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1.
The tectonic evolution of the Por’ya Guba segment of the White Sea Rift System began in the late Paleoproterozoic, i.e., soon
after completion of the Svecofennian collision. The fracture system that controlled localization of the lamproite dike complex
was formed under conditions of horizontal compression combined with shear. Subsequently, this system predetermined the location
of a rift-graben segment that formed as a result of simple shear. The reactivation of the rift system in the Middle Paleozoic
proceeded in two stages. The first stage, when strike-slip movements along previously formed faults predominated, resulted
in formation of quartz-carbonate veins bearing base-metal mineralization. The veins that filled the shear fractures opened
owing to local reorientation of the stress field. The second stage fitted the transtension conditions, and the Late Devonian
alkaline ultramafic dikes of this stage introded into the already existing fracture system, which was oriented at a roughly
right angle to the predominant stress orientation. 相似文献
2.
E. A. Bataleva E. S. Przhiyalgovskii V. Yu. Batalev E. V. Lavrushina M. G. Leonov V. E. Matyukov A. K. Rybin 《Doklady Earth Sciences》2017,475(2):930-934
Based on a complex study of the upper crust structure in the southern margin of Kochkor basin (Northern Tien Shan), including study of the structure of the Cenozoic sedimentary cover, the deep geoelectrical structure, the structural unconformities, and occurrences of recent deformations in the basement rocks, new geological–geophysical cross sections are constructed. The cross sections show both fault structures that penetrate the cover from the basement and flat interplate detachments with related fold-overthrust structures. The comparison of the cross sections has established the absence of common planes of fault extensions along the entire margin of the hollow, except for the zone where the margin and the hollow adjoin, which can be caused by the zones of dynamic influence of secondary faults, the zones of fracturing, and the zones of cataclasis of blockwise disintegrated granite massifs. 相似文献
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4.
M. G. Leonov Yu. G. Tsekhovskii E. S. Przhiyalgovskii A. V. Poleshchuk E. V. Lavrushina 《Lithology and Mineral Resources》2014,49(1):81-102
Disintegrated granitoids, which frequently enclose abundant clastic material of the same rocks, are widespread in the upper parts of the Earth’s crust. They occur both on the surface and under the thick sedimentary cover. Two processes are responsible for the formation of such rocks: supergenic (chemical and physical weathering) and tectonic (prototectonics and posthumous disintegration). These processes result in the formation of similar (in compositions, textures, and attitude) clastic rocks, which complicates the interpretation of their genesis in particular situations. In this work, we discuss processes of the exogenic and tectonic disintegration of granitoids, structure of disintegrated rocks, and mineral transformations. Typomorphic features of the disintegrated granitoids related to tectonic and exogenic processes are compared. 相似文献
5.
A structural–geological study has been performed on the northern slope of the Kyrgyz Ala-Too Range. Deformations of the peneplaned Paleozoic basement surface, structures of granite disintegration, and morphostructural manifestation of Late Cenozoic tectonic movements have been investigated. Based on the location of pre-Paleocene peneplain remnants with the retained weathering mantle partly overlapped by Paleocene–Miocene sedimentary complexes, we have reconstructed the morphology of the folded surface of the Chunkurchak Trough separated from the Chu Basin at the early Miocene. The dome–fold forms, the morphology and arrangement of which are controlled by disintegration of the basement, have been described for the basement surface. It has been established that granites are broken by systems of steeply dipping, fanshaped, and gently dipping faults and fractures. Variously oriented insignificant offsets along slickensides, as well as displacements deduced from the geometry of fracture intersections, are a result of volumetric cataclastic flow of rocks. The tectonic mobility of disintegrated granites, which are abundant in the Paleozoic–Precambrian basement, explains the complexity and scale of tectonic processes initiated by Cenozoic activation. In paleotectonic reconstructions, which take into consideration tectonic flow and the redistribution of basement masses, the estimates of Cenozoic relative rapprochement of the Chu Basin and the Kyrgyz Ala-Too Range decrease substantially to 4–6 km. 相似文献
6.
Complex geological and geophysical data obtained during recent research by the Marine Arctic Geological Survey Expedition
OJSC (MAGSE) indicate that the Riphean Chapoma graben located on the southeastern shore of the Kola Peninsula has its extension
under the Gorlo Strait of the White Sea water area and joins the Leshukonsk riftogenous graben as an extended narrow trench
in the crystal foundation of the platform. From this it follows that the Chapoma graben is the central segment of the White
Sea paleorift system. Only the northwestern edge and probably the upper part of the graben section outcrop on the Kola Peninsula,
which represents a highly elevated block of the platform foundation. To emphasize the unity of this paleorift zone, it makes
sense to call it the Chapomo-Leshukonsk Paleorift in contrast to the traditional name Kerets-Leshukonsk. The echelon position of the riftogenous troughs of the Chapomo-Leshukonsk paleorift, the form itself of the Leshukonsk and
Azopolsk troughs being close to pull-apart assumes their occurrence and development under transtension conditions with elements
of the right-side shear along the steep northeastern edges of the grabens. 相似文献
7.
