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.

Granitoid-hosted gold mineralization in Ikibzyaksky ore field: a new milestone in Baikal-Patom metallogenic province gold potential study

New data is provided on gold mineralization in the southern Baikal-Patom metallogenic province, Ikibzyakskoye ore field, located in Pravo-Mamakansky deep fault zone separating Patom fold area from Baikal-Vitim volcanic-plutonic belt. For the first time, the metallogenic province was found to comprise granitoid-hosted ore vein-stringer zones with high-grade economic gold sulfide-quartz mineralization. This mineralization is localized within fault shistosity zones manifesting intense beresitization and listvenitization (in metabasite xenoliths).

LATERAL ZONALITY OF THE ANYUI SEGMENT OF THE CHUKCHI PLUTONIC BELT (WESTERN CHUKOTKA)

Early Cretaceous granitoids of the Anyui segment of the Chukchi plutonic belt are represented by associations: gabbro-granite, monzodiorite-granite and granite-leucogranite. For the rocks of gabbro-granite and monzonite-granite associations with respect to the primitive mantle, enrichment of Cs, Rb, K was established, with depletion of Nb, Hf, Ti. Granitoids of the granite-leucogranite association are characterized by the most contrasting ratios of enriched and depleted elements, with deep lows of Ba, Nb, Sr, P, Ti against the background of high Cs, Rb, K, Th, U, as well as the absence of a minimum of Hf. Along with the presence of lateral zonality in the placement of granitoids in relation to the southwestern border of the Anyuy Terrain, these data suggest the subductive nature of the formation of gold-bearing gabbro-granite and monzonite-granite associations in the conditions of an active continental margin that arose in the southwestern part of the Chukchi Terrain in Early Cretaceous time due to subduction.

U-Pb Age, by Zircon, of the Pre-Klesiv Breed Association of the Osnytsky Block

The Osnytsky block is an integral part of the Osnytsky-Mikashevytsky volcanic-plutonic belt, represented by early proterozoic igneous rocks of different compositions. This is a new type of igneous belts for the early precambrian – a paleotypical analogue of intracontinental volcanic-plutonic belts by the phanerozoic, which was formed in the conditions of mature continental crust in the initial stage of radical structural rearrangement of the cratonized gneiss base of the Eastern European platform. Volcanogenic formations have undergone regional metamorphism at a level not higher than the epidote-amphibolite facies, classified in the klesiv series, which combines effusives of basic, acidic and medium composition and occupies a higher stratigraphic position compared to the metamorphites of the teteriv series. Intrusive rocks (gabbro-diorite-granodiorite granite association) – to the osnitsky complex. Rocks of the osnitsky complex are widespread, they account for 80-85% of the area of the Osnitsky block. The pre-klesiv association, represented mainly by gneisses of the teteriv series and plagiogranitoids of the sheremetivsky complex, has a limited distribution. The LA-ICP-MS U-Pb method was applied to date zircon from plagiogranite and plagiomigmatite of the sheremetivsky complex, and from gneiss and amphibolite. The plagiogranite yielded an age of 2110 ± 8, and plagiomigmatite of 2165 ± 22 Ma. Hence, granitoids of the sheremetivsky complex in the Osnitsk block were formed between 2.16 and 2.11 Ga. The age of the metamorphism of gneisses was defined as 2198 ± 29 Ma, whereas zircon from amphibolite crystallized at 1981 ± 36 Ma. Correspondingly, gneiss can be attributed to the teteriv series, whereas amphibolite can belong to either osnitsky complex, or nartsyzivsky complex.

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.

Tectonic factors of impurity elements accumulation at the Shubarkol coal deposit (Kazakhstan)

Purpose. To study the features of the paleotectonic development of the area and to construct paleotectonic reconstruction of the deposit formation to establish the nature of impurity elements accumulation in the coals and enclosing rocks of the Shubarkol deposit, as well as to increase the mineral resource potential of coals. Methodology. 25 samples of coal and mudstone from the Shubarkol deposit were analyzed. The samples were studied by instrumental neutron- activation analysis (INAA) at the Nuclear Geochemical Laboratory of National Research Tomsk Polytechnic University. Findings. An analysis of geological-structural and paleotectonic formation conditions of the Jurassic coal deposit was carried. The factors of formation of coal and carbon-containing rocks enriched with impurity elements and the conditions needed for its leaching and transportation to the coal seam were analyzed. It was found that the coals in individual samples have average concentrations of Ce, Ba, Sr, Sc, Zn that are higher than the clarke, and Sm, Ce, U, Cr, Yb, Ba, Sr, Nd, As, Sc, Zn, Eu, La in the composition of mudstone have average values that are higher than in coals, and higher than the clarke. It was established that one of the sources of rare-metal mineralization of coals (peat) in the Mesozoic and Cenozoic times were the rock massifs of the Kokchetau uplift in the north and northwest, the Kaptyadyr, Arganatinsk and Ulutau mountains in the west. They form the chain of the Kokchetau-North Tien Shan ancient folded structure and the Central Kazakhstan (Devonian) volcanic-plutonic belt in the east. They surround the sedimentation basin and serve as suppliers of clastic material during the coal-bearing strata formation due to tectonic processes of the Mesozoic-Cenozoic time. Originality. The paleotectonic development of the Shubarkol deposit area during the coal-bearing formation has been reconstructed. It has been established that the Sarysu-Teniz uplift in the Permian-Triassic is separated into an independent block, to which the studied deposit is spatially and genetically related. It has been established that the distribution of elements in the coals of the Shubarkol deposit is determined by the peculiarities of metallogeny, geochemistry of the framing area and the mechanisms of the elements entering the coal seams. Practical value. A purposeful analysis of materials for the peculiarities of high concentrations of impurity elements accumulation in coal in connection with deep fault zones at the Shubarkol deposit serves as an objective justification of the possibility of their integrated use, ensuring the development of the countrys coal industry.

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.