High-density electrical method has been proved to be an effective method for probing shallow sedimentary layers.It is principally used to identify the boundary between the Quaternary soil layer and bedrock according t...High-density electrical method has been proved to be an effective method for probing shallow sedimentary layers.It is principally used to identify the boundary between the Quaternary soil layer and bedrock according to the vertical change of apparent resistivity.However,the artificial filling layer has the characteristics of heterogeneity and high porosity,which makes it challenging to detect the artificial filling layer by high-density electrical method.The key to solve this problem is to detect the difference of conductivity between the filling layer and the underlying bedrock.This paper takes the land in Chengjiangshan area of Huaibei City,Anhui Province as the detection target.On the basis of fully analyzing the physical properties of the artificial filling layer,two-dimensional high-density electrical survey and inversion are used to define the thickness of the artificial filling layer.The research shows that the highdensity resistivity method has obvious advantages in delineating the distribution of bedrock and the thickness of the filling layer,and the reliability of the high-density electrical method in the detection of the artificial filling layer,and delineates the scope of the filling layer is verified by the borehole data.展开更多
The 2D data processing adopted by the high-density resistivity method regards the geological structures as two degrees, which makes the results of the 2D data inversion only an approximate interpretation;the accuracy ...The 2D data processing adopted by the high-density resistivity method regards the geological structures as two degrees, which makes the results of the 2D data inversion only an approximate interpretation;the accuracy and effect can not meet the precise requirement of the inversion. Two typical models of the geological bodies were designed, and forward calculation was carried out using finite element method. The forward-modeled profiles were obtained. 1% Gaussian random error was added in the forward models and then 2D and 3D inversions using a high-density resistivity method were undertaken to realistically simulate field data and analyze the sensitivity of the 2D and 3D inversion algorithms to noise. Contrast between the 2D and 3D inversion results of least squares inversion shows that two inversion results of high-density resistivity method all can basically reflect the spatial position of an anomalous body. However, the 3D inversion can more effectively eliminate the influence of interference from Gaussian random error and better reflect the distribution of resistivity in the anomalous bodies. Overall, the 3D inversion was better than 2D inversion in terms of embodying anomalous body positions, morphology and resistivity properties.展开更多
In order to explore the mineral resources buried in sea mud,it is necessary to use seabed resistivity measuring equipment,which works closer to the sediments than ordinary ship-based geophysical measuring equipment. B...In order to explore the mineral resources buried in sea mud,it is necessary to use seabed resistivity measuring equipment,which works closer to the sediments than ordinary ship-based geophysical measuring equipment. Because of the harsh environment of seafloor,high pressure and highly conductive seawater,marine magnetotelluric method developed slowly. The sea floor environment is similar to the environment of logging, According to the design of dual lateral logging equipment,a new equipment for seafloor electrical resistivity measurement is designed. Four 3D FEM models that contain resistivity abnormal targets are built to test the ability of this equipment to locate different shape of shallow buried resistivity abnormal targets in sea mud. The authors propose the method to correct the response curve while the bottom surface of this equipment is suspended or not parallel to the seafloor. The resistivity of targets can be calculated accurately.展开更多
The principles, methods, technologies and application effects of several electromagnetic methods for the detection of the hidden danger of water gushing at the coal face were introduced. Also, emphasis was laid on exp...The principles, methods, technologies and application effects of several electromagnetic methods for the detection of the hidden danger of water gushing at the coal face were introduced. Also, emphasis was laid on expounding the methods, principles and effects of down-hole detections by electric transmission tomography and transient electromagnetic method. The potential of point power supplied in the underground homogeneous semi-space, as well as the response to a low-resistivity abnormal body in the homogeneous semi-space, was simulated by adopting 3-D finite element method to interpret the basic theory of the electric transmission tomography. The results of actual measurement show that the mine electromagnetic method is sensitive to water-bearing low-resistivity bodies and can play a unique role in detecting the hidden danger of water gushing at the coal face.展开更多