M. G. Leonov Yu. G. Tsekhovskii E. S. Przhiyalgovskii A. V. Poleshchuk E. V. Lavrushina 《Lithology and Mineral Resources》2014,49(2):184-200
Clastogenic rocks spatially associated with granite massifs have been reported in the geological literature from different regions: Caucasus (Leonov, 1974, 1991), Urals (Puchkov, 1968), Kazakhstan (Svarichevskaya and Skublova, 1973), Transbaikal region (Leonov, 2008; Lobanov et al., 1991), Tien Shan (Leonov et al., 2008), North America (Beroush, 1991; Lukin, 1989, 2007; Pippin, 1973). In some places, they represent crushed rocks of indigenous massifs. In other places, they make up accumulations and aprons of clastic products of the granitic composition both on the surface and beneath the sedimentary cover. In the first communication (Leonov et al., 2014) devoted to the origin of granite clastites, we examined specific features of the structure and evolution of granite bodies at the posthumous development stage, i.e., after cooling and introduction into the consolidated layer of the Earth’s crust. It was shown that such rocks are formed at least due to two main processes: supergene1 (chemical and physical weathering) and tectonic (prototectonics and posthumous disintegration). Although the rocks are highly similar in composition, structure, and bedding conditions, they are marked by several specific features described in the first communication that provide insight into their genetic nature. However, the problem of morphostructural characteristics and genetic interpretation of granite clastites cannot be closed here. Reconstruction of the “primary” origin of clastic granitic bodies in some, far from single, cases is complicated by the following fact: the exhumed massifs of tectonically disintegrated granitoids undergo supergene transformations, while sediments in the weathering crust are involved in tectonic reworking. Thus, clastites can be formed in several stages with different successions of events: supergene processes (formation of the weathering crust) can precede the tectonic reworking of rocks or succeed the formation of tectonomixtites. Determination of diagnostic properties of genetically different clastic rocks and stages of their lithostructural alteration is important for solving the issues of regional geology, development of methods for the study of genetically complex sequences, as well as paleogeographic and paleotectonic reconstructions. This problem acquires a specific importance because of two circumstances: first, its solution is at the intersection of two geological disciplines (lithology and tectonics); second, granitic clastite bodies often represent commercial hydrocarbon reservoirs (Areshev et al., 1997; Gavrilov, 2000; Izotov et al., 2003; Lobanov et al., 1991; Lobusev et al., 2002; Lukin, 2007; Martynova, 2002; Pippin, 1973; Sitdikova and Izotov, 2002). Let us discuss two scenarios of the succession of events: scenario 1—“tectonic mixtite” → “supergene reworking”; scenario 2—“weathering crust” → “tectonic reworking”. All other versions are combinations of these two types. 相似文献
8.
Baluev A. S. Moralev V. M. Przhiyalgovskii E. S. Terekhov E. N. Sukach V. S. 《Lithology and Mineral Resources》2003,38(4):350-360
The southeastern coast of the White Sea and Kii Island incorporates outcrops of conglomerate-type rocks similar to boulder dikes filling tensile fractures in the early Precambrian basement of the platform. They are related to the southwestern flank of the Onega Graben representing the southeastern segment of the Onega–Kandalaksha paleorift. Genesis of these conglomerate-type rocks, previously considered sedimentary ones, is problematic. Special study of the cement of these rocks revealed that it has probably an endogenic nature. It is dominated by carbonate material replacing ultramafic volcanic glass. Carbonatization and analcime mineralization took place at the regressive stage of cement formation within a temperature range of 450–550°C with active release of H2O- and CO2-saturated fluids. Data on the isotopic composition (13C and 18O) for carbonate material of cement from the brecciated rocks testify that the carbonatization was related to input of deep-seated carbon dioxide under subsurface environment. The studies carried out allow us to suppose that these rocks were formed as a result of consolidation of solid–gaseous suspensions inside fractures in the crystalline basement. Penetration of fluidized material along them produced dike-shaped bodies. Such rocks are recently called fluidizates. The sources of solid–gaseous suspension fluxes were basic magmas with a high content of volatiles. Discharge of gases from the magmas was caused by their decompression due to the appearance of tensile zones in lithosphere during rifting. 相似文献
9.
A. K. Rybin M. G. Leonov E. S. Przhiyalgovskii V. Yu. Batalev E. A. Bataleva V. D. Bragin Yu. A. Morozov G. G. Schelochkov 《Doklady Earth Sciences》2016,470(1):968-971
We studied the infrastructure of granite massifs of the Central Tien Shan and its correlation with the electric conductive layer of the upper crust, which made possible to reveal new peculiarities of the structure of the granite layer in the region and to clarify the nature of low resistivity layers. 相似文献
10.
Leonov M. G. Morozov Yu. A. Przhiyalgovskii E. S. Rybin A. K. Bakeev R. A. Lavrushina E. V. Stefanov Yu. P. 《Geotectonics》2020,54(2):147-172
Geotectonics - The article provides geological data on the morphostructural differentiation of sedimentary basins and the results of tectonophysical and digital modeling reflecting the shape and... 相似文献