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S-wave velocity and Poisson's ratio structure of crust in Yunnan and its implication

Science china Earth Sciences 2005年第2期48卷 210-218页

作者： HU Jiafu, SU Youjin, ZHU Xiongguan & CHEN Yun Geophysical Department of Yunnan University, Kunming 650091, china seismological {2. of Yunnan Province, Kunming 650041, china institute of Geology and geophysics, Chinese Academy of Sciences, beijing 100101, china Geophysical Department of Yunnan University Kunming China seismological bureau of Yunnan Province Kunming China institute of Geology and geophysics Chinese Academy of Sciences Beijing China

Receiver function of body wave under the 2. stations in Yunnan was extracted from 3-component broadband digital recording of teleseismic event. Thus, the S-wave velocity structure and distribution characteristics of Poisson's ratio in crust of Yunnan are obtained by inversion. The results show that the crustal thickness is gradually thinned from north to south. The crustal thickness in Zhongdian of northwest reaches as many as 62.0 km and the one in Jinghong of further south end is only 30.2.km. What should be especially noted is that there exists a Moho upheaval running in NS in the Chuxiong region and a Moho concave is generally parallel to it in Dongchuan. In addition, there exists an obvious transversal inhomogeneity for the S-wave velocity structure in upper mantle and crust in the Yunnan region. The low velocity layer exists not only in 10.0-15.0 km in upper crust in some regions, but also in 30.0-40.0 km in lower crust. Generally, the Poisson's ratio is on the high side, however it has a better corresponding relation to the crustal velocity structure. An obvious block distribution feature is still shown on such a high background of Poisson's ratio. It is discovered by synthetically analyzing the velocity structure and Poisson's ratio distribution that there are high Poisson's ratio and complicated crust-mantle velocity structure feature in the Sichuan-Yunnan Diamond Block with Xiaojiang fault to be the east boundary and Yulong Snow Mountain fault to be the west boundary besides the frequent seismicity. This feature differs obviously from that of surrounding areas, which would provide geophysical evidence to deeply study the eastwardly flowage of lithospheric substances in the Qinghai-Tibet Plateau.

关键词： Yunnan, S-wave velocity, Poisson's ratio, Sichuan-Yunnan Diamond Block.

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Contemporary crustal movement of continental china obtained by global positioning system(GPS) measurements

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Chinese Science Bulletin 2001年第18期46卷 1552-1554,1588页

作者： MA Zongjin, CHEN Xinlian, YE Shuhua, LAI Xian, WEI Ziqing, CHEN Junrong, NING Jinsheng, XU Huoze & DING Guoyu1. Insitute of Geology, china seismological bureau, beijing 10002.,{2. (e-mail: disgroup@***)2. Center for Analysis and Prediction, china seismological bureau, beijing 100036,{2. 3. Shanghai Astronomic Observatory, Chinese Academy of Sciences, Shanghai 2.0030,{2. 4. institute of Seismology, china seismological bureau, Wuhan 430077,{2. 5. institute of Survey and Mapping, Xi’an 710054,{2. 6. National {12. of Survey and Mapping, beijing 100830,{2. 7. Wuhan University, Wuhan 430077,{2. 8. institute of Geodesy and geophysics, Wuhan 430077,{2. 9. china seismological bureau, beijing 100036,{2. Insitute of Geology China Seismological Bureau Beijing China Center for Analysis and Prediction China Seismological Bureau Beijing China Shanghai Astronomic Observatory Chinese Academy of Sciences Shanghai China institute of Seismology China Seismological Bureau Wuhan China institute of Survey and Mapping Xi’an China National bureau of Survey and Mapping Beijing China Wuhan University Wuhan China institute of Geodesy and geophysics Wuhan China china seismological {2. Beijing China

We obtain a unified horizontal velocity field of continental china and vicinity through measurements at 81 GPS stations provided by the National Key Infrastructure Project, Crustal Movement Observation Network of china. The velocity field delineates patterns of movements and deformation of active crustal blocks in continental china under the Eurasia-fixed reference frame. The space-based geodesy also clearly shows for the first time the horizontal movementand deformation of continental china induced by indentation of the Indian plate. The data provide kinematic constraints for simulating dynamic process of continental litho-spheric deformation.

关键词： crustal movement velocity field tectonic deformation.

