This paper describes fracture and low-amplitude fault systems in Upper Cretaceous deposits in the vicinity of the Chufut-Kale “cave town.” Analysis of the orientations and kinematics of the faults and fracture parageneses has made it possible to reconstruct stress-fields of the Alpine tectonic stage and their rough order. An assumption on the appearance of sublatitudinal compression in Mountainous Crimea has been made.
The Liskin fault zone located in the southeastern part of the East European Platform at the boundary between two large neotectonic structures, that is, the Voronezh Uplift and the Oka–Don basin, is considered. Earthquake epicenters are concentrated in the fault zone and the adjacent territory. The neotectonic structures of the territory, topography, structure of the multi-depth and age horizons of the sedimentary cover, basement, crust, Moho surface are investigated, and the causes of neotectonic and seismic activity of the zone are determined. At present, the Liskin fault develops as a thrust fault with a dextral strike-slip component under the conditions of submeridional compression and the adjacent territory is under the influence of multidirectional tectonic compression stresses: from the north, from the Oka–Don basin and from the south, from the Caucasian segment of the Alpine collision belt. This is reflected in the morphology and structure of the neotectonic structures. The deformation of multi-depth horizons as well as the Earth’s surface and the activation of seismicity are associated with the submeridional compression. The deep material and structural inhomogeneities of the Earth’s crust are of great importance. The collision zone between two oncoming submeridional stresses that led to active seismicity has been identified in the neotectonic structure of the south-eastern part of the East European Platform for the first time.
Tourmaline, rutile, and associated minerals from veinlets cutting chromitites are characteristic of the Kamennoozerskoe occurrence belonging to the Shabrovskii district in the Central Urals. Tourmaline belongs to the dravite–oxy-dravite series and contains Cr (0.52–2.06 apfu), Ni (up to 0.03 apfu), and V (up to 0.02 apfu). Raman spectroscopy indicates Fe3+ in tourmaline. Rutile associated with tourmaline contains, wt %: Sb2O5 4.68–11.69, Cr2O3 2.00–8.02, and WO3 0.88–1.14. It is suggested that tourmaline and associated minerals were formed under oxidizing conditions.
A new anomalous section of the Bazhenov Formation has been described on the territory of the Urengoy deposit in the northern part of Western Siberia. This article describes mesostructural complexes in the core, which have served as a basis for the suggestion of a new model for the formation of the anomalous section of the Bazhenov Formation. It has been found that the mesostructural complexes were formed at different landslide stages and during the movement of the landslide body along the uneven surface of the detachment. The main role in the formation of large injection “sand veins” in the studied section was probably played by the landslide-induced grain flow from the coastal shallow water area. The penetration of its sandy material into the rocks of the Bazhenov Formation and, to a lesser extent, the Achimov Formation was determined by the energy of a hydraulic shock and hydraulic fracturing along layer-by-layer and secant fractures.
The Caspian Sea is one of the most perspective areas for oil and gas exploration. Significant hydrocarbon reserves are contained in polymictic sand reservoirs of the Lower Cretaceous (Aptian–Albian) deposits of the North Caspian fields, which are characterized by an irregular distribution of pelitic and silty fractions. This results in high residual water content and low permeability and poor consistency between filtration and capacity properties. This determines the high heterogeneity of reservoirs in hydrocarbon accumulations and unusually low specific electrical resistivities when producing water-free hydrocarbon inflows. As our studies have shown, the most important reason for the complex structure is the intense bioturbation of deposits virtually throughout the productive section, which actively affects the redistribution of clay material in the reservoir rocks and ultimately leads to a decrease in the resistivity of reservoirs to the point where they can be classified as low resistivity ones.
We revealed traces of two earthquakes of the 10th and 12th centuries at six objects of the Afrasiab archaeological site. These traces include numerous ruptures and fractures that form a “flower” structure, a subsided graben, and the slopes and turns of fragments of fortress walls. The type of the deformation indicates that the epicenter of the earthquake of the 10th century was located to the west-southwest of the ancient city; the epicenter of the earthquake of the 12th century was to the south-southwest of it. The intensity of both events was VIII–IX points on the MSK-64 scale.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：