检索结果-南通市图书馆

Tectonic evolution of convergent plate margins and its geological effects

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第7期65卷 1247-1276页

作者： Yongfei ZHENG Yixiang CHEN Renxu CHEN liqun dai CAS Key Laboratory of Crust and Mantle Materials and Environments School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China

Oceanic lithosphere is generated at divergent plate boundaries and disappears at convergent plate *** spreading and plate subduction together constitute the physical coupling and mass conservation relationships to the movement of lithospheres on *** zones are a key site for the transfer of both matter and energy at converging plate boundaries,and their study has been the hot spot and frontier of Earth system science since the development of plate tectonics *** far as the dynamic regime and geothermal gradient of convergent plate margins are concerned,they have different properties in different stages of the subduction zone *** general,the early low-angle subduction leads to compressional tectonism dominated by low geothermal gradients at the plate interface,and the late high-angle subduction results in extensional tectonism dominated by high geothermal gradients at the plate interface and its hanging *** rifts are produced along suture zones through not only slab rollback or slab breakoff in the terminal stage of oceanic subduction but also foundering and thinning of the lithosphere in the post-subduction *** to the differences and changes in the geometric and thermobaric structures of convergent plate margins,a series of changes in the type of metamorphism and magmatism can occur in active and fossil subduction *** and melting of the subducting oceanic crust are prominent at subarc depths,giving rise to fluids that dissolve different concentrations of fluid-mobile incompatible *** subduction zone fluids at subarc depths would chemically react with the overlying mantle wedge peridotite,generating metasomatites as the mantle sources of mafic magmas in oceanic and continental ***,these metasomatites did not partially melt immediately upon the fluid metasomatism to trigger arc magmatism,and they did not melt until they were heated by asthenospheric convection due to rollback of th

关键词： Plate tectonics Continental geology Convergent margins Continental rifting Subduction zone Orogenic belt

Mesozoic mafic magmatism in North China:Implications for thinning and destruction of cratonic lithosphere

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第4期61卷 353-385页

作者： Yongfei ZHENG Zheng XU Zifu ZHAO liqun dai CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space ScienceUniversity of Science and Technology of China

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 *** 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 patterrs and enriched Sr-Nd isotope *** 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 notonly with aqueous solutions

关键词： Cratonic destruction Mafic magmas IAB-like series OIB-like series Lithospheric thinning Slab subduction

Zircon U-Pb geochronology of the volcanic rocks from Fanchang-Ningwu volcanic basins in the Lower Yangtze region and its geological implications

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第16期54卷 2895-2904页

作者： YAN Jun LIU HaiQuan SONG ChuanZhong XU XiSheng AN YaJun LIU Jia dai liqun School of Resources and Environmental Engineering Hefei University of Technology Hefei 230009 China State Key Laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China

The latest eruptions in two important Mesozoic volcanic basins of Fanchang and Ningwu located in the middle-lower reaches of the Yangtze River formed the bimodal volcanic rocks of the Kedoushan Formation and ultrapotassic volcanic rocks of the Niangniangshan Formation, respectively. The repre-sentative volcanic rocks of the two Formations were selected for LA-ICPMS zircon U-Pb dating. The results indicate that there exist a large amount of magmatic zircons as indicated by high Th/U ratios in these volcanic rocks. The weighted mean age of 21 analyses is 130.7±1.1 Ma for the Kedoushan Formation, and that of 20 analyses is 130.6±1.1 Ma for the Niangniangshan Formation. These U-Pb ages are interpreted to represent the formation times of the volcanic rocks. In combination with other known geochronological data for Mesozoic volcanic rocks from the Lower Yangtze region, it is proposed that the latest volcanic activations in the Jinniu, Luzong, Fanchang and Ningwu volcanic basins probably came to end prior to ca. 128 Ma. There is no significant time interval between the early and later volcanic activities in the Luzong and Ningwu basins, suggesting a short duration of volcanic activities and thus implying the onset of an extensional tectonic setting at about 130 Ma in the Lower Yangtze region. Integrated studies reveal that the Early Cretaceous magmatic activities and their geochronological framework in the Lower Yangtze region are a response to progressively dynamic deep processes that started with the transformation of tectonic setting from compression to extension, followed by delaminating of the lower part of the thickened lithosphere, lithospheric thinning, asthenosphere upwelling, and crust-mantle interaction.

