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1.
The crustal architecture of the Southern Urals is dominated by an orogenic wedge thrusted westward upon the subducted East European continental margin. The N–S trending wedge constitutes an antiformal stack composed mainly of the high-P Maksyutov Complex, the overlying Suvanyak Complex and the allochthonous synformal Zilair flysch further west. These tectono-metamorphic units are separated by tectonic contacts and record discontinously decreasing metamorphic conditions from bottom to top. In the east, the E-dipping Main Uralian Normal Fault cross-cuts the metamorphic footwall and juxtaposes the non metamorphic Magnitogorsk island arc. This syncollisional normal fault compensated crustal thickening and exhumation of the high-P rocks. Orogenic shortening was accommodated by the Main Uralian Thrust, a W-vergent crustal-scale shear zone at the base of the wedge. Geological investigations and reflection seismics (URSEIS '95) argue in favour of a geodynamic evolution integrating subduction and basal accretion of high-P rocks during sinistral oblique thrusting along the Main Uralian Thrust and coeval normal-faulting along the Main Uralian Normal Fault. 相似文献
2.
In the Middle Urals, volcanic-arc and back-arc basin rocks of Ordovician to Devonian age occur in the Tagil Synform. These outboard terranes were thrust westwards in the late Carboniferous onto continental margin associations of late Proterozoic and Palaeozoic age, now exposed in the Central Uralian Uplift. The Main Uralian Fault coincides approximately with the suture separating the outboard terranes from the East European Platform margin. New fieldwork in the hinterland of the Middle Urals in the area east of the Tagil Synform has found structural evidence favouring E-directed thrusting of accreted terranes and eugeoclinal allochthons in the late Palaeozoic. The upper tectonic units are composed of ophiolite mélange and volcano-sedimentary rocks of Ordovician to Devonian age; they are thrust onto high-grade gneisses, some of possible microcontinental affinities, extensively intruded by mid-Palaeozoic granitic plutons. The nappes in the hinterland are refolded by major upright antiforms and synforms that fold the entire tectonostratigraphy. After thrust assembly, all tectonic units east of the Main Uralian Fault were intruded by late Carboniferous to early Permian granites. Reflection seismic profiles (recorded to 8 s TWT), recently reprocessed at Cornell University, image the major fold structures and demonstrate that they are restricted to the upper crust, being underlain by an extensive zone of flat-lying middle crustal reflectivity. At 10–15 km depth the latter appears to truncate all structures, including the late- to post-tectonic granitoids and extensional faults, east of the Main Uralian Fault. Previous studies (potential-field, refraction- and wide-angle-reflection seismics) have identified an anomalously deep crust under the Tagil Synform and have concluded that the root zone of the orogen is located beneath this belt. The new evidence presented here supports this interpretation, with back-thrusting of the oceanic rocks eastwards over Palaeozoic accreted terranes. © 1998 John Wiley & Sons, Ltd. 相似文献
3.
受多期非均衡造山作用以及多构造体制的叠加,东秦岭-大别造山带北侧中新生代发生差异构造变形.基于区域构造动力学机制,将中新生代构造变形分为4个期次:印支期(T2-T3)、早燕山期(J1)、中燕山期(J2-K1)和晚燕山-早喜马拉雅期(K2-E).通过野外地质剖面和地震剖面的构造解析,认为印支期-中燕山期主体变形方式为逆冲... 相似文献
4.
