The junction of the eastern Central Asian Fold Belt and the Siberian Platform: deep structure and Mesozoic tectonics and geodynamics (original) (raw)
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Late Paleozoic faults of the Altai region, Central Asia: tectonic pattern and model of formation
Journal of Asian Earth Sciences, 2004
The present kinematic and dynamic analysis of large-scale strike-slip faults, which enabled the formation of a collage of Altai terranes as a result of two collisional events. The Late Devonian-Early Carboniferous collision of the Gondwana-derived Altai-Mongolian terrane and the Siberian continent resulted in the formation of the Charysh-Terekta system of dextral strike-slip faults and later the Kurai and Kuznetsk-Teletsk-Bashkauss sinistral strike-slip faults. The Late Carboniferous-Permian collision of the Siberian and Kazakhstan continents resulted in the formation of the Chara, Irtysh and NorthEast sinistral strike-slip zones. The age of deformation of both collisional events becomes younger toward the inner areas of the Siberian continent. In the same direction the amount of displacement of strike-slip faulting decreases from several thousand to several hundred kilometers. The width of the Late Paleozoic zone of deformation reaches 1500 km. These events deformed the accretion-collision continental margins and their primary paleogeographic pattern.
Russian Geology and Geophysics, 2011
According to the new geological, geochronological, and structural data, the Tunka bald mountains (East Sayan) have a nappe structure, which formed in the Late Carboniferous-Early Permian. The deformations have been dated by the 40 Ar-39 Ar method on the basis of syntectonic micas and amphiboles, whose structural and spatial positions have been determined in oriented thin sections. The geometrical analysis of macro-and microstructures has revealed three development stages of the structures, which followed one another in progressive deformation. The first (thrust-fault) stage (316-310 Ma) comprised a group of N-verging thrust sheets. In the second (fold deformation) stage (305-303 Ma), they were folded. The third (strike-slip fault) stage (286 Ma) comprised high-angle shears, along which V-shaped blocks were squeezed westward from the most compressed areas. All the structures developed under near-N-S-trending compression. The thrusting in the Tunka bald mountains was coeval with the major shear structures in the eastern Central Asian Fold Belt (Main Sayan Fault; Kurai, Northeastern, and Irtysh crumpled zones, etc.). Also, it was simultaneous with the formation of continental-margin calc-alkalic and shoshonite series (305-278 Ma) as well as that of the alkali and alkali-feldspar syenites and granites (281-278 Ma) of the Tarim mantle plume in the Angara-Vitim pluton, located near and east of the studied region. Thus, the simultaneous development of the Late Paleozoic structures, active-margin structures, and plume magmatism in southern Siberia might have resulted from the global geodynamic events caused by the interaction between the tectonic plates which formed the Central Asian Fold Belt. (M.M. Buslov) Fig. 1. Geologic structure of the Arshan area (A) and its location in the southern framing of the Siberian Platform (B). A, 1, Quaternary sediments; 2, gneisses, mafic granulites, garnet amphibolites; 3, mélange zone with diaphthorized plagiogneisses, mafic granulites, garnet amphibolites, and mylonitized marbles; 4, mylonitized marbles with bodies of garnet-biotite blastomylonites, actual (a) and presumed (b); 5, greenschists; 6, Late Devonian-Early Carboniferous molasse (Sagan-Sair Formation); 7, Late Devonian microcline granites and granosyenites; 8, ruptures with inclined (a) and steep (b) fault planes; 9, stratigraphic contact; 10, sampling sites and results of Ar-Ar dating. B,
Russian Journal of Earth Sciences, 2002
The Paleozoic fold-and-thrust belt, confined between the European, Siberian, Tarim, and North China Precambrian continents, results from a complex evolution of the Paleo-Asian Ocean. At the end of the Ordovician, the Kazakhstan-Kyrghyz continent, originating from the accretion of island arcs and Gondwanan continental fragments, divided the Paleo-Asian Ocean into four oceanic basins, Uralian, Turkestan, Junggar-Balkhash, and Ob-Zaisan. The Middle to Late Paleozoic history of these oceanic basins, which closed completely in the terminal Carboniferous to Permian, is portrayed in eight detailed, 1:10,000,000 scale, palinspastic reconstructions for the Early Silurian (430 Ma), Early Devonian (Emsian, 390 Ma), Middle Devonian (Givetian, 380 Ma), Late Devonian (Famennian, 360 Ma), Early Carboniferous (late Visean to Serpukhovian, 330 Ma), early Late Carboniferous (305 Ma), Early Permian (280 Ma), and Late Permian (255 Ma) time slices. These reconstructions draw on 1:2,500,000 scale sedimentologic-paleogeographic maps and paleomagnetic measurements from ancient continents and Variscan orogenic zones of the Urals, Kazakhstan, Tien Shan, Junggaria, and Altay. The shrinking and collision-induced closure of