首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 828 毫秒
1.
Tectonic Evolution of the Himalayan Collision Belt   总被引：5，自引：0，他引：5  
This paper discusses the tectonic divisions of the Himalayan collision belt anddeals with the tectonic evolution of the collision belt in the context of crustal accretion in thefront of the collision belt, deep diapirism and thermal-uplift extension and deep material flow-ing of the lithosphere-backflowing. Finally it proposes a model of the tectonic evolution-progressive intracontinental deformation model-of the Himalayan belt.  相似文献   

2.
<正>Objective The tectonic characteristics and evolution of the Paleoproterozoic Jiao-Liao-Ji belt have been extensively studied in recent decades(Fig.1 a).Two main models have been proposed for the formation of this belt:a continental-or arc-continent collisional belt,and the opening and closure of an intra-continental rift.The main reasons for these ongoing debates are own to the complex composition,including metamorphosed volcano-sedimentary rocks,multiple pulses of granitic magmatism,meta-mafic intrusions,and tectonometamorphic history.In addition,earlier work focused on the geochronology and metamorphic evolution,whereas the  相似文献   

3.
A series of tectonites were formed in the shear zone array of the Tongbai--Dabie Orogenic Belt, including mylonites, blastomylonites, semi--plastic mylonites and foliated cataclasitesas a result of multiple strain localization, strain softening and deformation partitioning.  相似文献   

4.
A Metallogenic Model of Gold Deposits of the Jiaodong Granite-Greenstone Belt   总被引：34，自引：0，他引：34  
An analysis of trace elements and isotopic geochemistry suggest that the ore-forming materials of gold deposits in the Jiaodong granite-greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust-mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono-metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean-Proterozoic-the embryonic form of Au-source system; (2) stable tectonic setting in the Paleozoic-an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic-tectono-mineralization and tectono-diagensis; (4) posthumous structural activity in the Cenozoic-destruction of orebodies in the later stage. In the middle and late Ind  相似文献   

5.
Based on fission track dating of apatite, and measurement of vitrinite reflectance of rock samples from the Longmenshan (Longmen Mountain)area and the West Sichuan foreland basin and computer modelling it is concluded that (l)the Songpan-Garze fold belt has uplifted at least by 3-4 km with an uplift rate of no less than 0.3-0.4 mm/a since 10 Ma B.P.; (2) the Longmenshan thrust nappe belt has uplifted at least by 5-6 km with an uplift rate of more than 0.5- 0.6 mm /a since 10 Ma B.P.; (3) the Longmenshan detachment belt has uplifted by 1 - 2 km at a rate of 0.016-0.032 mm/a since 60 Ma B.P.; (4) the West Sichuan foreland basin has uplifted by 1.7-3 km at a rate of 0.028-0.05 mm/a since 60 Ma B.P.; (5) the uplift rate of the area on the west side of the Beichuan-Yingxiu-Xiaoguanzi fault for the last 10 Ma is 40 times as much as that on its east side; (6) the uplifting of the the Songpan - Garze fold belt and the subsidence of the West Sichuan foreland basin 60 Ma ago exhibit a mirro-image correlation, i.e  相似文献   

6.
International Journal of Earth Sciences - In order to better constrain the evolution of the Xing’an-Mongolia Orogenic Belt and the resulting closure of the Paleo-Asian Ocean, we conducted an...  相似文献   

7.
Coesite was discovered as inclusions in zircon separates from pelitic gneiss associated with a large eclogite body in the North Qaidam ultrahigh-pressure (UHP) terrane. Some graphite inclusions were also found. This finding suggested the occurrence of in-situ UHP metamorphism and that the terrane was most likely recrystallized at pressures below the diamond stability field. It supported other previous indirect UHP evidence, such as polycrystalline quartz inclusions in eclogitic garnet, quartz lamellae in omphacite and P-T estimates for both eclogite and garnet peridotite. The U-Pb and Sm-Nd ages of the North Qaidam eclogite indicated that subduction of continental crust occurred in the Early Palaeozoic, which probably recorded a collision between the Sino-Korean and Yangtze plates.  相似文献   

8.
The Changle-Zhao' an fault belt is an important belt bordering the southeast coast of China. It wasformed in pre-Mesozoic time and has undergone polyphase activities of different modes ever since. Through astudy of the data concerning the Cenozoic strata, volcanism. seismicity, hydrothermal activity and crustaldeformation, the characteristics of the neotectonic movement of this fault belt were preliminarily ascertained,the amplitudes and rates of recent faulting in some places were calculated, and the intensities of the activities invarious structural basins along the fault zone were compared. Besides, this paper also discusses the main causefor the origin of the Quanzhou-Shantou strong earthquake tectonic zone.  相似文献   

9.
Doklady Earth Sciences - New geochronological and geochemical data on the age and composition of undifferentiated Cretaceous volcanics from the Palyavaam River basin, Central Chukotka region, are...  相似文献   

