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1.
《中国科学:地球科学(英文版)》2017,(3)
Accretionary wedge is the typical product of subduction-zone processes at shallow depths.Determining the location,composition and mechanism of accretionary wedge has important implications for understanding the tectonism of plate subduction.The Central Asian Orogenic Belt(CAOB) is one of the world's largest accretionary orogenic belts,and records the bulk evolution of Paleo-Asian Ocean from opening to closure,with multi-stages and multi-types of crust-mantle interaction in the Paleozoic.West Junggar(western part of Junggar Basin),located in the core area of CAOB,is characterized by a multiple intra-oceanic subduction system during the Paleozoic.In its eastern part crop out Devonian-Carboniferous marine sedimentary rocks,Darbut and Karamay ophiolitic melanges,alkali oceanic island basalts,island arc volcanic rocks and thrusted nappe structure.Such lithotectonic associations indicate the occurrence of accretionary wedge at Karamay.In order to decipher its formation mechanism,this paper presents a synthesis of petrography,structural geology and geochemistry of volcanic rocks.In combination with oceanic subduction channel processes,itis suggested that the accretionary wedge is acomposite melange with multiple stages of formation.The application of oceanic subduction channel model to the Karamay accretionary wedge provides new insights into the accretion and orogenesis of CAOB. 相似文献
2.
The Central Asian Orogenic Belt (CAOB) represents the world's largest Phanerozoic accretionary orogen, the major phase of which was built during the closure of the Paleo-Asian Ocean. The Tianshan orogenic belt forms the southwestern segment of the CAOB and has been the focus of investigations related to the evolution of the CAOB. Here we present results from an analysis of the crustal structure and upper mantle discontinuity beneath the Chinese Tianshan by employing H-k stacking technique as well as depth domain and synthetic receiver functions. Our results identify a double peak of Moho Ps in the Tianshan orogenic belt, suggesting the possibility of insertion of the lower crust of the Tarim Basin into this belt, with the latter retaining its initial crustal architecture. Our results provide insights into the dynamics of northward extrusion and the N–S trending crustal shortening of the Tianshan orogen during the convergence of the India and Eurasia blocks. 相似文献
3.
Yanbin Zhang Fuyuan Wu Simon A. Wilde Mingguo Zhai Xiaoping Lu Deyou Sun 《Island Arc》2004,13(4):484-505
Abstract The Yanbian area is located in the eastern part of the Central Asian Orogenic Belt (CAOB) of China and is characterized by widespread Phanerozoic granitic intrusions. It was previously thought that the Yanbian granitoids were mainly emplaced in the Early Paleozoic (so-called 'Caledonian' granitoids), extending east–west along the northern margin of the North China craton. However, few of them have been precisely dated; therefore, five typical 'Caledonian' granitic intrusions (the Huangniling, Dakai, Mengshan, Gaoling and Bailiping batholiths) were selected for U–Pb zircon isotopic study. New-age data show that emplacement of these granitoids extended from the Late Paleozoic to Late Mesozoic (285–116 Ma). This indicates that no 'Caledonian' granitic belt exists along the northern margin of the North China craton. The granitoids can be subdivided into four episodes based on our new data: Early Permian (285 ± 9 Ma), Early Triassic (249–245 Ma), Jurassic (192–168 Ma) and Cretaceous (119–116 Ma). The 285 ± 9 Ma tonalite was most likely related to subduction of the Paleo-Asian Oceanic Plate beneath the North China craton, followed by Triassic (249–245 Ma) syn-collisional monzogranites, representing the collision of the CAOB orogenic collage with the North China craton and final closure of the Paleo-Asian Ocean. The Jurassic granitoids resulted from subduction of the Paleo-Pacific plate and subsequent collision of the Jiamusi–Khanka Massif with the existing continent, assembled in the Triassic. The Early Cretaceous granitoids formed in an extensional setting along the eastern Asian continental margin. 相似文献
4.
