Dynamic Characteristics of Fault Structure and Its Controlling Impact on Rock Burst in Mines

As one of the most serious shock dynamic disasters in coal mining, rock burst only occurs under the certain geodynamic environment. Geodynamic is the necessary requirement for the occurrence of rock burst, and the disturbance of mining engineering is the sufficient requirement. In terms of the fault structure, the method of geodynamic zoning is used to classify fault structure forms of rock burst in mines, and a model of geological structure is established to reveal the connection between fault structure and mine engineering. Besides, the influence of fault structure on rock burst is analyzed, and the controlling mechanism of the fault structure on the tectonic evolution of the mine area and the occurrence of rock burst is revealed. This research provides a treatment plan for the prediction and prevention of rock burst and guides the safe production in the coal mining engineering.

ROLE OF PYROXENITE MANTLE IN MAGMA GENESIS OF THE OLIGOCENE BASALTS FROM THE NORTHERN PART OF EAST SIKHOTE ALIN

Identification of magma sources as well as its role in creating the diversity of magma compositions still remains one of the fundamental petrological problems. In our work, on the basis of new comprehensive isotope-geochemical and mineralogical data, we made an attempt to reconstruct the contribution of pyroxenite mantle source in the Oligocene basaltic magma genesis of the northern part of East Sikhote Alin volcanic belt. The most important indicators of this source are significant variations the first order transit elements ratios (Zn/Fe = 11–17, Zn/Mn = 6–10, Cr/Ni (1.8–6) and concentration of Ni (2000–3600 г/т) in olivine. LIL elements behavior suggests the presence of amphibole in pyroxenite substrate. The data obtained can be useful for the correct reconstruction of the magma generation and the geodynamic environment of this territory at the Late Cenozoic.

Repeated S–I–A-type granite trilogy in the Lachlan Orogen and geochemical contrasts with A-type granites in Nigeria: implications for petrogenesis and tectonic discrimination

The classical S–I–A-type granites from the Lachlan Orogen, SE Australia, formed as a tectonic end-member of the accretionary orogenic spectrum, the Paleozoic Tasmanides. The sequence of S- to I- to A-type granite is repeated at least three times. All the granites are syn-extensional, formed in a dominantly back-arc setting behind a single, stepwise-retreating arc system between 530 and 230 Ma. Peralkaline granites are rare. Systematic S–I–A progressions indicate the progressive dilution of an old crustal component as magmatism evolved from arc (S-type) to proximal back-arc (I-type) to distal back-arc (A-type) magmatism. The alkaline and peralkaline A-type Younger granites of Nigeria were generally hotter and drier than the Lachlan A-type granites and were emplaced into an anhydrous Precambrian basement during intermittent intracontinental rifting. This geodynamic environment contrasts with the distal back-arc setting of the Lachlan A-type granites, where magmatism migrated rapidly across the orogen. Tectonic discrimination diagrams are inappropriate for the Lachlan granites, placing them in the wrong settings. Only the peralkaline Narraburra suite of the Lachlan Orogen fits the genuine ‘within-plate’ setting of the Nigerian A-type granites. Such discrimination diagrams require re-evaluation in the light of an improved modern understanding of tectonic processes, particularly the role of extensional tectonism and its geodynamic drivers.

THE CHARACTERISTICS OF THE GEODYNAMIC ENVIRONMENT AND ELEMENTS OF STRUCTURAL-MATERIAL COMPLEXES OF THE CENTRAL CAUCASUS AT A DEEP INCISION HEALTHSCOPE PROFILE

