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1.
V. A. Vernikovsky D. V. Metelkin T. Yu. Tolmacheva N. A. Malyshev O. V. Petrov N. N. Sobolev N. Yu. Matushkin 《Doklady Earth Sciences》2013,451(2):791-797
The New Siberian Islands terrane, represented on the Arctic shelf by the archipelagos of the New Siberian Islands and De Long Islands, is one of the key structures of the Arctic. However many questions of its structure, borders and formation history are under intense discussion. During the international expedition in 2011 we solved many problems concerning structural geology, paleontology, petrology and geochronology. A particular attention was given to obtaining paleomagnetic data for the sedimentary and igneous rocks of the archipelago. The primary objects of paleomagnetic studies were the Early Paleozoic sedimentary rocks of the Kotelny (Anzhu) and Bennett (De Long) islands. In this paper we present new paleontological data, including the first one for conodonts of the New Siberian Islands, which help us to specify the age of the Early Paleozoic deposits of the studied sections. In these sections we took a series of paleomagnetic samples. The match of the paleomagnetic directions we determined for Bennett Isl. and Kotelny Isl. indicates the tectonic unity between the territories of the Anzhu and De Long archipelagos. These first paleomagnetic data allow us to affirm that at least from the Early Ordovician the rocks of the Anzhu and De Long archipelagos formed within the same New Siberian Islands terrane, that is to say, on the same basement. 相似文献
2.
V.A. Vernikovsky N.L. Dobretsov D.V. Metelkin N.Yu. Matushkin I.Yu. Koulakov 《Russian Geology and Geophysics》2013,54(8):838-858
The particularities of the current tectonic structure of the Russian part of the Arctic region are discussed with the division into the Barents–Kara and Laptev–Chukchi continental margins. We demonstrate new geological data for the key structures of the Arctic, which are analyzed with consideration of new geophysical data (gravitational and magnetic), including first seismic tomography models for the Arctic. Special attention is given to the New Siberian Islands block, which includes the De Long Islands, where field work took place in 2011. Based on the analysis of the tectonic structure of key units, of new geological and geophysical information and our paleomagnetic data for these units, we considered a series of paleogeodynamic reconstructions for the arctic structures from Late Precambrian to Late Paleozoic. This paper develops the ideas of L.P. Zonenshain and L.M. Natapov on the Precambrian Arctida paleocontinent. We consider its evolution during the Late Precambrian and the entire Paleozoic and conclude that the blocks that parted in the Late Precambrian (Svalbard, Kara, New Siberian, etc.) formed a Late Paleozoic subcontinent, Arctida II, which again “sutured” the continental masses of Laurentia, Siberia, and Baltica, this time, within Pangea. 相似文献
3.
《Russian Geology and Geophysics》2007,48(2):167-176
The study was inspired by information on Paleozoic andesites, dacites, and diabases in Bel'kov Island in the 1974 geological survey reports used to reconstruct the tectonic evolution of the continental block comprising the New Siberian Islands and the bordering shelf. We did not find felsic volcanics or Middle Paleozoic intrusions in the studied area of the island. The igneous rocks are mafic subvolcanic intrusions, including dikes, randomly shaped bodies, explosion breccias, and peperites. They belong to the tholeiitic series and are similar to Siberian traps in petrography and trace-element compositions, with high LREE and LILE and prominent Nb negative anomalies. The island arc affinity is due to continental crust contamination of mantle magma and its long evolution in chambers at different depths. The 252±5 Ma K-Ar biotite age of magmatism indicates that it was coeval to the main stage of trap magmatism in the Siberian craton at the Permian-Triassic boundary. The terrane including the New Siberian Islands occurred on the periphery of the Siberian trap province where magmatism acted in a rifting environment. Magma intruded semiliquid wet sediments at shallow depths, shortly after their deposition. Therefore, the exposed Paleozoic section in Bel’kov Island may include Permian or possibly Lower Triassic sediments, of younger ages than it was believed earlier. 相似文献
4.
