共查询到19条相似文献，搜索用时 78 毫秒
1.
The Rapid Inversion of 3-D Potential Field and Program Design 总被引：1，自引：0，他引：1
The application of three-dimensional inversion of gravity and magnetic fields is very important not only in geophysical researches, but also in the study of geological structures. A formula of potential field in frequency-domain, developed by Parker in 1973, can be used as a rapid and effective algorithm in gravity and magnetic inversion. The technique has been improved then by Oldenburg, Sprenke, Feng and others.In addition to a brief introduction of Parker's algorithm and its applications, this paper includes the following five parts: basic computational techniques, inversion of single layer, convergence and constraints, simultaneous inversion for density and topography as well as inversion of multilayers. The authors present relevant practical iterative formulas and its varieties when density distribution varies with depth in linear or exponential relation. In order to maintain computation stability and speed up iteration convergence, some approaches are taken in the program design, for instance shifting lower interface of the studied layer, inverting corrections of topography, reducing grid boundary effects and utilizing low-pass filter. With the consideration of the nonuniqueness of the inversion, a method of using seismic data to constrain the range ofpossible models is discussed. It is pointed out that the density variation generates less effects than those of topography on the spectrum of gravity anomaly in second order. Therefore density contrast and topography can be inverted simultaneously by an alternative weighting iteration. By analogy, the inversion of multilayer model can be done in the above procedure. An approach of model decomposition is useful in the computation of multilayer model. The techniques discussed in the present paper for gravitational field are also valid for magnetic field. 相似文献
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《物探化探计算技术》2009,31(4):I0001-I0006
2D INVERSION OF VES DATA UNDER ROLLING TOPOGRAPHY AND ITS APPLICATION
Considering to meet usually the rolling topogra- phy in the groundwater resource investigation, mineral exploration, engineering detection, etc. and based on the published literature in existence, this paper pres- ent our settlement of 2D inversion problem of VES da- m with the rolling topography by applying the total smooth constraint in the inversion. The approach can effectively process the FEM grid division and the in version software is made. Finally, it is proved that the inverted results is reliable through inverting the simulated and measured VES data, and the inversion software can be applied to the practical work. 相似文献
Considering to meet usually the rolling topogra- phy in the groundwater resource investigation, mineral exploration, engineering detection, etc. and based on the published literature in existence, this paper pres- ent our settlement of 2D inversion problem of VES da- m with the rolling topography by applying the total smooth constraint in the inversion. The approach can effectively process the FEM grid division and the in version software is made. Finally, it is proved that the inverted results is reliable through inverting the simulated and measured VES data, and the inversion software can be applied to the practical work. 相似文献
3.
YAN Jiayong Lü Qingtian QI Guang FU Guangming ZHANG Kun LAN Xueyi GUO Xin WEI Jin LUO Fan WANG Hao WANG Xu 《《地质学报》英文版》2020,94(6):1940-1959
The Zhuxi tungsten deposit in Jiangxi Province, South China, contains a total W reserve of about 2.86 Mt at an average grade of 0.54 wt% WO3, representing the largest W deposit in the world. Numerous studies on the metallogeny of the deposit have included its timing, the ore-controlling structures and sedimentary host rocks and their implications for mineral exploration. However, the deep nappe structural style of Taqian–Fuchun metallogenic belt that hosts the W deposit, and the spatial shape and scale of deeply concealed intrusions and their sedimentary host rocks are still poorly defined, which seriously restricts the discovery of new deposits at depth and in surrounding areas of the W deposit. Modern 3D geological modeling is an important tool for the exploration of concealed orebodies, especially in brownfield environments. There are obvious density contrast and weak magnetic contrast in the ore-controlling strata and granite at the periphery of the deposit, which lays a physical foundation for solving the 3D spatial problems of the ore-controlling geological body in the deep part of the study area through gravity and magnetic modeling. Gravity data (1:50000) and aeromagnetic data (1:50000) from the latest geophysical surveys of 2016–2018 have been used, firstly, to carry out a potential field separation to obtain residual anomalies for gravity and magnetic interactive inversion. Then, on the basis of the analysis of the relationship between physical properties and lithology, under the constraints of surface geology and borehole data, human–computer interactive gravity and magnetic inversion for 18 cross-sections were completed. Finally, the 3D geological model of the Zhuxi tungsten deposit and its periphery have been established through these 18 sections, and the spatial shape of the intrusions and strata with a depth of 5 km underground were obtained, initially realizing “transparency” for ore-controlling bodies. According the analysis of the geophysical, geochemical, and geological characteristics of the Zhuxi tungsten deposit, we discern three principles for prospecting and prediction in the research area, and propose five new?exploration?targets in?its?periphery. 相似文献
4.
