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Crustal thickness and composition in the South China Block:Constraints from earthquake receiver function

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Science China Earth Sciences 2022年第4期65卷 698-713页

作者： Changxin CHEN qingtian lü ling CHEN Danian SHI Jiayong YAN Yinshuang AI Chinese Academy of Geological Sciences Beijing 100037China Chinese MNR laboratory of Deep Earth Sciences and Technology Beijing 100094China Key laboratory of Deep-Earth Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China State Key laboratory of lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China CAS Center for Excellence in Deep Earth Science Guangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China Key laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Crustal thickness and composition are closely related to geology and tectonic evolution of the region.Studying the differences in the crustal thickness and composition of the South China Block(SCB)is important to gain a comprehensive understanding of multi-phase amalgamation,breakup,reworking,and regional geodynamic processes.In this study,teleseismic data from 135 high-density portable broadband stations from Sino Probe were processed using Common Conversion Point(CCP)stacking and H-κstacking methods.The Moho depth and P-wave and S-wave velocity ratio(V_(p)/V_(s))were studied.Our results revealed several insights about the tectonic processes in the SCB.First,the crustal structure and V_(p)/V_(s)ratios of the Cathaysia Block,Jiangnan Orogenic Belt,and Yangtze Block were significantly different.The average depth of the Moho in the Cathaysia Block was approximately 31 km,and the V_(p)/V_(s)ratios increased from the inland area(1.66)to the coastal area(1.78),indicating the oceanward increase of mafic proportion in the lower crust,which is related to the influence of the Paleo-Pacific Plate westward subduction.Second,the crustal thickness of Jiangnan Orogenic Belt deepens from east ca.31 to the west ca.42 km and the V_(p)/V_(s)ratios varied from 1.75 to 1.64,illustrating a relatively felsic crust,which could have been related to the Mesozoic upper crustal thickening under compression followed by the lower crust removal under the extensional background.Third,the average crustal thickness of the Yangtze Block was 42 km,and the V_(p)/V_(s)ratios ranged from 1.64 to 1.84,presenting a positive correlation between the Moho depth and the V_(p)/V_(s)ratio,which is explained by the relatively thick mafic lower crust.Based on the variations in the crustal structure and V_(p)/V_(s)ratios of the profile,we inferred that the central part of the Jiangnan Orogenic Belt was bounded by the Jiangshan-Shaoxing-Hengyang in the east and the Jiujiang-Shitai-Jishou in the west.The small-scale Moho depth undulations at the intersection of t

关键词： P wave receiver function The South China Block Crustal thickness Crustal composition Block boundary

长江中下游及邻区地震各向异性对区域构造演化的启示

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地球物理学报 2024年第3期67卷 900-915页

作者：张永谦吕庆田石玉涛史大年严加永张洪双阮小敏中国地质科学院北京100037 自然资源部深地科学与探测技术实验室中国地质科学院北京100094 中国地震局地震预测研究所地震预测重点实验室北京100036 中国地质科学院地质研究所北京100037

大别山东缘和长江中下游地区是我国东部构造格局最复杂的地区之一.为深入理解和认识该区的构造演化过程和壳幔变形特征,本文利用NW-SE向跨越长江中下游地区的密集宽频带流动地震台站数据,开展了远震接收函数Pms各向异性研究,并结合已有... 详细信息

大别山东缘和长江中下游地区是我国东部构造格局最复杂的地区之一.为深入理解和认识该区的构造演化过程和壳幔变形特征,本文利用NW-SE向跨越长江中下游地区的密集宽频带流动地震台站数据,开展了远震接收函数Pms各向异性研究,并结合已有研究进一步分析了该区地壳与上地幔各向异性特征及其产生机制.结果表明:长江中下游及邻区地壳各向异性呈明显的横向分区性,华北克拉通东南部以近NWW向为主,而长江中下游和华南东北部以NE向为主.在垂向上,该区地壳与上地幔各向异性方向也存在明显差异,Pms各向异性快波方向与XKS(PKS,SKS,SKKS)快波偏振方向整体上存在30°~60°左右差异,形成了该区壳幔各向异性的“立交桥”式分层结构.本研究认为印支期和燕山期的区域构造演化差异以及华北与华南块体的流变学强度不同是造成该区壳幔各向异性“立交桥”式分层结构的重要因素.华北地区Pms各向异性特征反映了华南与华北块体在印支期陆陆碰撞所形成的中下地壳变形痕迹,华南东北部地区的Pms各向异性则主要受控于燕山期古太平洋板块俯冲造成的陆内挤压作用.燕山期古太平洋板块的北西向俯冲作用不仅导致了软流圈物质沿NW或近W向流动和橄榄岩矿物晶体的定向排列,也在地壳和岩石圈尺度产生了陆内挤压作用并最终导致了目前观测到的中下地壳变形和各向异性特征.