A. F. M. Kisters F. M. Meyer I. B. Seravkin S. E. Znamensky A. M. Kosarev R. G. W. Ertl 《International Journal of Earth Sciences》1999,87(4):603-616
The late-Paleozoic Uralides represent one of the largest lode-gold metallogenic provinces in the world. In the southern Urals, gold distribution is heterogeneous and is confined mainly to two tectonostratigraphic zones, namely the Main Uralian fault and the East Uralian zone. The important lode-gold districts within and in the immediate hangingwall of the first-order crustal suture of the Main Uralian fault are characterized by a complex tectonic history of earlier compressional tectonics involving thrusting, folding and reverse faulting and later transcurrent shearing. Gold mineralization is hosted by second- and third-order brittle to brittle–ductile strike-slip faults that developed late during the kinematic history of the Main Uralian fault. Strike-slip reactivation of earlier compressional structures was related to the late-stage docking of the passive margin of the East European platform with island-arc complexes of the southern Urals, an event that is tentatively related to changes in plate motion during the final stages of terrane accretion during the upper Permian and lower Triassic. Gold mineralization was controlled by the permeability characteristics of the hydrothermal conduits, as well as by competence contrasts and geochemistry of the mainly volcanic host rocks. Mineralization occurred at relatively shallow crustal levels (2–6 km) and largely post dates peak-metamorphism of the host rocks. The large and very large (up to 300 to Au) gold deposits of the East Uralian zone are hosted by upper-Paleozoic granitoid massifs. Gold mineralization is temporally associated with the main phase of regional-scale compressional tectonics and granite plutonism during the upper Carboniferous and lower Permian. Controlling structures have a dominantly east–west strike and occur as hybrid shear-tensional vein systems in competent granitoids subjected to east/west-directed regional shortening. Deformation textures and alteration mineral assemblages indicate lower-amphibolite-facies conditions of mineralization close to peak metamorphic conditions that are associated with the mid-Permian regional metamorphism and tectonism. Gold deposits in the southern Urals are, therefore, polygenetic and are temporally and genetically distinct in each of the two major mineralized tectonostratigraphic zones of this well-preserved collisional orogenic belt. The different timing of ore fluid generation and fluid discharge is interpreted to be the result of the different tectonic, metamorphic and magmatic evolution of terranes in the southern Urals. 相似文献
5.
J. von Raumer G. Stampfli G. Borel F. Bussy 《International Journal of Earth Sciences》2002,91(1):35-52
Pre-Variscan basement elements of Central Europe appear in polymetamorphic domains juxtaposed through Variscan and/or Alpine tectonic events. Consequently, nomenclatures and zonations applied to Variscan and Alpine structures, respectively, cannot be valid for pre-Variscan structures. Comparing pre-Variscan relics hidden in the Variscan basement areas of Central Europe, the Alps included, large parallels between the evolution of basement areas of future Avalonia and its former peri-Gondwanan eastern prolongations (e.g. Cadomia, Intra-Alpine Terrane) become evident. Their plate-tectonic evolution from the Late Proterozoic to the Late Ordovician is interpreted as a continuous Gondwana-directed evolution. Cadomian basement, late Cadomian granitoids, late Proterozoic detrital sediments and active margin settings characterize the pre-Cambrian evolution of most of the Gondwana-derived microcontinental pieces. Also the Rheic ocean, separating Avalonia from Gondwana, should have had, at its early stages, a lateral continuation in the former eastern prolongation of peri-Gondwanan microcontinents (e.g. Cadomia, Intra-Alpine Terrane). Subduction of oceanic ridge (Proto-Tethys) triggered the break-off of Avalonia, whereas in the eastern prolongation, the presence of the ridge may have triggered the amalgamation of volcanic arcs and continental ribbons with Gondwana (Ordovician orogenic event). Renewed Gondwana-directed subduction led to the opening of Palaeo-Tethys. 相似文献
6.
E. N. Gorozhanina V. M. Gorozhanin T. N. Isakova 《Stratigraphy and Geological Correlation》2018,26(2):139-156
In the conjunction zone of the East European Platform and the Uralian foredeep, involved in structures of the Southern Urals (Bashkiria), sediments deposited at the shelf zone edge in the Late Carboniferous–Early Permian crop out. The Upper Carboniferous bioherm and Lower Permian deep marine–shelf boundary limestones, composing Voskresenka Mount near Tabynsk township, were studied. Results of the complex analysis of lithofacies, paleontological, structural, and also geological and geophysical data show that the Voskresenka carbonate massif, previously attributed to a single reef structure, represents the SW-dipping tectonic horst block, composed of Upper Carboniferous shelf–bioherm limestones, which is uplifted in a near break zone. As a result of tectonic processes, the edge of the late Carboniferous carbonate platform, overlain by Asselian deep-water sediments, was exhumed. The sedimentary succession shows that the paleogeographic setting at the margin of the East European Craton changed at the Carboniferous–Permian boundary during the formation of the Ural collisional orogen. 相似文献
7.