《Earth and Planetary Science Letters》2003,205(3-4):225-237
Two global-scale mantle convection cells presently exist on Earth, centred on upwelling zones in the South Pacific Ocean and northeast Africa: one cell (Panthalassan) contains only oceanic plates, the other (Pangaean) contains all the continental plates. They have remained fixed relative to one another for >400 Ma. A transverse (Rheic–Tethyian) subduction system splits the Pangaean cell. Poloidal plate motion in the oceanic cell reflects circumferential pull of Panthalassan slabs, but toroidal flow in the Pangaean cell, reflected by vortex-type motion of continents toward the Altaids of central-east Asia throughout the Phanerozoic, has resulted from the competing slab-pull forces of both cells. The combined slab-pull effects from both cells also controlled Pangaean assembly and dispersal. Assembly occurred during Palaeozoic clockwise toroidal motion in the Pangaean cell, when Gondwana was pulled into Pangaea by the NE-trending Rheic subduction zone, forming the Appalachian–Variscide–Altaid chain. Pangaean dispersal occurred when the Rheic trench re-aligned in the Jurassic to form the NW-trending Tethyside subduction system, which pulled east Gondwanan fragments in the opposite direction to form the Cimmerian–Himalayan–Alpine chain. This re-alignment also generated a new set of (Indian) mid-ocean ridge systems which dissected east Gondwana and facilitated breakup. 100–200-Myr-long Phanerozoic Wilson cycles reflect rifting and northerly migration of Gondwanan fragments across the Pangaean cell into the Rheic–Tethyian trench. Pangaean dispersal was amplified by retreat of the Panthalassan slab away from Europe and Africa, which generated mantle counterflow currents capable of pulling the Americas westward to create the Atlantic Ocean. Thermal blanketing beneath Pangaea and related hotspot activity were part of a complex feedback mechanism that established the breakup pattern, but slab retreat is considered to have been the main driving force. The size and longevity of the two cells, organised and maintained by long-lived slab-pull forces, favours deep mantle convection as the dominant circulation process during the Phanerozoic. 相似文献
5.
本文使用时间域迭代反褶积算法,从张家口(怀来)—巴音温多尔一线布设的41个宽频地震台站、1年期间记录的连续三分量数据中提取到高质量的P波接收函数1844个.用H-κ扫描方法获得了测线下方Moho深度与波速比值(VP/VS)进而计算出泊松比,用共转换点(CCP)叠加方法获得了沿测线Moho面起伏图像.结果显示:(1)测线下方Moho深度平均40km,仅各块体边界处出现Moho深度小尺度急剧变化.整体上,Moho面产状相对于索伦缝合带大致对称,在缝合带南侧的温都尔庙带和白乃庙带下方呈南倾趋势,在缝合带北侧的宝力道带、贺根山杂岩带下方呈北倾趋势.(2)华北克拉通北缘泊松比总体较高,兴蒙造山带整体较低;各次级块体内部泊松比分布相对稳定,块体分界带附近往往存在泊松比值的升降扰动.(3)整条测线地壳厚度和泊松比之间存在弱的负相关关系,表明存在构造作用的影响.(4)整条测线泊松比呈现以索伦缝合带南缘为对称轴的非线性分布.本文所获得的地壳上地幔结构以及泊松比分布特征,支持古亚洲(索伦)洋(南北)双向俯冲,最终沿林西断裂闭合的动力学模式. 相似文献
6.
Cretaceous episodic growth of the Japanese Islands 总被引：1，自引：0，他引：1
G. Kimura 《Island Arc》1997,6(1):52-68
Abstract The Japanese Islands formed rapidly in situ along the eastern Asian continental margin in the Cretaceous due to both tectonic and magmatic processes. In the Early Cretaceous, huge oceanic plateaus created by the mid-Panthalassa super plume accreted with the continental margin. This tectonic interaction of oceanic plateau with continental crust is one of the significant tectonic processes responsible for continental growth in subduction zones. In the Japanese Islands, Late Cretaceous-Early Paleogene continental growth is much more episodic and drastic. At this time the continental margin uplifted regionally, and intra-continent collision tectonics took place in the northern part of the Asian continent. The uplifting event appears to have been caused by the subduction of very young oceanic crust (i.e. the Izanagi-Kula Plate) along the continental margin. Magmatism was also very active, and melting of the young oceanic slab appears to have resulted in ubiquitous plutons in the continental margin. Regional uplift of the continental margin and intra-continent collision tectonics promoted erosion of the uplifted area, and a large amount of terrigenous sediment was abruptly supplied to the trench. As a result of the rapid supply of terrigenous detritus, the accretionary complexes (the Hidaka Belt in Hokkaido and the Shimanto Belt in Southwest Japan) grew rapidly in the subduction zone. The rapid growth of the accretionary complexes and the subduction of very young, buoyant oceanic crust caused the extrusion of a high-P/T metamorphic wedge from the deep levels of the subduction zone. Episodic growth of the Late Cretaceous Japanese Islands suggests that subduction of very young oceanic crust and/or ridge subduction are very significant for the formation of new continental crust in subduction zones. 相似文献
7.
