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1.
《中国科学:地球科学(英文版)》2021,(9)
The North China Craton(NCC) experienced strong destruction(i.e., decratonization) during the Mesozoic, which triggered intensive magmatism, tectonism and thermal events and formed large-scale gold and other metal deposits in the eastern part of the craton. However, how the decratonization controls the formation and distribution of large-scale of gold and other metal deposits is not very clear. Based on a large number of published data and new results, this paper systematically summarizes all the data for the rock assemblages, chronology, geochemistry and petrogenesis of Mesozoic magmatic rocks, as well as for the mineralizing ages of gold and other metal deposits and the evolution of the Mesozoic basins in the eastern NCC. The results are used to restore the extensional rates of Mesozoic to Cenozoic basins and the strike-slip distance of the Tanlu Fault, to ascertain the location of the Paleo-Pacific plate subduction zones during the Mesozoic to Cenozoic, and to reconstruct the temporal and spatial distribution of Mesozoic gold and other metal deposits and magmatic rocks in the eastern NCC. It is obtained that the magmatism and mineralization in the eastern NCC westward migrate from east to west during the Early to Middle Jurassic, but they eastward migrate from west to east during the Early Cretaceous. The metallogenesis of these deposits is genetically related to magmatism, and the magmas provided some ore-forming materials and fluids for the generation of metal deposits. The geodynamic mechanism of decratonization and related magmatism and mineralization is proposed, i.e., the westward low-angle subduction of the Paleo-Pacific slab beneath the NCC formed continental magmatic arc with plenty of porphyry Cu-Mo-Au deposits in the Jurassic, similar to the Andean continental arc in South America. The mantle wedge was metasomatized by the fluids/melts derived from the subducting slab, laying a material foundation for hydrothermal mineralization in the Early Cretaceous. While the rollback of the subducting slab with gradually increasing subduction angle and the retreat of the subduction zones during the Early Cretaceous induced strong destruction of the craton and the formation of extensive magmatic rocks and large-scale gold and other metal deposits. 相似文献
2.
大别造山带是全球最大的碰撞造山带之一,三叠纪时期,扬子板块深俯冲至地幔的200km处,经历了超高压变质作用。白垩纪早期,该造山带发生了强烈的伸展和垮塌,以及大规模的后造山地幔源岩浆侵入和火山活动。本研究收集了大别造山带及其邻区(29°~34°N、114°~119°E)的震相资料,采用双差层析成像技术,对大别造山带地壳结构进行反演,研究地壳结构与后造山地幔源岩浆侵入和火山活动之间的关系。结果显示,大别造山带中上地壳存在低速结构,该低速结构可能是熔融的幔源侵入物质,由于俯冲板片断裂,或下地壳/岩石圈发生拆沉,导致软流圈物质上涌至地壳底部、侵入地壳中,形成大别造山带地壳中的低速结构;同时,合肥盆地显示为低速区,可能是受浅部沉积层影响。研究中横切大别山的4条剖面显示,该地区下方存在北向倾斜高速结构,该高速结构可能是襄樊-广济断层,或者是扬子板块向华北板块下方俯冲的遗迹。 相似文献
3.
Thinning of the cratonic lithosphere is common in nature, but its destruction is not. In either case, the mechanisms for both thinning and destruction are still widely under debate. In this study, we have made a review on the processes and mechanisms of thinning and destruction of cratonic lithosphere according to previous studies of geological/geophysical observations and numerical simulations, with specific application to the North China Craton (NCC). Two main models are suggested for the thinning and destruction of the NCC, both of which are related to subduction of the oceanic lithosphere. One is the “bottom-up” model, in which the deeply subducting slab perturbs and induces upwelling from the hydrous mantle transition zone (MTZ). The upwelling produces mantle convection and erodes the bottom of the overriding lithosphere by the fluid-melt-peridotite reaction. Mineral compositions and rheological properties of the overriding lithospheric mantle are changed, allowing downward dripping of lithospheric components into the asthenosphere. Consequently, lithospheric thinning or even destruction occurs. The other is the “top-down” model, characterized by the flat subduction of oceanic slab beneath the overriding cratonic lithosphere. Dehydration reactions from the subducting slab would significantly hydrate the lithospheric mantle and decrease its rheological strength. Then the subduction angle may be changed from shallow to steep, inducing lateral upwelling of the asthenosphere. This upwelling would heat and weaken the overriding lithospheric mantle, which led to the weakened lithospheric mantle dripping into the asthenosphere. These two models have some similarities, in that both take the subducting oceanic slab and relevant fluid migration as the major driving mechanism for thinning or destruction of the overriding cratonic lithosphere. The key difference between the two models is the effective depth of the subducting oceanic slab. One is stagnation and flattening in the MTZ, whereas the other is flat subduction at the bottom of the cratonic lithosphere. In the NCC, the eastern lithosphere was likely affected by subduction of the Izanagi slab during the Mesozoic, which would have perturbed the asthenosphere and the MTZ, and induced fluid migration beneath the NCC lithosphere. The upwelling fluid may largely have controlled the reworking of the NCC lithosphere. In order to discuss and analyze these two models further, it is crucial to understand the role of fluids in the subduction zone and the MTZ. Here, we systematically discuss phase transformations of hydrous minerals and the transport processes of water in the subduction system. Furthermore, we analyze possible modes of fluid activity and the problems to explore the applied feasibility of each model. In order to achieve a comprehensive understanding of the mechanisms for thinning and destruction of cratonic lithosphere, we also consider four additional possible dynamic models: extension-induced lithospheric thinning, compression-induced lithospheric thickening and delamination, large-scale mantle convection and thermal erosion, and mantle plume erosion. Compared to the subduction-related models presented here, these four models are primarily controlled by the relatively simple and single process and mechanism (extension, compression, convection, and mantle plume, respectively), which could be the secondary driving mechanisms for the thinning and destruction of lithosphere. 相似文献
4.