YanHanjie YanHong LiYunping ZhangXiaofeng 《中国地质大学学报(英文版)》2003,14(3):227-233
As gravity field,magnetic field,electric field and seismic wave field are all physical fields,their object function,reverse function and compound function are certainly infinite contiuously differentiable func-tions which can be expanded into Taylor (Fourier) series within domain of definition and be further reduced in-to solving stochastic distribution function of series and statistic inference of optimal approximation,This is the basis of combined gravity-magnetic-electric-seismic inversion built on the basis of separation of field and source gravity-magnetic difference-value(D-value)trend surface,taking distribution-independent fault sys-tem as its unit,depths of seismic and electric interfaces of interests as its corresponding bivariate compound re-verse function of gravity-magnetic anomalies and using high order polynomial(high order trigonometric func-tion)approximating to its series distribution,The difference from current dominant inversion techniques is that,first,it does not respectively create gravity-seismic,magnetic-seismic deterministic inversion model from theoretical model,but combines gravity-magnetic-electric-seismic stochastic inversion model from stochastic model;second,after the concept of equivalent geological body being introduced,using feature of independent variable of gravity-magnetic field functions,taking density and susceptibility related to gravity-magnetic func-tion as default parameters of model,the deterministic model is established owing to better solution to the con-tradictioc of difficulty in identifying strata and less test analytical data for density and susceptibility in newly explored area;third,under assumption of independent parent distribution,a real modeling by strata,the prob-lem of difficult plane closure arising in profile modeling is avoided,This technology has richer and more detailed fault and strata information than sparse pattern seismic data in newly explored area,successfully inverses and plots structural map of Indosinian discontinuty in Hefei basin with combined gravity-magnetic-electric-seismic inversion,With development of high precision gravity-magnetic and overall geophysical technology,it is certain for introducing new methods of stochastic modeling and computational intelligence and promoting the develop-ment of combined gravity-magnetic-electric-seismic inversion to open a new substantial and promoting the develop-ment of combined gravity-magnetic-electric-seismic inversion to open a new substantial path. 相似文献
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We present relative sea level （RSL） curves in Antarctica derived from glacial isostatic adjustment （GIA）predictions based on the melting scenarios of the Antarctic ice sheet since the Last Glacial Maximum （LGM）given in previous works.Simultaneously,Holocene-age RSL observations obtained at the raised beaches along the coast of Antarctica are shown to be in agreement with the GIA predictions.The differences from previously published ice-loading models regarding the spatial distribution and total mass change of the melted ice are significant.These models were also derived from GIA modelling; the variations can be attributed to the lack of geological and geographical evidence regarding the history of crustal movement due to ice sheet evolution.Next,we summarise the previously published ice load models and demonstrate the RSL curves based on combinations of different ice and earth models.The RSL curves calculated by GIA models indicate that the model dependence of both the ice and earth models is significantly large at several sites where RSL observations were obtained.In particular,GIA predictions based on the thin lithospheric thickness show the spatial distributions that are dependent on the melted ice thickness at each sites.These characteristics result from the short-wavelength deformation of the Earth.However,our predictions strongly suggest that it is possible to find the average ice model despite the use of the different models of lithospheric thickness.By sea level and crustal movement observations,we can deduce the geometry of the post-LGM ice sheets in detail and remove the GIA contribution from the crustal deformation and gravity change observed by space geodetic techniques,such as GPS and GRACE,for the estimation of the Antarctic ice mass change associated with recent global warming. 相似文献
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Ari Roisenberg Maria Paula C. Marimon Antonio P. Viero 《中国地球化学学报》2006,25(B08):121-121