Subduction history of the Paleo-Pacific slab beneath Eurasian continent: Mesozoic-Paleogene magmatic records in Northeast Asia 总被引：6，自引：0，他引：6
This paper presents a review on the rock associations, geochemistry, and spatial distribution of Mesozoic-Paleogene igneous rocks in Northeast Asia. The record of magmatism is used to evaluate the spatial-temporal extent and influence of multiple tectonic regimes during the Mesozoic, as well as the onset and history of Paleo-Pacific slab subduction beneath Eurasian continent. Mesozoic-Paleogene magmatism at the continental margin of Northeast Asia can be subdivided into nine stages that took place in the Early-Middle Triassic, Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, Late Cretaceous, and Paleogene, respectively. The Triassic magmatism is mainly composed of adakitic rocks, bimodal rocks, alkaline igneous rocks, and A-type granites and rhyolites that formed in syn-collisional to post-collisional extensional settings related to the final closure of the Paleo-Asian Ocean. However, Triassic calc-alkaline igneous rocks in the Erguna-Xing’an massifs were associated with the southward subduction of the Mongol-Okhotsk oceanic slab. A passive continental margin setting existed in Northeast Asia during the Triassic. Early Jurassic calc-alkaline igneous rocks have a geochemical affinity to arc-like magmatism, whereas coeval intracontinental magmatism is composed of bimodal igneous rocks and A-type granites. Spatial variations in the potassium contents of Early Jurassic igneous rocks from the continental margin to intracontinental region, together with the presence of an Early Jurassic accretionary complex, reveal that the onset of the Paleo- Pacific slab subduction beneath Eurasian continent occurred in the Early Jurassic. Middle Jurassic to early Early Cretaceous magmatism did not take place at the continental margin of Northeast Asia. This observation, combined with the occurrence of low-altitude biological assemblages and the age population of detrital zircons in an Early Cretaceous accretionary complex, indicates that a strike-slip tectonic regime existed between the continental margin and Paleo-Pacific slab during the Middle Jurassic to early Early Cretaceous. The widespread occurrence of late Early Cretaceous calc-alkaline igneous rocks, I-type granites, and adakitic rocks suggests low-angle subduction of the Paleo-Pacific slab beneath Eurasian continent at this time. The eastward narrowing of the distribution of igneous rocks from the Late Cretaceous to Paleogene, and the change from an intracontinental to continental margin setting, suggest the eastward movement of Eurasian continent and rollback of the Paleo- Pacific slab at this time. 相似文献
8.
中亚造山带东段经历了古亚洲洋、蒙古—鄂霍茨克洋和古太平洋构造体制的多重作用,多期次的构造活动不仅改造了地形地貌、岩石圈结构,同时也改造了软流圈分布,因此对软流圈结构研究具有重要的科学意义.为了揭示复杂多重构造体系下软流圈的分布特征,完成了中亚造山带东段约1800km长大地电磁测深剖面,并对数据进行非线性共轭梯度反演,获得二维电性结构模型.研究发现:中亚造山带东段岩石圈内部存在多处低阻异常,地表多对应第四纪火山群或古缝合带,表明这些低阻异常与软流圈上侵有关.软流圈呈现高导特征,南部略薄,电阻率值为10～30Ωm,北部厚度较大,电阻率值为10～0.1Ωm,这种电性结构特征体现了中亚造山带东段软流圈南北两侧厚度、部分熔融程度的不均一性.而已有的层析成像结果显示中亚造山带软流圈东西向则呈现东厚西薄的特征.结合区域地质,提出软流圈与岩石圈一样在碰撞造山过程中厚度、部分熔融程度也会随之变化的动力学认识.中亚造山带东段软流圈主要经历了古亚洲洋构造体系、蒙古—鄂霍茨克构造体系和太平洋构造体系三阶段的构造事件影响,因此中亚造山带东段软流圈的南北向差异,推断为古亚洲洋闭合早于鄂霍茨克洋闭合的时限差异所致,东西向差异则主要受太平洋构造体系的影响. 相似文献
9.
