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1.
Palaeozoic and Mesozoic tectonic evolution and palaeogeography of East Asian crustal fragments: The Korean Peninsula in context 总被引：38，自引：2，他引：38
I. Metcalfe 《Gondwana Research》2006,9(1-2):24
East and Southeast Asia comprises a complex assembly of allochthonous continental lithospheric crustal fragments (terranes) together with volcanic arcs, and other terranes of oceanic and accretionary complex origins located at the zone of convergence between the Eurasian, Indo-Australian and Pacific Plates. The former wide separation of Asian terranes is indicated by contrasting faunas and floras developed on adjacent terranes due to their prior geographic separation, different palaeoclimates, and biogeographic isolation. The boundaries between Asian terranes are marked by major geological discontinuities (suture zones) that represent former ocean basins that once separated them. In some cases, the ocean basins have been completely destroyed, and terrane boundaries are marked by major fault zones. In other cases, remnants of the ocean basins and of subduction/accretion complexes remain and provide valuable information on the tectonic history of the terranes, the oceans that once separated them, and timings of amalgamation and accretion. The various allochthonous crustal fragments of East Asia have been brought into close juxtaposition by geological convergent plate tectonic processes. The Gondwana-derived East Asia crustal fragments successively rifted and separated from the margin of eastern Gondwana as three elongate continental slivers in the Devonian, Early Permian and Late Triassic–Late Jurassic. As these three continental slivers separated from Gondwana, three successive ocean basins, the Palaeo-Tethys,. Meso-Tethys and Ceno-Tethys, opened between these and Gondwana. Asian terranes progressively sutured to one another during the Palaeozoic to Cenozoic. South China and Indochina probably amalgamated in the Early Carboniferous but alternative scenarios with collision in the Permo–Triassic have been suggested. The Tarim terrane accreted to Eurasia in the Early Permian. The Sibumasu and Qiangtang terranes collided and sutured with Simao/Indochina/East Malaya in the Early–Middle Triassic and the West Sumatra terrane was transported westwards to a position outboard of Sibumasu during this collisional process. The Permo–Triassic also saw the progressive collision between South and North China (with possible extension of this collision being recognised in the Korean Peninsula) culminating in the Late Triassic. North China did not finally weld to Asia until the Late Jurassic. The Lhasa and West Burma terranes accreted to Eurasia in the Late Jurassic–Early Cretaceous and proto East and Southeast Asia had formed. Palaeogeographic reconstructions illustrating the evolution and assembly of Asian crustal fragments during the Phanerozoic are presented. 相似文献
2.
为了解兴蒙造山带基底属性和多个构造体系演化与叠加历史,系统总结了近年来在基础地质研究中取得的新成果,并利用这些成果讨论了兴蒙造山带的基底属性与演化历史.兴蒙造山带是指我国东北地区古生代构造作用影响的地区,这些地区也遭受了中生代构造作用的叠加与改造.兴蒙造山带主要由微陆块和其间的造山带组成.虽然传统上认为属于前寒武纪结晶基底的地质体主要已解体为古生代和早中生代,但随着新太古代和古元古代地质体的相继发现,以及新生代玄武岩中幔源古元古代橄榄岩包体的发现,可以判定兴蒙造山带内微陆块应具有古老的前寒武纪基底,并且壳幔是耦合的.微陆块内部地壳增生以垂向增生为主,且主要发生在新元古代和中元古代,以及次要的新太古代和古生代.相反,陆块间造山带或岛弧地体的陆壳则以侧向增生为主,且主要发生在新元古代和古生代.额尔古纳地块与兴安地块的拼合发生在早古生代早期;兴安地块与松嫩地块的拼合发生在早石炭世晚期;松嫩地块与佳木斯地块的拼合发生在早古生代晚期,中生代早期又经历了裂解与再闭合的构造演化过程;华北克拉通北缘增生杂岩带与北方微陆块群的最终拼合发生在晚二叠世-中三叠世,古亚洲洋的最终闭合发生在中三叠世,且为剪刀式闭合.晚古生代晚期蒙古-鄂霍茨克大洋板块南向俯冲作用的发生以及早中生代(三叠纪-早侏罗世)的持续南向俯冲,控制了大兴安岭-冀北-辽西地区的岩浆活动,蒙古-鄂霍茨克大洋的闭合发生在中侏罗世,晚侏罗世-早白垩世主要表现为闭合后的伸展环境.古太平洋板块中生代的俯冲起始时间为早侏罗世,晚侏罗世-早白垩世早期东北亚陆缘主要表现为走滑的构造属性和陆缘地体从低纬度到高纬度的构造就位过程,早白垩世晚期-古近纪岩浆作用的向东收缩揭示了古太平洋板块的持续俯冲和俯冲板片的后撤过程,古近纪晚期日本海的打开标志着东北亚陆缘从活动陆缘已经转变为沟-弧-盆体系,并且标志着东亚大地幔楔的形成. 相似文献
3.