the oceans were ensured by the three large and long-lived (100-130 m.y.) Urals-Tien Shan, Junggar, and Siberian subduction belts, spanning thousands of kilometers, whose polarities remained stable. The belts were represented by systems of roughly parallel and branching subduction zones, each with a 10-30 m.y. lifespan, plunging beneath the Kazakhstan-Kyrghyz and Siberian continents. Taken together, they constituted a system that diverged in a southwesterly direction and ensured differential rotations of the European, Siberian, and Kazakhstan-Kyrghyz continents. The Urals-Turkestan belt began to form at the beginning of the Silurian, and the Siberian and Junggar belts, at the beginning of the Devonian. The subduction belts ceased to exist as they were crushed between continents during a general collision that set on in the second half of the Devonian and in which the Junggar belt became involved prior to the beginning of the Permian. Geologic and paleomagnetic evidence points to oblique motions of oceanic plates being consumed in the subduction belts and, accordingly, to an oblique collision in the Urals and South Tien Shan foldbelts that propagated through time and space to finally give rise to large-scale post-collisional lengthwise strike slips. We believe the subduction belts to be surface manifestations of descending mantle convection flows that drove the long-lasting sinking of oceanic plates into the mantle.
Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence
Gondwana Research, 2010
This paper presents paleomagnetic data for Late Mesozoic (Middle Jurassic to end-Cretaceous) rocks of the Siberian platform (Verkhoyansk Trough) and its southwestern margin (Transbaikalian basins and Minusa Trough). We determine a series of key paleomagnetic poles for 165, 155, 135, 120, and 75 Ma, which define the Mesozoic apparent polar wander path (APWP) for Siberia. This quantitative approach provides the opportunity for a general revision of Mesozoic tectonics of Central Asia. Many researchers have considered the Eurasian continent to have been completely stable during the Mesozoic era. However, we demonstrate systematic deviations of corresponding Mesozoic poles from Siberia and Europe, and interpret the discrepancies as evidence for large-scale sinistral strike-slip motion due to clockwise rotation of the Siberian plate relative to the European plate. We conclude that, following its Late Paleozoic assembly, the Eurasian plate was not internally stable, i.e. not rigid. The Mesozoic geological evolution of Siberia was dominated by strike-slip tectonics. Rift-related grabens formed within the basement of the West Siberia sedimentary basin and orogenic events occurred along the southwestern margin of the Siberian craton, within the Central Asia tectonic province. Our paleomagnetic reconstruction indicates also that the Mongol-Okhotsk Ocean was still not closed completely before the end of the Jurassic. We propose that final collision occurred in the Early Cretaceous, and during the Middle to Late Jurassic interval, northward subduction of oceanic lithosphere resulted in oblique, west-to-east ocean closure (a "scissors-like" model). The closure was controlled by significant sinistral strike-slip motion of the Siberian craton. This process is reflected in Transbaikalia by extensive bimodal volcanic activity and development of rift-related structures, including pull-apart basins.
Basin evolution in a folding lithosphere: Altai–Sayan and Tien Shan belts in Central Asia
Tectonophysics, 2013
Central Asia is a classical example for continental lithospheric folding. In particular, the Altay-Sayan belt in South-Siberia and the Kyrgyz Tien Shan display a special mode of lithospheric deformation, involving decoupled lithospheric mantle folding and upper crustal folding and faulting. Both areas have a heterogenous crust with a long history of accretion-collision, subsequently reactivated as a far-field effect of the Indian-Eurasian collision. Thanks to the youthfulness of the tectonic deformation in this region (peak deformation in late Pliocene-early Pleistocene), the surface expression of lithospheric deformation is well documented by the surface topography and superficial tectonic structures. A review of the paleostress data and tectonostratigraphic evolution of the Kurai-Chuya basin in Siberian Altai, Zaisan basin in Kazakh South Altai and Issyk-Kul basin in Kyrgyz Tien Shan suggests that they were initiated in an extensional context and inverted by a combination of fault-controlled deformation and flexural folding. In these basins, fault-controlled deformation alone appears largely insufficient to explain their architecture. Lithospheric buckling inducing surface tilting, uplift and subsidence also played an important role. They form typical basins in a folding lithosphere (FLB). Their characteristic basin fill and symmetry, inner structure, folding wavelength and amplitude, thermal regime, time frame are examined in relation to basement structure, stress field, strain rate, timing of deformation, and compared to existing modelling results.