10.
<正>The Ordos Basin in the western part of the North China Craton is commonly believed to be a multi-controlled oilbearing basin.It is bounded by the Xing’an-Mongolian Orogen to the north,the Qingling Orogen to the south,the Lüliang mountain to the east and the Helanshan-Liupanshan mountain belt to the west.The interpretation of geophysical data reveals a latitudinal(38°)fault belt in the centre of the Ordos Basin,which controls the hydrocarbon generation,migration and accumulation in the basin.This study attempts to  相似文献   

11.
This work presents the results of geological, geochemical, Sm–Nd isotope-geochemical studies of metasedimentary rocks of the Teploklyuchevskaya, Garmakan, and Algaja formations of the Tukuringra Terrane of the eastern part of the Mongol–Okhotsk fold belt, as well as U–Th–Pb geochronological (LA-ICP-MS) studies of detrital zircons from these rocks. It is established that the lower age boundary of formation of the protolith of metasedimentary rocks of the Teploklyuchevskaya Formation is about 243 Ma (Middle Triassic); those of the Garmakan and Algaja formations are ~175 Ma (Lower–Middle Jurassic boundary) and ~192 Ma (Lower Jurassic), respectively. This makes it possible to correlate the Teploklyuchevskaya, Garmakan, and Algaja formations with the youngest sedimentary complexes of the eastern part of the Mongol–Okhotsk fold belt. In terms of geochemistry, the protoliths of metasedimentary rocks of the above-mentioned formations are the most similar to sedimentary rocks of island arcs and active continental margins. The source terrigenous material was transported from the southern frame of the Mongol–Okhotsk fold belt. It is not improbable that Lower Mesozoic deposits of the western part of the Tukuringra Terrane, in particular, and the eastern part of the Mongol–Okhotsk fold belt, as a whole, are relics of residual basins, preserved in “gaps” in the collision zone between the southern margin of plates of the North Asian Craton and the Amur Superterrane.  相似文献   

12.
The Qinling Mountains separating the northern from the southern China plate is a key region for the study of structural evolution of eastern Asia. It is composed of the Palaeozoic fold belt in its northern part and the Variscan and Indosinian fold belts in its southern part. The evolution of the former is marked by the closure of a northward subducting oceanic basin in the early stage, followed by southward obduction of ophiolites and intracontinental thrusting during the Variscan; whereas that of the latter is represented by intracontinental, shallow crustal deformation on the basis of a large-scale detachment structure(with a horizontal slip of at least of 100 km). Since the late Palaeozoic, however, both of the belts have been cut by a series of east-west sinistral strike-slip faults.  相似文献   

13.
The Tuva–Mongolian terrane of the Central Asian Orogenic Belt is a composite structure with a Vendian–Cambrian terrigenous–carbonate cover. The Sangilen block in the southern part of the belt is a smaller composite structure, in which tectono–stratigraphic complexes of different age that were produced under various conditions were amalgamated in the course of Early Paleozoic tectonic cycle. The P–T parameters of the Early Paleozoic metamorphism in the western part of the Sangilen block corresponded to the amphibolite facies. The gneisses of the Erzin Complex contain relict granulite-facies mineral assemblages. The granulites are dominated by metasediments typical of deep-water basins on passive continental margins. The only exception is granulites of the Lower Erzin tectonic nappe of the Chinchlig thrust system: these rocks are metatholeiites, tonalites, and trondhjemites, whose REE patterns are similar to those of MORB. The composition of these granulites and their high Sm/Nd ratios indicate that the rocks were derived from juvenile crust that had been formed in an environment of a mature island arc or backarc basin. It is reasonable to believe that these rocks are fragments of the Late Riphean basement of the Sangilen block. The average 206Pb/238U zircon age of the garnet–hypersthene granulites is 494 ± 11 Ma. With regard for the zircon age of the postmetamorphic granitoids, the granulite-facies metamorphism occurred within the age range of 505–495 Ma. The peak metamorphic temperature reached 910–950°C, and the pressure was 3–4 kbar, which corresponds to ultrahigh-temperature/low-pressure (UHT–LP) metamorphism. The garnet–hypersthene orthogranulites were formed at a temperature that decreased to ~850°C and pressure that increased to ~5.5?7 kbar. It can be hypothesized that the earlier UHT–LP granulites were produced at an elevated heat flux and were later (in the course of continuing collision) overlain by a relatively cold tectonic slab, and this leads to a certain temperature decrease and pressure increase. This relatively cold slab could consist of fragments of the Vendian elevated-pressure metamorphic belt whose development terminated at the Vendian–Cambrian boundary before the onset of the Early Paleozoic regional metamorphism.  相似文献   

14.
New U–Pb Zircon SHRIMP ages of 1091 ± 7.1 Ma and 1093.1 ± 5.8 Ma have been determined for two discrete phases of the Munster Suite. The Munster Suite is a calc-alkaline mafic to intermediate suite of intrusive igneous rocks that form part of the southern-most tectonic Terrane of the Mesoproterozoic-aged Natal Metamorphic Belt. Previously published geochemical data indicate that the discrete phases of the Suite are consanguineous and that these rocks originated within an oceanic island arc environment. The new age determinations now show that the different phases are also coeval. Moreover, the ages also indicate that the intrusions were, within statistical error, coeval with S-type granites within the Terrane. This is interpreted to indicate that magmatic underplating provided both the magma by way of a number of progressively more evolved pulses to produce the Munster Suite, as well as the heat necessary for crustal melting to produce the S-type granites within an island arc environment. Therefore, these new age determinations indicate a period of crustal growth at circa 1090 Ma. This moreover, is a maximum constraint on the age of the northward-verging structures within the Margate Terrane.  相似文献   

