Features Of Geological Structure Research Articles

Структурные и минералого-геохими-ческие особенности золоторудного месторождения Амес-месса в Алжирской Сахаре

The geological structure, mineralogical and geochemical features of the Amesmessa gold quartz-vein type ore deposit located in In-Uzzal region of Hoggar shield (the Algerian Sahara) are described. The ore-bearing object has Proterozoic age and belongs to the gold - quartz - low-sulfide formation. The basis of its structure and a typical geological setting of the ore veins location are the fault paragenesis that had arisen in a process of the development of a big fault zone during the Ebourneisky tectonic and magmatic cycle. This object belongs to a formation typical for the metallogenic zones of the green belts of the ancient shields and has good prospects of accumulation of the ore resource potential.

On the applicability of geomechanical models for carbonate rock masses interested by karst processes

Rock mass classification and geomechanical models have a particular importance for carbonate rocks, due to their peculiar fabric, variability of the main features, and scarce availability of experimental data. Carbonates are particularly sensitive to syn-depositional and post-depositional diagenesis, including dissolution and karstification processes, cementation, recrystallisation, dolomitisation and replacement by other minerals. At the same time, as most of sedimentary rocks, they are typically stratified, laminated, folded, faulted and fractured. The strength and deformability of carbonate rock masses are, therefore, significantly affected by the discontinuities, as well as by their pattern and orientation with respect to the in situ stresses. Further, discontinuities generally cause a distribution of stresses in the rock mass remarkably different from those determined by the classical elastic or elasto-plastic theories for homogeneous continua. Goal of this work is the description of the difficulties in elaborating geomechanical models to depict the stress–strain behavior of karstified carbonate rock masses. Due to such difficulties, a high degree of uncertainty is also present in the selection of the most proper approach, the discontinuum one or the equivalent continuum, and in the numerical model to be used within a specific engineering application as well. The high uncertainty might cause wrong assessments as concerns the geological hazards, the design costs, and the most proper remediation works. Even though recent developments in the application of numerical modeling methods allow to simulate quite well several types of jointed rock masses, as concerns carbonate rock masses many problems in representing their complex geometry in the simulation models still remain, due to peculiarity of the structural elements, and the presence of karst features. In the common practice, the improper use of the geomechanical models comes from a superficial geological study, or from the lack of reliable geological and structural data that, as a consequence, bring to erroneous evaluations of the influence of the geological-structural features on the in situ stress state and the stress–strain rock mass behavior.

Characteristics of in situ stress field at Qingshui coal mine

In this study, the characteristics of geological structure at Qingshui coal mine were analyzed. And the hollow inclusion strain cell overcoring method was used to obtain the in situ stress. The effect of in situ stress on the stability of soft rock roadway was analyzed. The results show that the maximum principal stress is in the horizontal direction with a northeast orientation and has a value of about 1.2–1.9 times larger than gravity; the right side of roadway roof and floor is easily subject to serious deformation and failure, and the in situ stress is found to be a major factor. This paper presents important information for developing countermeasures against the large deformation of the soft rock roadway at Qingshui coal mine.

Особенности строения и интенсификации притоков нефти в сложных коллекторах баженовской свиты Пальяновского месторождения

Особенности строения и интенсификации притоков нефти в сложных коллекторах баженовской свиты Пальяновского месторождения

Crustal stress changes and characteristics of damage to geo-engineering structures induced by the Great East Japan Earthquake of 2011

T he Great 2011 Earthquake of East Japan, with a moment magnitude of 9.0, occurred off the shore of the Tohoku Region of Japan. Although seismologists anticipated an earthquake with a magnitude of 7.5 in the source area, the magnitude of this earthquake was much greater than anticipated. Furthermore, the level of the tsunami induced by this earthquake also exceeded expectations. Therefore, damage caused by the tsunami was tremendous and more than 18,000 people perished due to insufficient counter-measures. The author first presents characteristics of the earthquake and its associated tsunami and then describes damage to some geo-engineering structures. The final part of the article describes lessons learned from this earthquake and proposes recommendations. Changes in crustal stress occurred as forecasted by computations and in situ stress measurements. However, it is expected the orientation of the maximum principal stress would remain almost the same as those prior to the earthquake. The scale and number of slope failures were much larger on the hanging wall side of the earthquake fault as compared to those on the foot-wall side. It has also become clear that the scale of natural slope failures is much larger than that of cut-slopes (man-made) and, therefore, more attention should be given to potential natural rock slope failures. In addition, slope failures may also be induced by tsunamis, thus necessitating further studies on the effect of tsunamis on rock slopes, with consideration of their structural geological features. Strong ground shaking induced the collapse of semi-underground tunnel portals in the abandoned Oya quarries. In addition to potential caving of abandoned mines and quarries during earthquakes due to either pillar failure and/or roof failure, groundwater may present additional impacts on immersed mines. Sinkholes are thought to be due to ground rupture induced by the sloshing of groundwater in inclined shafts. Tsunami waves inundated many tunnels on the Onagawa, Minami-Sanriku and Kesennuma railways, although they did not cause any major structural damage. However, consideration should be given to the impact of high internal hydrostatic water pressure on conventional tunnels when they are located in tsunami-prone areas.

