检索结果-南通市图书馆

geophysical Significance of the Senegalo-Mali Discontinuity: Evidence from Secondary Structures, Kédougou-Kéniéba Inlier, western Mali

在线全文

学校读者我要写书评

暂无评论

Open Journal of Geology 2024年第10期14卷 943-962页

作者： Mamadou Yossi Mahamadou Diallo Mamoutou Ouattara Amadou Berthé Saidou Ly Sagax Afrique S.A geophysical Surveys and Consulting Ouagadougou Burkina Faso Laboratory of Cartography and Mineral Resources Department of Teaching and Research of Geology and Mines National School of Engineering Abderhamane Baba Tour (ENI-ABT) Bamako Mali

The present study focuses on the analysis and description of lineaments interpreted as secondary structures to describe the nature of Senegalo Malian Discontinuity. These lineaments cross-cut the large north-south oriented transcurrent lithospheric structure known as the Senegalo Malian Discontinuity (SMD). Two lineaments were selected oriented NNE (N15˚ to N25˚), one at Dialafara and one at Sadiola. Four profiles on each lineament of these 2 zones, so that there were 2 on each side of the SMD. The ground data collected were processed using proper parameter and software. Some filters were applied to enhance the signal level. These ground data were later compared to the existing airborne magnetic data for consistency and accuracy using the upward continuation filter. The results show that the quality of ground data is good. In addition, the ground magnetic data show the presence of certain local anomalies that are not visible in the regional data. The analytical signal was also used to determine domain boundaries or possible contact zones. The contact zone can be highlighted on certain profiles such as L300 and L600. The study showed that the west and east sides of the SMD are not the same. Secondary structures become wide when approaching the SMD on both sides. They are also duplicated to the east of the SMD when we move progressively away. In the Dialafara area, the ground magnetic data intersect an interpreted fold. The results of this work confirm the presence of the secondary structures and their evolution in relation to the SMD. The relationships between the secondary structures in the Dailafara and Sadiola zones and their relations with the SMD are highlighted. The technique used in this study, is an important approach to better description and interpreting of regional structures using the secondary structures and proposing a structural model.

关键词： Kédougou-Kéniéba Inlier Senegal Malian Discontinuity Secondary Structures Mapping Magnetic Data

Crustal structure of the western Indian shield: Model based on regional gravity and magnetic data

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2013年第6期4卷 717-728页

作者： Suman Kilaru Bandaru Karunakar Goud Vijay Kumar Rao National geophysical Research Institute

Regional surface gravity data and global satellite magnetic data have been utilized to generate a preliminary model of the crustal structure along a southwest-northeast profile （Gadra-Fatehpur） through western *** study area represents the western part of the Indian continental landmass which has undergone several major episodes of repeated subduction/collision,plume traces and rifting from Archaean to recent *** temporal and spatial relationship between the various geotectonic provinces is quite complex,thereby limiting the emergence of a suitable crustal structure model for this *** of the Malani Igneous Suite （MIS）,a product of bimodal volcanism （～780 Ma）,and considered to be the third largest felsic magmatic province of the world,is evident along the profile and also to the southwest of the study *** easternmost part of the profile is close to the DAFB （Delhi Aravalli Fold Belt）,a Proterozoic orogenic *** study probes the geometry of the different crustal units in terms of density and susceptibility variations in order to decipher the imprints of the major tectonic processes the region has *** order to decipher the crustal geometry of the Gadra-Fatehpur profile,two NW-SE gravity and magnetic profile vertical sections （A-A＇ in the south and B-B＇ in the north） are modelled on the basis of the constraints provided from previous seismic *** crustal model of the Gadra-Fatehpur profile is composed of alluvium,Tertiary sediments,MIS,Marwar Supergroup,low-density layers （LDLs） and the middle-lower crustal layers,with a distinct change in configuration from the southwest to *** Moho dips from SW to NE,the MIS in the SW gives way to the thick pile of the Marwar Supergroup to the *** evolution of MIS has been suggested to have occurred as a consequence of delamination of the upper *** are incorporated in Gadra-Fatehpur *** the SW,LDL （2550 kg/m3） lies below the MIS in the NE,another LDL （2604