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Palaeogene Biostratigraphic Characteristics of Red Basins In Western Henan and Its Adjacent Areas, With an Outline of Palaeogene Palaeobiogeographic Provinces of china

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Acta Geologica Sinica(English Edition) 1992年第1期66卷 101-117页

作者： Du Hengjian Ma Ancheng Cheng Jie Wu Weimin china University of Geosciences, beijing beijing Normal University china University of Geosciences, beijing institute of Crustal Dynamics, State seismological bureau, beijing china University of Geosciences Beijing China

This article is a preliminary summary of Paleogene biostratigraphy of the Liguanqiao, Tantou andYuanqu basins, with a new proposal for Paleogene paleobiogeographic provinces of china. On the basis of asynthetic analysis of the geological data, characters of the mammalian assemblages and their comparisons withother corresponding faunas, a new scheme on Paleogene biostratigraphic subdivision of the basins has been putforward here. Based on differences of biostratigraphic sequences, characteristics of mammalian assemblagesand directions of faults controlling Paleogene basins in china, six Paleogene paleobiogeographic provinces of{2. have been proposed in this paper, that is: Tianshan-Yinshan-Tumen Province; Tarim-North china Prov-ince; Kunlun-Qinling Province, Yangtze Province, Nanling and Southeastern Coastal Province, Qinghai andTibet Province.

关键词： With an Outline of Palaeogene Palaeobiogeographic Provinces of china

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Partial Melting and Its Implications for Understanding the Seismic Velocity Structure within the Southern Tibetan Crust

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Acta Geologica Sinica(English Edition) 2003年第1期77卷 64-71页

作者： YANG Xiaosong, MA Jin, JIN Zhenmin, GAO Shan and MA Shengli Geology institute, china seismological bureau, {2. 10002. Laboratory of Tectonophysics, china seismological bureau, {2. 10002. Faculty of Earth Sciences, china University of Geosciences, Wuhan, Hubei 430074 china Seismol Bur Inst Geol Beijing 100029 Peoples R China china Seismol Bur Lab Tectonophys Beijing 100029 Peoples R China china Univ Geosci Fac Earth Sci Wuhan 430074 Hubei Peoples R China

In order to constrain the crustal wave velocity structure in the southernTibetan crust and provide insight into the contribution of crustal composition, geothermal gradientand partial melting to the velocity structure, which is characterized by low average crustalvelocities and widespread presence of low-velocity zone(s), the authors model the crustal velocityand density as functions of depth corresponding to various heat flow values in light of velocitymeasurements at high temperature and high pressure. The modeled velocity and density are regarded ascomparison standards. The comparison of the standards with seismic observations in southern Tibetimplies that the predominantly felsic composition at high heat flow cannot explain the observedvelocity structure there. Hence, the authors are in favor of attributing low average crustalvelocities and low-velocity zone(s) observed in southern Tibet mainly to partial melting. Modelingbased on the experimental results suggests that a melting percentage of 7-12.could account for thelow-velocity zone(s).

关键词： partial melting intracrustal low-velocity zone high-pressure andhigh-temperature experiments Tibetan plateau

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Upper mantle P wave velocity structure of the northern part of china and Mongolia

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Acta Seismologica Sinica(English Edition) 1998年第6期11卷 24-33页

作者： JIAN PING WU RONG SHENG ZENG YUE HONG MING institute of geophysics,{2., beijing 100081, china

The average upper mantle P wave velocity structure and lateral heterogeneity in the northern part of china and Mongolia are investigated by waveform inversion of broadband body waveform data recorded by CDSN and digital stations around china. The average model has a low P wave velocity lid (about 7.8～8.0 km·s -1 ) with thickness about 60 km, and two discontinuities with velocity jumps of 0.2. km·s -1 and 0.55 km·s -1 at depth of 410 km and 665 km respectively. In the Jungger basin, the P wave velocity of uppermost mantle is about 7.7 km·s -1 . The lid thickness (90～100 km) and velocity gradient (average gradient is greater than 0.005 5/s) are large. At the depth of 140 km the P wave velocity reaches to 8.2.km·s -1 . Near in Baikal, the lid is about 30 km thick with average P wave velocity of 8.00～8.05 km·s -1 .