Pacific-type orogeny revisited: Miyashiro-type orogeny proposed 总被引：30，自引：0，他引：30
Abstract The concept of Pacific-type orogeny is revised, based on an assessment of geologic data collected from the Japanese Islands during the past 25 years. The formation of a passive continental margin after the birth of the Pacific Ocean at 600 Ma was followed by the initiation of oceanic plate subduction at 450 Ma. Since then, four episodes of Pacific-type orogeny have occurred to create an orogenic belt 400 km wide that gradually grew both oceanward and downward. The orogenic belt consists mainly of an accretionary complex tectonically interlayered with thin (<2 km thick), subhorizontal, high-P/T regional metamorphic belts. Both the accretionary complex and the high-P/T rocks were intruded by granitoids ～100 million years after the formation of the accretionary complex. The intrusion of calc-alkaline (CA) plutons was synchronous with the exhumation of high-P/T schist belts. Ages from microfossils and K-Ar analysis suggest that the orogenic climax happened at a time of mid-oceanic ridge subduction. The orogenic climax was characterized by the formation of major subhorizontal orogenic structures, the exhumation of high-P/T schist belts by wedge extrusion and subsequent domed uplift, and the intrusion-extrusion of CA magma dominantly produced by slab melting. The orogenic climax ended soon after ridge subduction, and thereafter a new Pacific-type orogeny began. A single Pacific-type orogenic cycle may correspond to the interaction of the Asian continental margin with one major Pacific oceanic plate. Ophiolites in Japan occur as accreted material and are not of island-arc but of plume origin. They presumably formed after the birth of the southern Pacific superplume at 600 Ma, and did not modify the cordilleran-type orogeny in a major way. Microplates, fore-arc slivers, intra-oceanic arc collisions and the opening of back-arc basins clearly contributed to cordilleran orogenesis. However, they were of secondary importance and served only to modify pre-existing major orogenic components. The most important cause of cordilleran-type orogeny is the subduction of a mid-oceanic ridge, by which the volume of continental crust increases through the transfer of granitic melt from the subducting oceanic crust to an orogenic welt. Accretionary complexes are composed mainly of recycled granitic sediments with minor amounts of oceanic material, which indicate that the accretion of oceanic material, including huge oceanic plateaus, was not significant for orogenic growth. Instead, the formation and intrusion of granitoids are the keys to continental growth, which is the most important process in Pacific-type orogeny. Collision-type orogeny does not increase the volume of continental crust. The name ‘Miyashiro-type orogeny’ is proposed for this revised concept of Pacific-type or cordilleran-type orogeny, in order to commemorate Professor A. Miyashiro's many contributions to a better understanding of orogenesis. 相似文献
10.