A. I. Zhdanova D. V. Metelkin V. A. Vernikovsky N. Yu. Matushkin 《Doklady Earth Sciences》2016,468(2):580-583
The first paleomagnetic data on dolerite dikes from the volcanogenic–sedimentary section of Jeannette Island (De Long Archipelago, New Siberian Islands) are discussed. The petromagnetic data and results of the baked contact and fold tests are used to substantiate the nature of the characteristic magnetization component, which in combination with the 40Ar/39Ar dates implies its likely Late Precambrian–Early Paleozoic age. The calculated paleomagnetic pole makes it possible to extend the trajectory of the apparent polar movement for the New Siberian Islands block and confirms the assumption that this structural element of the Arctic shelf evolved as a terrane. Two variants of paleotectonic interpretation of the obtained data and their consistency with the available data on the geology and tectonics of the New Siberian Islands are considered. 相似文献
5.
The vast Laptev and East Siberian shelves in the eastern Russian Arctic, largely covered by a shallow sea and buried beneath sea ice for 9 months of the year, remain one of the least studied parts of continental crust of the Earth and represent a big unknown when performing pre-Cenozoic reconstructions of the Arctic. The De Long Islands provide an important window into the geology of this area and are a key for understanding the Early Paleozoic history of the Amerasian Arctic. Four of them (Jeannette, Henrietta, Bennett and Zhokhov islands) were studied using structural data, petrographic and geochemical analyses and U–Pb zircon age dating to offer the following new constraints for the Early Paleozoic paleogeography of the Arctic realm. The basement beneath the De Long Islands is of Late Neoproterozoic to earliest Cambrian age, about 670–535 Ma. In the Early Paleozoic, the De Long Islands were located along the broad Timanian margin of Baltica, with a clastic sediment provenance from the Timanian, Grenville–Sveconorwegian, and Baltic Shield domains. The Cambro-Ordovician volcaniclastic successions on Jeannette and Henrietta islands formed part of a continental volcanic arc with a corresponding back-arc basin located to the south (in present co-ordinates). On the continent-ward side of the back-arc basin, shallow marine shelf clastic and carbonate rocks were deposited, which are exposed today on Bennett Island in the south-west of the archipelago (in modern coordinates). The De Long Islands together with other continental blocks, such as Severnaya Zemlya, Arctic Alaska–Chukotka, and the Alexander Terrane, formed the contiguous active continental margin of Baltica during the Early Paleozoic. Today however, these terranes are spread out over a distance of 5000 km across the Arctic and eastern Pacific margins due to the subsequent opening of a series of Late Paleozoic, Mesozoic and Cenozoic oceanic basins. 相似文献
6.
D.P. Gladkochub T.V. Donskaya V.S. Fedorovsky A.M. Mazukabzov A.N. Larionov S.A. Sergeev 《Russian Geology and Geophysics》2010,51(5):447-460
We report data from the Khadarta, Khoboi, and Orso metamorphic complexes of the Olkhon terrane in the western Baikal region. High-grade rocks in the three complexes may have been derived from active continental margin rocks (island arc–backarc basin system). The backarc basin history possibly began at 840–800 Ma, according to SHRIMP-II U-Pb zircon ages of the Orso gneiss. Many tectonic units in the Olkhon terrane belonged to the active margin of the Barguzin microcontinent which rifted off the Aldan province of the Siberian craton in the early Neoproterozoic. The accretion of the microcontinent to the craton was accompanied by high-grade metamorphism recorded in the Khadarta and Khoboi granulites. The 507 ± 8 Ma and 498 ± 7 Ma SHRIMP-II U-Pb zircon ages of the latter complexes, respectively, may refer to the earliest evolution stage of the Olkhon metamorphic terrane. New data for the Olkhon terrane agree well with the ages of other high-grade complexes along the southern Siberian craton (Slyudyanka, Kitoikin, Derba) and correspond to the initiation of the Central Asian orogen. With these data, the Olkhon metamorphic terrane has been interpreted as an Early Paleozoic collisional collage of fragments of the microcontinent’s Neoproterozoic active margin. 相似文献
7.
Arctic Alaska is a ‘suspect’ terrane that encompasses approximately 20% of Alaska, stretching from the southern Brooks Range all the way to the continental shelves of the Chukchi and Beaufort Seas. Although the origin and subsequent travels of this large crustal fragment are debated among geologists, most researchers agree upon its composite nature and exotic origin. To constrain the early geological history of this terrane, we describe a recent expedition to the Doonerak fenster of the central Brooks Range. This area has long been regarded as a key locality for understanding the structural evolution of the Mesozoic–Cenozoic Brooks Range orogen; however, our target was different: a unique sequence of volcanic and siliciclastic rocks (Apoon assemblage) exposed beneath a profound pre-Mississippian unconformity, which we argue is of key importance to understanding the early Paleozoic tectonic history of northern Alaska and the greater Arctic. 相似文献
8.