关键词：火山岩盆地长江下游地区地质意义年代学锆石定年 Pb

Two types of the crust-mantle interaction in continental subduction zones

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2015年第7期58卷 1269-1283页

作者： ZHAO ZiFu dai liqun ZHENG YongFei CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China

Plate subduction is an important mechanism for exchanging the mass and energy between the mantle and the crust,and the igneous rocks in subduction zones are the important carriers for studying the recycling of crustal materials and the crust-mantle *** study presents a review of geochronology and geochemistry for postcollisional mafic igneous rocks from the Hong’an-Dabie-Sulu orogens and the southeastern edge of the North China *** available results indicate two types of the crust-mantle interaction in the continental subduction zone,which are represented by two types of mafic igneous rocks with distinct geochemical *** first type of rocks exhibit arc-like trace element distribution patterns(*** of LILE,LREE and Pb,but depletion of HFSE)and enriched radiogenic Sr-Nd isotope compositions,whereas the second type of rocks show OIB-like trace element distribution patterns(*** of LILE and LREE,but no depletion of HFSE)and depleted radiogenic Sr-Nd isotope *** of them have variable zircon O isotope compositions,which are different from those of the normal mantle zircon,and contain residual crustal *** geochemical features indicate that the two types of mafic igneous rocks were originated from the different natures of mantle *** mantle source for the second type of rocks would be generated by reaction of the overlying juvenile lithospheric mantle with felsic melts originated from previously subducted oceanic crust,whereas the mantle source for the first type of rocks would be generated by reaction of the overlying ancient lithospheric mantle of the North China Block with felsic melts from subsequently subducted continental crust of the South China ***,there exist two types of the crust-mantle interaction in the continental subduction zone,and the postcollisional mafic igneous rocks provide petrological and geochemical records of the slab-mantle interactions in continental coll

关键词： geochemistry postcollisional mafic igneous rocks crust-mantle interaction continental subduction zone

同方期刊数据库

Developing plate tectonics theory from oceanic subduction zones to collisional orogens

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2015年第6期58卷 1045-1069页

作者： ZHENG YongFei CHEN YiXiang dai liqun ZHAO ZiFu CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China

Crustal subduction and continental collision is the core of plate tectonics theory. Understanding the formation and evolution of continental collision orogens is a key to develop the theory of plate tectonics. Different types of subduction zones have been categorized based on the nature of subducted crust. Two types of collisional orogens, i.e. arc-continent and continent-continent collisional orogens, have been recognized based on the nature of collisional blocks and the composition of derivative rocks. Arc-continent collisional orogens contain both ancient and juvenile crustal rocks, and reworking of those rocks at the post-collisional stage generates magmatic rocks with different geochemical compositions. If an orogen is built by collision between two relatively old continental blocks, post-collisional magmatic rocks are only derived from reworking of the old crustal rocks. Collisional orogens undergo reactivation and reworking at action of lithosphere extension, with inheritance not only in the tectonic regime but also in the geochemical compositions of reworked products(i.e., magmatic rocks). In order to unravel basic principles for the evolution of continental tectonics at the post-collisional stages, it is necessary to investigate the reworking of orogenic belts in the post-collisional regime, to recognize physicochemical differences in deep continental collision zones, and to understand petrogenetic links between the nature of subducted crust and post-collisional magmatic rocks. Afterwards we are in a position to build the systematics of continental tectonics and thus to develop the plate tectonics theory.

