IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-10-01 DOI: 10.6038/CJG20161024

Xiongwen Wang, Huazhong Wang, J. Qian

引用次数: 0

Identification of magnetic minerals in surface sediments of Miyun Lake, Beijing 北京密云湖表层沉积物中磁性矿物的鉴定

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-08-01 DOI: 10.6038/cjg20160818

Han Fei, Wang Fuxian, Liao Jinhua, Qin Huafeng, Deng Chenglong, Pan Yongxin

{"title":"Identification of magnetic minerals in surface sediments of Miyun Lake, Beijing","authors":"Han Fei, Wang Fuxian, Liao Jinhua, Qin Huafeng, Deng Chenglong, Pan Yongxin","doi":"10.6038/cjg20160818","DOIUrl":"https://doi.org/10.6038/cjg20160818","url":null,"abstract":"Understanding the magnetic properties of natural sediments, which include magnetic concentration, composition and grain size, is fundamental in paleomagnetic and paleoenvironmental studies. Systematic magnetic measurements and non-magnetic methods (e.g., transmission electron microscopy, TEM) provide detailed information of magnetic minerals. In this paper, we established a high efficient magnetic extraction method to separate magnetic minerals from surface sediments of Miyun lake in Beijing. We analyzed the bulk samples, magnetic extracts and residues. Saturation magnetization (M-s), volume magnetic susceptibility (kappa) and saturation isothermal remanent magnetization (SIRM) of the magnetic extracts is about 85%, 75% and 70% of the bulk samples, respectively. Multiple-parameter rock magnetic measurements indicated that the major magnetic minerals in sediments are multi-domain (MD) and single domain (SD) magnetite. TEM analyses revealed detrital MD titano-magnetite, biogenic SD magnetite (magnetofossils) and authigenic superparamagnetic (SP) magnetite. We propose that the combination of rock magnetism and TEM observations is useful to accurately identify the magnetic minerals in sediments.","PeriodicalId":55257,"journal":{"name":"地球物理学报","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2016-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86585854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Correcting on logging-derived temperatures of the Pearl River Mouth Basin and characteristics of its present temperature field 珠江口盆地测井温度校正及现今温度场特征

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-08-01 DOI: 10.6038/CJG20160816

X. Tang, Shaopeng Huang, Shuchun Yang, G. Jiang, Shenghui Hu

引用次数: 10

Dynamically triggered aftershock activity and far-field microearthquakes following the 2014 M(s)7. 3 Yutian, Xinjiang Earthquake 2014年M(s)7地震后的动态触发余震活动和远场微地震。3新疆玉田地震

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-04-01 DOI: 10.6038/CJG20160419

W. Qiong, Xie Chao-di, Jiang Zhan-bo, Liu Jianming

{"title":"Dynamically triggered aftershock activity and far-field microearthquakes following the 2014 M(s)7. 3 Yutian, Xinjiang Earthquake","authors":"W. Qiong, Xie Chao-di, Jiang Zhan-bo, Liu Jianming","doi":"10.6038/CJG20160419","DOIUrl":"https://doi.org/10.6038/CJG20160419","url":null,"abstract":"We systematically examine how dynamic stresses from seismic waves following the 2014 M(s)7. 3 Yutian, Xinjiang, earthquake affect aftershocks and regional microseismicity in the near and far field. The full Coulomb stress changes are computed based on the discrete wavenumber method. We find that the static Coulomb stress changes caused by the M(s)7. 3 earthquake discourage aftershocks occurrence in the southwestern part of the aftershock zone, which may explain why the aftershock activity in this region is relatively weak. Aftershock rates at the region about 30 km to the northeast of the mainshock are relatively high, which are consistent with positive dynamic and static stress changes in that region, with the peak values of 2. 78 MPa and 0. 80 MPa, respectively. Aftershocks about 45 km north of the mainshock are mostly triggered by the dynamic stress change with a peak value of 0. 72 MPa. The peak values of dynamic stress change in the remote Shaya and Jiashi areas are 0. 09 MPa and 0. 1 MPa, respectively, which are high enough to trigger microearthquakes in these areas. Overall the spatial distributions of dynamic stress changes induced by the Yutian mainshock show asymmetrical patterns, and there is a positive correlation between the aftershock distribution and the positive area of dynamic stress change in the northeastern and northern regions.","PeriodicalId":55257,"journal":{"name":"地球物理学报","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90266400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Forward modeling of pseudo P waves in TTI medium using staggered grid TTI介质中伪纵波的交错网格正演模拟

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-03-01 DOI: 10.6038/CJG20160325

Wang Luchen, Chang Xu, W. Yibo

{"title":"Forward modeling of pseudo P waves in TTI medium using staggered grid","authors":"Wang Luchen, Chang Xu, W. Yibo","doi":"10.6038/CJG20160325","DOIUrl":"https://doi.org/10.6038/CJG20160325","url":null,"abstract":"A tilted transversely isotropic (TTI) medium is a good approximation for anisotropic problems. We discuss the property of a 3D tilted transversely isotropic (TTI) medium and use pseudo P waves to simulate the P component of the elastic wave field in the weak elastic anisotropy approximation. We compare forward features of 3 second-order difference equations of pseudo P waves based on Hooke's law, elastic wave projection and dispersion equation, respectively. Now numerical calculation of these equations uses regular grid finite difference method, which is of low efficiency, low accuracy and is unstable in TTI simulation. In order to improve the calculating accuracy, this paper builds the staggered grid finite difference format for each forwarding simulation. Comparing three different numerical expressions of pseudo P wave equation in a 3D TTI medium, we find that the method based on dispersion equation is more convenient to simulate elastic P wave propagation and has lowest numerical noise. By analyzing the frequency dispersion characteristics based on different angles of isotropic symmetry axis, we introduce appropriate SV wave velocity in calculation to keep calculation stable. An example of a 2D simple synthetic model shows that the staggered grid forwarding method allow us to obtain a smooth and stable pseudo P wave field. With this strategy, 2D BP TTI reverse time migration can also achieve basically stable migration results.","PeriodicalId":55257,"journal":{"name":"地球物理学报","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2016-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84683419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Frequency-domain inversion of marine CSEM data in one-dimensional vertically anisotropic structures 一维垂直各向异性结构海洋CSEM数据的频域反演