A. I. Chernova D. V. Metelkin V. A. Vernikovsky N. Yu. Matushkin 《Doklady Earth Sciences》2018,481(1):847-851
This study demonstrates rock-magnetic and paleomagnetic investigations of Devonian and Mesozoic deposits of Kotelny, Stolbovoy, and Great Lyakhovsky islands. The results indicate that local remagnetization took place on the southwestern periphery on the archipelago of the New Siberian Islands. A comparison of new data with the apparent polar wander path for Siberia shows that the remagnetization happened during collisional events between 140 and 80 Ma and affected only the marginal part of the terrane of the New Siberian Islands that was directly facing the deformation front. The consistent younging of the remagnetization age from the south to the north indicates dextral rotation of the terrane of the New Siberian Islands during its collision with Siberia. 相似文献
9.
The archipelago of New Siberian Islands situated on the northeastern continental shelf of Eurasia is considered a part of an exotic terrane that collided with Siberia in the Early Cretaceous. Bel’kov Island is located close to the inferred western boundary of this terrane and thus should demonstrate attributes of its localization at the margin of the Paleozoic oceanic basin. The Upper Devonian section on Bel’kov Island is a continuous sequence of deepwater terrigenous rocks, which indicates a tendency toward deepening of the basin previously revealed on adjacent Kotel’ny Island. The lowermost Upper Devonian unit on Bel’kov Island is represented by thin Domanik-like strata resting on the Middle Devonian carbonate platform. The main body of the Upper Devonian sequence, more than 4 km in total thickness, is made up of gravity-flow sediments including turbidites, clay and block diamictites, and olistostromes in the upper part of the section, which accumulated at the slope of the basin or its rise. At many levels, these sediments have been redeposited by along-slope currents. The uppermost unit of organogenic limestone is evidence for compensation of the trough. According to conodont assemblages, the deepwater terrigenous rocks were deposited from the early Frasnian to the early Tournaisian. This time is known for extensive rifting in the eastern Siberian Platform. The data obtained allowed us to reconstruct a NNW-trending Late Devonian rift basin on the Laptev Sea shelf similar to other rifts at the eastern margin of the Siberian Platform. 相似文献
10.
11.
新疆北部古生代大陆增生构造 总被引：35，自引：2，他引：35
古生代亚洲中部是一幅两陆夹一洋、洋中多地体的构造图案，大地构造框架与现代西南太平洋格局十分相似。中亚造山带是晚古生代复杂地体的拼贴带。新疆北部古生代存在4类成因的8个地体构造。它们以裂解陆块地层块体、海山和火山弧的形式散布在中蒙大洋中，诸地体间是一系列的小洋盆。晚古生代，这些地体开始彼此拼贴并导致强烈推覆作用。石炭纪末－二叠纪初，中蒙大洋闭合，散布其中的诸地体分别增生到塔里木大陆北缘和西伯利亚大陆南缘。北天山－准噶尔地区6条蛇绿岩带记录了诸地体间碰撞事件。 相似文献
12.
