检索结果-南通市图书馆

Geodesy and Geodynamics 2022年第6期13卷 535-543页

作者： Songbai Xuan Chongyang Shen Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Institute of Seismology China Earthquake AdministrationWuhan 430071 China

Numerous geophysical studies have revealed the lithospheric structure of the Qiangtang and the Songpan-Ganzi terranes in the eastern Tibetan ***,crust-mantle evolution and crustal response to the Indian lithospheric subduction are still *** these questions requires additional information regarding crustal *** this study,the 2-D normalized full gradient(NFG)of the Bouguer gravity anomaly was used to investigate anomalous sources and interpret the crustal structure underneath the Qiangtang and Songpan-Ganzi *** NFG-derived structures with loworder harmonic numbers(N=33 and N=43)showed that an anomalous source beneath the southern Qiangtang terrane had a characteristic northeastward-dipping shape,suggesting the northeastward motion of the crustal material induced by underthrusting Indian lithospheric *** NFG images with harmonic number N=53 showed a large-scale anomalous source in the lower crust of the transformational zone from the Qiangtang terrane to the Songpan-Ganzi terrane,consistent with thickening crust and resistance of lower crustal *** anomalous source demonstrated by the NFG results with harmonic number N=71,located in the upper crust underneath the Ganzi-Yushu fault,suggested a seismogenic body of the 2010 M6.9 Yushu event.

关键词： gravity anomaly Normalized full gradient Crustal structures Anomalous sources Qiangtang and Songpan-Ganzi terranes

Estimation of Depth to Salt Domes from Normalized Full Gradient of gravity anomaly and Examples from the USA and Denmark

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2009年第6期20卷 1012-1016页

作者： Hamid Aghajani Ali Moradzadeh 曾华霖 Faculty of Mining Petroleum and GeophysicsShahrood University of Technology School of Geophysics and Information Technology China University of GeosciencesBeijing

We present an estimation of depth of anomalous bodies using normalized full gradient （NFG） of gravity anomaly. Maxima in the NFG map can locate the bodies and indicate their depth. Model calculation using a sphere and application of the NFG method to gravity anomalies over salt domes in the USA and Denmark shows effectiveness of the method. However, the accuracy of depth estimation strongly depends on the number of term N in the Fourier series used to calculate the NFG. An optimum N for the calculation can be given from a test.

关键词： depth estimation anomalous body normalized full gradient gravity anomaly Fourier series.

Frozen subduction in the Yangtze block:insights from the deep seismic profiling and gravity anomaly in east Sichuan fold belt

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2016年第2期29卷 61-70页

作者： Xiaosong Xiong Rui Gao Haiyan Wang Jisheng Zhang Lianghui Guo Key Laboratory of Earth Probe and Geodynamics MLRInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China School of Geophysics and Information Technology ChinaUniversity of GeosciencesBeijing 100083China

The Sichuan basin is the main part of the middle-upper Yangtze block, which has been experienced a long-term tectonic evolution since Archean. The Yangtze block was regarded as a stable block until the collision with the Cathaysia block in late Neoproterozoic. A new deep seismic reflection profile conducted in the eastern Sichuan fold belt（ESFB） discovered a serials of south-dipping reflectors shown from lower crust to the mantle imply a frozen subduction zone within the Yangtze block. In order to prove the speculation, we also obtain the middle-lower crustal gravity anomalies by removing the gravity anomalies induced by the sedimentary rocks and the mantle beneath the Moho, which shows the mid-lower crustal structure of the Sichuan basin can be divided into eastern and western parts. Combined with the geochronology and Aeromagnetic anomalies, we speculated the Yangtze block was amalgamated by the West Sichuan and East Sichuan blocks separated by the Huayin-Chongqing line. The frozen subduction zone subsequently shifted to a shear zone accommodated the lower crustal shortening when the decollement at the base of the Nanhua system functioned in the upper plate.

关键词： Sichuan basin Frozen subduction Deep seismic reflection gravity anomaly

Relationship between the regional tectonic activity and crustal structure in the eastern Tibetan plateau discovered by gravity anomaly

在线全文

学校读者我要写书评

暂无评论

Earthquake Science 2016年第2期29卷 71-81页

作者： Xiao Xu Rui Gao Xiaoyu Guo Key Laboratory of Earthprobe and Geodynamics MLR Instituteof GeologyChinese Academy of Geological Sciences Sinoprobe Center Chinese Academy of Geological Sciences

The eastern Tibetan plateau has been getting more and more attention because it combines active faults,uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus,a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative（THD） had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks,including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the SongpanGarze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion,which is coincident with the flowing direction indicatedfrom the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault.

关键词： Eastern Tibetan plateau Tectonic activity Crustal structures gravity anomaly

On　the　colocation　iterative　solution　model　and　algorithm　for　gravity　anomaly

在线全文

学校读者我要写书评

暂无评论

Acta Seismologica Sinica(English Edition) 1996年第4期9卷 76-81页

作者：杨元喜刘长建

An effective method of random approach of gravity anomaly is collocation. To improve the reliability of collocation root, it is crucial to improve the reliability of covariance function of gravity anomaly. In this paper, a set of theoretical models of iterative fitting covariance function and predicting gravity anomaly is established. Through practical calculation, it shows that after finite iterative collocating, they do work well.

关键词： gravity anomaly random approach collocation iterative root covariance.