The Jiamusi and Songnen blocks converged in the easternmost segment of the Central Asian Orogenic Belt as a result of the subduction and subsequent closure of the Mudanjiang oceanic plate during the Permian-Jurassic.T...The Jiamusi and Songnen blocks converged in the easternmost segment of the Central Asian Orogenic Belt as a result of the subduction and subsequent closure of the Mudanjiang oceanic plate during the Permian-Jurassic.The Mudanjiang suture zone was later directly affected by subductions of the Paleo-Pacific plate and Pacific plate and is therefore an ideal place to study the subduction polarity and later transformation of a paleo-suture zone.Using three-dimensional inversion of magnetotelluric data collected along a 160-km-long profile across the Mudanjiang suture zone,we established a resistivity model of the suture zone and adjacent area.Our results reveal the subduction polarity and subduction trace of the Mudanjiang oceanic plate and provide geoelectrical evidence for reactivation of the Mudanjiang suture zone induced by the(Paleo-)Pacific plate subduction.The suture zone shows a complex conductive structure.The west-dipping crustal-scale conductor beneath the Songnen-Jiamusi collision zone represents the fossil subduction zone and indicates the westward subduction polarity of the Mudanjiang oceanic plate.Furthermore,the Mudanjiang fault identified by surface geology does not fully represent the deep structure of the Mudanjiang suture zone.The definition of the suture zone should be extended to the whole conductive region with a lateral extent of~70 km.Solid conductive minerals beneath the arc in front of the subduction zone were exhumated up from deep to the upper crust.The“chimney”-shaped conductor connected with the mantle represents the intrusive pathways of mantle-derived materials,suggesting that the Mudanjiang suture zone was reactivated by subductions of the Paleo-Pacific plate and Pacific plate,leading to remelting of the cooled and crystallized materials in the pathways.Therefore,subduction of the(Paleo-)Pacific plate destroyed the lithospheric structure of the paleo collision zone in the eastern segment of the Central Asian orogenic belt,and the large-scale crustal conductor beneath the suture zone reflects reactivation of the paleo-suture zone.展开更多
文摘High-density electrical method has been proved to be an effective method for probing shallow sedimentary layers.It is principally used to identify the boundary between the Quaternary soil layer and bedrock according to the vertical change of apparent resistivity.However,the artificial filling layer has the characteristics of heterogeneity and high porosity,which makes it challenging to detect the artificial filling layer by high-density electrical method.The key to solve this problem is to detect the difference of conductivity between the filling layer and the underlying bedrock.This paper takes the land in Chengjiangshan area of Huaibei City,Anhui Province as the detection target.On the basis of fully analyzing the physical properties of the artificial filling layer,two-dimensional high-density electrical survey and inversion are used to define the thickness of the artificial filling layer.The research shows that the highdensity resistivity method has obvious advantages in delineating the distribution of bedrock and the thickness of the filling layer,and the reliability of the high-density electrical method in the detection of the artificial filling layer,and delineates the scope of the filling layer is verified by the borehole data.
基金Projects(41074085,41374118)supported by the National Natural Science Foundation of ChinaProject(20120162110015)supported by Doctoral Fund of Ministry of Education of ChinaProject(NCET-12-0551)supported by Program for New Century Excellent Talents in University,China
文摘The 2D data processing adopted by the high-density resistivity method regards the geological structures as two degrees, which makes the results of the 2D data inversion only an approximate interpretation;the accuracy and effect can not meet the precise requirement of the inversion. Two typical models of the geological bodies were designed, and forward calculation was carried out using finite element method. The forward-modeled profiles were obtained. 1% Gaussian random error was added in the forward models and then 2D and 3D inversions using a high-density resistivity method were undertaken to realistically simulate field data and analyze the sensitivity of the 2D and 3D inversion algorithms to noise. Contrast between the 2D and 3D inversion results of least squares inversion shows that two inversion results of high-density resistivity method all can basically reflect the spatial position of an anomalous body. However, the 3D inversion can more effectively eliminate the influence of interference from Gaussian random error and better reflect the distribution of resistivity in the anomalous bodies. Overall, the 3D inversion was better than 2D inversion in terms of embodying anomalous body positions, morphology and resistivity properties.