The Lower Tasna Detachment (LTD) is a low-angle fault contact between serpentinized peridotite below and continental basement above. It was formed during Jurassic to Early Cretaceous rifting of a Tethyan continental margin and later captured in a thrust nappe during Tertiary plate convergence. Foliated gabbro, gabbro mylonite, and granitoid mylonite occurring along the LTD record shearing under decreasing temperatures. U–Pb dating of zircon from the gabbro mylonite yielded a Permian age, interpreted as the age of gabbro intrusion, whereas the breakup of the passive margin occurred as late as Early Cretaceous. This suggests that the gabbro belongs to a prerift, lower to middle crustal intrusion 'smeared out' along the detachment by extensional faulting. The juxtaposition of mantle and upper crust along the Lower Tasna detachment may serve as a model for several seismic reflectors observed in distal passive continental margins (e.g. S reflector of the Galicia margin). 相似文献
4.
In situ U‐Th/Pb (LA‐ICP‐MS) monazite ages from the Hindu Kush of NW Pakistan provide new petrochronologic constraints on the tectonic evolution of the Himalaya–Karakoram–Tibet orogen. Monazites from two adjacent garnet + staurolite schist specimens yield multiple age populations that record the major Mesozoic and Cenozoic deformational, magmatic and metamorphic events along the southern margin of Eurasia. These include the accretion of the Hindu Kush–SW Pamir to Eurasia during the Late Triassic, followed by the accretion of the Karakoram terrane in the Early Jurassic. Younger Jurassic and Cretaceous ages record the development of an Andean‐style volcanic arc along the southern Eurasian margin, which ended with the docking of the Kohistan island arc and the emplacement of the Kohistan–Ladakh batholith during the Late Cretaceous. The initial Eocene collision of India with Eurasia was followed by widespread high‐temperature metamorphism and anatexis associated with crustal thickening within the Himalaya system in the Late Oligocene and Early Miocene. 相似文献
5.
The Cimmerian Orogeny in northern Iran: tectono-stratigraphic evidence from the foreland 总被引：2，自引：0，他引：2
Markus Wilmsen Franz T. Fürsich Kazem Seyed-Emami Mahmoud Reza Majidifard Jafar Taheri 《地学学报》2009,21(3):211-218
From the Permian onwards, the Gondwana-derived Iran Plate drifted northward to collide with Eurasia in the Late Triassic, thereby closing the Palaeotethys. This Eo-Cimmerian Orogeny formed the Cimmeride fold-and-thrust belt. The Upper Triassic–Middle Jurassic Shemshak Group of northern Iran is commonly regarded as the Cimmerian foreland molasse. However, our tectono-stratigraphic analysis of the Shemshak Group resulted in a revised and precisely dated model for the Triassic–Jurassic geodynamic evolution of the Iran Plate: initial Cimmerian collision started in the Carnian with subsequent Late Triassic synorogenic peripheral foreland deposition (flysch, lower Shemshak Group). Subduction shifted south in the Norian (onset of Neotethys subduction below Iran) and slab break-off around the Triassic–Jurassic boundary caused rapid uplift of the Cimmerides followed by Liassic post-orogenic molasse (middle Shemshak Group). During the Toarcian–Aalenian (upper Shemshak Group), Neotethys back-arc rifting formed a deep-marine basin, which developed into the oceanic South Caspian Basin during the Late Bajocian–Late Jurassic. 相似文献
6.
