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Comparison Analysis of Longitudinal Electrical Conductivity Distribution and seismic tomography Velocity Models for the Central Tien Shan Region

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Journal of Earth Science 2023年第2期34卷 580-587页

作者： Olga Zabinyakova Elena Bataleva Irina Medved Research Station of the Russian Academy of Sciences in Bishkek City Bishkek 720049Kyrgyzstan Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of SciencesNovosibirsk 630090Russia Trofimuk Institute of Petroleum Geology and Geophysics Siberian Branch of the Russian Academy of SciencesNovosibirsk 630090Russia

The paper is dedicated to consider the approach of longitudinal electrical conductivity maps construction for Central Tien Shan region and to complete the comparison analysis of these maps with related seismic tomography data.The results of joint analysis of longitudinal electrical conductivity distribution and seismic tomography velocity models with respect to geological and geophysical senses allow to confirm the already known and to establish the new patterns of structure and geodynamics of the Tien Shan segment of Central Asia such as the manifestation of characteristic structural ensembles,reflection of the longitudinal and transverse segmentation of the Tien Shan,the existence within the framework of a“single”orogen of segments with different near-surface and deep structure and morphological expression.As well,the correlation between the velocity characteristics and geoelectric properties was found.This correlation allows to identify signs of reflection of fault structures in geophysical fields and to clarify the territorial and structural position of both visible and hidden faults.Additionally,in the paper,the geological interpretation of geophysical anomalies is considered.

关键词： profile magnetotelluric soundings longitudinal electrical conductivity map seismic tomography velocity model Tien Shan geophysics

New Insights into the Mesozoic Large-scale Intra-plate Magmatism and Mineralization in South China from seismic tomography

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Acta Geologica Sinica(English Edition) 2023年第4期97卷 1243-1251页

作者： SHI Danian LÜQingtian SHEN Yang XU Xiaoming ZHANG Yongqian XU Yao ZHAO Jinhua GU Yumin SHI Jianyu CHEN Changxin SinoProbe Laboratory Chinese Academy of Geological SciencesBeijing 100037China University of Rhode Island KingstonRhode IslandUSA Institute of Geophysics China Earthquake AdministrationBeijing 100081China National Marine Environmental Forecasting Center Beijing 100081China

A great amount of new S-wave data has been combined to image the mantle structure down to lower mantle depth near the southeastern margin of Eurasia and understand the tectonics in South China since the Mesozoic.Our results reveal a large-scale structure beneath the South China Sea,with a prominent,broad low-velocity feature of at least 1500-km wide in and below the mantle transition zone(MTZ)and a pronounced low-velocity feature of nearly 500-km wide in the lowermost mantle.Together these features may represent the head-and-tail of an upwelling mantle plume that has interacted with and deformed by the subducting plates in the region.The Andaman-Sumatra plate is seen subducting steeply without stagnation in the MTZ over the large-scale low-velocity structure,suggesting that the upwelling mantle may have exerted significant influence on the overlying plate tectonics.Our results suggest a long-term extensional regime near the southeastern margin of Eurasia,which may help to understand the formation of the large-scale intra-plate magmatism and mineralization with accumulation of huge amount of rare metal elements in South China during the Mesozoic,and the continental breakup,the southeastward extrusion of Indochina,and the opening of the South China Sea during the Cenozoic.

关键词： seismic tomography intra-plate tectonics mantle dynamics South China

seismic tomography of the northwest Pacific and its geodynamic implications

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Progress in Natural Science:Materials International 2001年第1期11卷 48-51+83页

作者：邵济安刘福田陈辉 Beijing 100101 Beijing 100871 China Chinese Academy of Sciences Institute of Geology ami Geophysics Peking University

High-resolution tomographic images across Japan Trench-Changbai Mountains-Dong Ujimqinqi are displayed, showing the morphological feature of the subducted slab in the northwestern Pacific margin and the characteristics of lithosphere structures under the Changbai Mountains and the Da Hinggan Mountains. The Pacific plate began to penetrate into the deeper mantle after it subducted to the 660 km discontinuity with an underthoisting angle of 26°, but did not continue to move further westward. In contrast, there appeared a remarkable thermal upwelling zone to the west of the downward plate. In addition, the evidence from the subduction time and time lag between the subduction and consequent magmatism indicates that there is no direct genetic correlation between the Mesozoic magmatism in eastern China and subduction of the Pacific plate. In this work, we also emphasize that what the tomographic images reflect is the present structure in the deep earth interior, which should preserve some Mesozoic lithospher

关键词： seismic tomography Pacific plate subduction continental margin volcano-plutonic rock belt.