华北克拉通破坏存在空间上的差异性,至今其内在的动力学机制仍存在较大的争议,这种差异性在岩石圈热结构上必然有所表现.广义上岩石圈热结构包括热流结构、温度场结构和热岩石圈厚度,是揭示岩石圈演化及其内在动力学过程的重要基础.基于二维地震剖面和大地热流数据,建立二维稳态热传导有限元模型,对华北克拉通东部岩石圈热结构进行模拟计算并与西部进行对比分析,在此基础上对比热岩石圈与地震岩石圈厚度差异的变化.结果显示,华北克拉通东、西部岩石圈热结构有着较为明显的差异,地幔热流值波动范围分别在24~44/20.5~24.5mW·m~(-2),壳幔比1.61~0.70/1.84~1.51,以1300℃等温线计算得到的热岩石圈厚度变化范围在75~139km/128~162km.华北克拉通东部相对西部有着较高的深部地幔热流值和较小的地震/热岩石圈厚度差异,这可能意味着东部软流圈地幔有效黏度相比西部低,估算差异可达2~3个数量级. 相似文献
5.
Cratons have a long history of evolution. In this paper, applications of the magnetotelluric method used in the study of craton lithosphere over the past 30 years were reviewed, examining case studies of cratons in North America, South America, Asia, Australia, and Africa. The nuclei of the Archean cratons, for example the Kalahari Craton and Rae Craton, are usually characterized by thick and highly resistive lithospheric roots. During or after the formation of the cratons, tectonothermal events, such as collision, mantle plume, and asthenosphere upwelling led to the formation of high-conductivity zones in the craton lithosphere, which could be attributed to the increased hydrogen content (of nominally anhydrous minerals), higher iron content, and formation of graphite films or sulfides along the grain boundary of minerals. These conductive zones are characterized by resistivity discontinuities in craton lithosphere. In particular, the conductive zones include (1) large-scale lithospheric mantle conductors beneath the Slave Craton, Gawler Craton, and central part of North China Craton(Trans-North China Orogen); (2) near-vertical high-conductivity zone associated with the fossil subduction zone beneath the Dharwar Craton and Slave Craton; and (3) regional lateral electrical discontinuities, such as a conductive anomaly under the Bushveld Complex of the Kaapvaal Craton. The eMoho refers to the electrical discontinuity in the crust-mantle boundary. In existing research, this has been detected under the condition of extremely high lithospheric resistivity with only a slight decrease in the lower crust, and in the case of a very thin conductive lower crust or the lack thereof. In the resistivity model, the unique “mushroom-like” lower crust-lithosphere mantle conductor and very thin lower crust layer of the North China Craton may represent lithosphere destruction and/or thinning. We also find that some of the cratons are still not well understood. Therefore, extensive three-dimensional inversion and joint interpretation of geochemical, geophysical, and geologic data are necessary to understand the tectonic evolutionary history of craton lithosphere.
相似文献6.