Fault and dyke detectability in high resolution seismic surveys for coal: a view from numerical modelling

Modern underground coal mining requires certainty about geological faults, dykes and other structural features. Faults with throws of even just a few metres can create safety issues and lead to costly delays in mine production.In this paper, we use numerical modelling in an ideal, noise-free environment with homogeneous layering to investigate the detectability of small faults by seismic reflection surveying. If the layering is horizontal, faults with throws of 1/8 of the wavelength should be detectable in a 2D survey. In a coal mining setting where the seismic velocity of the overburden ranges from 3000 m/s to 4000 m/s and the dominant seismic frequency is ~100 Hz, this corresponds to a fault with a throw of 4–5 m. However, if the layers are dipping or folded, the faults may be more difficult to detect, especially when their throws oppose the trend of the background structure. In the case of 3D seismic surveying we suggest that faults with throws as small as 1/16 of wavelength (2–2.5 m) can be detectable because of the benefits offered by computer-aided horizon identification and the improved spatial coherence in 3D seismic surveys.With dykes, we find that Berkhout’s definition of the Fresnel zone is more consistent with actual experience. At a depth of 500 m, which is typically encountered in coal mining, and a 100 Hz dominant seismic frequency, dykes less than 8 m in width are undetectable, even after migration.

A new fracture model for the prediction of longwall caving characteristics

A new numerical model is presented to simulate fracture initiation and propagation in geological structures. This model is based on the recent amalgamation of established failure and fracture mechanics theory, which has been implemented to the finite difference FLAC code as a constitutive FISH user-defined-model. Validation of the model has been studied on the basis of comparing the transitional failure modes in rock. It is shown that the model is capable of accurately simulating fracture distributions over entire brittle to ductile rock phases. The application of the model during longwall retreat simulation highlighted several caving characteristics relevant to varying geological condition. The distribution and behaviour of modelled fractures were both realistic and shown to provide an enhanced post failure analysis to geological structures in FLAC. Moreover, the model introduces new potential insight towards the failure analysis of more complicated problems. This is best suited towards improving safety and efficiency in mines through the prediction of various key fractures and caving characteristics of geological structures.

Особенности геологического строения и пространственного размещения промышленной нефтегазоносности основных продуктивных комплексов рифей-вендского возраста на территории Пермского края

Особенности геологического строения и пространственного размещения промышленной нефтегазоносности основных продуктивных комплексов рифей-вендского возраста на территории Пермского края

Features of the subsurface geological structures formed by strike-slip faults in Yatsushiro Bay

Features of the subsurface geological structures formed by strike-slip faults in Yatsushiro Bay

Analysis on spatial distribution characteristics and geographical factors of Chinese National Geoparks

AbstractThis study presents the Pearson correlation analyses of the various factors influencing the Chinese National Geoparks. The aim of this contribution is to offer insights on the Chinese National Geoparks by describing its relations with geoheritage and their intrinsic linkages with geological, climatic controls. The results suggest that: 1) Geomorphologic landscape and palaeontology National Geoparks contribute to 81.65% of Chinese National Geoparks. 2) The NNI of geoparks is 0.97 and it belongs to causal distributional patternwhose regional distributional characteristics may be best characterized as’ dispersion in overall and aggregation in local’. 3) Spatial distribution of National Geoparks is wide. The geographic imbalance in their distribution across regions and types of National Geoparks is obvious, with 13 clustered belts, including Tianshan-Altaishan Mountain, Lesser Higgnan-Changbai, Western Bohai Sea, Taihangshan Mountain, Shandong, Qilianshan-Qinling Mountain, Annulus Tibetan Plateau, Dabashan Mountain, Dabieshan Mountain, Chongqing-Western Hunan, Nanling Mountain, Wuyishan Mountain, Southeastern Coastal, of which the National Geoparks number is 180, accounting for 82.57%. 4) Spatial distribution of National Geoparks coincide with latitudinal tectonic zone and longitude tectonic zone of geological structure features, which is consistent with the areas around the Pacific Rim of volcanic tectonic zones. The coupling relationships are obvious between the spatial distributional pattern and the natural and geological conditions.