The Malay Peninsula is characterised by three north–south belts, the Western, Central, and Eastern belts based on distinct differences in stratigraphy, structure, magmatism, geophysical signatures and geological evolution. The Western Belt forms part of the Sibumasu Terrane, derived from the NW Australian Gondwana margin in the late Early Permian. The Central and Eastern Belts represent the Sukhothai Arc constructed in the Late Carboniferous–Early Permian on the margin of the Indochina Block (derived from the Gondwana margin in the Early Devonian). This arc was then separated from Indochina by back-arc spreading in the Permian. The Bentong-Raub suture zone forms the boundary between the Sibumasu Terrane (Western Belt) and Sukhothai Arc (Central and Eastern Belts) and preserves remnants of the Devonian–Permian main Palaeo-Tethys ocean basin destroyed by subduction beneath the Indochina Block/Sukhothai Arc, which produced the Permian–Triassic andesitic volcanism and I-Type granitoids observed in the Central and Eastern Belts of the Malay Peninsula. The collision between Sibumasu and the Sukhothai Arc began in Early Triassic times and was completed by the Late Triassic. Triassic cherts, turbidites and conglomerates of the Semanggol “Formation” were deposited in a fore-deep basin constructed on the leading edge of Sibumasu and the uplifted accretionary complex. Collisional crustal thickening, coupled with slab break off and rising hot asthenosphere produced the Main Range Late Triassic-earliest Jurassic S-Type granitoids that intrude the Western Belt and Bentong-Raub suture zone. The Sukhothai back-arc basin opened in the Early Permian and collapsed and closed in the Middle–Late Triassic. Marine sedimentation ceased in the Late Triassic in the Malay Peninsula due to tectonic and isostatic uplift, and Jurassic–Cretaceous continental red beds form a cover sequence. A significant Late Cretaceous tectono-thermal event affected the Peninsula with major faulting, granitoid intrusion and re-setting of palaeomagnetic signatures. 相似文献
7.
Gondwanaland origin, dispersion, and accretion of East and Southeast Asian continental terranes 总被引：3，自引：0，他引：3
East and Southeast Asia is a complex assembly of allochthonous continental terranes, island arcs, accretionary complexes and small ocean basins. The boundaries between continental terranes are marked by major fault zones or by sutures recognized by the presence of ophiolites, mélanges and accretionary complexes. Stratigraphical, sedimentological, paleobiogeographical and paleomagnetic data suggest that all of the East and Southeast Asian continental terranes were derived directly or indirectly from the Iran-Himalaya-Australia margin of Gondwanaland. The evolution of the terranes is one of rifting from Gondwanaland, northwards drift and amalgamation/accretion to form present day East Asia. Three continental silvers were rifted from the northeast margin of Gondwanaland in the Silurian-Early Devonian (North China, South China, Indochina/East Malaya, Qamdo-Simao and Tarim terranes), Early-Middle Permian (Sibumasu, Lhasa and Qiangtang terranes) and Late Jurassic (West Burma terrane, Woyla terranes). The northwards drift of these terranes was effected by the opening and closing of three successive Tethys oceans, the Paleo-Tethys, Meso-Tethys and Ceno-Tethys. Terrane assembly took place between the Late Paleozoic and Cenozoic, but the precise timings of amalgamation and accretion are still contentious. Amalgamation of South China and Indochina/East Malaya occurred during the Early Carboniferous along the Song Ma Suture to form “Cathaysialand”. Cathaysialand, together with North China, formed a large continental region within the Paleotethys during the Late Carboniferous and Permian. Paleomagnetic data indicate that this continental region was in equatorial to low northern paleolatitudes which is consistent with the tropical Cathaysian flora developed on these terranes. The Tarim terrane (together with the Kunlun, Qaidam and Ala Shan terranes) accreted to Kazakhstan/Siberia in the Permian. This was followed by the suturing of Sibumasu and Qiangtang to Cathaysialand in the Late Permian-Early Triassic, largely closing the Paleo-Tethys. North and South China were amalgamated in the Late Triassic-Early Jurassic and finally welded to Laurasia around the same time. The Lhasa terrane accreted to the Sibumasu-Qiangtang terrane in the Late Jurassic and the Kurosegawa terrane of Japan, interpreted to be derived from Australian Gondwanaland, accreted to Japanese Eurasia, also in the Late Jurassic. The West Burma and Woyla terranes drifted northwards during the Late Jurassic and Early Cretaceous as the Ceno-Tethys opened and the Meso-Tethys was destroyed by subduction beneath Eurasia and were accreted to proto-Southeast Asia in the Early to Late Cretaceous. The Southwest Borneo and Semitau terranes amalgamated to each other and accreted to Indochina/East Malaya in the Late Cretaceous and the Hainanese terranes probably accreted to South China sometime in the Cretaceous. 相似文献
8.