The Vendian (Baikalian), Late Devonian (Ellesmerian), and Mid-Cretaceous (Brookian) orogenies were three cardinal events in the history of formation and transformation of the continental crust in the eastern Arctic region. The epi-Baikalian Hyperborean Craton was formed by the end of the Vendian (660–550 Ma), when the Archean-Proterozoic Hyperborean continental block was built up by the Baikalian orogenic belt and concomitant collision granitoids. As judged from the localization of deepwater facies, the Early Paleozoic ocean occupied the western part of the Canadian Arctic Archipelago, western Alaska, and the southern framework of the Canada and Podvodnikov basins and was connected with the Iapetus ocean. The closure of the Early Paleozoic Arctic basins is recorded in two surfaces of structural unconformities corresponding to the pre-Middle Devonian Scandian orogenic phase and the Late Devonian Ellesmerian Orogeny; each tectonic phase was accompanied by dislocations and metamorphism. The Ellesmerian collision was crucial in the Caledonian tectogenesis. The widespread Late Devonian-Mississippian rifting probably was a reflection of postorogenic relaxation. As a result, the vast epi-Caledonian continental plate named Euramerica, or Laurussia, was formed at the Devonian-Carboniferous boundary. The East Arctic segment of this plate is considered in this paper. In the Devonian, the Angayucham ocean, which was connected with the Paleoasian and Uralian oceans [62], separated this plate from the Siberian continent. The South Anyui Basin most likely was a part of this Paleozoic oceanic space. The shelf sedimentation on the epi-Caledonian plate in the Carboniferous and Permian was followed by subsidence and initial rifting in the Triassic and Jurassic, which further gave way to the late Neocomian-early Albian spreading in the Canada Basin that detached the Chukchi Peninsula-Alaska microplate from the continental plate [25]. The collision of this microplate with the Siberian continent led to the closure of the South Anyui-Angayucham ocean and the development of the Mid-Cretaceous New Siberian-Chukchi-Brooks Orogenic System that comprised the back Chukchi Zone as a hinterland and the frontal New Siberian-Wrangel-Herald-Lisburne-Brooks Thrust Zone as a foreland; the basins coeval with thrusting adjoined the foreland. Collision started in the Late Jurassic; however, the peak of the orogenic stage fell on the interval 125–112 Ma, when ophiolites had been obducted on the margin of the Chukchi Peninsula-Alaska microplate along with folding and thrusting accompanied by an increase in the crust’s thickness, amphibolite-facies metamorphism, and growth of granite-gneiss domes. The magmatic diapir of the De Long Arch that grew within the continental plate in the Mid-Cretaceous reflected a global pulse of the lower mantle upwelling that coincided with the maximum opening of the Canada Basin. The present-day appearance of the eastern Arctic region arose in the Late Mesozoic and Cenozoic owing to the opening of the Amerasia and Eurasia oceans. Sedimentary basins of various ages and origins—including the Late Devonian-Early Carboniferous grabens, the spatially coinciding Late Jurassic-Early Cretaceous rifts related to the opening of the Canada Basin, the syncollision basins in front of the growing orogen, and the Cretaceous-Cenozoic basins coeval with strike-slip faulting and rifting at the final stages of orogenic compression and during the opening of the Eurasia ocean were telescoped on sea shelves. 相似文献
13.
Inna Safonova 《地学前缘(英文版)》2014,5(4):537-552
The paper reviews previous and recently obtained geological, stratigraphic and geochronological data on the Russian-Kazakh Altai orogen, which is located in the western Central Asian Orogenic Belt （CAOB）, between the Kazakhstan and Siberian continental blocks. The Russian-Kazakh Altai is a typical Pacific-type orogen, which represents a collage of oceanic, accretionary, fore-arc, island-arc and continental margin terranes of different ages separated by strike-slip faults and thrusts. Evidence for this comes from key indicative rock associations, such as boninite- and turbidite （graywacke）-bearing volcanogenic-sedimentary units, accreted pelagic chert, oceanic islands and plateaus, MORB-OIB-protolith blueschists. The three major tectonic domains of the Russian-Kazakh Altai are： （1） Altai-Mongolian terrane （AMT）; （2） subduction-accretionary （Rudny Altai, Gorny Altai） and collisional （Kalba-Narym） terranes; （3） Kurai, Charysh-Terekta, North-East, Irtysh and Char suture-shear zones （SSZ）. The evolution of this orogen proceeded in five major stages： （i） late Neoproterozoic-early Paleozoic subduction-accretion in the Paleo-Asian Ocean; （ii） Ordovician-Silurian passive margin; （iii） Devonian-Carboniferous active margin and collision of AMT with the Siberian conti- nent; （iv） late Paleozoic closure of the PAO and coeval collisional magmatism; （v） Mesozoic post-collisional deformation and anarogenic magmatism, which created the modern structural collage of the Russian- Kazakh Altai orogen. The major still unsolved problem of Altai geology is origin of the Altai-Mongolian terrane （continental versus active margin）, age of Altai basement, proportion of juvenile and recycled crust and origin of the middle Paleozoic units of the Gorny Altai and Rudny Altai terranes. 相似文献
14.
The structure and geodynamic history of the northern Barents–Kara continental margin, which had formed mostly by the latest Paleozoic, have been investigated using offshore geological and geophysical data and geological evidence from adjacent landmasses. In the context of the suggested model, the Saint Anna trough is interpreted as a boundary tectonic element between the Svalbard and Kara plates. Thus, the study focuses on a complex tectonic node with its structure having implications for the trough origin, as well as for the history of geodynamic relations among Arctic cratons and microplates. Trough structures of different ages in the area, including the northeastern East Barents trough and the St. Anna trough, appear to be a zone of triple or T-shaped junction. The reported reconstruction of the trough system history since the Middle Paleozoic shows that the St. Anna trough joined the East-Barents system in the Late Permian–Triassic to become its new segment extending the system to the north. 相似文献
15.