Crustal thickness beneath the Tanlu fault zone and its tectonic significance based on two-layer H-κ stacking 
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下载免费PDF全文 Tanlu fault zone(TLFZ)is the largest active fault zone in eastern China.It is characterized by complex tectonic evolution and multiple faults and marks the boundary between the North and South China blocks.An in-depth understanding of the distinct crustal structures of both parts of the TLFZ will provide valuable insights into the lithospheric and crustal thinning in eastern China,extensive magmatism since the Mesozoic,and formation mechanisms of metallogenic belts along the Yangtze River.In this study,a two-layer H-κ stacking approach was adopted to estimate the thicknesses of the sediment and crystalline crust as well as the corresponding vp/vs ratios based on high-quality teleseismic P-wave receiver functions recorded by permanent and temporary stations in and around the TLFZ.The geological units in the study region were delineated,especially the crustal structures beneath extensive sedimentary basins on both sides of the TLFZ.The following conclusions can be drawn:(1)The crustal thickness in and around the TLFZ greatly varies depending on the segment.In the northern segment,the crust is relatively thin beneath the eastern part of the Songliao Basin,a broad uplift of the Moho can be observed,and the Moho descends from south to north.The crust below the central and southern segments becomes thinner from west to east.The thickness of the crust is less than 30 km toward the eastern side of the boundary between the Jiangsu and Anhui provinces,that is,significantly thinner than in other areas.In terms of the vp/vs ratios,high anomalies were detected in the central-southern segments of the TLFZ,indicating the upwelling of deep mantle magma via deep faults.(2)Positive isostatic gravity anomalies were observed in the eastern part of the northern segment of the TLFZ and in the eastern part of the Suwan segment.The crustal thickness is smaller than that obtained from the Airy model of isostasy.This suggests that the lower crust in this area may have experienced intensive transformation processes,which may be related to crustal thinning(caused by crustal extension)and the strong uplift of the mantle in eastern China.The isostatic gravity anomalies between the eastern and western parts of the TLFZ indicate that the fault zone plays a dominant role in controlling the development of the deep crustal structure.(3)Significant crustal thinning was observed beneath the eastern part of the boundary between the Jiangsu and Anhui provinces in the southern segment of the TLFZ,suggesting that this area is prone to lithospheric thinning of the North China Craton.Due to the subduction,compression,and retreat of the Paleo-Pacific Plate during the Yanshanian Period as well as the dehydration of subducting oceanic crust(within subduction zones),the asthenosphere and oceanic crust in eastern China partially melted,resulting in mantle enrichment.The basic magma from the mantle is accumulated at the base of the crust,leading to magmatic underplating.In areas with weak topography toward the east of the TLFZ,magma rises to the upper crust and surface,resulting in the enrichment of multiple'metal deposits in this area. 相似文献
7.
Mesozoic mafic magmatism in North China: Implications for thinning and destruction of cratonic lithosphere 总被引：3，自引：0，他引：3
The North China Craton (NCC) has been thinned from >200 km to <100 km in its eastern part. The ancient subcontinental lithospheric mantle (SCLM) has been replaced by the juvenile SCLM in the Meoszoic. During this period, the NCC was destructed as indicated by extensive magmatism in the Early Cretaceous. While there is a consensus on the thinning and destruction of cratonic lithosphere in North China, it has been hotly debated about the mechanism of cartonic destruction. This study attempts to provide a resolution to current debates in the view of Mesozoic mafic magmatism in North China. We made a compilation of geochemical data available for Mesozoic mafic igneous rocks in the NCC. The results indicate that these mafic igneous rocks can be categorized into two series, manifesting a dramatic change in the nature of mantle sources at ~121 Ma. Mafic igneous rocks emplaced at this age start to show both oceanic island basalts (OIB)-like trace element distribution patterns and depleted to weakly enriched Sr-Nd isotope compositions. In contrast, mafic igneous rocks emplaced before and after this age exhibit both island arc basalts (IAB)-like trace element distribution patterns and enriched Sr-Nd isotope compositions. This difference indicates a geochemical mutation in the SCLM of North China at ~121 Ma. Although mafic magmatism also took place in the Late Triassic, it was related to exhumation of the deeply subducted South China continental crust because the subduction of Paleo-Pacific slab was not operated at that time. Paleo-Pacific slab started to subduct beneath the eastern margin of Eruasian continent since the Jurrasic. The subducting slab and its overlying SCLM wedge were coupled in the Jurassic, and slab dehydration resulted in hydration and weakening of the cratonic mantle. The mantle sources of ancient IAB-like mafic igneous rocks are a kind of ultramafic metasomatites that were generated by reaction of the cratonic mantle wedge peridotite not only with aqueous