关键词：长江中下游地震各向异性接收函数区域构造演化

Crustal Electrical Structure and Deep Metallogenic Potential in Northern Wuyi Area(South China),based on Magnetotelluric Data

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Acta Geologica Sinica(English Edition) 2022年第3期96卷 791-805页

作者： lUO Fan lü qingtian ZHANG Kun YAN Jiayong Colin GFARQUHARSON ZHANG Chong FU Guangming School of Geophysics and Measurement-control Technology' East China University of TechnologyNanchang 330013China Chinese Academy of Geological Sciences Beijing 100037China China Deep Exploration Center China Geological Survey&Chinese Academy of Geological SciencesBeijing 100037China Department of Earth Sciences Memorial University of NewfoundlandSt.John'sNL A1B 3X5Canada

The northern Wuyi area,which is located in the northern Wuyi metallogenic belt,has superior mineralization conditions.The Pingxiang-Guangfeng-Jiangshan-Shaoxing fault(PSF)extends across the whole region regardless of whether or how the PSF relates to the near-surface mineralization.We carried out an MT survey in the region and obtained a reliable 2D model of the crustal electrical structure to a depth of 30 km.In the resistivity model,we inferred that a continuous high conductivity belt that ranges from the shallow to deep crust is a part of the PSF.Then,we estimated the fluid content and pressure gradient to identify the deep sources of fluid as well as its pattern of motion pattern.Finally,we proposed a model for the deep metallogenic migration processes that combines geological data,fluid content data,pressure gradient data,and the subsurface resistivity model.The model analysis showed that the Jiangnan orogenic belt and the Cathaysia block formed the PSF during the process of com.The deep fluid migrated upward through the PSF to the shallow crust.Therefore,we believe that the PSF is an ore-forming fluid migration channel and that it laid the material basis for large-scale mineralization in the shallow crust.

关键词： magnetotellurics crustal electrical structure PSF deep metallogenic background model northern Wuyi area

Mineral Resource Science in China:Review and perspective

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Geography and Sustainability 2021年第2期2卷 107-114页

作者： Mingguo Zhai Ruizhong Hu Yan Wang Shaoyong Jiang Rucheng Wang Jianwei li Huayong Chen Zhiming Yang qingtian lü Tao Qi Xuefa Shi Yuansheng li Jianming liu Ziying li Xiyan Zhu Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081China Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China China University of Geosciences Wuhan 430074China Nanjing University Nanjing 210023China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Chinese Academy of Geological Sciences Beijing 100037China Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China First Institute of Oceanography Ministry of Natural Resources of the People’s Republic of ChinaQingdao 266061China Polar Research Institute of China Shanghai 200136China Beijing Research Institute of Uranium Geology Beijing 100029China

Mineral resources are essential to prosperity and security of modern societies.How mineral resources can guar-antee sustainable development of economy in countries,especially those developing countries,has long been a focus of attention of international communities.This paper provides a comprehensive summary for major ad-vance of the research on mineral resources in past decades,and proposes some key issues regarding ore-forming mechanism,exploration and utilization of major and critical mineral resources.On the basis of these aspects,we also identify four priority science issues to be addressed in the future,including(1)mechanism of both metal circulation and extremely high concentration,(2)theories and technologies of prospecting deep-earth resources,(3)investigation of mineral resources in seafloor and polar regions,and(4)efficient,clean and recycling utiliza-tion of mineral resources.It can be expected that new advances in these four issues would tremendously promote the innovation of mineral resource science,and provide scientific and technologic support to meet the demand of mineral resources for human activities and the harmonious development of both mineral-resource exploration and ecological restoration.