Fluoride anomalies （up to 11 mg/L） have been detected in the porous confined Santa Maria Aquifer （Guarany Aquifer System） in the central region of Rio Grande do Sul State, southern Brazil, leading to endemic fluorosis. Two hypotheses are investigated concerning the fluoride origin： contamination by long-term phosphate-fertilizer application due to extensive tobacco plantation or lithogeochemical affiliation from regional rocks. The results are discussed based on statistical and geochemical modeling and stable isotope data of water, nitrate and sulfate. Field monitoring of phreatic and confined aquifer during two years and laboratory leaching and retention experiments were performed. Regional statistical analysis （factorial and cluster analysis） on the basis of 350 wells discriminates four different hydrochemical groups in the confined aquifer, considering magnesium, calcium bicarbonate, sodium chlorinate and sodium bicarbonate as specific parameters. The last two groups reach higher fluoride contents and represent deeper aquifer levels where geochemical modeling shows carbonates （calcite and dolomite） are of super-saturation. The laboratory experiments confirmed that local soils with high CTC and aluminum contents （Udults） represent an efficient geochemical barrier, preserving the aquifer from fluoride contamination and supporting remediation strategies for fluoride removal. δ^18O and δD groundwater data and the local meteoric water line （LMWL） indicate that local precipitation is the main groundwater recharge source in the area. 相似文献
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《地学前缘》2007,(3)
<正>(1)Dr. El-Sayed Mohamed Abdelrahman Professor of Geophysics, Cairo University, Egypt. His primary research interests are potential field methods. His research has focused on gravity, magnetic, self-potential methods including depth and shape determination. He has been awarded 5 prizes between 1992 and 2003, including the state prize in Earth sciences, the state prize in advanced technological sciences and the others. (2)Dr. Norman Bleistein Emeritus Professor of Geophysics, Colorado School of Mines, USA. His primary research interests: asymptotic methods for forward modeling and inversion in seismic exploration.He is a Fellow of the Institute of Physics, UK, and Guest Professor, China University of Geosciences, Wuhan, China. 相似文献
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The Guxiang–Tongmai segment of the Jiali fault is situated northeast of the Namche Barwa Syntaxis in northeastern Tibet. It is one of the most active strike-slip faults near the syntaxis and plays a pivotal role in the examination of seismic activity within the eastern Himalayan Syntaxis. New study in the research region has yielded a 1:200000 gravity dataset covering an area 1500 km2. Using wavelet transform multiscale decomposition, scratch analysis techniques, and 3D gravity inversion methods, gravity anomalies, fault distributions, and density structures were determined across various scales. Through the integration of our new gravity data with other geophysical and geological information, our findings demonstrate substantial variations in the overall crustal density within the region, with the fault distribution closely linked to these density fluctuations. Disparities in stratigraphic density are important causes of variations in the capacity of geological formations to endure regional tectonic stress. Earthquakes are predominantly concentrated within the density transition zone and are primarily situated in regions of elevated density. The hanging wall stress within the Guxiang–Tongmai segment of the Jiali fault exhibits a notable concentration, marked by pronounced anisotropy, and is positioned within the density differential zone, which is prone to earthquakes. 相似文献
9.
3D Positional and Quantitative Prediction of the Xiaoqinling Gold Ore Belt in Tongguan,Shaanxi, China 总被引：1，自引：0，他引：1
Quantitative prediction of deep orebody based on 3D visualization technology is of great significance in mineral exploration. Based on the 2D traditional quantitative predicting method, the geoanomaly theory and the mineral exploration model idea, we constructed 3D models of the topography, strata, structure, magmatite and prospecting engineering of the study area using the commercial 3D modeling software Micromine, delineated eight prospective areas and estimated the gold resources amount with methods of Abundance Estimation and Volume Estimation. Then, we compared and counted the known ore blocks and the predicted blocks, which quantitatively explains this prediction’s validity. The results show that Xiaoqinling gold belt in Tongguan has convincing potential for gold development and utilization and the prediction method based on 3D visualization technology proves to be effective. 相似文献
10.