《International Geology Review》2012,54(5):452-472
The southern Pre-Uralian Foredeep and the northeastern Pre-Caspian Basin of southern Russia and Kazakhstan are at the juncture of two major oil-producing regions, the Volga-Ural Basin and the new fields of the Northern Caspian Basin (e.g., Tengiz). The southern Pre-Uralian Foredeep has produced little oil; nevertheless, the Permian-Carboniferous stratigraphy and the general fold-thrust structure of the Pre- Uralian Foredeep, and adjacent Pre-Caspian Basin, afford the possibility for classic and largely untested sub-salt and sub-thrust plays. Prior to the onset of Uralian orogenic activity, Late Devonian-Early Carboniferous rifting disrupted the East European continent, forming a series of rift basins including the Kama-Kinel troughs and the Pre- Caspian Basin. The Middle Carboniferous to Early-Middle Triassic Uralian Orogenic Belt consists of a complicated series of lower Paleozoic continental margin sequences, basement nappes, and accreted terranes, structurally interleaved via large-scale folding and thrusting. The orogen formed as a result of a progressive series of collisions between the East European continent and microcontinental plates and island arcs (the Tagil-Magnitogorsk and Eastern Uralian megazones), and the Kazakhstan and Siberian continents. N-S and W-E divisions of the Uralian Orogenic Belt and Pre-Uralian Foredeep reflect the basic tectonic structure of the orogen. The Pre-Uralian Foredeep is not a simple flexural foreland basin, but the exact structural configuration is unresolved. In general, the regional stratigraphy and structure of the foredeep is more complicated than depicted in the literature and on published maps; the biostratigraphy critically needs to be updated. The foredeep developed as a series of regional depressions with up to fourth-order sub-basins. Within these sub-basins, both tectonic and eustatic mechanisms appear to control the sequence stratigraphy. Because of the tectonic influence, subsurface correlation based on sequence stratigraphic concepts may be valid only within each sub-basin. In part, the present structure of the Pre-Uralian Foredeep may reflect the structurally controlled Permian-Carboniferous paleogeography. This complex paleogeography also suggests that application of a simple “balanced cross-section” methodology could lead to erroneous results. Also unresolved are the paleogeographic, stratigraphic, and structural relationships between the Pre- Caspian Basin and the Pre-Uralian Foredeep. 相似文献
8.
准噶尔盆地南缘山前冲断带经历了多期叠加构造活动,构造变形特征复杂,对研究陆内造山变形机制具有重要意义。阿什里背斜处于北天山后方前陆部位,构造样式为分层滑脱变形体系控制的复式叠加背斜,垂向上包括浅层薄皮推覆构造系统和中深层复合构造楔系统。钻井和地震反射信息揭示,阿什里地区主要滑脱层为基底滑脱层,石炭系、二叠系泥岩层,中下侏罗统八道湾组、西山窑组煤层。阿什里背斜侏罗系底部不整合面受基底发育的叠加构造楔(由2~3个冲断席构成)控制,反冲断层之上石炭系-三叠系构成不对称背斜。阿什里西南大型石炭系推覆体之下发育泥盆系-石炭系组成的冲断席,构成(楔端点向上方突破的)构造楔。阿什里背斜北侧以一向斜与喀拉扎背斜过渡,指示冲断位移沿浅部滑脱层向北继续传播。阿什里及邻区发育的石炭系与三叠系-中下侏罗统不整合、二叠系内部不整合、二叠系与三叠系削截不整合、三叠系与侏罗系不整合、新近系与第四系不整合揭示了中-晚二叠世以来多期构造活动。其中,阿1井核部二叠系梧桐沟组之下钻遇的凝灰岩锆石SHRIMP U-Pb同位素分析结果显示其年龄为289.1±7Ma(95%置信度),指示了晚海西期的构造活动。根据阿什里地区地震剖面的精细构造几何学、运动学解析,结合关键不整合面,划分了5个关键构造演化期次:中二叠世阿什里西南逆冲推覆形成古隆起;晚二叠世-晚三叠世阿什里地区存在两期小规模冲断活动;侏罗纪整体稳定沉降或弱坳陷;白垩纪-古近纪多幕隆升构造活动使阿什里地区沿基底发育叠加构造楔;中新世北天山剧烈造山活动中阿什里基底构造楔向北突破形成阿克屯-喀拉扎背斜。 相似文献
9.