关键词： Mineral resource science Review Priority science issues

Intra-continental Orogeny:Insights from Magnetotelluric Data into the Mesozoic Uplift History of the Eastern Jiangnan Orogen in South China

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Acta Geologica Sinica(English Edition) 2023年第1期97卷 55-67页

作者： ZHANG Kun lÜ qingtian ZHAO Jinhua YAN Jiayong lUO Fan MAN Zuhui XIAO Xiao ZHANG Gang YONG Fan Chinese Academy of Geological Sciences Beijing 100037China Key laboratory of Deep Earth Science and Exploration Technology of Ministry of Natural Resources East China Institute of Technology Nanchang 330013China China’s University of Geosciences(Wuhan) Wuhan 430074China Central South University Changsha 410083China China’s University of Geosciences(Beijing) Beijing 100086China Institute of Geophysical and Geochemical Exploration Chinese Academy of Geological SciencesLangfangHebei 065000China

Despite extensive efforts to understand the tectonic evolution of the Jiangnan Orogen in South China,the orogenic process and its mechanism remain a matter of dispute.Previous geodynamic studies have mostly focused on collisional orogeny,which is commonly invoked to explain the Jiangnan Orogen.However,it is difficult for such hypotheses to reconcile all the geological and geophysical data,especially the absence of ultrahigh-pressure metamorphic rocks.Based on the magnetotelluric data,we present a group of resistivity models produced through the combination of two-dimensional and three-dimensional inversions,revealing the geo-electrical structures of Jiangnan and a typical collisional orogen.In our models,the resistive crust is separated into three parts by a prominent conductive layer with opposite dipping directions on both sides.A special thrust-nappe system,which is different from that developed in a typical collisional process,is revealed in the Jiangnan Orogen.This structure suggests a process different from the simple collisional orogeny.To interpret our observations,an'intra-continental orogeny'is proposed to address the development of the Jiangnan Orogen in the Mesozoic.Furthermore,this'reworked'process may contain at least two stages caused by the decoupling of the lithosphere,which is revealed by an extra conductive layer beneath Jiangnan.

关键词： magnetotelluric sounding 2D inversion 3D inversion intra-continental orogeny Jiangnan Orogen

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

Formation Mechanism of "Drag Depressions" and Irregular Boundaries in Intraplate Deformation

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Acta Geologica Sinica(English Edition) 2004年第1期78卷 267-272页

作者： DENGJun HUANGDinghua WANGQingfei HOUZengqian lüqingtian YAOlingqing XINHongbo ZHANGQiang WEIYanguang Keylaboratoryoflit-hosphericTectonicsandExploration ChinaUniversityofGeosciencesBeijingMinistryofEducationBeijing100083 ChinaUniversityofGeosciences WuhanHubei430074 InstituteofMineralResources ChineseAcademyofGeologicalSciencesBeijing100037

Almost all intraplate caprocks experienced strong deformation during the convergence of microplates, and then disintegrated into many secondary geologic units with the special characters, such as irregular boundaries and particular structural assemblages. In order to understand the formation mechanism of these special phenomena, a rheological experiment on the structural scenery of the Tongling area is carried out. The result shows that the primary regular and uniform boundaries of the Tongling area becomes irregular because of the enclosing and confinement of surrounding geological units in the process of 'compression-shearing-rotation-drag'; simultaneously, two specific 'drag depressions' developed at two opposite corners of the block. The former and the later phenomena can be regarded as a typical regional-scale rheological effect and necessary outcome of intraplate deformation respectively.

关键词： intraplate deformation simulation experiment drag depression irregular boundaries Tongling area

Coal-bearing strata sequence stratigraphy of Paleogene Meihe Formation,Meihe Basin,NE China

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International Journal of Coal Science & Technology 2021年第4期8卷 547-561页

作者： Yueyue Bai qingtian lii Zhaojun liu Pingchang Sun Rong liu Shuqing Yao SinoProbe-China Deep Exploration Center Chinese Academy of Geological SciencesBeijng 100037China Key laboratory for Oil Shale and Coexisting Minerals Mineralization and Exploration and Exploitation Jilin UniversityChangchun 130061China