solutions derived from dehydration of the subducting Paleo-Pacific oceanic crust in the Jurassic but also with hydrous melts derived from partial melting of the subducting South China continental crust in the Triassic. On the other hand, the mantle sources of juvenile OIB-like mafic igneous rocks are also a kind of ultramafic metasomatites that were generated by reaction of the asthenospheric mantle underneath the North China lithosphere with hydrous felsic melts derived from partial melting of the subducting Paleo-Pacific oceanic crust. The subducting Paleo-Pacific slab became rollback at ~144 Ma. Afterwards the SCLM base was heated by laterally filled asthenospheric mantle, leading to thinning of the hydrated and weakened cratonic mantle. There was extensive bimodal magmatism at 130 to 120 Ma, marking intensive destruction of the cratonic lithosphere. Not only the ultramafic metasomatites in the lower part of the cratonic mantle wedge underwent partial melting to produce mafic igneous rocks showing negative εNd(t) values, depletion in Nb and Ta but enrichment in Pb, but also the lower continent crust overlying the cratonic mantle wedge was heated for extensive felsic magmatism. At the same time, the rollback slab surface was heated by the laterally filled asthenospheric mantle, resulting in partial melting of the previously dehydrated rocks beyond rutile stability on the slab surface. This produce still hydrous felsic melts, which metasomatized the overlying asthenospheric mantle peridotite to generate the ultramafic metasomatites that show positive εNd(t) values, no depletion or even enrichment in Nb and Ta but depletion in Pb. Partial melting of such metasomatites started at ~121 Ma, giving rise to the mafic igneous rocks with juvenile OIB-like geochemical signatures. In this context, the age of ~121 Ma may terminate replacement of the ancient SCLM by the juvenile SCLM in North China. Paleo-Pacific slab was not subducted to the mantle transition zone in the Mesozoic as revealed by modern seismic tomography, and it was subducted at a low angle since the Jurassic, like the subduction of Nazca Plate beneath American continent. This flat subduction would not only chemically metasomatize the cratonic mantle but also physically erode the cratonic mantle. Therefore, the interaction between Paleo-Pacific slab and the cratonic mantle is the first-order geodynamic mechanism for the thinning and destruction of cratonic lithosphere in North China. 相似文献
8.
Petrogenesis and significance of the Mesozoic North Taihang complex: Major and trace element evidence 总被引：22，自引：1，他引：21
The intensive Mesozoic magmatism in the North China Craton (NCC) has drawn great attention for its particular geochemical signatures (e.g. high-K), petrogenesis and tectonic setting. The North Taihang complex represents the westernmost magmatic belt of th… 相似文献
9.
10.
It is well known that the destruction of the North China Carton(NCC) is closely related to subduction of the PaleoPacific slab, but materials recording such subduction has not been identified at the peak time of decratonization. This paper presents data of whole-rock major and trace elements and Sr-Nd-Hf isotopes and zircon U-Pb ages and Hf-O isotopes for Mesozoic volcanic rocks from the Liaodong-Jinan region in the northeastern NCC, in order to trace the subduction-related materials in their source and origin. The Mesozoic volcanic rocks in the Liaodong-Jinan region are mainly composed of two series of rocks, including alkaline basaltic trachyandesite, trachyandesite and trachyte, and subalkaline trachyandesite and andesite. Zircon U-Pb dating yields eruption ages of 129–124 Ma for these rocks. The Early Cretaceous volcanic rocks are all enriched in LILEs(such as Rb, Sr, Ba and Th) and LREEs, depleted in HFSEs(such as Nb, Ta and Ti), indicating that they were originated from mantle sources that had been modified by subducted crustal materials. However, they have relatively heterogeneous and variable isotopic compositions. The alkaline basaltic trachyandesite, trachyandesite and trachyte have enriched whole-rock Sr-Nd-Hf and zircon Hf isotopic compositions and mantle-like δ~(18)O values, suggesting that they were derived from low-degree partial melting of an isotopically enriched lithospheric mantle source. In contrast, the subalkaline trachyandesite and andesite have relatively depleted isotopic compositions with zircon ε_(Hf)(t) values up to +5.2 and heavy zircon O isotopic compositions with δ~(18)O values of +8.1‰ to +9.0‰, indicating that they were originated from a lithospheric mantle source that had been metasomatized by melts/fluids derived from the recycled low-T altered oceanic basalt. All of these geochemical features suggest that the Early Cretaceous volcanic rocks in the Liaodong-Jinan region would result from mixing of mafic magmas with different compositions. Such magmas were originated from the enriched lithospheric mantle and the young metasomatized mantle, respectively, with variable extents of enrichment and depletion in trace elements, radiogenic isotopes and O isotopes. Importantly, the identification of the low-T altered oceanic crust component in the origin of Early Cretaceous volcanic rocks by the zircon Hf-O isotopes provides affirmative isotopic evidence and direct material records for Mesozoic subduction of the Paleo-Pacific slab that induced decratonization of the North China Craton. 相似文献
11.