YILONG LI HANWEN ZHOU FRAUKJE M. BROUWER WENJIAO XIAO ZENGQIU ZHONG JAN R. WIJBRANS 《Island Arc》2011,20(4):535-549
The Solonker Suture Zone is thought to record the terminal evolution of the Central Asian Orogenic Belt (CAOB) in Inner Mongolia. However, two contrasting interpretations of the timing of suturing of the Solonker Suture Zone exist: (i) Permian to Early Triassic; and (ii) Middle Devonian or Late Devonian to Carboniferous. The Shuangjing Schist is exposed in the Linxi area along the Xar Moron Fault Zone, which marks the southern boundary of the Solonker Suture Zone in the eastern section of the CAOB, and thus provides insight into the timing of suturing of the Solonker Suture Zone. Detailed and systematic analysis of the petrology and geochemistry of the Shuangjing Schist shows that the Shuangjing Schist developed by greenschist facies prograde metamorphism of a volcanisedimentary rock series protolith. The volcanic parts of the Shuangjing Schist are a calc‐alkaline series with large volumes of intermediate members and subordinate acidic members. Volcanism occurred in a magmatic arc on the continental margin and was induced by subduction‐related magmatism resulting from mantle metasomatism. The sedimentary parts of the Shuangjing Schist reflect a transition from continental shelf to abyssal plain sedimentation. The formation of the Shuangjing Schist is suggested to be related to closure of an arc/forearc‐related ocean basin. The timing is constrained by a laser ablation inductively coupled plasma–mass spectrometry (LA‐ICP–MS) U–Pb magmatic zircon age of 298 ± 2 Ma from a carbonaceous biotite–plagioclase schist that was intruded by granite at 272 ± 2 Ma. In the Linxi area, southward subduction of the arc/forearc basin led to uplift, thickening, collapse, and erosion of the overriding continental crust. Collapse induced extension and widespread magmatism along the volcanic arc at the northern margin of the North China Craton. The closure of the arc/forearc‐related oceanic basin led to the formation of Late Permian to Middle Triassic collisional granites and the subsequent end of the collision of the Solonker Suture Zone. 相似文献
11.
Regional metamorphic belts of the Japanese Islands 总被引：1，自引：0，他引：1
Abstract An overview of the regional metamorphic belts of Japan is given in the context of the tectonic evolution of the Japanese Islands. The Japanese Islands were situated on an active margin of the Eurasian continent or its constituent landmass before their assembly during the Phanerozoic. The Japanese Islands are composed mainly of metamorphosed and unmetamorphosed accretionary complexes, granitoids and their effusive equivalents that were formed by the Cordilleran-type orogeny. The metamorphic belts are regarded essentially as a deep-seated portion of an accretionary complex. In spite of continuous subduction of oceanic plates beneath the continents, these orogenic rocks were formed quite episodically, as evidenced by discontinuous matrix ages of the accretionary complexes and a striking concentration of isotopic ages of the granitoids. A systematic along-arc age shift of Cretaceous large-scaled granitic magmatism and regional metamorphism suggests a tectonic control such as ridge subduction, which triggered the episodic orogeny. A tectonic model based on the paired metamorphic belts, combined with the non-steady tectonic control, works well to explain this magmatism and metamorphism in a single arc-trench system as a continental margin process. However, the juxtapositional process of the paired metamorphic belts is still a problem. Two possible cases, namely transcurrent displacement and back-arc overthrusting are discussed. 相似文献
12.
Subduction is the core process of plate tectonics. The mantle wedge in subduction-zone systems represents a key tectonic unit, playing a significant role in material cycling and energy exchange between Earth's layers. This study summarizes research progresses in terms of subduction-related peridotite massifs, including supra-subduction zone(SSZ) ophiolites and mantle-wedge-type(MWT) orogenic peridotites. We also provide the relevant key scientific questions that need be solved in the future. The mantle sections of SSZ ophiolites and MWT orogenic peridotites represent the mantle fragments from oceanic and continental lithosphere in subduction zones, respectively. They are essential targets to study the crust-mantle interaction in subduction zones. The nature of this interaction is the complex chemical exchanges between the subducting slab and the mantle wedge under the major control of physical processes. The SSZ ophiolites can record melt/fluid-rock interaction, metamorphism,deformation, concentration of metallogenic elements and material exchange between crust and mantle, during the stages from the generation of oceanic lithosphere at spreading centers to the initiation, development, maturation and ending of oceanic subduction at continental margins. The MWT orogenic peridotites reveal the history of strong metamorphism and deformation during subduction, the multiple melt/fluid metasomatism(including silicatic melts, carbonatitic melts and silicate-bearing C-HO fluids/supercritical fluids), and the complex cycling of crust-mantle materials, during the subduction/collision and exhumation of continental plates. In order to further reveal the crust-mantle interaction using subduction-zone peridotites, it is necessary to utilize high-spatial-resolution and high-precision techniques to constrain the complex chemical metasomatism, metamorphism,deformation at micro scales, and to reveal their connections with spatial-temporal evolution in macro-scale tectonics. 相似文献
13.