塔里木盆地断裂构造分期差异活动及其变形机理 总被引：9，自引：3，他引：6
本文的目的是探讨塔里木盆地断裂构造分期差异活动过程及其变形机理.在地震剖面解释、钻井资料和地质资料综合分析的基础上,通过编制塔里木盆地不同时期断裂系统图,提出控制塔里木盆地断裂构造形成和演化主要构造活动期次为:加里东早期、加里东中期、加里东晚期-海西早期、海西晚期、印支期、燕山期和喜马拉雅期.加里东早期断裂活动受伸展环境制约,沿先存基底断裂带形成张性正断层.加里东中期、加里东晚期-海西早期断裂活动以逆冲作用为主,在塔东、塔中、塘古巴斯、巴楚和麦盖提地区最为发育.海西晚期断裂活动也是以逆冲作用为特征,并从早期断裂强烈活动的塔中、塘古巴斯、玛东等地区,迁移到塔北隆起和东部地区.印支、燕山和喜马拉雅期,前陆地区断裂构造发育,形成叠瓦冲断带、褶皱-冲断带、双重构造、盐相关构造等;但在盆内稳定区,断裂构造不发育,活动性弱.古生代断裂构造发育分布的控制机理,主要与区域大地构造环境的变化和构造转换、先存基底断裂带、大型区域性不整合、滑脱带等要素密切相关.区域大地构造环境的变化和构造转换主要受控于塔里木周缘洋盆的伸展裂解、俯冲消减和洋盆闭合的时限和强度.先存基底断裂带或基底构造软弱带往往控制着后期断裂的发育位置和展布方向.大型区域性不整合和滑脱带控制着断裂构造的发育和分布层位.中、新生代断裂构造发育分布的控制机理,与区域大地构造环境及其构造转换、区域构造位置有关.中、新生代塔里木断裂构造主要分为三种环境,即前陆构造环境、盆内稳定区构造环境和隆升剥蚀区构造环境.盆内稳定区断裂构造不发育,活动性较弱.中、新生代断裂构造主体发育在前陆构造环境中,主要受控于周缘造山带强烈隆升、挤压冲断、走滑-逆冲或逆冲-走滑作用,同时与喜马拉雅晚期盆-山耦合作用及滑脱层的发育有关. 相似文献
10.
