounds are associated with the Late Paleozoic-Mesozoic magmatic activity. It is shown that molybdenum and beryllium are the main ore mineral resources within the investigated ore district which establish its mineragenetic features. The new material characteristics of the Upper Paleozoic and Early Mesozoic intraplate magmatic complexes and the associated deposits of mineral raw materials (Mo, Be, Ti, quartz, fluorite and apatite raw materials) and other promising ore objects of gold, uranium and rare-earth-barium-strontium mineralization are obtained. The geodynamic conditions of their formation and the main age boundaries of the ore-forming processes are revealed, the prospects of mining in the Selenga ore district and the involvement of this ore potential in the program of the regions economic modernization are estimated.

Reconstruction of the Vendian–Cambrian active continental margin of the Southern Urals: results of studying of detrital zircon from the Ordovician terrigenous rocks

Detrital zircons of Ordovician terrigenous sequences are studied in various Southern Uralian tectonic units.The age of detrital zircons of the West Uralian and Transuralian megazones, Taganai–Beloretsk Zone, and Kraka allochthons spans from the Late Archean to the end of the Vendian– beginning of the Cambrian; Early Precambrian and Early–Middle Riphean zircons are the most abundant. Vendian–Cambrian detrital zircons are strongly dominant in the Uraltau Zone, Sakmara allochthons, and East Uralian Megazone; the zircons of other ages are absent or extremely rare. The Vendian–Cambrian detrital zircons of all Southern Urals zones probably derive from volcanic and granitic rocks of the marginal continental belt, which are part of the Uraltau Zone, Sakmara allochthons, and East Uralian Megazone. The Lu–Hf isotopic characteristics of Vendian–Cambrian detrital zircons indicate that their parental rocks formed on a heterogeneous basement that includes blocks of juvenile and ancient continental crust. According to a model of the pre-Ordovician tectonic evolution of the Southern Urals, at the end of the Late Riphean, the passive margin of the East European Platform collided with a block on a heterogeneous basement. The formation of the block terminated with the Grenville Orogeny. After collision, a volcano-plutonic belt originated in the Vendian–Cambrian at the actively evolved margin of the East European Platform.

The Tamunier gold deposit in the Northern Ural: Physicochemical formative conditions, ore and fluid sources, genesis

Research subject.This research study was aimed at investigating metasomatic minerals and ores in the Tamunier Deposit, which is located in the Northern Urals, at the Eastern side of the Tagil megazone within the Auerbach volcano-plutonic belt.Materials and methods.Well core samples were investigated using a complex of research methods, including optical and electron microscopy, X-ray spectral microanalysis, mineral geothermometry, thermobarogeochemistry (microthermometry, gas chromatography, determination of the salt composition of fluid inclusions in minerals) and isotope geochemistry (isotopes C, O, S, Sr, Pb).Results.A genetic model describing the formation of the Tamunier deposit was developed using the data obtained on its geological structure, mineral composition of metasomatites and ores, fluid formation mode, sources of ore matter and ore-bearing fluid. In the proposed model, the magmatogenic sodium chloride fluid carrying ore components and S is separated from the Auerbach complex at the depth of intrusion. Penetrating to the surface, this fluid interacts with the rocks of volcanic-sedimentary strata, thereby extracting a number of components, including CO2, S and Sr.Conclusion.Despite the presence of sulphide mineralization of hydrothermal-sedimentary genesis in the volcanogenic-sedimentary rock mass, the data obtained has allowed us to refer the gold-sulphide ores under study to magmatogenic-hydrothermal formations. The estimated P-T conditions (t= 100–370ºС andP= 0.4–0.6 kbar) and the shallow depth of the Tamunier field have shown its correspondence to the sub-epithermal level in the model of the porphyry-epithermal ore-magmatic system.