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-01-01 DOI: 10.6038/cjg20161134

M. Luo, Li Yuguo, Gang Li

{"title":"Frequency-domain inversion of marine CSEM data in one-dimensional vertically anisotropic structures","authors":"M. Luo, Li Yuguo, Gang Li","doi":"10.6038/cjg20161134","DOIUrl":"https://doi.org/10.6038/cjg20161134","url":null,"abstract":"The marine controlled-source electromagnetic (CSEM) method has proven to be an important addition to seismic imaging techniques in exploration of offshore hydrocarbon reservoirs and near-surface investigations. In inversion and interpretation of industrial CSEM data sets, this method can be used in a number of situations by assuming isotropy. However, the presence of electric anisotropy in the Earth's crust, due to thin layer interbedding or grain alignments in the sediments, can significantly alter the response measured by the EM receivers. Ignoring anisotropy in interpreting marine CSEM data may lead to distorted images of seabed conductivity structures, even misinterpretation.#br#In this paper, we present an inversion method for frequency domain marine controlled-source electromagnetic data generated by a titled dipole source in vertically anisotropic stratified media. This approach is based on the Gauss-Newton scheme. We extend and generalize the formulation of marine CSEM fields to calculation of the electromagnetic fields excited by arbitrarily oriented dipole sources. The partial derivatives of the electromagnetic fields with respect to both the horizontal and vertical resistivity are analytically calculated. Based on the relationship between the horizontal resistivity (ρh) and the vertical resistivity (ρv) of the inversion model, an adaptive selection method for regularization factors is proposed to balance the effects of the data misfit and the structural constraint.#br#The synthetic and real data inversion tests indicate that our inversion method can reconstruct the anisotropic resistivity of the overburden layer and the basement, and the burial depth, the thickness and the vertical resistivity of the reservoir layer can be well recovered. A better reconstruction can be obtained with multiple frequency and multiple component data sets. Combing inline and broadside geometry data sets can provide high resolution in reconstructing the burial depth of the reservoir layer and resistivity of the anisotropic basement.","PeriodicalId":55257,"journal":{"name":"地球物理学报","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71079938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Non-linear parameter estimation method based on T-matrix 基于t矩阵的非线性参数估计方法

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-01-01 DOI: 10.6038/CJG20160628

Wang Ben-feng, Wu Ru-Shan, C. Xiaohong, Lt, strong gt, Lu Wen-Kai lt

引用次数: 3

The influence of groundwater changes on gravity observations at Jiufeng station in Wuhan 地下水变化对武汉九峰站重力观测的影响

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-01-01 DOI: 10.6038/CJG20160804

He Qian-qian, Luo Shao-Cong, Sun He-ping, Lt, strong gt, Xu Jian-Qiao lt, Chen Xiao-dong

引用次数: 3

Short-term temporal variability of GPS receiver's differential code biases (DCB): retrieving and modeling GPS接收机差分码偏差(DCB)的短期时间变异性:检索与建模

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-01-01 DOI: 10.6038/CJG20160109

Baocheng Zhang, Y. Yuan, J. Ou

引用次数: 7

3D finite element modeling of marine controlled-source electromagnetic fields using locally refined unstructured meshes 海洋可控源电磁场的局部精细非结构化网格三维有限元建模

IF 1.4 4区地球科学

地球物理学报 Pub Date : 2016-01-01 DOI: 10.6038/CJG20161233

Yixin Ye, Li Yuguo, Y. Liu, Gang Li, Haiyan Yang

{"title":"3D finite element modeling of marine controlled-source electromagnetic fields using locally refined unstructured meshes","authors":"Yixin Ye, Li Yuguo, Y. Liu, Gang Li, Haiyan Yang","doi":"10.6038/CJG20161233","DOIUrl":"https://doi.org/10.6038/CJG20161233","url":null,"abstract":"We present a 3D forward modeling algorithm of marine controlled-source electromagnetic (CSEM) fields using finite element method based on unstructured meshes. As the unstructured mesh is incorporated, the algorithm can easily accommodate complex structures, such as dipping interfaces and rough topography. Secondary coupled-potential formulation of Maxwell's equations allows to avoid the singularities introduced by the sources. The primary electromagnetic fields excited by electric dipole source in layered isotropic media are derived from the semi-analytical formulas based on Schelkunoff potentials. To improve the accuracy and efficiency of the algorithm, we propose an effective local mesh refinement strategy, where the elements near the receiver locations and in the abnormal areas are refined using the volume constraints. We validate the finite element code against a 1D and 2D reservoir model and study the performance of the local mesh refinement strategy. The Canonical disc model illustrates the utility of the finite element method for 3D CSEM modeling. The bathymetry model study shows that the seafloor topography gives an important response which needs to be reproduced by numerical modeling to avoid the misinterpretation of measurements.","PeriodicalId":55257,"journal":{"name":"地球物理学报","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71079637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

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