Quasi-waveform seismic tomography of crustal structures in the capital circle region of China

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Science China Earth Sciences 2021年第1期64卷 110-126页

作者： Xueyuan HUANG Dinghui YANG Ping TONG Yuan GAO Yutao SHI Hao WU Department of Applied Statistics School of Mathematics and StatisticsBeijing Technology and Business UniversityBeijing 100048China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China Division of Mathematical Sciences School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore Asian School of the Environment Nanyang Technological UniversitySingapore 637371Singapore Institute of Earthquake Science China Earthquake AdministrationBeijing 100036China

seismic tomography is one of the main tools to explore the interior of the earth.In this study,the quasi-waveform seismic tomographic method is used for the first time to reveal the crustal structures in the capital region of China.3-D highresolution V_P,V_S and the Poisson’s ratio models are generated by inverting 29839 direct P-and 29972 direct S-wave traveltimes selected from 3231 local earthquakes.The results reveal strong crustal heterogeneities.The velocity anomalies at shallow depths are well consistent with surface geologic structures.The relatively low-velocity anomaly layer in the middle crust may be the result of multiple phases of tectonic activity.Earthquakes generally occurred on the boundaries of high-and low-velocity and Poisson’s ratio anomalies.There are obvious low-velocity anomalies below the hypocenters of the Tangshan earthquake and the historical Sanhe-Pinggu earthquake,implying the existence of fluids.The similar velocity structures around the hypocenters of the two earthquakes indicate that the occurrences of the two earthquakes may be related to the same mechanism.The highresolution velocity models provide important observational constraints on the small-scale heterogeneities and dynamic mechanism of the crust in the capital region of China.

关键词： Quasi-waveform inversion Capital circle region seismic tomography Crustal velocity structure Heterogeneity

A review of geophysical studies on the Mongolian Plateau

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Earthquake Science 2024年第3期37卷 224-240页

作者： Lei Zhang Zhouchuan Huang Xiaodong Song Qingju Wu SinoProbe Laboratory School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National Observatory on Thick Sediments and seismic Hazards Peking UniversityBeijing 100871China School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China Institute of Geophysics China Earthquake AdministrationBeijing 100081China

The Mongolian Plateau in Central Asia is an intracontinental tectonic system far from active plate boundaries.Despite its distance from these boundaries,the plateau is characterized by intense crustal deformation accompanied by voluminous Cenozoic volcanism and active modern seismicity.However,the intraplate deformation mechanism has long been debated owing to the scarcity of observations and contradictions between different results.In recent years,growing geophysical studies have been conducted on the Mongolian Plateau,providing constraints on its lithospheric structure and dynamics.Here,we review the geophysical research on the Mongolian Plateau over the last decade,including seismological,geodetic,gravity,magnetotelluric,and geodynamic aspects.This review aims to(a)describe crustal and mantle structures based on multiscale seismic images;(b)describe deformation patterns based on seismic anisotropy,focal mechanisms,and global positioning system(GPS)observations;and(c)discuss the mechanisms behind intraplate deformation,volcanism,and seismic activity across the Mongolian Plateau.seismic images show that the crustal structure of the plateau has significant east-west differences.Several blocks in the western Mongolian Plateau have thick crusts,including the Altai Mountains,Hovsgol Rift,and Hangay Dome.The lithospheric deformation across the Mongolian Plateau has strong lateral variation,with NE-SW shortening in the Altai Mountains and W-E or NW-SE shear deformation in the Hangay Dome region and the eastern part.The varied deformation may result from the superposition of multiple mechanisms,including far-field stress in the Altai Mountains,mantle upwelling,and mantle flow in the Hangay Dome region.However,it is difficult to identify the geodynamics of the formation of the entire Mongolian Plateau because the deformation is too complicated,and the present models are not sufficient and are always partial.Overall,this review encompasses recent advances in seismic observations of the Mongolian Plateau,illuminates the h

关键词： Mongolian Plateau Central Asia seismic tomography crust-mantle structure intraplate deformation

Source side seismic tomography(3STomo):A novelmethod to image the subsurface structure beneath seismically active region

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Earthquake Science 2010年第6期23卷 637-643页

作者： Ting Yang Shenyi Gu Khanh Phon Le State Key Laboratory of Marine Geology Tongji University Shanghai 200092 China Center for Earthquake Analysis and Prediction Earthquake Administration of Hainan Hainan 570203 China Faculty of Oil and Gas Hanoi University of Mining and Geology Dong Ngac Tu Liem Hanoi Vietnam

We propose a novel seismic tomography method, Source Side seismic tomography （3STomo）, which is designed particularly to image the subsurface structure beneath seismically active regions. Unlike the teleseismic tomography, in which the data are relative traveltime residuals between closely spaced stations for each teleseismic event, 3STomo uses relative traveltime shifts between earthquakes within the study region for each distant station. Given the relatively evener distribution of global seismic stations, this method has unique advantages for imaging the structure beneath regions that have numerous earthquakes but lack of dense seismic stations, for example, some subduction zones and spreading ridges in the ocean. In addition, 3STomo has potentially better vertical resolution at shallow depths than the traditional teleseismic tomo- graphy. The effect of the inaccurate source parameters on its resolution can be minimized by using depth phases and the technique of joint source and structure inversion. Numerical experiments and application to Luzon Island, Philippines show that 3STomo can be a valuable tool to investigate the subsurface structure beneath some areas where the traditional method cannot be applied to, or at least it can be used as a complementary component of conventional teleseismic tomography to obtain better back-azimuth coverage and achieve higher resolution at shallow depths in the inversion.