地震资料显示南海北部中生界发育褶皱和逆冲断层等挤压构造, 但目前对其成因仍存在争议.通过对南海北部珠江口盆地东南部陆坡的二维地震剖面进行研究, 发现在云荔低隆起-兴荔凸起-兴宁凹陷一带存在2条近NW-SE走向并往NE方向逆冲的逆断层, 在东沙隆起南部有2条近南-北走向并具有压扭性质的走滑断层, 上述4条断层的平面延伸距离分别约为130、110、55和58 km.综合分析可知, 现今位于南海南部的礼乐-巴拉望地块经中侏罗世-早白垩世与华南陆缘发生软碰撞后, 在晚白垩世与华南陆缘在现今荔湾-兴宁凹陷一带进行最后的"焊接缝合", 而上述4条断层可作为该次"焊接缝合"的间接证据.由于太平洋向华南的俯冲板片在晚白垩世发生了后撤, 华南大陆边缘在晚白垩世末开始张裂之前可能整体为区域均衡抬升、局部陆-陆碰撞缝合的构造格局. 相似文献
9.
The Black Sea region comprises Gondwana-derived continental blocks and oceanic subduction complexes accreted to Laurasia. The core of Laurasia is made up of an Archaean–Palaeoproterozoic shield, whereas the Gondwana-derived blocks are characterized by a Neoproterozoic basement. In the early Palaeozoic, a Pontide terrane collided and amalgamated to the core of Laurasia, as part of the Avalonia–Laurasia collision. From the Silurian to Carboniferous, the southern margin of Laurasia was a passive margin. In the late Carboniferous, a magmatic arc, represented by part of the Pontides and the Caucasus, collided with this passive margin with the Carboniferous eclogites marking the zone of collision. This Variscan orogeny was followed by uplift and erosion during the Permian and subsequently by Early Triassic rifting. Northward subduction under Laurussia during the Late Triassic resulted in the accretion of an oceanic plateau, whose remnants are preserved in the Pontides and include Upper Triassic eclogites. The Cimmeride orogeny ended in the Early Jurassic, and in the Middle Jurassic the subduction jumped south of the accreted complexes, and a magmatic arc was established along the southern margin of Laurasia. There is little evidence for subduction during the latest Jurassic–Early Cretaceous in the eastern part of the Black Sea region, which was an area of carbonate sedimentation. In contrast, in the Balkans there was continental collision during this period. Subduction erosion in the Early Cretaceous removed a large crustal slice south of the Jurassic magmatic arc. Subduction in the second half of the Early Cretaceous is evidenced by eclogites and blueschists in the Central Pontides and by a now buried magmatic arc. A continuous extensional arc was established only in the Late Cretaceous, coeval with the opening of the Black Sea as a back-arc basin. 相似文献
10.