《中国科学:地球科学(英文版)》2021,(9)
The craton is a long-lived stable geologic unit on the Earth's surface. However, since the Mesozoic, the North China Craton(NCC) experienced large-scale lithospheric removal, the fundamental change of physical and chemical characteristics of the lithospheric mantle, widely distributed crustal deformation, and extensive magmatism. This complex evolution contrary to other cratons is called the NCC destruction. Widespread magmatism in the eastern NCC is an important response to the lithospheric removal at depth and crustal deformation on the surface. The plutons emplace under a tectonic context and therefore record the information of the tectonics; especially, the anisotropy magnetic susceptibility(AMS) pattern of the pluton was acquired with the influence of regional stress. In the past fifteen years, about 22 plutons intruding during the different periods from the Late Triassic to the late stage of the Early Cretaceous have been studied with AMS. The emplacement mechanisms of plutons and the contemporary tectonic setting were discussed to constrain their relationship with the NCC destruction in different stages of magmatism. As a result, the Late Triassic, Early Jurassic, and Late Jurassic plutons exhibit consistent N(E)-S(W)trending magnetic lineations. The early stage of Early Cretaceous plutons display NW-SE trending magnetic lineations, while the late stage of Early Cretaceous plutons show magnetic lineations with various orientations. Combined with previous studies, it is concluded that the emplacements of the plutons intruding in these three stages were controlled by weak N(E)-S(W) trending extension, regional NW-SE trending extension, and weak extension in the shallow crustal level, respectively. The transformation of regional extension from the N(E)-S(W) to the NW-SE direction was accompanied by a strain-increasing tendency. The extensional tectonics in the eastern NCC was interpreted to represent the interaction between Mongol-Okhotsk belt, PaleoPacific plate, and eastern Eurasian continent. 相似文献
12.
Discussion on the relationship between the Yanshanian Movement and cratonic destruction in North China 总被引：3，自引：0，他引：3
The relationship between the Yanshanian Movement, destruction of the North China Craton(NCC), and subduction of the western Pacific plate is crucial to reconstructing the middle-late Mesozoic tectonic evolution of the eastern Asian continent and margin. The Yanshanian Movement was a globally important change in crustal tectonics during the Middle-Late Jurassic.Previous research has systematically studied the formation and evolution of the Yanshanian Movement, focusing on the timing and location of tectonic movements, and the sedimentary and volcanic strata. However, the question of whether the tectonic activity occurred globally, and the characteristics of the Yanshanian Movement remain debated. The main argument is that if a tectonic movement can only be characterized by a regional or local disconformity, and if the tectonic movement occurred in an intracontinental setting, with extensive deformation but with no disconformity despite volcanic eruptions and magmatic intrusions, accompanied by changes in crustal structure and composition, should it be defined as a tectonic event or process? This question requires further analysis. The main aim of this study is to distinguish whether the Yanshanian Movement is a local feature of the eastern Asian continent, or a global tectonic event related to subduction of the Pacific Plate. In this paper, based on previous research, we discuss the spatial and temporal evolution of the Yanshanian Movement, the controlling tectonic mechanisms, and its relationship to the reactivation and destruction of the NCC and the subduction of the western Paleo-Pacific slab.We emphasize that the Yanshanian Movement in the Middle-Late Jurassic is distinct from the lithospheric thinning responsible for Early Cretaceous extension and magmatism related to the destruction of the NCC. The various tectonic stages were constrained by different dynamics and tectonic settings, or by different tectonic events and processes. Therefore, it is possible that the deformation and reactivation of the NCC contributed to its destruction, in addition to lithospheric thinning. Finally, we discuss whether the Yanshanian Movement was associated with the destruction of the NCC. 相似文献
13.
Insight into craton evolution: Constraints from shear wave splitting in the North China Craton 总被引：7，自引：0，他引：7
The multi-episodic tectonic activities from the Precambrian to Cenozoic, including nucleus formation, cratonic amalgamation, and rejuvenation, make the North China Craton (NCC) an ideal natural laboratory for studying craton evolution. Spatial change in the upper deformation records is an important aspect for understanding cratonic formation and rejuvenation. In this study, we performed seismic shear wave splitting analysis using SKS phases from 50 portable stations. Two different methodologies, shear wave splitting measurement and amplitude analysis of transverse/radial components, produced mutually consistent splitting results. These results showed that the seismic anisotropy beneath the Ordos Block can be divided into three subgroups reflecting the tectonic control. Combining these results with those from previous splitting studies in the eastern NCC, we suggest that the Proterozoic amalgamation generated the seismic anisotropy in the boundary zone between the Ordos Block and the Trans-North China Orogen, while the anisotropy in the eastern Trans-North China Orogen and eastern NCC were possibly associated with the lithospheric rejuvenation during the Late Mesozoic to Cenozoic. 相似文献
14.