R. Hetzel 《International Journal of Earth Sciences》1999,87(4):577-588
The high-pressure/low-temperature Maksyutov Complex is situated in the southern Urals between the Silurian/Devonian Magnitogorsk island arc and the East European Platform. The elongated N-S-trending complex is made up of two contrasting tectono-metamorphic units. Unit 1 consists of a thick pile of Proterozoic clastic sediments suggested to represent the passive margin of the East European Platform. The overlying unit 2, composed of Paleozoic sediments, volcanic rocks, and a serpentinite mélange with rodingites, is interpreted as a remnant of the Uralian Paleo-ocean. Devonian eastward subduction of oceanic crust beneath the Magnitogorsk island arc resulted in an incipient blueschist-facies metamorphism of unit 2 indicated by lawsonite pseudomorphs in the rodingites. While unit 2 was accreted to the upper plate, subduction of the continental passive margin caused the high-pressure metamorphism of unit 1. Buoyancy-driven exhumation of unit 1 into the forearc region led to its juxtaposition with unit 2 along a retrograde top-to-the-ENE shear zone. Further exhumation of the Maksyutov Complex into its present tectonic position was accomplished by later shear zones that were active as normal faults and are exposed along the margins of the complex. At the western margin a top-to-the-west shear zone juxtaposed a low-grade remnant of a Paleozoic accretionary prism (Suvanyak Complex) above the Maksyutov Complex. Along the eastern margin a top-to-the-east shear zone and the brittle Main Uralian Normal Fault emplaced the Maksyutov Complex against the Magnitogorsk island arc in the hanging wall. 相似文献
11.
晚中生代东亚多板块汇聚与大陆构造体系的发展 总被引：4，自引：4，他引：0
东亚大陆原型形成于三叠纪印支造山运动旋回,其周邻环绕的三大洋（古太平洋、蒙古-鄂霍茨克洋、中特提斯洋）于早侏罗世初期几乎同时向东亚大陆俯冲,开启了东亚多板块汇聚历史。文章通过总结东亚大陆晚中生代构造变形和构造岩浆事件的新近研究成果,简述了东亚多板块汇聚产生的三个陆缘汇聚构造系统（北部蒙古-鄂霍次克碰撞造山带、东部与俯冲有关的增生造山系统、西南部班公湖-怒江缝合构造带）、陆内汇聚构造变形体系和大陆伸展构造体系。在此基础上,重新构建了东亚多板块汇聚大陆构造-岩浆演化的时间框架,将其划分为三个阶段:早侏罗世（200~170 Ma）周邻大洋板块初始俯冲阶段和陆缘裂解事件,中晚侏罗世-早白垩世早期（170~135 Ma）周邻陆缘碰撞造山或俯冲增生造山作用、陆内再生造山作用和汇聚构造体系的形成;中晚白垩世（135~80 Ma）大陆岩石圈的减薄作用和大陆伸展构造体系的发育。研究认为,晚中生代东亚多板块汇聚在时空上的有序演化和深浅构造的复合叠加,不仅产生了东亚大陆复杂的陆缘和陆内构造体系,同时控制了中国东部燕山期爆发式岩浆-成矿作用,也使东亚构造地貌发生东西翘变,早期陆缘汇聚产生的东部高原因晚期大陆岩石圈的减薄和伸展而垮塌。东亚大陆构造体系的形成和演化与联合古大陆的裂解同步,晚中生代东亚多板块汇聚完成了从东亚到欧亚大陆的演替,以东亚大陆为核心的多板块汇聚格局一直延续至新生代,可能成为未来超大陆形成的起点。 相似文献
12.
The Teplá–Barrandian unit (TBU) of Central Europe's Bohemian Massif exposes perhaps the best preserved fragment of an accretionary wedge in the Avalonian–Cadomian belt, which developed along the northern active margin of Gondwana during Late Neoproterozoic. In the central TBU, three NE–SW-trending lithotectonic units (Domains 1–3) separated by antithetic brittle faults differ in lithology, style and intensity of deformation, magnetic fabric (AMS), and degree of Cadomian regional metamorphism. The flysch-like Domain 1 to the NW is the most outboard (trenchward) unit which has never been significantly buried and experienced only weak deformation and folding. The central, mélange-like Domain 2 is characterized by heterogenous intense deformation developed under lower greenschist facies conditions, and was thrust NW over Domain 1 along a SE-dipping fault. To the SE, the most inboard (arcward) Domain 3 is lithologically monotonous (dominated by graywackes and slates), was buried to depths corresponding up to the lower greenschist facies conditions, where it was overprinted by a pervasive SE-dipping cleavage and then was exhumed along a major NW-dipping normal fault.We interpret these domains to represent allochtonous tectonic slices that were differentially buried and then exhumed from various depths within the accretionary wedge during Cadomian subduction. The NW-directed thrusting of Domain 2 over Domain 1 may have been caused by accretion at the wedge front, whereas the SE-dipping cleavage and SE-side-up exhumation of Domain 3 may record inclined pervasive shortening during tectonic underplating and subsequent horizontal extension of the rear of the wedge. The boundary faults were later reactivated during Cambro–Ordovician extension and Variscan compression.Compared to related terranes of the Cadomian belt, the TBU lacks exposed continental basement, evidence for regional strike-slip shearing, and extensive backarc magmatism and LP–HT metamorphism, which could be interpreted to reflect flat-slab Cadomian subduction. This, in turn, suggests that Cadomian accretionary wedges developed in a manner identical to those of modern settings, elevating the TBU to a key position for understanding the style, kinematics, and timing of accretionary processes along the Avalonian–Cadomian belt. 相似文献
13.