The Wangfeng gold deposit is one of the five most important gold deposits in the Tianshan. Studies of its metallogenic time, space, geodynamic background, ore feature and ore fluid have proved that the deposit formed in the late Paleozoic continental collision, and consequently is a suitable delegate to probe mineralizing regularities during collisional orogenesis. Isotopic studies including O, D, C, S, Pb and Sr reveal ore materials derived from sedimentary association (including carbonate and sulfate), which further refers to the Hercynian carbonate-silicolite-argillite formation north to Wangfeng camp. At the end of Paleozoic, the southward intracontinental subduction of Hercynian synthem along the Hongwuyueqiao fault down to the Central Tianshan terrane induced large-scale fluidization which extracted and out-transported ore materials from Hercynian synthem upto shallow fair positions, and finally resulted in the formation of the Wangfeng deposit. This study excludes the possibility of other tectonic metallogenic models other than the tectonic model for collisional metallogenesis, petrogenesis and fluidization. 相似文献
14.
The Palaeo-Tethyan suture: A line of demarcation between two fundamentally different architectural styles in the structure of Asia 总被引：5，自引：0，他引：5
Abstract The Palaeo-Tethyan suture separates regions characterized by two fundamentally different tectonic styles in the structure of the Tethysides. North of the suture in Iran, Turkmenistan, Afghanistan, Tadjikistan, Kirgizstan, Uzbekistan, Kazakhstan and large parts of the Russian Federation and China, orogenic development is characterized by very large subduction-accretion complexes developed since the late Proterozoic. Magmatic arc axes migrated radially outwards from the 'Old Vertex of Eurasia' and consolidated the accretionary prisms into a 'basement complex' dominated by a pelitic composition. In such orogens, called the 'Turkic-type' after the dominant ethnic population of Central Asia, ophiolites are unreliable indicators of sutures, because they are present throughout the 'basement' as in-faulted shreds and rarely as nappes. By contrast, south of the Palaeo-Tethyan suture, orogeny was commonly characterized by a Sumatra- or Andean-type continental margin arc (e.g. the Transhimalaya arc) that in places became an island arc by back-arc basin rifting (e.g. the Black Sea behind the Rhodope-Pontide fragment) and later collided with an Atlantic- (as in the Himalaya) or California-type (as in the Alps) continental margin to create Alpine- or Himalayan-type orogenic belts. Turkic-type orogenic belts result from the exaggeration of the Himalayan-type as a result of the subduction of very large oceanic areas that contain great amounts of sediment. They contribute to the enlargement and also possibly the growth of the continental crust which has a composition more silicic than basalt. The Palaeo-Tethyan suture is thus a line across which the rate of continental enlargement by subduction-accretion changed dramatically. 相似文献
15.
Tethyan ophiolites and Pangea break-up 总被引：6，自引：0，他引：6
Abstract The break‐up of Pangea began during the Triassic and was preceded by a generalized Permo‐Triassic formation of continental rifts along the future margins between Africa and Europe, between Africa and North America, and between North and South America. During the Middle–Late Triassic, an ocean basin cutting the eastern equatorial portion of the Pangea opened as a prograding branch of the Paleotethys or as a new ocean (the Eastern Tethys); westwards, continental rift basins developed. The Western Tethys and Central Atlantic began to open only during the Middle Jurassic. The timing of the break‐up can be hypothesized from data from the oceanic remnants of the peri‐Mediterranean and peri‐Caribbean regions (the Mesozoic ophiolites) and from the Atlantic ocean crust. In the Eastern Tethys, Middle–Late Triassic mid‐oceanic ridge basalt (MORB) ophiolites, Middle–Upper Jurassic MORB, island arc tholeiite (IAT) supra‐subduction ophiolites and Middle–Upper Jurassic metamorphic soles occur, suggesting that the ocean drifting was active from the Triassic to the Middle Jurassic. The compressive phases, as early as during the Middle Jurassic, were when the drifting was still active and caused the ocean closure at the Jurassic–Cretaceous boundary and, successively, the formation of the orogenic belts. The present scattering of the ophiolites is a consequence of the orogenesis: once the tectonic disturbances are removed, the Eastern Tethys ophiolites constitute a single alignment. In the Western Tethys only Middle–Upper Jurassic MORB ophiolites are present – this was the drifting time. The closure began during the Late Cretaceous and was completed during the Eocene. Along the area linking the Western Tethys to the Central Atlantic, the break‐up was realized through left lateral wrench movements. In the Central Atlantic – the link between the Western Tethys and the Caribbean Tethys – the drifting began at the same time and is still continuing. The Caribbean Tethys opened probably during the Late Jurassic–Early Cretaceous. The general picture rising from the previous data suggest a Pangea break‐up rejuvenating from east to west, from the Middle–Late Triassic to the Late Jurassic–Early Cretaceous. 相似文献
16.