CHANG Xu LIU YikeInstitute of Geology Geophysics Chinese Academy of Sciences All Datun Ro Chaoyang District Beijing E-mail: changxu@mail.c-geos.ac.cn 《《地质学报》英文版》2000,74(1):102-112
In this paper, 3-D velocity images of the crust and upper mantle beneath the Nanbei tectonic zone of China are constructed using P-wave travel time residuals of earthquakes, with the data supplied by China's seismic networks and the International Seismic Centre.During the model parameterization in the tomographic inversion the interpolation function of grid node velocities is used as the space function of velocity, and the velocity function is allowed to be discontinuous. The difficulties caused by large memory demand and high computing cost in solving the system of equations are avoided by utilizing the least squares QR decomposition algorithm. Thus, the stability of the algorithm is ensured. Though resolution images are not derived in the inversion process based on the resolution theory of Backus and Gilbert, a covariance resolution method is put forward by the authors. The resolution analyses have proved the reliability of the image results. 3-D ray tracing is conducted to obtain the ray paths in a s 相似文献
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《物探化探计算技术》2009,31(6):I0001-I0006
APPLICATION OF WAVELET ANALYSIS FOR GEOPHYSICAL DATA AND COPPER MINERAL DEPOSITS FORECAST IN MANDAMAH AREA
SHEN Wei, FANG Cong-hui, CHANG Xing-guo （State Key Laboratory of Geo-Processes and Mineral Resources, Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, China University of Geosciences, Beijing 100083, China）. COMPUTING TECHNIQUES FOR GEOPHYSICAL AND GEOCHEMICAL EXPLORA- TION. 2009. 31 （6）： 0525 相似文献
SHEN Wei, FANG Cong-hui, CHANG Xing-guo （State Key Laboratory of Geo-Processes and Mineral Resources, Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, China University of Geosciences, Beijing 100083, China）. COMPUTING TECHNIQUES FOR GEOPHYSICAL AND GEOCHEMICAL EXPLORA- TION. 2009. 31 （6）： 0525 相似文献
13.
《物探化探计算技术》2009,31(5):I0001-I0006
STUDY ON GRAVITY METHOD FOR DETECTING SUBSURFACE MASS;THE DYNAMIC RESPONSE OF SATURATED SANDSTONE BY CYCLIC LOADING;SOLUTION STRATEGIES FOR 2D AND 3D MAGNETOTELLURIC FORWARD MODELING BASED ON THE FINITE ELEMENT METHOD;A STABLE ALGORITHM FOR CALCULATING THE VERTICAL DERIVATIVES OF POTENTIAL FIELD;THE INSTANT DISPLAY FOUNCTION OF THE AIRBORNE ELECTROMAGNETIC PROFILE CURVE BASED ON SECONDARY DEVELOPMENT OF MAPGIS; 相似文献
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<正>Fourteen graptolite species of the Late Tremadoc and Early Floian are described from the Nanba section in the Yiyang area,Hunan Province.Among them,Paradelograptus onubensis, Kiaerograptus bulmani,K.kutchini and Paratemnograptus isolatus of the Late Tremadoc are first found in China.Based on the current graptolite materials,the correspondingly complete graptolite zones of Upper Tremadocian in China are recognized as follows(in ascending order):the Adelograptus tenellus Zone,the Aorograptus victoriae Zone,the Araneograptus murrayi Zone and the Hunnegraptus copiosus Zone.In the Nanba section,the Hunnegraptus copiosus Zone is overlain directly by the Tetragraptus approximatus Zone,there is no hiatus below the base of Floian. 相似文献
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<正>A new family of so-called‘higher' planthoppers,Weiwoboidae fam.nov.,from the Lower Eocene of Yunnan is described.A new monotypic genus,Weiwoboa gen.nov.,with Weiwoboa meridiana sp.nov.is also described and illustrated.The characters of tegmen venation of the new family,its evolution,and supposed relationships are briefly discussed. 相似文献