International Geology Review, 1996
This paper reviews and integrates new results on: (I) the Late Paleozoic and Mesozoic evolution of Central Asia; (2) Cenozoic mountain building and intramontane basin formation in the Altay-Sayan area; (3) comparison of the tectonic evolutionary paths of the Altay, Baikal, and Tien Shan regions; (4) Cenozoic tectonics and mantle-plume magmatic activity; and (5) the geodynamics and tectonic evolution of Central Asia as a function of the India-Himalaya collision. It provides a new and more complete scenario for the formation of the Central Asian intracontinental mountain belt, compared with the generally accepted model of the "indenta tion" of the Indian plate into the Eurasian plate. The new model is based on the hypothesis of a complex interaction of lithospheric plates and mantle-plume magmatism. Compilation and comparison of new and published structural, geomorphological, paleomagnetic, isotopic, fission-track, and plume magmatism data from the Baikal area, the Altay, Mongolia, Tien Shan, Pamir, and Tibet show that the main stages of their orogenic evolution and basin sedimentation are closely related in time and space. After a long period of tectonic quiescence and peneplana tion, Central and Southeast Asia were strongly affected by India-Eurasia collisional tectonics. During the first collisional stage (60 to 35 Ma), a first series of high mountains formed in the Himalayas, southern Tibet, and, possibly, the southern Tien Shan. Eocene deposits, younging northward, formed coevally with the orogeny in the near-Himalaya trough, Tarim, Tajik depression, and Fergana Basin. During post-collisional convergence, new depressions formed over wide territories, from the Tarim to Baikal and Altay areas. However, intensification of the deformation and uplift later were propagated northward, with development of the Qinghai Tibetan Plateau (20 to 12 Ma), Tien Shan mountains (18 to 11 Ma), Junggar mountains and depression (8 to 5 Ma), and Altay, Baikal, and Transbaikal depressions and mountains (3 Ma).
Russian Geology and Geophysics, 2013
The interplay of geodynamic and sedimentation processes in the Central Asian orogen and the Siberian craton is discussed in several aspects: (i) general tectonics of the Central Asian orogen, (ii) correlation of deposition and collision events, (iii) deposition history and sediment sources on the northern and eastern margins of the Siberian craton, compared, and (iv) history of the Central Asian orogen (Altaids) and formation of Early Mesozoic sedimentary basins.
Terra Nova, 2011
New geochronological data [zircon U ⁄ Pb, titanite fission-track (TFT) and apatite fission-track (AFT) dating and apatite (U-Th-Sm) ⁄ He thermochronology] and thermal history modelling yield constraints on the development of the granitoid basement of the Kuznetsk-Alatau Mountains, southern Siberia. The final stages of magmatism in the Kuznetsk-Alatau palaeo-island-arc are Late Cambrian, and collision of the arc with Siberia occurred in the Early Ordovician. The basement was exhumed by the Early Devonian. Continuous Devonian-Early Triassic sedimenta-tion filled the adjoining Kuznetsk and Minusa basins and buried (and re-heated) the Kuznetsk-Alatau basement. After initial Pangaea break-up and Siberian flood-basalt magmatism, the basement reached TFT and AFT retention-temperatures in the Middle Triassic and Early Cretaceous, respectively, during denudation-induced cooling.
Russian Geology and Geophysics, 2016
There are continuing issues concerning the formation and reconstruction of the geographic position of the Neoproterozoic Yenisei Ridge—a key element of the western framing of the Siberian craton and the Central Asian orogenic belt. This study focuses on the inner structure, composition, and boundaries of the Central Angara terrane, which is the largest in the Transangarian segment of the Yenisei Ridge. We propose a scheme of fault deformation of the region and demonstrate that the fault tectonics of the Central Angara terrane is distinct from that of adjacent terranes. We study in detail the Yeruda pluton granitoids of the Teya complex, which indicate accretionary-collisional magmatic events in this terrane prior to its collision with Siberia. New geochemistry and SHRIMP U–Th–Pb zircon geochronology of the granites indicate that they formed at 880–860 Ma in a collisional setting. Integrated petromagnetic and paleomagnetic investigations yield a paleomagnetic pole that is significant...