柴北缘超高压变质带作为中国西部深俯冲的一个研究热点,对其变质泥质岩的碎屑锆石年龄研究对了解此区内深俯冲大陆的前寒武纪演化历史,及与华北克拉通及华南克拉通的亲缘性讨论具有重要意义。本文选取柴北缘超高压变质带中绿梁山和都兰的变质泥质岩,筛选锆石利用LA-ICP-MS进行定年并讨论其地质意义。实验结果表明碎屑锆石年龄分为三个组别集中,分别是1100Ma、1000~800Ma和800~500Ma,并分别代表了古老的结晶基底、与Rodinia超大陆相关的碰撞和裂解事件以及古祁连洋的演化。板块亲缘性分析表明柴达木-祁连地区可能与扬子克拉通西缘具有亲缘性,可能作为扬子克拉通西缘的延伸而与扬子克拉通相连。通过结合碎屑锆石数据及板块亲缘性分析并对比现今西太平洋边缘的演化模式,本文提出了一个在早古生代北祁连为主动大陆边缘,柴北缘为被动大陆边缘;在祁连地体北侧的古祁连洋闭合后柴北缘转变为主动大陆边缘的构造演化模式。 相似文献
16.
《International Geology Review》2012,54(11):1058-1066
The plate-tectonic evolution of the Tarim basin and nearby western Tianshan region during Paleozoic time is reconstructed in an effort to further constrain the tectonic evolution of Central Asia, providing insights into the formation and distribution of oil and gas resources. The Tarim plate developed from continental rifting that progressed during early Paleozoic time into a passive continental margin. The Yili terrane (central Tianshan) broke away from the present eastern part of Tarim and became a microcontinent located somewhere between the Junggar ocean and the southern Tianshan ocean. The southern Tianshan ocean, between the Tarim craton and the Yili terrane, was subducting beneath the Yili terrane from Silurian to Devonian time. During the Late Devonian-Early Carboniferous, the Tarim plate collided with the Yili terrane by sinistral accretional docking that resulted in a late Paleozoic deformational episode. Intracontinental shortening (A-type subduction) continued through the Permian with the creation of a magmatic belt. 相似文献
17.
In this paper we present new paleomagnetic and paleontological data from the Ordovician and Silurian carbonate rocks of Kotelny Island (the Anjou Archipelago), and from the Ordovician turbidities of Bennett Island (the De Long Archipelago). It is assumed that both archipelagos belong to the NSI (New Siberian Islands) terrane — a key tectonic element in the Arctic region. Ages of the studied rocks have been established by paleontological data and lithological correlations. Our new data on conodonts combined with those from previous studies of Ordovician and Silurian fauna indicate a biogeographic similarity between the shelves of the Siberian paleocontinent and the NSI in the Early Paleozoic. Three new paleomagnetic poles for the NSI (48.9°N, 13.8°E, A95 = 18.1° for 475 Ma; 45.5°N, 31.9°E, A95 = 11.0° for 465 Ma, and 33.7°N, 55.7°E, A95 = 11.0° for 435 Ma) fall between the south-eastern part of Central Europe and the Zagros Mountains. The similarity of paleomagnetic directions from Kotelny and Bennet islands confirms that both the Anjou and De Long archipelagos belong to the same terrane. Calculated paleolatitudes indicate that in Ordovician–Silurian times this terrane has been located between 30° and 45°, possibly in the northern hemisphere. Based on this observation, we suggest a linkage between the NSI and the Kolyma–Omolon superterrane. Comparison of apparent polar wander paths (APWPs) of the NSI, Siberia and other cratons/terranes suggests that the NSI drifted independently. We demonstrate that the structural line between Svyatoy Nos Peninsula and Great Lyakhovsky Island is the continuation of the Kolyma Loop suture on the Arctic shelf, and expect that the continuation of the South Anyui suture is to be found east of the NSI. 相似文献
18.
19.