The Meihe Basin is an important Paleogene coal-bearing basin located in the Dunhua-Mishan Fault Zone,northeastern China.Based on a comprehensive study of well logs,seismic profiles,cores and rock geochemical properties,the coal distribution,paleoenvironment evolution within a sequence stratigraphic framework and the accumulation model to explain how coal seams developed in small fault basin were discussed in detail.Three-third-order sequences were identified in the Paleogene Meihe Formation of Meihe Basin and the two coal-bearing sequences are the lower Coalbearing Member of Sequence I and the Upper Coal-bearing Member of Sequence III.All three types of system tracts are developed in both sequences,i.e.,the lowstand systems tract(lST),the transgressive systems tract(TST),and the highstand systems tract(HST).In lST of Sequence I,fan delta plain marsh is the main coal accumulating environment where coal seams are thin,discontinuous and therefore uneconomic for mining,and it is the same with all coal seams developed in Sequence III.While in TST and HST of Sequence I,lake swamp is the main sedimentary environment where coal seams are thick,continuous,widely distributed,and thus economically attractive for mining.In the study area,the nice thick economical coal seams are usually developed in an ideal stable depositional environment where organic matter accommodation space grows at a balanced rate with peat,in other words,free of sediment input or channel migration.The key findings of this study could provide guidance for the exploration of coal seams in the Meihe Basin and other similar basins.

关键词： Coal seam Sequence stratigraphy Fan delta Swamp Meihe Basin

Three-dimensional P-wave Velocity Structure Modelling of the Middle and lower Reaches of the Yangtze River Metallogenic Belt: Crustal Architecture and Metallogenic Implications

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Acta Geologica Sinica(English Edition) 2020年第6期94卷 1808-1821页

作者： CHEN Anguo lÜ qingtian ZHOU Taofa DU Jianguo DING Juan YAN Jiayong lU Zhitang School of Resources and Environmental Engineering Hefei University of TechnologyHefei 230009China Geological Survey of Anhui Province Hefei 230001China Chinese Deep Exploration Center(SinoProbe Center) Chinese Academy of Geological SciencesBeijing 100037China Anhui Earthquake Agency Hefei 230031China

In this study,we compiled and analyzed 69310 P-wave travel-time data from 6639 earthquake events.These events(M≥2.0)occurred from 1980 s to June 2019 and were recorded at 319 seismic stations(Chinese Earthquake Networks Center)in the study area.We adopted the double-difference seismic tomographic method(tomo DD)to invert the 3-D P-wave velocity structure and constrain the crust-upper mantle architecture of the Middle and lower Reaches of the Yangtze River Metallogenic Belt(MlYB).A 1-D initial model extracted from wide-angle seismic profiles was used in the seismic tomography,which greatly reduced the inversion residual.Our results indicate that reliable velocity structure of th e uppermost mantle can be obtained when Pn is involved in the tomography.Our results show that:(1)the pattern of the uppermost mantle velocity structure corresponds well with the geological partitioning:a nearly E-W-trending low-velocity zone is present beneath the Dabie Orogen,in contrast to the mainly NE-trending low-velocity anomalies beneath the Jiangnan Orogen.They suggest the presence of thickened lower crust beneath the orogens in the study area.In contrast,the Yangtze and Cathaysia blocks are characterized by relatively high-velocity anomalies;(2)both the ultra-high-pressure(UHP)metamorphic rocks in the Dabie Orogen and the low-pressure metamorphic rocks in the Zhangbaling dome are characterized by high-velocity anomalies.The upper crust in the Dabie Orogen is characterized by a low-velocity belt,sandwiched between two high velocity zones in a horizontal direction,with discontinuous low-velocity layers in the middle crust.The keel of the Dabie Orogen is mainly preserved beneath its northern section.We infer that the lower crustal delamination may have mainly occurred in the southern Dabie Orogen,which caused the mantle upwelling responsible for the formation of the granitic magmas emplaced in the middle crust as the low-velocity layers observed there.Continuous deep-level compression likely squeezed the granitic magma upward to int

关键词： 3D P-wave velocity structure double-difference seismic tomography crust-upper mantle Dabie Orogen Middle and lower Reaches of the Yangtze River Metallogenic Belt