Terrigenous formation of the Upper Triassic of the west of the Scythian platform

Popkov, V. I.; Попков, И.В.; Pinchuk, T. N.; Rulevskiy, Victor

doi:10.54398/2077-6322_2022_1_9

Cited by 1 publication

(5 citation statements)

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“…The absolute age of phyllitic schists recovered from a depth interval of 1646-1650 m of the Kumsebshen borehole is 262 Ma (Early Permian). These units are clearly correlated with the lower molasse complex of Upper Carboniferous-Lower Permian age, which was found in the Cape Rakushechny area and within the Zhetybai-Uzen' Zone of the South Mangyshlak geoblock [22]; in addition, based on the data from the boreholes presented above, these units are also present in the northwestern Kara-Bogaz Arch.…”

Section: Tectonics and Composition Of Rocks From Boreholes Drilled In...mentioning

confidence: 54%

“…These rocks are similar in composition to Upper Paleozoic sediments from the Cape Peschany-Rakushechnaya Zone of the South Mangyshlak geoblock, which, in our opinion, belong to Upper Paleozoic lower molasse [20,22]. The overlying Middle Jurassic continental sequences underwent much less secondary alteration, corresponding to the initial stages of catagenesis.…”

Section: Tectonics and Composition Of Rocks From Boreholes Drilled In...mentioning

confidence: 64%

“…Nevertheless, the local increase in the degree of metamorphic alteration in rocks may be related to the proximity of intrusive bodies; as a result, contact thermal metamorphism has overprinted regional metamorphism, and this is quite normal. As an example, we can mention the Oimasha area of the South Mangyshlak geoblock: here, a granitic intrusive body and host metamorphic rocks were recovered in multi-ple boreholes with a high core removal rate [22,24]. However, the degree of metamorphism is a relative parameter of the age of rocks, as indicated, in particular, by researchers who suggested the Precambrian age of the discussed rocks [8].…”

Section: Discussionmentioning

confidence: 99%

“…Recent research has revealed the broad distribution of Precambrian rocks within the terranes comprising the Phanerozoic fold belts in Europe, as borehole as in the southern and southeastern frames of the East European Platform (including the Scythian and Turan plates). It is believed that these terranes are fragments of the northern Late Neoproterozoic-Cambrian margin of the Gondwana paleocontinent (peri-Gondwanan terranes) [11,25,27,30,38], and this viewpoint has been reflected in many tectonic and palinspastic reconstructions [8,13,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

“…Our previous studies dealt with the South Mangyshlak geoblock, where the basement was penetrated by more than 150 boreholes within 29 survey areas [22]. Studies of the material composition of basement rocks showed that the South Mangyshlak geoblock is composed of relatively weakly metamorphosed terrigenous units, intruded by Carboniferous granitoids within highs.…”

Section: Introductionmentioning

confidence: 99%

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Tectonics of the Basement of the Kara-Bogaz Arch (Turan Plate)

Popkov

Попков

2022

Geotecton.

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The Kara-Bogaz geoblock is interpreted by many researchers as a structure underlain by the Precambrian sialic crust, incorporated in the young (epi-Hercynian) Turan Plate. The paper presents the results of a detailed study of the material composition of igneous and metamorphic rocks making up the basement of the Kara-Bogaz Arch and recovered by deep boreholes. To subdivide and correlate the sections, we employed data of geophysical borehole surveys, including all types of logging. Microscopic examination of rocks was also performed to determine their composition, genesis, and degree of postsedimentation alterations. Data on absolute ages of rocks and paleontological data were also employed. The results of the work of our predecessors have been studied and critically analyzed. It is established that there are no direct indications of the continental crust older than Paleozoic in the basement of the Near-Kara-Bogaz region. The metamorphic units of the Kara-Bogaz Arch are represented by primary sedimentary and volcanosedimentary deposits that were altered at the stage of regional greenschist metamorphism. These rocks are intruded by granitoid bodies corresponding to the final stages of Hercynian tectogenesis. In parts spatially close to intrusions, the degree of secondary alterations in metamorphic rocks increases due to the thermal effect. Amphibolites of the Kara-Bogaz Arch are metamorphosed igneous rocks, which are closely associated with primary terrigenous deposits and have undergone subsequent metamorphosis (greenschist facies regional metamorphism). Gneisses of the discussed region refer to the marginal facies of granitoid plutons that formed as a result of metasomatic reworking of the host strata (protomagmatic gneissic banding). We think that the Kara-Bogaz Arch is a Hercynian megaanticlinorium of the young platform, and this does not exclude the possibility of fragments of more ancient crust in the structure of this arch. The sedimentary–metamorphic and volcanosedimentary rocks making it up and intruded by multiple granitoid bodies are units of the active margin.

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Section: Tectonics and Composition Of Rocks From Boreholes Drilled In...mentioning

confidence: 54%

Section: Tectonics and Composition Of Rocks From Boreholes Drilled In...mentioning

confidence: 64%