The Penninic oceanic sequence of the Glockner nappe and the foot-wall Penninic continental margin sequences exposed within the Tauern Window (eastern Alps) have been investigated in detail. Field data as well as structural and petrological data have been combined with data from the literature in order to constrain the geodynamic evolution of these units. Volcanic and sedimentary sequences document the evolution from a stable continent that was formed subsequent to the Variscan orogeny, to its disintegration associated with subsidence and rifting in the Triassic and Jurassic, the formation of the Glockner oceanic basin and its consumption during the Upper Cretaceous and the Paleogene. These units are incorporated into a nappe stack that was formed during the collision between a Penninic Zentralgneis block in the north and a southern Austroalpine block. The Venediger nappe and the Storz nappe are characterized by metamorphic Jurassic shelf deposits (Hochstegen group) and Cretaceous flysch sediments (Kaserer and Murtörl groups), the Eclogite Zone and the Rote Wand–Modereck nappe comprise Permian to Triassic clastic sequences (Wustkogel quartzite) and remnants of platform carbonates (Seidlwinkl group) as well as Jurassic volcanoclastic material and rift sediments (Brennkogel facies), covered by Cretaceous flyschoid sequences. Nappe stacking was contemporaneous to and postdated subduction-related (high-pressure) eclogite and blueschist facies metamorphism. Emplacement of the eclogite-bearing units of the Eclogite zone and the Glockner nappe onto Penninic continental units (Zentralgneis block) occurred subsequent to eclogite facies metamorphism. The Eclogite zone, a former extended continental margin, was subsequently overridden by a pile of basement-cover nappes (Rote Wand–Modereck nappe) along a ductile out-of-sequence thrust. Low-angle normal faults that have developed during the Jurassic extensional phase might have been inverted during nappe emplacement. 相似文献
11.
《International Geology Review》2012,54(5):405-418
A section across a major Tethyan suture in northwestern Turkey is described in detail. The suture of Early Tertiary age juxtaposes two continental blocks with distinct stratigraphic, structural, and metamorphic features. The Sakarya Zone in the north is represented by Permo-Triassic accretion-subduction complexes, which are unconformably overlain by Jurassic to Paleocene sedimentary rocks. The Anatolide-Tauride Block to the south of the suture consists of two tectonic zones. The Tavsanli Zone consists of a coherent blueschist sequence with Late Cretaceous isotopic ages. This blueschist sequence is tectonically overlain by Cretaceous oceanic accretionary complexes and peridotite slabs. The Bornova Flysch Zone consists of Triassic to Cretaceous limestone blocks in an uppermost Cretaceous to Paleocene flysch. The suture is represented by a N-vergent thrust fault separating lithologies from these two continental blocks. The orogenic history of the region can be considered in two stages. In the Late Cretaceous, the northern margin of the Anatolide-Tauride Block was subducted under the Tethyan oceanic lithosphere and was metamorphosed in blueschist-facies conditions. Blueschists were largely exhumed by the latest Cretaceous or early Paleocene, prior to the continental collision. In the second stage, during the Paleocene, the continent-continent collision produced a doubly vergent orogen involving both S- and N-vergent thrusting, but did not lead to major crustal thickening. 相似文献
12.
攀西的结晶基底岩系——康定群,褶皱基底岩系——会理群、昆阳群与北澳大利亚地区一致,是泛冈瓦纳大陆的组成部分。泥盆—二叠纪时期,扬予古陆发生强烈地裂运动,后期扬予古陆向北漂移,导致了它与澳大利亚的分裂,这时攀西不再是一个单纯的内陆裂谷,它发展为原大洋,成为扬予古陆西缘的被动大陆边缘裂谷。二叠纪末它可能与同步向北漂移的羌塘-印支古陆拼合:三叠纪初与华北陆块拼合;于侏罗纪、白垩纪分别与藏北及藏南陆块拼合;喜马拉雅运动,印度板块碰撞,形成了统一的亚洲大陆,本区受造山作用影响,形成广泛的冲断-推覆体构造形体。 相似文献
13.