关键词： western Indian shield Gravity and magnetic modelling MIS Delamination Bimodal volcanism

Lithospheric structure and faulting characteristics of the Helan Mountains and Yinchuan Basin： Results of deep seismic reflection profiling

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2017年第3期60卷 589-601页

作者： LIU BaoJin FENG ShaoYing JI JiFa WANG ShuaiJun ZHANG JianShi YUAN HongKe YANG GuoJun geophysical Exploration Center of China Earthquake Administration Zhengzhou 450002 China

The Helan Mountains and Yinchuan Basin （HM-YB） are located at the northern end of the North-South tectonic belt, and form an intraplate tectonic deformation zone in the western margin of the North China Craton （NCC）. The HM-YB has a complicated history of formation and evolution, and is tectonically active at the present day. It has played a dominant role in the complex geological structure and modem earthquake activities of the region. A 135-km-long deep seismic reflection profile across the HM-YB was acquired in early 2014, which provides detailed information of the lithospheric structure and faulting characteristics from near-surface to various depths in the region. The results show that the Moho gradually deepens from east to west in the depth range of 40-48 km along the profile. Significant differences are present in the crustal structure of different tectonic units, including in the distribution of seismic velocities, depths of intra-cmstal discontinuities and undulation pattern of the Moho. The deep seismic reflection profile further reveals distinct structural characteristics on the opposite sides of the Helan Mountains. To the east, The Yellow River fault, the eastern piedmont fault of the Helan Mountains, as well as multiple buried faults within the Yinchuan Basin are all normal faults and still active since the Quaternary. These faults have controlled the Cenozoic sedimentation of the basin, and display a ＂negative-flower＂ structure in the profile. To the west, the Bayanhaote fault and the western piedmont fault of the Helan Mountains are east-dipping thrust faults, which caused folding, thrusting, and structural deformation in the Mesozoic stratum of the Helan Mountains uplift zone. A deep-penetrating fault is identified in the western side of the Yinchuan Basin. It has a steep inclination cutting through the middle-lower crust and the Moho, and may be connected to the two groups of faults in the upper crest. This set of deep and shallow fault system con

关键词： North China Craton Deep seismic reflection profile Lithospheric structure Helan Mountains Yinchuan Basin

Crustal P-wave velocity structure in the northeastern margin of the Qinghai-Tibetan Plateau and insights into crustal deformation

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第9期61卷 1221-1237页

作者： Shuaijun WANG Baojin LIU Xiaofeng TIAN Baofeng LIU Xianghui SONG Xiaoguo DENG Yinan SUN Cejun MA Yudong YANG geophysical Exploration Center of China Earthquake Administration Zhengzhou 450002 China

The transitional area between the northeastern margin of the Qinghai-Tibetan Plateau, Ordos Block and Alxa Block, also being the northern segment of the North-South Seismic Belt, is characterized by considerably high seismicity level and high risk of strong earthquakes. In view of the special tectonic environment and deep tectonic setting in this area, this study used two seismic wide-angle reflection/refraction cross profiles for double constraining, so as to more reliably obtain the fine-scale velocity structure characteristics in both the shallow and deep crust of individual blocks and their boundaries in the study area, and further discuss the seismogenic environment in seismic zones with strong historical earthquakes. In this paper, the P-wave data from the two profiles are processed and interpreted, and two-dimensional crustal velocity structure models along the two profiles are constructed by travel time forward modeling. The results show that there are great differences in velocity structure, shape of intra-crustal interfaces and crustal thickness among different blocks sampled by the two seismic profiles. The crustal thickness along the Lanzhou-Huianbu-Yulin seismic sounding profile （L1） increases from -43 km in the western margin of Ordos Block to -56 km in the Qilian Block to the west. In the Ordos Block, the velocity contours vary gently, and the average velocity of the crust is about 6.30 km s^-1; On the other hand, the velocity structures in the crust of the Qilian Block and the arc-like tectonic zone vary dramatically, and the average crustal velocities in these areas are about 0.10 km s^-1 lower than that of the Ordos Block. In addition, discontinuous low-velocity bodies （LVZ1 and LVZ2） are identified in the crust of the Qilian Block and the arc-like tectonic zone, the velocity of which is 0.10-0.20 krn s^-1 lower than that of the surroundings. The average crustal thickness of the Ordos Block is consistently estimated to be around 43 km along both Pr