关键词： upper mantle P wave velocity structure waveform inversion the northern part of china Mongolia

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Joint exploration of crustal structure in Fuzhou basin and its vicinities by deep seismic reflection and high-resolution refraction as well as wide-angle reflection/refraction

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Science china Earth Sciences 2005年第7期48卷 925-938页

作者： ZHU Jinfang1, XU Xiwei2. ZHANG Xiankang3, HUANG Zonglin1, CHEN Xiangxiong1, FANG Shengming3, LIU Baojin3, ZHENG Rongzhang2.4 1. seismological bureau of Fujian Province,Fuzhou 350003,{2. 2. institute of Geology,{2. Earthquake Administration,beijing 10002.,{2. 3. Research Center for Exploration geophysics,{2. Earthquake Administration,Zhengzhou 450002.{2. 4. State Key Laboratory of Earthquake Dynamics,institute of Geology,{2. Earthquake Administration,beijing 10002.,{2. seismological bureau of Fujian Province Fuzhou 350003 China institute of Geology China Earthquake Administration Beijing 100029 China Research Center for Exploration geophysics China Earthquake Administration Zhengzhou 450002 China State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing 100029 China

The Fuzhou basin and its vicinities are located at the northern end of the southeastern coastal seismic zone of the mainland of china. By the joint explorations of high-resolution seismic refraction and wide-angle reflection/refraction as well as deep seismic reflection in the region, which is the first synthetic profile in china, its fine velocity structure and geometric structure from the ground to Moho discontinuity is obtained. The result shows that the crust is obviously layered with a thickness of about 32.km. Basically, it consists of two parts: upper crust and lower crust. The velocity of the upper crust is 5.9-6.2.km/s in which there is a 3-4-km-thick weak low-velocity layer between the depths of 10-15 km, while the velocity of the lower crust in the range of 6.3-7.2.km/s. There exists a strong velocity gradient layer about 3 km thick above the Moho discontinuity whose velocity increases from 6.5 to 7.2. km/s. There exist high-angle normal faults that are small in size and extend only in the shallow crust. These faults are the secondary developed on the hanging wall of westward dipping low-angle normal faults. Thus, their seismogenic ability is limited, however, there exists a high-angle deep fault in the crust from Changle-Zaoan fault zone to seashore fault zone. This deep fault has cut the interface between the upper and lower crusts and Moho discontinuity, and may be the deep structure to trigger destructive earthquake source in future to affect Fuzhou City. These results have advanced the detecting precision of the deep structure in the southeastern coastal seismic zone of the mainland of china. In the aspect of the combined feature of the deep and shallow extensional structures that consist of the westward dipping low-angle normal faults and secondary normal faults on their hanging walls in the upper crust, it is firstly obtained that a united structural interpretation has deepened the knowledge about the deep dynamic process in the southeastern coasta

关键词： deep seismic reflection high-resolution seismic refraction wide-angle.

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Elastic wave propagation in inhomogeneous anisotropic media

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Acta Seismologica Sinica(English Edition) 1998年第6期11卷 3-15页

作者： XIU CHENG WEI 1) MIN YU DONG 1) YUN YAI CHEN 2. 1) Geoscience Department, University of Petroleum, beijing 102.00, china {2., china seismological bureau, beijing 100081, china

Plane wave decomposition is a convenient and effective method in the study of wave field. Various complex wave fields can be obtained by using plane wave composition. In this paper, the method of plane wave is used to study elastic wave propagation in inhomogeneous and anisotropic media. The f k transformation is applied to time space domain wave equation in inhomogeneous anisotropic media. As a result, the frequency wave number domain wave equation (Christoffel equation) can be obtained. Using the relation between elastic parameters or its spatial derivatives and Christoffel matrix elements, a method for solving the Christoffel matrix in inhomogeneous anisotropic media is formulated and applied to inhomogeneous TIV as well as inhomogeneous EDA media. The results obtained show that directional derivative of wave amplitude in continuum is negative, so amplitude is reduced, when propagating direction directs to velocity increasing direction; and directional derivative of wave amplitude is positive that means amplitude enhanced when propagating direction directs to velocity decreasing direction. Thus, wave amplitude depends on propagation direction (even in isotropic medium), but does not always attenuate. The conclusion that in continuum wave amplitude attenuates does not apply to all propagation direction.