Analysis of zircons from Australian affinity Permian–Triassic units of the Timor region yield age distributions with large age peaks at 230–400 Ma and 1750–1900 Ma, which are similar to zircon age spectra found in rocks from NE Australia and crustal fragments now found in Tibet and SE Asia. It is likely that these terranes, which are now widely separated, were once part of the northern edge of Gondwana near what is now the northern margin of Australia. The Cimmerian Block rifted from Gondwana in the Early Permian during the initial formation of the Neo-Tethys Ocean. The zircon age spectra of the Gondwana Sequence of NE Australia and in the Timor region are most similar to the terranes of northern Tibet and Malaysia, further substantiating a similar tectonic affinity. A large 1750–1900 Ma zircon peak is also very common in other terranes in SE Asia.Hf analysis of zircon from the Aileu Complex in Timor and Kisar Islands shows a bimodal distribution (both radiogenically enriched and depleted) in the Gondwana Sequence at ~ 300 Ma. The magmatic event from which these zircons were derived was likely bimodal (i.e. mafic and felsic). This is substantiated by the presence of Permian mafic and felsic rocks interlayered with the sandstone used in this study. Similar rock types and isotopic signatures are also found in Permian–Triassic igneous units throughout the Cimmerian continental block.The Permian–Triassic rocks of the Timor region fill syn-rift intra-cratonic basins that successfully rifted in the Jurassic to form the NW margin of Australia. This passive continental margin first entered the Sunda Trench in the Timor region at around 7–8 Ma causing the Permo-Triassic rocks to accrete to the edge of the Asian Plate and emerge as a series of mountainous islands in the young Banda collision zone. Eventually, the Australian continental margin will collide with the southern edge of the Asian plate and these Gondwanan terranes will rejoin. 相似文献
14.
AbstractThe study of the exotic blocks of the Hawasina Nappes (Sultanate of Oman) leads to give apposit data that allow us to propose a new paleogeographic evolution of the Oman margin in time and space. A revised classification of exotic blocks into different paleogeographical units is presented. Two newly introduced stratigraphic groups, the Ramaq Group (Ordovician to Triassic) and the Al Buda’ah Group (upper Permian to Jurassic) are interpreted as tilted blocks related to the Oman continental margin. The Kawr Group (middle Triassic to Cretaceous) is redefined and interpreted as an atoll-type seamount. The paleogeography and paleoenvironments of these units are integrated into a new scheme of the Neotethyan rifting history. Brecciae and olistoliths of the Hawasina series are interpreted to have originated from tectonic movements affecting the Oman margin and the Neotethyan ocean floor. The breccias of late Permian age were generated by the extension processes affecting the margin, and by the creation of the Neotethyan oceanic floor. The breccias of mid-late Triassic age coincide in time with the collision of the Cimmerian continents with Eurasia. In constrast, the breccias of late Jurassic and Cretaceous age are interpreted as resulting to the creation of a new oceanic crust (Semail) off the Oman margin. 相似文献
15.
博格达山地区二叠纪以来构造应力场解析及地质意义 总被引：1，自引：0，他引：1
博格达山是现代地质学研究的一个热点,但是大部分研究都集中在博格达何时隆升,对于其构造应力场的研究较少。作者通过对博格达山地区不同时代地层中岩墙、节理、褶皱和断层等构造进行分期配套以及构造要素测量分析,认为二叠纪以来博格达山及周缘地区具有较强构造变形,构造应力场可划分为3期:二叠纪末期最大主压应力方向为北西西向,可能与后碰撞伸展作用和乌拉尔碰撞带向东挤压的远程效应有关;侏罗纪末-早白垩世最大主压应力为近南北向,与欧亚板块和拉萨地块的碰撞有关;新近纪以来由于印度板块与欧亚板块相互碰撞的远程效应,博格达山地区最大主应力方向为NNE-NE向。这些结果表明,博格达山具有多期次的构造运动,主要受欧亚板块南缘不同时期小陆块碰撞的控制,并且这些构造应力场对周缘盆地油气成藏具有一定影响。 相似文献
16.