关键词： Northeastern margin of the Qinghai-Tibetan Plateau The Ordos Block Crustal velocity structure Deep seismicsounding

Investigation of plateau basin crustal structures and thickening mechanisms in the northeastern margin of the Tibetan plateau

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2012年第5期25卷 385-397页

作者： Shixu Jia Zhaofan Xu Zhi Liu Jianshi Zhang Baofeng Liu Jiyan Lin Wenbin Guo geophysical Exploration Center China Earthquake Administration

This paper uses deep seismic sounding （DSS） data to contrast and analyze the crustal structures of three plateau basins （Songpan-Garze, Qaidam, Longzhong） in the northeastern margin of the Qinghai-Xizang （Tibetan） plateau, as well as two stable cratonic basins （Ordos, Sichuan） in its peripheral areas. Plateau basin crustal structures, lithological variations and crustal thickening mechanisms were investigated. The results show that, compared to the peripheral stable cratonic basins, the crystalline crusts of plateau basins in the northeastern margin are up to 10 15 km thicker, and the relative medium velocity difference is about 5% less. The medium velocity change in crustal layers of plateau basin indicates that the upper crust undergoes brittle deformation, whereas the lower crust deforms plastically with low velocity. The middle crust shows a brittle-to-plastic transition zone in this region. Thickening in the lower crust （about 5 10 km）, and rheological characteristics that show low- medium velocity （relatively reduced by 7%）, suggest that crustal thickening mainly takes place in lower crust in the northeastern margin of the Tibetan plateau. The crust along the northeastern margin shows evidence of wholesale block movement, and crustal shortening and thickening seem to be the main deformation features of this region. The GPS data show that the block motion modes and crustal thickening in the Tibetan plateau is closely related to the peripheral tectonic stress field and motion direction of the Indian plate. The Mani-Yushu- Xianshuihe fold belt along the boundary between the Qiangtang block and the Bayan Har block divides the different plateau thickening tectonic environments into the middle-western plateau, the northeastern margin and the southeastern plateau.

关键词： northeastern margin of the Tibetan plateau plateau basin stable cratonic basin deep seismic sounding thickening mechanism

Shallow velocity structure of the Luoyang basin derived from dense array observations of urban ambient noise

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2018年第5期31卷 252-261页

作者： Ming Zhou Xiaofeng Tian Fuyun Wang Yunhao Wei Hailiang Xin geophysical Exploration Center China Earthquake Administration

Determining the shallow structure of a sediment basin is important when evaluating potential seismic hazards given that such basins can significantly amplify seismic energy. The Luoyang basin is located in the western He’nan uplift and is a Meso-Cenozoic depression basin. To characterize the shallow structure of the basin, we develop a model of the shallow high-resolution three-dimensional(3D)shear-wave velocity structure of the basin by applying ambient noise tomography to a dense array of 107 portable digital seismometers deployed over the basin. More than 1,400 Rayleigh-wave dispersion curves for periods in the range 0.5–5 s are extracted. The 3D variations of shear-wave velocity in the shallow crust are inverted using a direct surface-wave tomographic method with period-dependent ray tracing, with all the surface-wave group-velocity dispersion data being inverted simultaneously. The results show that in the shallow crust of the study area, the velocity distribution corresponds to surface geology and geological features. The Luoyang basin exhibits a low shear-wave velocity feature that is consistent with the distribution of sediment in the region,while the Xiongershan and Songshan uplifts exhibit higher shear-wave velocity structures. The results provide a shallow high-resolution 3D velocity model that can be used as a basis for simulation of strong ground motion and evaluation of potential seismic hazards.