关键词： crustal subduction continental collision postcollisional reworking magmatism metamorphism continental tectonics

同方期刊数据库

大陆碰撞造山带镁铁质岩浆岩记录俯冲古洋壳物质再循环

在线全文

学校读者我要写书评

暂无评论

地球科学 2019年第12期44卷 4128-4134页

作者：戴立群赵子福中国科学院壳幔物质与环境重点实验室中国科学技术大学地球和空间科学学院

在大陆碰撞造山带中寻找消失的古洋壳再循环及其壳幔相互作用的证据,对理解从洋壳俯冲到陆壳俯冲化学地球动力学过程的转变,以及板块构造理论的发展具有重要意义.通过对桐柏-红安造山带晚古生代和晚中生代镁铁质岩浆岩的岩石地球化学特... 详细信息

在大陆碰撞造山带中寻找消失的古洋壳再循环及其壳幔相互作用的证据,对理解从洋壳俯冲到陆壳俯冲化学地球动力学过程的转变,以及板块构造理论的发展具有重要意义.通过对桐柏-红安造山带晚古生代和晚中生代镁铁质岩浆岩的岩石地球化学特征进行总结,可以识别出俯冲古洋壳再循环的岩石学和地球化学记录.晚古生代岛弧型镁铁质岩石具有弧型微量元素特征和相对亏损的放射成因同位素组成,记录了俯冲古洋壳在弧下深度(80~160 km)的流体交代作用;而晚中生代洋岛型镁铁质岩石OIB型微量元素特征和亏损-弱富集的放射成因同位素组成,记录了俯冲古洋壳在弧后深度(>200 km)的熔体交代作用.这一定性的解释也进一步得到了定量计算的证实,其结果表明镁铁质岩浆岩中的不相容元素的含量以及放射性成因同位素的富集程度,主要受控于地幔源区中所加入的地壳组分的性质和比例.因此,碰撞造山带中的岛弧型和洋岛型镁铁质岩浆岩,分别记录了弧下和弧后深度的俯冲古洋壳物质再循环.

关键词：碰撞造山带镁铁质岩浆岩古洋壳再循环壳幔相互作用岩石学

Attraction and Stability for Neutral Stochastic Functional Differential Equations

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2009年第3期14卷 205-209页

作者： CEN liqun, dai Weixing, HU Shigeng School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China School of Mathematics and Statistics Huazhong University of Science and Technology Wuhan Hubei China

The main aim of this paper is to establish several new criteria on the attractor for the solutions of neutral stochastic func- tional differential equations. A kind of ψ-function is introduced to our discussion, and some results on the attractor for the product of the ψ-function and the solutions are obtained. As a byproduct, a number of new criteria on asymptotic stability are also shown.

关键词： Lyapunov's method attractor semimartingale convergence theorem Ito's formula

Near-field wideband beam training for ELAA with uniform circular array

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第6期67卷 370-383页

作者： Yuhao CHEN Linglong dai Department of Electronic Engineering Tsinghua UniversityBeijing National Research Center for Information Science and Technology (BNRist)

Extremely large-scale antenna array(ELAA) at millimeter wave(mmWave) and Terahertz(THz)band has been considered a key technology for combating high attenuation in high-frequency bands in future6G communications. Uniform circular arrays(UCAs) have attracted much attention because of their ability to provide flat beamforming gain at all angles. To realize efficient beamforming, beam training is widely used to acquire channel state information. However, with a large antenna number, the beam training overhead in ELAA systems becomes overwhelming. Moreover, with a large bandwidth, the beam defocus effect severely degrades beam training accuracy. To address these issues, this paper proposes a frequency-dependent focusing(FDF)-based beam training scheme to realize effective beam training in near-field wideband ELAA systems with UCA. Specifically, we first analyze the FDF property of UCA, where signals at different subcarriers can simultaneously focus on different distances. Then, by exploiting the FDF property to search different distances using different subcarriers simultaneously, we design a hierarchical codebook and propose an FDFbased beam training scheme. To reveal the effectiveness of the proposed scheme, we compare its necessary beam training overhead with that of existing schemes. Finally, the simulation results demonstrate that the proposed scheme can achieve accurate beam training in near-field wideband UCA systems with a low beam training overhead.

关键词： extremely large-scale antenna array (ELAA) uniform circular array (UCA) near-field wideband beam training

Seismic performance evaluation of water supply pipes installed in a full-scale RC frame structure based on a shaking table test

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第1期23卷 163-178页

作者： Wu Houli Guo Endong Wang Jingyi dai Xin dai Chenxi Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much *** paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame *** material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic *** response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical *** acceleration response and displacement response of different combinations are *** results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.

关键词： water supply pipe different materials shaking table test amplification factor seismic fragility