Mesozoic Granitoid Types and Metallogeny of the East China Circum-Pacific Continental Margin 总被引：3，自引：0，他引：3
Jinchu ZHU 《Resource Geology》1998,48(4):265-273
Abstract: This paper synthesizes the geotectonic background, genetic types and metallogenetic relations of the Mesozoic granitoids in the East China continental margin. By the Mesozoic, the Siberia Plate, North China Plate and South China Plate amalgamated together, resulting in formation of a unified Eurasia super–continent. Since the late Triassic to early Jurassic period, the territory of East China gradually became a Cordilleran style active continental margin. During the Jurassic to early Cretaceous (early to middle episodes of Yanshanian orogeny), the Paleo-Pacific plate strongly collided with and subducted under the Eurasia continent, reactivated the consolidated East China continental margin. The granitoids of both transformation series and syntexis series were generated. Many granitoid-related large and giant metal deposits were formed. Furthermore, the W, Sn, Be, Nb, Ta and U mineralizations are mostly associated with the transformation series; while the Fe, Cu, Mo and Au mineralizations are mostly associated with the syntexis series. The late Yanshanian orogeny (late Cretaceous) began a transition to the western Pacific style continental margin. A tensional environment resulted in development of alkaline granitoids and formation of continental red basins. The Cenozoic orogeny was characterized by a backarc spreading and rifting regime in this region. 相似文献
17.
《Gondwana Research》2014,25(3-4):1237-1266
The Cimmerian orogen resulted from the collision and accretion of several Perigondwanan blocks to the southern margin of Eurasia between the Late Triassic and Early Jurassic, following the closure of the Palaeotethys ocean. Remnants of this orogen discontinuously crop out in N (Alborz range) and NE Iran (Mashhad–Fariman area) below the syn- to post-collisional clastic successions of the Shemshak Group (Upper Triassic–Middle Jurassic) and the Kashaf Rud Formation (Bajocian). In NE Iran rock associations exposed in the Binalood Mountains, Fariman and Darreh Anjir areas include mafic–ultramafic intrusive rocks, basalts, silicoclastic turbidites and minor limestones, which have been interpreted in the past as ophiolitic remnants of the Palaeotethys ocean. Original stratigraphic, structural, geochemical and geochronological data, described in this paper, suggest a different interpretation. The volcano-sedimentary units of Fariman and Darreh Anjir complexes where deposited during Permian in a subsiding basin were siliciclastic turbidites, derived from the erosion of a magmatic arc and its basement, interfinger with carbonates and basaltic lava flows with both transitional and calc-alkaline affinity. The coexistence of magmatic rocks with different geochemical signature and the sedimentary evolution of the basin can be related to a supra-subduction setting, possibly represented by a fault-controlled intra-arc basin. The Fariman and the Darreh Anjir complexes are thus interpreted as remnants of a magmatic arc and related basins developed at the southern Eurasia margin, on top of the north-directed Palaeotethys subduction zone long before the collision of Iran with Eurasia. They were later involved in the Cimmerian collision during the Triassic. New radiometric ages obtained on I-type post-collisional granitoids postdating the collision-related deformational structures suggest that the suture zone closed before mid-Norian times. Deformation propagated later northward into the Turan domain involving the Triassic successions of the Aghdarband region. 相似文献
18.
Shelf, forereef and basin margin (slope) olistoliths (Exotic blocks of limestone) of Permian–Jurassic age are tectonically juxtaposed within the Triassic to Eocene age pre-orogenic, deep abyssal plain turbidites of the Lamayuru. The pre-collision tectonic setting and depositional environment of the limestone olistoliths can be reconstructed from within the neighbouring Zanskar range. The disorganized Ophiolitic Melange Zone, an association of different tectonic rock slivers of Jurassic–Eocene age, is tectonically underlain by the overthrusted Lamayuru Formation and tectonically overlain by the Nindam Formation. Tectonic slivers of Late Jurassic–Early Cretaceous age red radiolarian cherts represent a characteristic lithotectonic unit of the Ophiolitic Melange Zone, those occurring near the contact zone with the Lamayuru Formation, were deposited within the neo-Tethyan deep-ocean floor of the Indian passive margin below the carbonate compensation depth. These tectonic slivers accumulated along the northern margin of the Indus–Yarlung Suture Zone of the Ladakh Indian Himalaya during subduction accretion associated with the initial convergence of the Indian plate beneath the Eurasian plate. 相似文献
19.