关键词： ambient noise tomography three-dimensional velocity structure Luoyang basin dense array

Imaging the western Boundary of the Sichuan Craton from Multiple geophysical Observations

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第6期35卷 1860-1877页

作者： Qihang Yin Xi Xu Xiaodong Yang Xuhua Shi Lei Wu Andrew V.Zuza Liu Yang Hefeng Tian Yuanhai Shu Shufeng Yang School of Earth Sciences Zhejiang UniversityHangzhou310058China China Aero geophysical Survey and Remote Sensing Center for Natural Resources China Geological SurveyBeijing100083China SINOPEC Key Laboratory of Geophysics Nanjing211103China Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyInnovation Academy of South China Sea Ecology and Environmental EngineeringChinese Academy of SciencesGuangzhou511458China Nevada Bureau of Mines and Geology University of NevadaRenoNevada89557USA School of Mechanical and Electrical Engineering Hubei Open UniversityWuhan430074China

The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric *** Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,resists the eastward escape of plateau's crustal materials,resulting in the uplift of the Songpan-Ganzi Block(SGB)and crustal deformation of the Longmenshan tectonic belt(LMTB).To elucidate the compressional structures and deformational modes of the LMTB and SCC,it is essential to accurately determine the location and geometry of the SCC'western *** investigate this issue,the lithospheric properties of the obducted SGB,underthrusting SCC,and LMTB were analyzed using various geophysical data,including seismic reflection profiles,magnetotellurics,aeromagnetics,gravity,and seismic *** SGB crust is characterized by low magnetism,seismic velocity,resistivity and Bouguer gravity,whereas the SCC crust exhibits non-uniform high magnetism,seismic velocity,resistivity and Bouguer *** LMTB,as the boundary between the SGB and SCC,exhibits geophysical characteristics similar to those of the SCC in the southern and central *** integration of these geophysical observations indicate that the SCC's western boundary is situated west of the Wenchuan-Maoxian fault zone in the southern and central segments,exhibiting distinct westward wedging and ***,this boundary aligns with the Yingxiu-Beichuan fault in the northern segment,without significant *** irregular geometry of the SCC's western boundary further elucidates the variation in structural deformation along the *** comparing crustal thickness and lithospheric strength between the SGB and SCC,this study posits that the differing crustal strength between tectonic blocks may control the irregular geometry of the SCC's western boundary.

关键词： Sichuan Craton Longmenshan tectonic belt geophysical imaging lithospheric structure tectonic wedging geophysics structural geology

Structural Styles of Fronts of Thrust-Detachment Faults in Petroleum-bearing Areas of western China

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 1999年第4期73卷 371-383页

作者： Wang Tonghe Institute of Geology Bureau of Oil Geophysical ProspectingHebei 072750

The front of a thrust-detachment fault may have various styles such as decoupling, fold, forethrust and backthrust ones because of differences in magnitude, direction and time of the forces exerted on the fault and the inhomogeneity of rock mechanical properties. They have different characteristics and are usually associated with gravity structure, inverse structure and diapir structure. These structures exist together in the same thrust-detachment fault and can influence, compensate for and convert into each other. They provide important grounds not only for the study of the dynamic state, propagation mode, evolutionary process and formation mechanism but also for the analysis of the petroleum generation, migration, accumulation and preservation and arrangement of drill holes in foreland basins.

关键词： structural style front thrust-detachment fault petroleum-bearing areas of western China

Optimization of Groundwater Pumping on Coral Islands Through the Application of Artificial Neural Network

在线全文

学校读者我要写书评

暂无评论

地学前缘 2009年第S1期16卷 19-20页

作者： Pallavi Banerjee V.S.Singh National geophysical Research Institute(CSIR)

The development and growing population has resulted in the increasing demand for potable water in tiny atolls of Lakshadweep group,off the western coast of *** recent years,the groundwater quality,in such atolls,has been deteriorated due to indiscriminate exploitation of groundwater to meet the *** arranging a sustainable supply of groundwater has become the most challenging task on these tiny atolls for the survival of human life. Groundwater floats in the form of thin lens,which

关键词： artificial neural network aquifer salinity groundwater draft coral islands Lakshad-weep