Thermal histories of Cretaceous sedimentary basins in the Korean peninsula have been assessed to understand the response of the East Asian continental margin to subduction of the Paleo‐Pacific (Izanagi) Plate. The Izanagi Plate subducted obliquely beneath the East Asian continent during the Early Cretaceous and orthogonally in the Late Cretaceous. First, the Jinan Basin, a pull‐apart basin, was studied by illite crystallinity and apatite fission‐track analyses. Analytical results indicate that Jinan Basin sediment was heated to a maximum temperature of approximately 287°C by burial. The sediment experienced two cooling episodes during ca 95–80 Ma and after ca 30 Ma, with a quiescent period between them. A similar cooling pattern is recognized in the Gyeongsang Basin, the largest Cretaceous basin in Korea. The Jinan and Gyeongsang Basins were cooled mainly by exhumation between ca 95 and 80 Ma, but the former was exhumed slightly earlier than the latter by transpressional force due to the subduction direction change of the Izanagi Plate. Comparison of thermal history of Korean Cretaceous basins with those of granitoids in northeastern China and the accretionary complexes in southwestern Japan reveals that the Upper Cretaceous regional exhumation of the East Asian continental margin including the Korean peninsula during ca 95–80 Ma was facilitated by the subduction of the Izanagi–Pacific ridge, which migrated northeastwards with time, resulting in the end of regional exhumation at ca 80 Ma in this region. 相似文献
17.
The times of original fractionation of the Sm and Nd component of clastic sediments from a mantle source (≡ crustal residence age) have been estimated from Sm-Nd model ages calculated relative to a depleted mantle evolution. In this way the provenance and evolution of selected Precambrian and Phanerozoic sediments and metasediments from the British Isles have been examined. Whereas some Archaean and early Proterozoic sediments have Sm-Nd model ages that are close to their stratigraphic age, the Phanerozoic sediments analysed have model ages as much as 2.0 Ga in excess of their stratigraphic age.A more detailed study of Lower Palaeozoic sediments deposited on the northern margin of the Iapetus Ocean provides evidence for a marked change of provenance in the Ordovician after the deposition of the Dalradian Supergroup. A component with comparatively high143Nd/144Nd and Sm/Nd ratio (presumably basaltic) is present in the sediments throughout the accretionary prism. Crustal residence age estimates average about 1.5 Ga for both these Lower Palaeozoic sediments, and modern pelagic clays, and collectively fail to provide any evidence for significant continental growth during the Phanerozoic. 相似文献
18.