Palaeozoic collisional tectonics and magmatism of the Chinese Tien Shan, central Asia 总被引：31，自引：0，他引：31
The Chinese Tien Shan range is a Palaeozoic orogenic belt which contains two collision zones. The older, southern collision accreted a north-facing passive continental margin on the north side of the Tarim Block to an active continental margin on the south side of an elongate continental tract, the Central Tien Shan. Collision occurred along the Qinbulak-Qawabulak Fault (Southern Tien Shan suture). The time of the collision is poorly constrained, but was probably in in the Late Devonian-Early Carboniferous. We propose this age because of a major disconformity at this time along the north side of the Tarim Block, and because the Youshugou ophiolite is imbricated with Middle Devonian sediments. A younger, probably Late Carboniferous-Early Permian collision along the North Tien Shan Fault (Northern Tien Shan suture) accreted the northern side of the Central Tien Shan to an island arc which lay to its north, the North Tien Shan arc. This collision is bracketed by the Middle Carboniferous termination of arc magmatism and the appearance of Late Carboniferous or Early Permian elastics in a foreland basin developed over the extinct arc. Thrust sheets generated by the collision are proposed as the tectonic load responsible for the subsidence of this basin. Post-collisional, but Palaeozoic, dextral shear occurred along the northern suture zone, this was accompanied by the intrusion of basic and acidic magmas in the Central Tien Shan. Late Palaeozoic basic igneous rocks from all three lithospheric blocks represented in the Tien Shan possess chemical characteristics associated with generation in supra-subduction zone environments, even though many post-date one or both collisions. Rocks from each block also possess distinctive trace element chemistries, which supports the three-fold structural division of the orogenic belt. It is unclear whether the chemical differences represent different source characteristics, or are due to different episodes of magmatism being juxtaposed by later dextral strike-slip fault motions. Because the southern collision zone in the Tien Shan is the older of the two, the Tarim Block sensu stricto collided not with the Eurasian landmass, but with a continental block which was itself separated from Eurasia by at least one ocean. The destruction of this ocean in Late Carboniferous-Early Permian times represented the final elimination of all oceanic basins from this part of central Asia. 相似文献
20.
《Journal of Asian Earth Sciences》2003,21(4):397-412
The Sanandaj–Sirjan Zone contains the metamorphic core of the Zagros continental collision zone in western Iran. The zone has been subdivided into the following from southwest to northeast: an outer belt of imbricate thrust slices (radiolarite, Bisotun, ophiolite and marginal sub-zones, which consist of Mesozoic deep-marine sediments, shallow-marine carbonates, oceanic crust and volcanic arc, respectively) and an inner complexly deformed sub-zone (late Palaeozoic–Mesozoic passive margin succession). Rifting and sea-floor spreading of Tethys occurred in the Permian to Triassic but in the Sanandaj–Sirjan Zone extension-related successions are mainly of Late Triassic age. Subduction of Tethyan sea floor in the Late Jurassic to Cretaceous produced deformation, metamorphism and unconformities in the marginal and complexly deformed sub-zones. Deformation climaxed in the Late Cretaceous when a major southwest-vergent fold belt formed associated with greenschist facies metamorphism and post-dated by abundant Palaeogene granitic plutons. In the southwest of the zone a Late Cretaceous island arc—passive margin collision occurred with ophiolite emplacement onto the northern Arabian margin similar to that in Oman. Final closure of Tethys was not completed until the Miocene when Central Iran collided with the northeast Arabian margin. 相似文献