文摘In order to explore the mineral resources buried in sea mud,it is necessary to use seabed resistivity measuring equipment,which works closer to the sediments than ordinary ship-based geophysical measuring equipment. Because of the harsh environment of seafloor,high pressure and highly conductive seawater,marine magnetotelluric method developed slowly. The sea floor environment is similar to the environment of logging, According to the design of dual lateral logging equipment,a new equipment for seafloor electrical resistivity measurement is designed. Four 3D FEM models that contain resistivity abnormal targets are built to test the ability of this equipment to locate different shape of shallow buried resistivity abnormal targets in sea mud. The authors propose the method to correct the response curve while the bottom surface of this equipment is suspended or not parallel to the seafloor. The resistivity of targets can be calculated accurately.
基金Supported by the National Basic Research of China(2006CB202207)the National Natural Science Foundation of China(40674060)
文摘The principles, methods, technologies and application effects of several electromagnetic methods for the detection of the hidden danger of water gushing at the coal face were introduced. Also, emphasis was laid on expounding the methods, principles and effects of down-hole detections by electric transmission tomography and transient electromagnetic method. The potential of point power supplied in the underground homogeneous semi-space, as well as the response to a low-resistivity abnormal body in the homogeneous semi-space, was simulated by adopting 3-D finite element method to interpret the basic theory of the electric transmission tomography. The results of actual measurement show that the mine electromagnetic method is sensitive to water-bearing low-resistivity bodies and can play a unique role in detecting the hidden danger of water gushing at the coal face.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230303,41504076,41874125)the China Geological Survey Project(Grant No.DD20190010)the Fundamental Research Funds for the Central Universities(Grant No.JLUXKJC2021ZZ11).
文摘The Jiamusi and Songnen blocks converged in the easternmost segment of the Central Asian Orogenic Belt as a result of the subduction and subsequent closure of the Mudanjiang oceanic plate during the Permian-Jurassic.The Mudanjiang suture zone was later directly affected by subductions of the Paleo-Pacific plate and Pacific plate and is therefore an ideal place to study the subduction polarity and later transformation of a paleo-suture zone.Using three-dimensional inversion of magnetotelluric data collected along a 160-km-long profile across the Mudanjiang suture zone,we established a resistivity model of the suture zone and adjacent area.Our results reveal the subduction polarity and subduction trace of the Mudanjiang oceanic plate and provide geoelectrical evidence for reactivation of the Mudanjiang suture zone induced by the(Paleo-)Pacific plate subduction.The suture zone shows a complex conductive structure.The west-dipping crustal-scale conductor beneath the Songnen-Jiamusi collision zone represents the fossil subduction zone and indicates the westward subduction polarity of the Mudanjiang oceanic plate.Furthermore,the Mudanjiang fault identified by surface geology does not fully represent the deep structure of the Mudanjiang suture zone.The definition of the suture zone should be extended to the whole conductive region with a lateral extent of~70 km.Solid conductive minerals beneath the arc in front of the subduction zone were exhumated up from deep to the upper crust.The“chimney”-shaped conductor connected with the mantle represents the intrusive pathways of mantle-derived materials,suggesting that the Mudanjiang suture zone was reactivated by subductions of the Paleo-Pacific plate and Pacific plate,leading to remelting of the cooled and crystallized materials in the pathways.Therefore,subduction of the(Paleo-)Pacific plate destroyed the lithospheric structure of the paleo collision zone in the eastern segment of the Central Asian orogenic belt,and the large-scale crustal conductor beneath the suture zone reflects reactivation of the paleo-suture zone.