关键词： seismic tomography teleseismic tomography subduction zone lithosphere Luzon Island

seismic active faults in the northwestern Beijing by seismic tomography

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Acta Seismologica Sinica(English Edition) 2007年第1期20卷 11-20页

作者：王培德李春来 Wetzig E 黄瑗赵华 Institute of Geophysics China Earthquake Administration Beijing 100081 China Seismological Central Observatory Federal Institute for Geosciences and Natural Resources Erlangen 91054 Germany

Using the arrival times of 197 earthquakes well recorded by the Beijing seismic Network and the China-Germany cooperative Yanqing Digital seismic Array in the period from October of 2001 to December of 2005, we accurately relocate these earthquakes by the joint-inversion program for hypocentral position and 3-D velocity structure The distribution of hypocenters shows that there are two major seismic active belts in the northwestern Beijing. The first belt stretches from Qinghe, Wenquan to the NW direction and the second extends from Nankou, Changping to the ENE direction.

关键词： seismic activity fault northwestern Beijing seismic tomography high accuracy location Yanqing seismic array

Study of seismic tomography in Panxi paleorift area of southwestern China——Structural features of crust and mantle and their evolution

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Science China Earth Sciences 2001年第3期44卷 277-288页

作者：刘建华刘福田何建坤陈辉游庆瑜 Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100101 China

Structural features of the typical continental paleorift in Panxiarea are revealed by seismic tomography. (1) In the profile along the minor axis of Panxi paleorift, we found alternating high and low-velocity strips existing at different depths in the crust, presenting itself as a "sandwich" structure. The existence of these high and low-velocity anomaly strips is related to the basal lithology in the rift area. (2) An addition layer with velocity values of 7.1-7.5 km/s and 7.8 km/s exists from the base of lower crust to uppermost mantle and its thickness is about 20 km. Some study results indicate that the addition layer results from the invasion of mantle material. (3) A lens-shaped high-velocity body surrounded by relatively low-velocity material is observed at depths of 110-160 km between Huaping and Huidong in the axis of the paleorift. This is the first time to discover it in the upper mantle of the paleorift. Based on the results of geology, petrology and geochemistry, we infer that the formation of the addition layer and the lens-shaped high-velocity body in the upper mantle are related to the deep geodynamic process of generation, development and termination of the rift. On the one hand, the upwelling of asthenosphere mantle caused partial melting, and then the basaltic magma from the partial melted material further resulted in underplating and formed the crustal addition layer. On the other hand, the high-density content of mineral facies was increased in the residual melted mass of intensely depleted upper mantle, formed by basalt withdrawing. The solid-melt medium in the depleted upper mantle was mainly an accumulation of garnet and peridotite because the heating effect of lithosphere was relatively weakened in the later riftogenesis, so that a lens-shaped high-density and high-velocity zone was produced in the upper mantle. The results indicate that the energy and material exchange between asthenosphere and lithosphere and remarkable underplating would have an important effect on the material state a

关键词： Panxi paleorift seismic tomography underplating of mantle material high-velocity anomaly body in mantle lithosphere.

Studies on the Velocity Structure of Crust-Upper Mantle beneath Eastern Qinghai-Tibet Plateau Using seismic tomography

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Continental Dynamics 1999年第2期 79-85页

作者： XUE Guangqi QIAN Hui JIANG Mei (Institute of Mineral Resources, CAGS Beijing 100037,China)Wittlinger Gerard Vergne Jerome (Eost,5 rue Rene Descartes, 67084, Strasbourg France )POUPINET Georges (LGIT-IRIGM,University Joseph Fourier BP53X.38041 Grenoble,

seismic tomographic analysis is performed using the teleseismic data acquired from the eastern QinghaiTibet plateau in 1998. Inversion results of tomography and receiver functions show a gradually southward increasing in crustal thickness in a stepping manner. The analysis on the residual approves that the QinghaiTibet plateau has a thick crust, especially and it is thicker in the south and west than in the north and east. The Eastern Kunlun Fault and other faults match the boundaries between high velocity and low velocity bodies. An overwhelming low velocity perturbation (up to -3 %) bctwecn the depth of 100 km and 400 km beneath the Eastern Kunlun Fault Belt with its north end corresponding to the southern part of the Eastern Kunlun Fault with its north end cuts in northeast through the high velocity lithosphere and connects to low velocity materials coming deeply from the mantle. Beneath the Qiangtang terrane on the south of the Jinska suture, distributes the other low velocity perturbation above the depth of 200 km.

关键词： velocity structure seismic tomography Qinghai-Tibet plateau