MingGuo Zhai YanBin Zhang XiaoHui Zhang FuYuan Wu Peng Peng QiuLi Li QuanLin Hou TieSheng Li Lei Zhao 《中国科学:地球科学(英文版)》2016,59(12):2355-2388
Widespread Mesozoic magmatism occurs in the Korean Peninsula (KP). The status quo is poles apart between the northern and southern parts in characterizing its distribution and nature, with the nearly absence of any related information in North Korea. We have the opportunity to have conducted geological investigations in North Korea and South Korea during the past ten years through international cooperation programs. This led to the revelation of a number of granitoids and related volcanic rocks and thus facilitates the comparison with those in East China and Japan. Mesozoic granitoids in the KP can be divisible into three age groups: the Triassic group with a peak age of ~220 Ma, the Jurassic one of ~190–170 Ma and the late Early Cretaceous one of ~110 Ma. The Triassic intrusions include syenite, calc-alkaline to alkaline granite and minor kimberlite in the Pyeongnam Basin of North Korea. They have been considered to form in post-orogenic settings related to the Central Asian Orogenic Belt (CAOB) or the Dabie-Sulu Orogenic Belt (DSOB). The Jurassic granitoids constitute extensive occurrence in the KP and are termed as the Daebo-period magmatism. They correlate well with coeval counterparts in NE China encompassing the northeastern part of the North China Craton (NCC) and the eastern segment of the CAOB. They commonly consist of biotite or two-mica granites and granodiorites, with some containing small dark diorite enclaves. On one hand, Early Jurassic to early Middle Jurassic magmatic rocks are rare in most areas of the NCC, whilst Middle-Late Jurassic ones are not developed in the KP. On the other hand, both NCC and KP host abundant Cretaceous granites. However, the present data revealed contrasting age peaks, with ~130–125 Ma in the NCC and ~110–105 Ma in the KP. Cretaceous granites in the KP comprise the dominant biotite granites and a few amphibole granites. The former exhibit mildly fractionated REE patterns and zircon ε Hf(t) values from -15 to -25, whereas the latter feature strongly fractionated REE patterns and zircon ε Hf(t) values from -10 to -1. Both granites contain inherited zircons of ~1.8–1.9 or ~2.5 Ga. These geochemical characters testify to their derivation from re-melting distinct protoliths in ancient basement. Another Cretaceous magmatic sub-event has been entitled as the Gyeongsang volcanism, which is composed of bimodal calc-alkaline volcanic rocks of 94–55 Ma and granitic-hypabyssal granitic bodies of 72–70 Ma. Synthesizing the Mesozoic magmatic rocks across the KP, NCC and Japan can lead to the following highlights: (1) All Triassic granites in the NCC, KP and Japan have similar characteristics in petrology, chronology and geochemistry. Therefore, the NCC, KP and Japan tend to share the same tectonic setting during the Triassic, seemingly within the context of Indosinian orogensis. (2) Jurassic to earliest Cretaceous magmatic rocks in the NCC seem to define two episodes: episode A from 175 to 157 Ma and episode B from 157 to 135 Ma. Jurassic magmatic rocks in the KP span in age mainly from 190 to 170 Ma, whereas 160–135 Ma ones are rare. With the exception of ~197 Ma Funatsu granite, Jurassic magmatic rocks are absent in Japan. (3) Cretaceous granites in the KP have a peak age of ~110, ~20 Ma younger than those in the NCC, while Japan is exempt from ~130–100 Ma granites. (4) The spatial-temporal distribution and migratory characteristics of the Jurassic-Cretaceous magmatic rocks in Japan, KP, and NE China-North China indicate that the subduction of the Paleo-Pacific plate might not be operative before Late Cretaceous (~130–120 Ma). (5) Late Cretaceous magmatic rocks (~90–60 Ma) occur in the southwestern corner of the KP and also in Japan, coinciding with the metamorphic age of ~90–70 Ma in the Sanbagawa metamorphic belt of Japan. The magmatic-metamorphic rock associations and their spatial distribution demonstrate the affinities of sequentially subduction zone, island arc and back-arc basin from Japan to Korea, arguing for the Pacific plate subduction during Late Cretaceous. (6) This study raises another possibility that the Mesozoic cratonic destruction in the NCC, which mainly occurred during ~150–120 Ma, might not only be due to the subduction of the Paleo-Pacific Plate, but also owe much to the intraplate geodynamic forces triggered by other adjacent continental plates like the Eurasian and Indian plates. 相似文献
15.
It has been proposed that the North China Craton(NCC)was thinned up to a thickness of100 km during the Phanerozoic,and underwent an associated craton destruction.Evidently,it is an important topic worthy of future study to understanding the mechanism of cratonic destruction and its role played in the continental evolution.After synthesized the global cratons of India,Brazil,South Africa,Siberia,East Europe(Baltic)and North America,we found that lithospheric thinning is common in the cratonic evolution,but it is not always associated with craton destruction.Most cratons was thinned by thermal erosion of mantle plume or mantle upwelling,which,however,may not cause craton destruction.Based on the studies of the North American and North China Cratons,we suggest that oceanic subduction plays an important role in caton destruction.Fluids or melts released by dehydration of the subducted slabs metasomatize the mantle wedge above and trigger extensive partial melting.More importantly,the metasomatized mantle lost its original rigidity and make craton easier to be deformed and then to be destoyed.Therefore,we suggest that the widespread crust-derived granite and large-scale ductile deformation within the continental crust can be regarded as the petrological and structural indicators of craton destruction,respectively. 相似文献
16.