Changes of Late Mesozoic Tectonic Regimes around the Ordos Basin (North China) and their Geodynamic Implications 总被引：4，自引：0，他引：4
A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates (the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west) towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton. 相似文献
14.
Eugene V. Artyushkov Michael A. Baer Peter A. Chekhovich Nils-Axel Mrner 《Tectonophysics》2000,320(3-4):271-310
An analysis is presented of the mechanisms of tectonic evolution of the southern part of the Urals between 48N and 60N in the Carboniferous–Triassic. A low tectonic activity was typical of the area in the Early Carboniferous — after closure of the Uralian ocean in the Late Devonian. A nappe, ≥10–15 km thick, overrode a shallow-water shelf on the margin of the East European platform in the early Late Carboniferous. It is commonly supposed that strong shortening and thickening of continental crust result in mountain building. However, no high mountains were formed, and the nappe surface reached the altitude of only ≤0.5 km. No high topography was formed after another collisional events at the end of the Late Carboniferous, in the second half of the Early Permian, and at the start of the Middle Triassic. A low magnitude of the crustal uplift in the regions of collision indicates a synchronous density increase from rapid metamorphism in mafic rocks in the lower crust. This required infiltration of volatiles from the asthenosphere as a catalyst. A layer of dense mafic rocks, 20 km thick, still exists at the base of the Uralian crust. It maintains the crust, up to 60 km thick, at a mean altitude 0.5 km. The mountains, 1.5 km high, were formed in the Late Permian and Early Triassic when there was no collision. Their moderate height precluded asthenospheric upwelling to the base of the crust, which at that time was 65–70 km thick. The mountains could be formed due to delamination of the lower part of mantle root with blocks of dense eclogite and/or retrogression in a presence of fluids of eclogites in the lower crust into less dense facies.
The formation of foreland basins is commonly attributed to deflection of the elastic lithosphere under surface and subsurface loads in thrust belts. Most of tectonic subsidence on the Uralian foreland occurred in a form of short impulses, a few million years long each. They took place at the beginning and at the end of the Late Carboniferous, and in the Late Permian. Rapid crustal subsidence occurred when there was no collision in the Urals. Furthermore, the basin deepened away from thrust belt. These features preclude deflection of the elastic lithosphere as a subsidence mechanism. To ensure the subsidence, a rapid density increase was necessary. It took place due to metamorphism in the lower crust under infiltration of volatiles.
The absence of flexural reaction on the Uralian foreland on collision in thrust belt together with narrow-wavelength basement deformations under the nappe indicate a high degree of weakening of the lithosphere. Such deformations took also place on the Uralian foreland at the epochs of rapid subsidences when there was no collision in thrust belt. Weakening of the lithosphere can be explained by infiltration of volatiles into this layer from the asthenosphere and rapid metamorphism in the mafic lower crust. Lithospheric weakening allowed the formation of the Uralian thrust belt under convergent motions of the plates which were separated by weak areas. 相似文献
15.