В статье рассматривается возможность выделения наследственных признаков геодинамической обстановки и элементов структурно-вещественных комплексов, участвующих в геологическом развитии Кавказа, на глубинных геоэлектрических и сейсмологических разрезах для создания геолого-геофизической моделей земной коры вдоль региональных профилей. Современные структурно-тектонические и структурно-вещественные комплексы восточной части Центрального Кавказа интерполируются с основными структурами консолидированной коры и низов коры. Обосновывается научный и практический интерес корреляционной увязки глубинных коровых и мантийных структур с месторождениями твердых полезных ископаемых и углеводородов, роль границы Мохоровичича в локализации месторождений. Субширотная структура реликтового рубца (геосутуры), уверенно выделяемая по минимумам напряженности полного вектора магнитного поля по структурно-вещественным элементам (олистостромы, офиолиты, микститы) представляется убедительным наследственным признаком субдукции. Реликтовый рубец представляется выполненным тектонизированным терригенным материалом, содержащим разного размера глыбы и блоки вулканогенно-осадочных пород и ремобилизованные олистостромы пород офиолитового комплекса, что является формационным признаком геодинамической обстановки, фиксируемой в развитии структуры Кавказа. The article deals with the possibility of identifying hereditary features of the geodynamic situation and elements of structural and material complexes involved in the geological development of the Caucasus, in deep geoelectric and seismological sections to create geological and geophysical models of the earth's crust along the regional profiles. Modern structural-tectonic and structural-material complexes of the Eastern part of the Central Caucasus are interpolated with the main structures of the consolidated crust and the lower crust. The scientific and practical interest of correlation linking of deep crustal and mantle structures with deposits of solid minerals and hydrocarbons, the role of the boundary of Mokhorovichych in the localization of deposits is substantiated. Latitudinal structure of the relic scar (geostructure), confidently allocated to the minimum of the tension of magnetic field full vector on structural-material elements (olistostromes, ophiolites, mixtite) persuasive inherited character of subduction. Relict scar is represented by tectonized terrigenous material containing different size blocks and blocks of volcanogenic-sedimentary rocks and remobilized olistostromes of rocks of the ophiolite complex, which is a formative sign of geodynamic situation, recorded in the development of the structure of the Caucasus.

Seismogenic sources and related active faults in the gulf of Corinth; a combined approach

The neotectonic graben of Corinth gulf forms an interesting case study from the geodynamical and seismological point of view, since specific characteristics met on the fault zones around the gulf and the adjacent seismological data pose several questions related with the overall modern activity across a number of neotectonic faults. Indexing active fault zones with structural, seismological and sedimentological criteria leads to thorough understanding of the evolution and modern activity and provide researchers useful tools in order to evaluate the degree of present day activity of the broader area. The combined approach proposed here, with joint use of both, seismogenic sources and structural evidence, contributes to the re-evaluation of the earthquake potential by assessing the role of active features in the already complex geodynamic environment of the Corinthian gulf

Prospects for identifying strategic metals deposits in the Russian Arctic

Mineral deposits are important in the economy of the Russian Arctic. In addition to the petroleum and gas, the resources of PGE minerals and gold, nickel and titanium are more than 10% of global significance. Meanwhile, the most arctic territory is out of availability of detailed geological and geophysical data due to severe climatic situation. The spatial relations of ore deposits and ore-bearing sequences of different geodynamic settings at Russia territory show that the geological sequences of three basic types of geodynamic environment contain an overwhelming number (over 70%) deposits: archaean-proterozoic basement, passive continental margin, volcanic arcs of active margins. There are two groups of ore types. The first are the types (i.e. BIF) are specific to definite sedimentary or igneous rocks, the second (i.e. gold veins etc.) are due to superimposed geotectonic processes. The complex metallogeny may be found in the subductional and accretional terrains, where the blocks of different geodynamic formation are combined. In these areas ores, previously deposited, might been transformed under the later processes until the regeneration and development of new type ores. The convergence of passive margins also might had caused the changes of geodynamic environments and led to form the vertical and lateral facies with metallogenic features combined. In Arctic regions, despite the similar ratio formation areas, the relative number of discovered and evaluated ore deposits is low in areas of active margin, including volcanic arcs and collision. This is especially true for deposits of lead and zinc, ferrous and rare metals. The significant lack of gold deposits is evident. In the areas of passive margin facies the most hidden deposits are of rare and ferrous metals, as well as lead, zinc and gold.