We investigate the mantle dynamics beneath the North China Craton (NCC) and surrounding regions based on a synthesis of recent P-wave mantle tomographic data down to depths of 600–800 km and their correlation with the surface geological features, with particular reference to the Paleoproterozoic tectonic events associated with the incorporation of the NCC within the Columbia supercontinent amalgam. From the tomographic images, we identify a hot corridor in the mantle transition zone beneath the central region of the Western Block of the NCC sandwiched between two cold corridors. This scenario is similar to the donut-shaped high-velocity anomaly surrounding a region of low-velocity anomaly in the lowermost mantle under the Pacific and suggests that the cold regions might represent slab graveyards which provide the fuel for the plumes rising from the center. A tomographic transect along the collisional suture of the NCC with the Columbia supercontinent, covering the Yinshan-Ordos Blocks in the Western Block through the Central Orogenic Belt and into the Eastern Block of the NCC reveals a ca. 250 km thick lithospheric keel below the Ordos Block defined by a prominent high-velocity anomaly. We identify slab break-off and asthenospheric upwelling in this region and suggest that this process probably initiated the thermal and material erosion of the tectosphere beneath the Eastern Block from the Paleoproterozoic, which was further intensified during the Mesozoic when a substantial part of the sub-continental mantle lithosphere was lost. We visualize heat input from asthenosphere and interaction between asthenosphere and overlying carbonated tectosphere releasing CO2-rich fluids for the preservation of ultra-high temperature (ca. 1000 °C) metamorphic rocks enriched in CO2 as well as high-pressure mafic granulites as a paired suite in this region. We also identify a hot swell of the asthenosphere rooted to more than 200 km depth and reaching up to the shallow mantle in the tomographic section along 35°N latitude at a depth of 800 km. This zone represents a cross-section through the southern part of the NCC. The surface distribution of Paleoproterozoic Xiong’er lavas and mafic dykes in this region would indicate that this region might have evidenced similar upwellings in the past. Our study has important implications in understanding the evolution of the NCC and suggests that the extensive modification of the mantle architecture and lithospheric structure beneath one of the fundamental Precambrian nuclei of Asia had a prolonged history probably dating from the Paleoproterozoic suturing of the NCC within the Columbia supercontinent amalgam. 相似文献
17.
华北克拉通破坏的重要标志是岩石圈减薄、地幔性质转变以及伸展构造活动.长期以来这一重大地质事件发生的时代备受关注,目前已有大量地质、地球物理和地球化学研究结果,但对于华北克拉通破坏的准确时代,尚存争议.本文试图从地磁学的角度为华北克拉通破坏时代提供可靠约束.选取位于华北克拉通北缘的燕山造山带中段-承德盆地作为研究对象.磁性地层学研究结果表明研究剖面记录了三个磁极性段:下部正极性段(N2)、中部负极性段(R1)和上部正极性段(N1),与2004年地磁极性年表对比并结合129～128 Ma的火山岩同位素年龄(与B. Schoene 私人通信),认为剖面下部正极性段(N2)对应于M3n,负极性段(R1)对应于M1r,上部正极性段(N1)对应于M1n,由此得出承德盆地袁家庄剖面沉积作用起始年龄约为128 Ma.作为华北克拉通重要断陷盆地之一,承德盆地的沉积年龄可以为华北克拉通破坏时代提供有力约束.岩石磁学研究结果表明,研究剖面火山岩的剩磁载体十分复杂,可能与伴随华北克拉通破坏峰期出现的地壳变形、岩浆活动、地幔上涌、下地壳重熔等深部动力过程密切相关.综合分析结果表明,华北克拉通破坏的峰期为128～125 Ma. 相似文献
18.