L.P. Zonenshain V.G. Korinevsky V.G. Kazmin D.M. Pechersky V.V. Khain V.V. Matveenkov 《Tectonophysics》1984,109(1-2)
The Uralian Fold Belt originated due to the East European-Kazakhstan continental collision in the Late Paleozoic-Early Triassic. The Uralian paleo-ocean existed from the Ordovician to Early Carboniferous. It evolved along the Western Pacific pattern with island arcs and subduction zones moving oceanwards from the East European margin and leaving newly opened back-arc basins behind from the Silurian to the Middle Devonian. A fossil spreading pattern similar to present one can be reconstructed for the Mugodjarian back-arc basin with the spreading rate of 5 cm/yr and depth of basaltic eruption of 3000 m. Since the Devonian, the closure of the Uralian paleo-ocean has begun. A subduction zone flipped over under the Kazakhstan continent, and remnants of an oceanic floor were completely consumed before the Late Carboniferous. After that the continental collision began which lasted nearly 90 Ma. As a result, the distinct linear shape and nappe structure of the Urals were formed. 相似文献
16.
Based on the LA-ICP-MS data, detrital zircons from the tillite-type conglomerates of the Tanin Formation (Serebryanka Group)
on the western slope of the Central Urals include approximately equal proportions of crystals with Neoarchean and Paleoproterozoic
U-Pb ages. Therefore, we can assume that crystalline rocks of the basement beneath the eastern part of the East European Craton
served as a provenance for aluminosilicate clastics in the initial Serebryanka period. Detrital zircons from sandstones of
the Kernos Formation have the Meso-Neoarchean (∼15%), Paleoproterozoic (∼60%), and Mesoproterozoic (∼26%) age. Comparison
of the obtained data with the results of the study of detrital zircons from Riphean and Vendian sandstones of the Southern
Urals shows that the Riphean and Lower Vendian rocks are mainly represented by erosional products of Middle and Upper Paleoproterozoic
crystalline rocks that constitute the basement of the East European Craton. In addition, a notable role belonged to older
(Lower Proterozoic, Neoarchean and Mesoarchean) rock associations during the formation of the Serebryanka Group. The terminal
Serebryanka time (Kernos Age) differed from its initial stage (Tanin Age) by the appearance of Mesoproterozoic complexes in
provenances. According to available data, these complexes played an insignificant role in the formation of Riphean-Vendian
rocks in the neighboring South Uralian segment. This implies a spatiotemporal diversity of clastic material sources for Upper
Precambrian rocks in the western megazone of the Southern and Central Urals. 相似文献
17.
The Central Ural uplift occupies the near-Vodorazdelnaya part of the Urals. It is composed of metaterrigenous and metavolcanogenic Riphean–Vendian formations. Distributed folds, which formed in several stages, and various tectonic faults are widespread. The study of these structures in the areas located in the Northern and Subpolar Urals showed their lateral and temporal variability, which was reflected in the difference in morphology and nature of faulting. In the Vodorazdelnaya area of the Northern Urals, as a result of thrust–fold deformations, a complex fold structure of the sequence was formed, subsequently broken by two submeridional subparallel faults into blocks. In the Khalmerya area of the Subpolar Urals, there are several tectonic blocks bounded by gently eastward dipping and overlapping tectonic blocks that form a duplex structure. This series of thrust structures created a complex cover structure contrasting in composition and degree of deformation. Later, a northeastern strike-slip fault zone arose. The orientation of early isoclinal folds in the rocks indicates pressure from the northeast, during the formation of tectonic scales and sheets in the Precambrian basement. Then this pressure occurred from the southeast and the Lower Paleozoic sediments were involved in the thrust process. Differences in the features of the formation of structures apparently depend on the morphology of the eastern margin of the East European platform and the change in the vector of displacement of the thrust sheet. The movement of the thrust sheets within the continental margin occurred along the main surface of the fault, with which the thrust structures are articulated at depth. At the final stages, extended strike-slip-upthrust zones were established, which affected the distribution of he gold mineralization.