Flavien Choulet Michel Faure Dominique Cluzel Yan Chen Wei Lin Bo Wang Bei Xu 《中国科学:地球科学(英文版)》2016,59(1):25-57
The Altaid tectonic collage extends over Central Asia, exposing numerous accretionary orogens that can account for the Palaeozoic continental crust growth. A pluridisciplinary approach, using geochronological, geochemical, structural and palaeomagnetic tools was carried out to unravel the architecture and the evolution of West Junggar(Northwestern China), a segment of the Altaid Collage. A polycyclic geodynamic evolution is inferred and includes:(1) an Early Palaeozoic cycle, characterized by the closure of two oceanic basins bounded by island-arc systems;(2) an Early Devonian subduction jamming resulting in a minor-scale collision documented by thrusting, syntectonic sedimentation and subsequent crutal thinning associated with alkaline magmatism;(3) a Late Palaeozoic cycle, driven by the evolution of two opposite subduction zones developed upon the Early Palaeozoic basement. Detailed structural analysis and paleomagnetic data provide constraints for the late evolution of Junggar in the frame of the development of the Late Palaeozoic Kazakh orocline, which led to oblique subduction and transpression in the West Junggar accretionary complex. Progressive buckling of the Kazakh orocline further resulted in Late Carboniferous to Permian wrench tectonics, and lateral displacement of lithotectonic units. Block rotations that continued after the Late Triassic are due to diachronous intraplate reactivation. This scenario mirrors the Palaeozoic geodynamics of the Altaid Collage. Multiple Early Palaeozoic collisions of intra-oceanic arcs and micro continents have contributed to the formation of the Kazakhstan Microcontinent. Since the Late Palaeozoic, subductions formed around this microcontinent and the final oblique closure of oceanic domains resulted in the transcurrent collage of Tarim and Siberia cratons. Palaeozoic strike-slip faults were later reactivated during Mesozoic intracontinental tectonics. 相似文献
19.
马尼拉俯冲带是南海的东部边界,记录了南海形成演化的关键信息,同时也是地震和海啸多发区域.本文利用过马尼拉俯冲带北段的高分辨率多道地震剖面,分析了研究区内海盆和海沟的沉积特征,精细刻画了区内增生楔前缘的构造变形、结构以及岩浆活动特征.研究区内增生楔下陆坡部分由盲冲断层、构造楔和叠瓦逆冲断层构成,逆冲断层归并于一条位于下中新统的滑脱面上,滑脱面向海方向的展布明显受到增生楔之下埋藏海山和基底隆起的影响;上陆坡的反射特征则因变形强烈和岩浆作用而难以识别;岩浆活动开始于晚中新世末期并持续至第四纪.马尼拉俯冲带北段增生楔的形成时间早于16.5 Ma,并通过前展式逆冲向南海方向扩展;马尼拉俯冲带的初始形成时间可能在晚渐新世,而此时南海海盆扩张仍在持续.南海东北缘19°N-21°N区域为南海北部陆坡向海盆的延伸,高度减薄的陆壳的俯冲造成马尼拉海沟北段几何形态明显地向东凹进. 相似文献
20.
A. A. Sidorov A. V. Volkov A. D. Chekhov N. E. Savva V. Yu. Alekseev K. V. Uyutnov 《Journal of Volcanology and Seismology》2011,5(6):386-398
According to the concepts of accretionary tectonics, the region of interest was a dynamically evolving active continental
margin during Mesozoic/Cenozoic time; this is reflected in the generation of nine volcano-plutonic belts that successively
evolved from northwest to southeast. Most of these evolved in parallel with the present-day location of the Kuril-Kamchatka
deep-sea trench: the Late Jurassic/Early Cretaceous Uda-Murgali belt (UMVB) the Uyandina-Yasachnaya (UYVB), the Oloi belt
(OVB), the Late Cretaceous/Paleogene Okhotsk-Chukchi belt (OChVB), the Late Cretaceous/Paleogene East-Sikhote-Alin’ belt (ESVB),
the Eocene/Oligocene Koryak-West-Kamchatka belt (KWKVB), the Oligocene/Quaternary Central Kamchatka belt (CKVB), and the Pliocene/Quaternary
East Kamchatka belt (EKVB). The successively younger age of the volcanic belts since the Early Cretaceous is in correspondence
with the displacement of the volcanic arc-trench system toward the Pacific Ocean. Apart from the above-mentioned volcanogenic
belts, the Omolon craton terrane also contains the pre-accretionary Devonian Kedon marginal volcanogenic belt (KVB). All the
volcanogenic belts and the surrounding perivolcanic zones of tectono-magmatic activation (TMA) form the world-largest metallogenic
province with a polychronous volcanogenic-plutonogenic metallization of various compositions. 相似文献