The North China Craton (NCC) is an important part of eastern China. Recent studies have shown that the eastern NCC (ENCC) has undergone significant lithospheric thinning and destruction since the late Mesozoic. Destruction of the cratonic lithosphere is necessarily accompanied by crustal deformation. Therefore, a detailed crustal deformation model can provide basic observational constraints for understanding the process and mechanisms of the destruction of the NCC. In this study, we estimated the crustal azimuthal anisotropy beneath 198 broadband stations in the NCC with a joint analysis of Ps waves converted at the Moho from radial and transverse receiver function data. We also performed a harmonic analysis to test the reliability of the measured anisotropy. We obtained robust crustal azimuthal anisotropy beneath 23 stations that are mostly located on the western margin of the Bohai Bay Basin, Yin-Yan orogenic belt, and Taihang Mountains, which reflects the crustal deformation characteristics in those regions. The crustal shear wave splitting time was found to range from 0.05 s to 0.68 s, with an average value of 0.23 s, which reveals a distinct crustal anisotropy in the Trans-North China Orogen (TNCO) and its adjacent areas. Our analysis of the results suggests that the strong NW-SE tectonic extension in the late Mesozoic and Cenozoic played an important role in crustal anisotropy in this region. In addition, the E-W trending crustal anisotropy on the margin of the Bohai Bay Basin indicates an effect of the ENE-WSW trending horizontal principal compressive stress. The crustal anisotropy in the Yin-Yan orogenic belt may be an imprint of the multiple-phase shortening of a dominant N-S direction from the early-to-middle Jurassic to the Early Cretaceous. Stations in the Taihang Mountains show large splitting times and well-aligned NW-SE fast directions that correlate with those measured from SKS splitting and that are possibly related to the lithospheric modification and magmatic underplating from the Late Mesozoic to Cenozoic in this area. 相似文献
19.
《中国科学:地球科学(英文版)》2021,(9)
The Early Cretaceous represents a peak period of the North China Craton(NCC) destruction. A comprehensive analysis of crustal deformation during this period can reveal processes and dynamics of the destruction. The peak destruction of the NCC was associated with intense extension whose representative deformation products are metamorphic core complexes(MCCs), extensional domes and rifted basins. These MCCs occurred along both northern and southern margins of the NCC, and resulted from synchronous extension and magmatism, showing difference from the typical orogen-type MCCs in many aspects.The MCCs of the Early Cretaceous were replaced by extensional domes under relatively weak extension and uplift. In contrast to a major depression-type basin of the Early Cretaceous in the western NCC, rifted basins of the same age in the eastern NCC appeared as medium-to small-scale ones extensively. In the eastern NCC, the rifted basins north of the Bohai Bay are characterized by a feature similar to an active rift whereas those south of the Bohai present similarity to a passive rift. Various sorts of extensional structures developed during the peak destruction indicate a stable stress state of NE-SE extension over the entire central to eastern NCC, consistent with the plate margin-driven stress field. Spatial distribution of the extensional structures presents an 1800 km wide back-arc extension region in the central to eastern NCC, consistent with the Paleo-Pacific slab rollback model following flat subduction. Temporal-spatial variation of initial extension and volcanic activity during the peak period also supports the rollback model right after the flat oceanic slab. The crustal deformation evolution demonstrates that the peak destruction of the NCC took place after the B-episode compression of the Yanshan Movement of the earliest Early Cretaceous and terminated with onset of the C-episode compression of the earliest Late Cretaceous. 相似文献
20.
P-wave velocity structure in the crust and the uppermost mantle of Chao Lake region of the Tan-Lu Fault inferred from teleseismic arrival time tomography 下载免费PDF全文
下载免费PDF全文 Bem Shadrach Terhemba Huajian Yao Song Luo Lei Gao Haijiang Zhang Junlun Li 《地震科学（英文版）》2022,35(6):427-447
Chao Lake is a Geoheritage site on the active Tan-Lu Fault between the Yangtze craton, the North China craton, and the Dabie orogenic belt in the southeast. This segment of the fault is not well constrained at depth partly due to the overprinting of the fault zone by intrusive materials and its relatively low seismic activity and sparse seismic station coverage. This study took advantage of a dense seismic array deployed around Chao Lake to delineate the P-wave velocity variations in the crust and uppermost mantle using teleseismic earthquake arrival time tomography. The station-pair double-difference with waveform cross-correlation technique was employed. We used a multiscale resolution 3-D initial model derived from the combination of high-resolution 3-D vS models within the region of interest to account for the lateral heterogeneity in the upper crust. The results revealed that the velocity of the upper crust is segmented with structures trending in the direction of the strike of the fault. Sedimentary basins are delineated on both sides of the fault with slow velocities, while the fault zone is characterized by high velocity in the crust and uppermost mantle. The high-velocity structure in the fault zone shows characteristics of magma intrusion that may be connected to the Mesozoic magmatism in and around the Middle and Lower Yangtze River Metallogenic Belt (MLYMB), implying that the Tan-Lu fault might have formed a channel for magma intrusion. Magmatic material in Chao Lake is likely connected to the partial melting, assimilation, storage, and homogenization of the uppermost mantle and the lower crustal rocks. The intrusions, however, seem to have suffered severe regional extension along the Tan-Lu fault driven by the eastward Paleo-Pacific plate subduction, thereby losing its deep trail due to extensional erosion. 相似文献