相似文献18.
秦岭造山带基本组成与结构及其构造演化 总被引：51，自引：7，他引：51
秦岭造山带主要由三大套构造岩石地层单元组成，经历了三个主要演化阶段：1．前寒武纪古老基底形成演化阶段，2．主造山期（Pt3—T2）板块构造演化阶段，3．中新生代陆内构造演化阶段。在早中元古代以扩张构造体制占主导，形成裂谷与小洋盆兼杂并存的基本构造格局，经10—8亿年晋宁期从扩张垂向加积增生构造体制为主向以侧向增生为主的板块构造体制的过渡，于晚元古代中晚期开始进入板块构造演化阶段。在晚古生代早期由于东古特提斯洋的形成，扬子板块北缘沿秦岭南部扩张打开，形成华北板块、扬子板块及其间的秦岭微板块，沿商丹和勉略二缝合带自南向北俯冲消减碰撞，于中三叠世最后全面陆陆碰撞造山，而后又发生了强烈陆内造山作用，终成今日之秦岭山脉面貌。现今的秦岭造山带岩石圈结构是一正在调整演化中的具流变学分层的“立交桥式”三维结构，上部地壳呈多层逆冲推覆迭置的不对称扇形几何学模式，岩石圈中部则是成水平状流变层，而深部地幔则是最新调整的近南北向的地球物理异常状态与结构，形成从下到上构造方向近乎正交的圈层非耦合关系。 相似文献
19.
云南楚雄盆地位于场子陆块的西南边缘,为一典型的中生代周缘前陆盆地,盆地演化阶段明显,晚三叠世为前陆早期复理石沉积,侏罗纪则为前陆晚期磨拉石沉积。对盆地构造沉降史研究后笔者认为：①晚三叠世复理石沉积盆地构造沉降幅度巨大,沉降与沉积中心位于盆地最西部,紧邻古哀牢山造山带,沉积体呈形楔形展布;③侏罗纪磨拉石沉积盆地构造沉降和沉积中心以及前缘隆起向内陆方向迁移明显;③中生代构造快速沉降的沉积体的楔形展布表 相似文献
20.
华南大陆的结构、属性、过程与动力学一直是地质学家关注的热点。本文以钦杭构造带东段为主要研究地区,通过精细的构造解析、变质变形研究、年代学分析,结合反射地震剖面,探讨了华南大陆东部几个科学问题。（1）江南造山带形成于新元古代华夏板块与扬子板块的“软碰撞”作用,可划分为扬子板块南缘、扬子—华夏汇聚带和华夏板块北缘3个构造单元,江南断裂带和武夷山—遂昌断裂带分别为江南造山带的北界和南界。（2）扬子—华夏板块汇聚带由多个小板块拼合而成,其间有多条缝合带,大约900 Ma开始汇聚,760 Ma全面闭合,850~780 Ma为活动高峰期,具有递变式的汇聚拼合过程,由南向北发展,先斜向俯冲,后右旋走滑,最晚集中在中部活动。（3）华南大陆东部为中生代奠定的构造格架,主要构造为一系列北东走向褶皱和逆冲断层,大量地壳范围内的叠瓦状逆冲推覆构造,由南向北逆冲,可下切到中—下地壳。（4）华南大陆燕山晚期区域性伸展构造广泛发育,存在“华南热隆”构造,震旦系内的滑覆构造典型,同期大规模岩浆活动、火山活动和大规模的热液成矿。（5）华南大陆构造演化为：850 Ma扬子—华夏板块递进式汇聚,760 Ma全面拼合,江南造山带形成;600 Ma华南大陆盖层发育;430 Ma钦杭构造带受南部构造影响;220 Ma钦杭构造带受北部远程构造影响;160 Ma逆冲推覆构造产生;140 Ma大规模伸展,构造-岩浆-成矿关系密切;随后江南持续隆升,华南强烈热隆。 相似文献