Effi cient modeling of the gravity anomaly caused by a sedimentary basin with lateral variable density contrast and its application in basement relief estimation

在线全文

学校读者我要写书评

暂无评论

Applied Geophysics 2021年第2期18卷 145-158,272页

作者： Feng Xu-Liang Liu Sheng-Rong Shen Hong-Yan School of Earth Sciences and Engineering Xi’an Shiyou UniversityXi’an 710065China Shaanxi Key Laboratory of Petroleum Accumulation Geology Xi’an Shiyou UniversityXi’an 710065China Xi’an Center of Geological Survey(Northwest China Center for Geoscience Innovation) Xi’an 710054China

The forward calculation of gravity anomalies is a non-negligible aspect contributing to the time consumption of the entire process of basement relief *** this study,we develop a fast hybrid computing scheme to compute the gravity anomaly of a *** use the vertical prism source equation in a given region R centered at a certain gravity observation point and the vertical line source equation outside R to derive the gravity *** observe that the computation with the vertical line source equation is much faster than that of the vertical prism source equation,but the former is slightly ***,our method is highly effi cient and able to avoid the errors caused by the low accuracy of the vertical line source equation near the observation *** then derive the general principle of choosing the size of R via a series of prism model *** tests on the gravity anomaly over the Los Angeles Basin confirm the correctness of our proposed forward *** modify Bott’s method with an accelerating factor to expedite the inversion procedure and presume that the density contrast between the sediments and the basement in a sedimentary basin varies laterally and can be obtained using the equivalent *** data and real data applications in the Weihe Basin illustrate that our proposed method can accurately and effi ciently estimate the basement relief of sedimentary basins.

关键词： gravity anomaly basement relief fast forward inversion lateral variable density contrast

gravity anomaly during the Mohe total solar eclipse

在线全文

学校读者我要写书评

暂无评论

Gravity anomaly during the Mohe total solar eclipse

Comparative analysis of fracture identification methods based on gravity anomaly in Heilongjiang

中国科学院地质与地球物理研究所2001学术年会

作者： WANG Qianshen~1,YANG Xinshe~(1,2) & TANG Keyun~1 1.Institute of Geophysics,Chinese Academy of Sciences,Beijing 100101,China 2.Department of Applied Mathematics,University of Leeds,Leeds LS2 9JT,UK

By using a high-precision LaCoste-Romberg (D-122#) gravimeter,continuous and precise measurements were carried out during the March 9,1997 total solar eclipse in the Mohe region in Northeast *** gravity variations were digitally recorded during the total solar eclipse so as to investigate the possible anomaly of the sun and the moon’s gravitational fields on the *** the careful processing and analysis of the observed data,no significant anomaly during the very solar eclipse has been ***, there are two ’gravity anomaly valleys’ with near symmetrical decrease of about 6—7μGal at the first contact and the last contact This is the anomaly phenomenon observed and reported for the first time in the *** note presents some analyses and discussions.

关键词： Mohe total solar eclipse gravity anomaly

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Global Geology 2015年第2期18卷 134-139页

作者： CHANG Chang YANG Changbao WU Yangang CHEN Jingyi College of Geo-Exploration Science and Technology Jilin University College of Engineering and Natural Sciences University of Tulsa

The identification of fractures is of great importance in gravity and magnetic data processing and *** this study,four fracture identification methods are applied,and widely used in processing and analysis of the gravity anomaly,including vertical second derivative method,tilt derivative method,theta map method and normalized differential method,for gravity data acquired in a given area in *** comparing the distribution of the zero contour or maximum contour,we summarize the application effects,and both advantages and disadvantages of each *** is found that tilt derivative method and normalized differential method provide better effects than other two methods:the narrower anomaly gradient belt and higher identification precision of fracture or geological *** inferred fractures and geological boundaries have a great match with the results obtained from geologic map and remote sensing data *** study results have definitely provided the theoretical foundation for identifying faults and the geological boundaries.

关键词： gravity anomaly fracture identification Heilongjiang

Cascade Kalman filter for gravity anomaly distortion correction based on second order potential model

在线全文

学校读者我要写书评

暂无评论

Journal of Southeast University(English Edition) 2008年第4期24卷 482-486页

作者：赵立业李宏生周百令李坤宇东南大学仪器科学与工程学院南京210096

Using a gravity anomaly covariance function based on the second-order Ganssian Markov gravity anomaly potential model, the state equation of a gravity anomaly signal is obtained in marine gravimetry. Combined with the system state equation and the measurement equation, a new method of the cascade Kalman filter is proposed and applied to the correction of gravity anomaly distortion. In the signal processing procedure, an inverse Kalman filter is used to restore the gravity anomaly signal and high frequency noises first. Then an adaptive Kalman filter, which uses the gravity anomaly state equation as the system equation, is set to estimate the actual gravity anomaly data. Emulations and experiments indicate that both the cascade Kalman filter method and the single inverse Kalman filter method are effective in alleviating the distortion of the gravity anomaly signal, but the performance of the cascade Kalman filter method is better than that of the single inverse Kalman filter method.

关键词： gravimeter gravity anomaly cascade Kalman filter inverse Kalman filter distortion correction

High-Order Radial Derivatives of Harmonic Function and gravity anomaly

在线全文

学校读者我要写书评

暂无评论

Journal of Physical Science and Application 2014年第7期4卷 454-467页

作者： Ziqing Wei Xian Research Institute of Surveying and Mapping Xian 710054 China

The first through ninth radial derivatives of a harmonic function and gravity anomaly are derived in this paper. These derivatives can be used in the analytical continuation application. For the downward continuation of gravity anomaly, the Taylor series approach developed in the paper is equivalent theoretically to but more efficient and storage-saving computationally than the well-known gradient operator approach. Numerical simulation shows that Taylor series expansion constructed by the derived formulas for the radial derivatives of gravity disturbance is still convergent for height up to 4 km.

关键词： Harmonic function gravity anomaly gravity disturbance high-order radial derivative analytical continuation.