新疆库米什变质地体研究 总被引：1，自引：0，他引：1
新疆库米什地区的变质杂岩,过去曾被认为是泥盆系地层和海西期花岗岩体。本文研究表明,该杂岩体的诸方面特征与其周围古生代岩块存在明显差异,而与塔里木克拉通北缘库鲁克塔格地区的托格拉克布拉克群可以对比。实际上,库米什变质杂岩并非泥盆系地层和海西期花岗岩体。而是天山造山带中的前寒武纪变质地体,是因弧后扩张从塔里木克拉通北缘裂解出来的大陆碎块。 相似文献
20.
《Gondwana Research》2014,25(1):170-189
The Lhasa terrane in southern Tibet is composed of Precambrian crystalline basement, Paleozoic to Mesozoic sedimentary strata and Paleozoic to Cenozoic magmatic rocks. This terrane has long been accepted as the last crustal block to be accreted with Eurasia prior to its collision with the northward drifting Indian continent in the Cenozoic. Thus, the Lhasa terrane is the key for revealing the origin and evolutionary history of the Himalayan–Tibetan orogen. Although previous models on the tectonic development of the orogen have much evidence from the Lhasa terrane, the metamorphic history of this terrane was rarely considered. This paper provides an overview of the temporal and spatial characteristics of metamorphism in the Lhasa terrane based mostly on the recent results from our group, and evaluates the geodynamic settings and tectonic significance. The Lhasa terrane experienced multistage metamorphism, including the Neoproterozoic and Late Paleozoic HP metamorphism in the oceanic subduction realm, the Early Paleozoic and Early Mesozoic MP metamorphism in the continent–continent collisional zone, the Late Cretaceous HT/MP metamorphism in the mid-oceanic ridge subduction zone, and two stages of Cenozoic MP metamorphism in the thickened crust above the continental subduction zone. These metamorphic and associated magmatic events reveal that the Lhasa terrane experienced a complex tectonic evolution from the Neoproterozoic to Cenozoic. The main conclusions arising from our synthesis are as follows: (1) The Lhasa block consists of the North and South Lhasa terranes, separated by the Paleo-Tethys Ocean and the subsequent Late Paleozoic suture zone. (2) The crystalline basement of the North Lhasa terrane includes Neoproterozoic oceanic crustal rocks, representing probably the remnants of the Mozambique Ocean derived from the break-up of the Rodinia supercontinent. (3) The oceanic crustal basement of North Lhasa witnessed a Late Cryogenian (~ 650 Ma) HP metamorphism and an Early Paleozoic (~ 485 Ma) MP metamorphism in the subduction realm associated with the closure of the Mozambique Ocean and the final amalgamation of Eastern and Western Gondwana, suggesting that the North Lhasa terrane might have been partly derived from the northern segment of the East African Orogen. (4) The northern margin of Indian continent, including the North and South Lhasa, and Qiangtang terranes, experienced Early Paleozoic magmatism, indicating an Andean-type orogeny that resulted from the subduction of the Proto-Tethys Ocean after the final amalgamation of Gondwana. (5) The Lhasa and Qiangtang terranes witnessed Middle Paleozoic (~ 360 Ma) magmatism, suggesting an Andean-type orogeny derived from the subduction of the Paleo-Tethys Ocean. (6) The closure of Paleo-Tethys Ocean between the North and South Lhasa terranes and subsequent terrane collision resulted in the formation of Late Permian (~ 260 Ma) HP metamorphic belt and Triassic (220 Ma) MP metamorphic belt. (7) The South Lhasa terrane experienced Late Cretaceous (~ 90 Ma) Andean-type orogeny, characterized by the regional HT/MP metamorphism and coeval intrusion of the voluminous Gangdese batholith during the northward subduction of the Neo-Tethyan Ocean. (8) During the Early Cenozoic (55–45 Ma), the continent–continent collisional orogeny has led to the thickened crust of the South Lhasa terrane experiencing MP amphibolite-facies metamorphism and syn-collisional magmatism. (9) Following the continuous continent convergence, the South Lhasa terrane also experienced MP metamorphism during Late Eocene (40–30 Ma). (10) During Mesozoic and Cenozoic, two different stages of paired metamorphic belts were formed in the oceanic or continental subduction zones and the middle and lower crust of the hanging wall of the subduction zone. The tectonic imprints from the Lhasa terrane provide excellent examples for understanding metamorphic processes and geodynamics at convergent plate boundaries. 相似文献