THE FEATURES OF SALT DEPOSITS GEOLOGICAL STRUCTURE AND LITHOLOGIC COMPOSITION IN THE CENTRAL PART OF BORYSLAV-POKUTIAN ZONE (UKRAINIAN CARPATHIAN FOREDEEP)

The main characteristics of the geological structure and lithologic features of the salt Verkhn’ovorotyschens’ka suite in central part of Boryslav-Pokutian zone Ukrainian Carpathian foredeep were considered namely in areas: Verkhniy Strutyn, Yasenovets, Roshnyato, Rozsil’na, Kosmach, Dzvinyach, Starunia, Solotvyn, Markova, Molod’kiv. The lithologic features of the salt deposits were analyzed in the investigated territory and the conclusions were made on the prospects and ways of salt resources use in these areas.

The Structural Analysis of Deep Gas Occurrence and Prevention of Gas Disaster in Fengfeng Coalfield

The geological structure is an important factor of gas occurrence in coal seam, and the gas occurrence in deep coal seam should be paid attention to enough because the occurrence was more controlled by geological structure and influence. Taken Fengfeng coalfield as target in this paper, the geological structure of this coalfield was described. The deep coal mining district which is monoclinic structure in Fengfeng is located in the east of Gushan anticlinoria, which the junior small anticlines and synclines of the sub-echelon are well developed. And regional fault structures are intensive, the pressure structure is the major structure among this region. The characteristics of geological structure in Fengfeng coalfield were analyzed. The tensional structure planes and pressure structure are the major effect factors, and the latter is the main form of gas occurrence in deep. Some suggestions on safe of deep mining in high gas environment is also put forward, in order to provide theoretical support for the deep coal mining and gas disaster prevention.

Research on the Relationship between Geothermal Field and the Tectonic in Himalayas and its Surrounding Regions

In this article,based on the terrestrial heat flow data, the terrestrial heat flow map in the area, geothermal gradient map and different depth geothermal contour map of study area within the Territory of China, I explored respectively the relationship between geothermal field and tectonic, geologic structures by analyzing respectively the corresponding relationships between the structural diagram and terrestrial heat flow diagram, temperature contour map, geothermal gradient map in study area. The main conclusions are as follows. Geothermal field has been restricted by the India plate and Eurasian plate collision. So the study area as a whole is a geothermal abnormal area. Features of regional geological structure control the geothermal flow distribution. Geothermal abrupt changing occurs between different tectonic units.

Geospatial technology and structural analysis for geological mapping and tectonic evolution of Feiran–Solaf metamorphic complex, South Sinai, Egypt

The Sinai Peninsula constitutes an important district of the Egyptian lands where it forms a triangular portion in northeastern Egypt. The southern Sinai metamorphic complexes are the northern uppermost part of the Arabian–Nubian Shield revealing the upper and middle crust from the East African Orogeny, in which they tectonically evolved. The Feiran–Solaf metamorphic complex (FSMC) of Sinai, Egypt is one of the highest grades metamorphic complexes of a series of basement domes that trends NW and crops out throughout the Arabian–Nubian Shield. The main aim of the present study is to apply the geospatial technology and to represent the capability of the geospatial technology to estimate the combined influence of lithology and structure studies, and to construct the lithological and structural maps of FSMC. Furthermore, detailed structural analysis is carried out to reveal the different ductile and brittle deformational events and proposed the tectonic evolutionary model for the study area. Mainly geospatial technology and structural analysis software have been used to go well with the aim of the present study. Developing specific image processing of satellite images and structural analysis were succeeded to discriminate the various lithological rock units, and the geological structural features of the FSMC, using geographic information system tools to construct the different thematic maps, were extracted. The present detailed investigations of the enhanced satellite images, structural analysis, and field verification reveal that the FSMC reached its present tectonic setting through more than four deformational phases concluding that the Pan-African Najd Fault System continued in Sinai and was reactivated during Red Sea tectonics as indicated by the dextral shear zone (Rihba) bordering the northern side of the FSMC.

On deep electric conductivity of the lithosphere in the Tobol-Ishim interfluve (West Siberia)

On the basis of exploration magnetotelluric soundings (MTS) carried out by the Tyumen Geological Survey in 1980–1981 within the Tobol-Ishim interfluve, the top of the conductive horizon with the electric resistivity of dozens of Ω m is identified in the geoelectrical section at a depth of 75–80 km. Two segments of the locally elevated top of this horizon are revealed. One segment, where the depth of the top of the conductor is 60–65 km, corresponds to the region of the Kiselevskii fault-the main fault in this territory; another segment is associated with the edge zone of the Ishim branch of the Triassic rift system within the West Siberian Plate. Within this segment, the top of the conductive layer rises to a depth of 55-60 km. It is assumed that the Ishim geoelectrical anomaly, which projects into the geothermal anomaly and is coherent with the features of the deep geological structure of its display region, is conditioned by the element of the mantle-crustal magmatogene fluid paleosystem.