关键词： inhomogeneous anisotropy continuum Christoffel equation

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THE GLOBAL TECTONIC SYSTEMS AND A LATITUDINAL MOUNTAIN-PLATEAU CHAIN ON THE NORTH HEMISPHERE

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地学前缘 2000年第S1期7卷 344-345页

作者： Ma Zongjin(institute of Geology,china {2. bureau,beijing 10002.,china)

Three global tectonic systems that formed since the middle Jurassic (160Ma ago)are outlined based on the global map of the Cenozoic and Mesozoic tectonics edited by Ma Zongjin et al.(1996).They are the circum\|Pacific tectonic system,the mid\|ocean ridge tectonic system and the intra\|continental tectonic system of the north *** map shows that about 80% of the total length of the continental orogens are concentrate on the north hemisphere of the earth,of which a latitudinal mountain\|plateau chain occur within a zone between north latitude 2.°and 50°.Seismic and volcanic activities demonstrate that the intracontinental tectonic system on the north hemisphere is still *** distribution of the continental deep\|focus earthquakes and almost ultra high\|pressure rock found so far over the World,that are assumed both related to recent or previous deep subduction of continent,along with this *** latitudinal mountain\|plateau chain is subdivided into four active tectonic region of Qinghai—Xizang(Tibet),Iranian,eastern mediterranean and North American,both characterized by an individual similar mountain\|plateau\|basin structure with major active boundaries or controlling faults (Fig.1).These active regions are all close to primary dynamic boundaries of continent\|continent *** of source mechanisms shows that regional tectonic stress field in these regions are dominated by a nearly NS or NNE—SSW direction compression corresponding to a local plate motions and a global compressive *** between the formation of the continental latitudinal mountain\|plateau chain on north hemisphere and the oceanic plate tectonics is discussed using the information of the “Map of Magnetic Lineations of the World’s Ocean Basins (Cande et al.,1989)”and the Cenozoic and Mesozoic tectonic evolution in the *** 49 accretion units formed during 6 accretion stages of the ocean spreading in three chief oceans (the Pacific,the India and th

关键词： global asymmetrical system geodynamics mountain\| plateau chain seismotectonic system latitudinal tectonic zone

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Some Evidence for a Possible Extraterrestrial Event at/near Permian-Triassic Boundary

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Journal of china University of Geosciences 2002年第2期13卷 151-156页

作者： Xu Daoyi institute of Geology, china seismological bureau, {2. 10002. institute of Geology China Seismological Bureau Beijing 100029

A selection of evidence, including a carbon isotopic excursion, iridium anomaly, fullerenes (C 60 and C 70 ) with trapped noble gases, microspherules and shocked quartz, is discussed in this paper. All the evidence in hand favors the hypothesis that the PTB event was probably related to an extraterrestrial cause, and the impact would lead to great physical change, including large volcanic eruptions on the earth's surface. The ET markers for the CTB event could be considered only as an example, and cannot be taken as a unique standard of an ET event.

关键词： Permian Triassic boundary extraterrestrial event iridium anomaly carbon isotopic excursion.

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Experimental study of ore gabbro liquid immiscibility

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Science china Earth Sciences 2005年第4期48卷 496-505页

作者： SANG Zunan1,2. XIA Bin1, ZHOU Yongsheng3 & JIN Zhenmin4 1. Guangzhou institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, china 2. Wuhan University, Wuhan 430072. china 3. institute of Geology, china seismological bureau, beijing 10002., china 4. Faculty of Earth Sciences, china University of Geosciences, Wuhan 430074, china Guangzhou institute of Geochemistry Chinese Academy of Sciences Guangzhou China Wuhan University Wuhan China institute of Geology China Seismological Bureau Beijing China Faculty of Earth Sciences China University of Geosciences Wuhan China

In this paper, the authors present the results of a preliminary experimental study on partial melting of fine-grained gabbro, Panzhihua, Sichuan Province, china. Experiments were conducted under (confining) pressure ranging from 450 to 500 MPa and temperature of 900— 12.0℃. The results show that the initial melt is distributed along grain boundaries and triple junctions. Liquid immiscibility phenomena are noted in the melt with two compositional different melt phases, i.e. matrix and sphere phases. The matrix phase is relatively rich in Si, Al and K, and is depleted in Mg, Fe, Ca, Na and Ti, whereas the sphere phase shows opposite trends. The calculation of the melt free energy indicates that the liquid immiscibility is governed by the rule of thermodynamics, as the liquid immiscibility would result in the decrease in free energy of the melt system. The field relationships suggest that the liquid immiscibility may have played an important role in the generation of ore magma of Panzhihua V-Ti magnetite ore deposit. This study thus provides experimental constraints on the mechanism of the formation of V-Ti magnetite deposite.

关键词： partial melting, experimental study, gabbro, liquid immiscibility, ore formation mechanism.

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