15.
The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on me  相似文献   

16.
The Penglai Group in the Jiaobei Belt is the only remaining cover of the Archaean to Early Proterozoic crystalline basement in eastern Shandong. The ages of deposition of the Penglai Group and of its deformation and metamorphism have long been a subject of speculation. Whole-rock Rb-Sr ages, illite-whole-rock pair Rb-Sr ages and illite K-Ar ages recently obtained from the Penglai Group slates are reported and interpreted in this paper. On the basis of structural and metamorphic studies coupled with analyses of illite crystallinity, XRD and SEM , a whole-rock age of 473±32 Ma (Ordovician) is interpreted as the time of termination of burial metamorphism experienced by the Penglai Group. Therefore, the age of the Penghai Group is older than Ordovician. The first-phase folding and syntectonic low greenschist facies metamorphism in the Penglai Group, i.e. the Penglai Movement, took place before 299±4 Ma B.P., i.e in the Late Carboniferous. The Penglai Movement that occurred in the Jiaobei Belt on the south  相似文献   

17.
The gigantic fold-thrust fracture belt that ex-tends for 900 kmto the NWin the southern NorthChina plate strides across three provinces : Shaanxi ,Henan and Anhui .It is one of the most characteristicstructural deformations in the North China plate .Along this structural belt a series of i mportantcoalfields occur ( e . g. Pingdingshan, Queshan,Huainan) inthe southernmost edge of the North Chi-na coal-concentrating basin. Consequently ,this beltis not only of key value for research onthe…  相似文献   

18.
The following geochemical types of granitoids have been investigated in the Mongol-Okhotsk belt:tholetitic,palingenic calc-alkaline,latitic,plumasitic and arpaitic rare-metal granites.Plagiogranites of the tholeiitic series occur within the Mongol-Okhotsk suture,indicating a subduction environment.The calc-alkaline granitoids responsible for the batholith-like intrusions and their formation are related to collision environments.The latest granitoids of the latite series and rare-metal granites came into existence after the collision of continental masses,providing evidence of intraplate magmatism.  相似文献   

19.
Please?refer?to?the?attachment(s)?for?more?details.  相似文献   

20.
Structural, metamorphic and geochronological studies of the Chewore Inliers of the Zambezi Belt within the Karoo age Zambezi Rift, allow recognition of a protracted multi-stage evolution, from the Mesoproterozoic to culminating in the Early. Palaeozoic Pan-African Orogeny. Tectono metamorphic events recognised in the Chewore Inliers occur throughout the Zambezi Belt and alternative models for the history of the Zambezi Belt are presented.Four terranes are recognised in the Chewore Inliers, and contacts between them are observed or inferred to be ductile thrusts, along which juxtaposition of the terranes occurred late in the Pan-African metamorphic cycle (M2, at 526 Ma). The oldest portion of the inliers is a metamorphosed sequence of mafic and ultramafic gneisses with an age of 1393 Ma. These constitute what is tentatively called the Ophiolite Terrane, together with closely associated high-P/moderate T schists possibly represents a suture. The other three terranes (Granulite, Zambezi and Quartzite Terranes) experienced a common history of tectonothermal events but show variable degrees of reworking during the latest tectono metamorphic event (M2). Concordant granitic orthogneisses were emplaced at 1087 Ma into supracrustal sequences. No Pan-African supracrustals are recognised in the Chewore Inliers, which are wholly basement gneisses and quartzites that have been reworked during successive orogenies including the Pan-African Orogeny.A high-T/low-P metamorphic event (M1 of possibly 1068–1071 Ma age, with a minimum age of 943 Ma, was responsible for totally recrystallizing the Granulite Terrane during south to north tectonic transport. M1 mineral parageneses are only preserved as inclusion phases and overgrown fabrics in the other terranes. These other terranes were pervasively recrystallised at high-P/moderate T conditions accompanying a clockwise P-T path related to northeast over southwest tectonic transport and crustal over-thickening during the Pan-African metamorphic cycle (M2) at approximately 526 Ma. Reworking of the Granulite Terrane during M2 was minor, leaving M1 fabrics and mineral assemblages preserved with little recrystallization. M2 orogenesis culminated in the juxtaposition of the terranes, rapid uplift through the thermal peak and eventual slow cooling accompanying a multitude of post-tectonic intrusions; pegmatites at 480 Ma, the Chewore Ultramafic Complex and dolerite dykes. The 830 Ma tectonothermal event involving pervasive syn-tectonic granitic orthogneisses in the south Zambezi Belt is not recognised in the Chewore Inliers, suggesting a localised, possibly extensional, regime restricted to the southern part of the Zambezi Belt at 830 Ma.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号