금산 함우라늄광상 분포지역의 항공자력/방사능 탐사자료 해석

We conducted the airborne magnetic and radiometric survey for the characterization of the black shale related and pyrometamorphic uranium deposits distributed in Geumsan area. For the successful characterization of the uranium deposits, the general geological and structural geological features were investigated based on the lithological and linear feature analysis to individual magnetic and radiometric data as the first step. Lithological analysis from the magnetic reduction to the pole and downward continuation map revealed that prominent positive anomalies caused by black and dark gray slate member were clearly recognized as magnetic sources. These results indicate that magnetic survey, even though it is not a direct method for the detection of uranium, can be a useful tool in uranium detection. By the linear feature analysis based on 2nd vertical derivative and curvature map, two linearments corresponded the gray hornfels and black slate member were extracted and in succession, the additional uranium potential zone was inferred. Final discrimination whether uranium-rich or not was confirmed by radiometric and uranium anomaly map. From these analysis, we finally concluded that uranium deposit originated by pyrometamorphic process was confined near the intrusive area only. On the contrary, it was found that black shale related uranium deposit is distributed and extended through out the entire survey area with south-west to north-east direction. In addition, from the linear feature analysis based on radiometric total anomaly map, the typical discontinuous characteristics were recognized in areas where uranium-contained linearments cross the faults. From the above discussion, we concluded that airborne magnetic and radiometric survey are complementary to each other. So it is preferable to carry out simultaneously for the efficient data processing and fruitful interpretation.

Оpen oil-and-gas content and perspective of Prypiat-Dnieper-Donets rift

The article dedicated to special features of geological structure and petroleum potential of Pripiat-Dniper-Donets-Karpinskiy rift, which extends into Manguslak territory. From petroleum point of view riftogenesis is positive factor, which creates in the basement and sedimentary rocks the system of fauls, which increases permeability. 

Особенности геологического строения сеноманской газовой залежи Еты-Пуровского месторождения

Особенности геологического строения сеноманской газовой залежи Еты-Пуровского месторождения

Morfometrijske značajke šireg područja Duvanjskog polja, Bosna i Hercegovina

Objekt ovog istraživanja su padine uzvišenja šireg područja Duvanjskog polja. Padine se mogu definirati kao reljefne plohe određene geografskim položajem, nagibom u odnosu na horizontalnu površinu, izloženošću (ekspozicijom) u odnosu na strane svijeta, te stupnjem zakrivljenosti (profilne i planarne). Recentni oblik padina posljedica je utjecaja niza prirodnih i društvenih faktora tijekom geneze i evolucije reljefa. Analizom morfometrijskih parametara moguće je dovesti u vezu značajke padina s geološkom građom i sastavom, ali i ostalim prirodno-geografskim čimbenicima (npr. klima, pedologija, vegetacija itd.). Ciljevi ovog istraživanja su: a) analiza morfometrijskih pokazatelja reljefa, b) analiza odnosa između morfometrijskih pokazatelja, strukturnih i litoloških značajki, i c) sinteza svih analiziranih pokazatelja da bi se dobio detaljniji uvid u egzogeomorfološke i morfostrukturne značajke područja i omogućila procjena opsega i intenziteta dominantnih geomorfoloških procesa. Pri tome, posebna pažnja posvećena je detaljnoj geomorfometrijskoj analizi makromorfostruktura šireg područja Duvanjskog polja u GIS okružju temeljem digitalnog modela reljefa (DMR). Geomorfometrijska analiza reljefa primijenjena u ovom radu uključila je korištenje različitih metoda za precizno računanje numeričkih parametara reljefa istraživanog područja, što je omogućilo međusobnu usporedbu navedenih parametara ali i usporedbu s kartom tektonskih jedinica i geološkom kartom. Cilj ovakvog pristupa je egzaktnija interpretacija morfometrijskih parametara reljefa kao indikatora značajki endogenih i egzogenih procesa na istraživanom području.

Study on Geological Structural Characteristics in Zhaoguan Mine Field

Based on a great deal of geological data, we analyzed the geological tectonic features of Zhaoguan mine field. On the basis of the analytical method of traditional geology, the paper revealed the general development mechanism of geological structures of this research area. Combined with the fractal theory, and taking the calculation chart of reserve in coal seam as the foundation drawing, the faults and folds can be deeply studied to obtain their fractal characteristics with geological structure complexity in this area quantificationally evaluated.