To test the performance of the Chinese whole-surface electromagnetic prospecting （SEP） system, system integrations, instrument performances, and large-scale production viabilities in Liaoning province and Inner Mong...To test the performance of the Chinese whole-surface electromagnetic prospecting （SEP） system, system integrations, instrument performances, and large-scale production viabilities in Liaoning province and Inner Mongolia were measured via extensive field tests. Resultant electric fields, magnetic fields, apparent resistivities, impedance phases, and inversion profiles compared favorably with results of commercial equipment from other countries. The inversion results agreed well with the geologic information from boreholes. Field tests showed that the SEP system is stable, reliable, lightweight, and easy to operate, making it suitable and ready for real-field exploration.展开更多
The depth of upper fault point is the key data for ascertaining the active age of a buried fault on a plain. The difference of depth obtained from same fault may be dozens to several hundred meters when using differen...The depth of upper fault point is the key data for ascertaining the active age of a buried fault on a plain. The difference of depth obtained from same fault may be dozens to several hundred meters when using different geophysical methods. It can result in the absolutely opposite conclusions when judging fault activity. Because of a lack of an artificial earthquake source with wide band and high central frequency, many kinds of methods have to be used together. The higher the frequency of the artificial earthquake wave, electromagnetic wave and sonic wave, the higher the resolution. However the attenuation is also very fast and the exploration depth is very shallow. The reverse is also true. The frequency of artificial seismic waves is in the tens of Hz. Its exploration depth is big and the resolution is poor. The frequency of radar electromagnetic waves is about a million Hz, indicating that the resolving power is better, but the exploration depth is very shallow. However, the acoustic frequency is thousands of Hz, its resolving power is better than that of the artificial earthquake method and the exploration depth is larger than that of the radar method. So it is suitable for extra shallow exploration in the thick deposit strata of the Quaternary. The preliminary results detected using the high frequency acoustic method in extra shallow layers indicates that previous inferences about some fault activity in the eastern part of the North China plain may need to be greatly corrected.展开更多
The present paper investigates the application of high resolution magnetic survey to detecting igneous bodies. The slight difference in magnetism between igneous bodies and their surrounding rocks is measured first an...The present paper investigates the application of high resolution magnetic survey to detecting igneous bodies. The slight difference in magnetism between igneous bodies and their surrounding rocks is measured first and then the magnetic survey data are processed to determine whether there exist igneous bodies by analog among several measuring lines, and finally the modified Marquart inversion was used to determine the occurrence and distribution of the igneous bodies.展开更多
A ground magnetic survey was conducted on the Kusi mineral prospect, Papua New Guinea, to provide insights into the magnetic properties of the mineralisation and help define drill targets for an exploration programme....A ground magnetic survey was conducted on the Kusi mineral prospect, Papua New Guinea, to provide insights into the magnetic properties of the mineralisation and help define drill targets for an exploration programme. The results of the survey suggest three distinct magnetic zones： （1） a magnetic high zone covering the northern portion of the survey area; （2） a northeast-southwest trending magnetic low zone occupying the southern portion and （3） a possible buried intrusive body separating the magnetic high from the low magnetic zone. The results of the survey suggest that drilling is concentrated on the zone of low magnetic response, and the periphery of the interpreted intrusion is adjacent to the contact to the limestone defining the mineralisation style of the two zones. A further ground magnetic survey is required to determine the western limits of the low magnetic zone.展开更多
A convenient numerical calculation method (inverse spline interpolation) for all-time apparent resistivity intransient electromagnetic method (TEM) is proposed in this paper. Characteristic of early and late normalize...A convenient numerical calculation method (inverse spline interpolation) for all-time apparent resistivity intransient electromagnetic method (TEM) is proposed in this paper. Characteristic of early and late normalized inductiveelectromotive force was investigated. According to the turning point, the transient process is divided into the earlyphase, the turning point, and the late phase. Afterwards, apparent resistivity is obtained through inverse spline interpo-lation in the early and the late phases, respectively. Finally, the resistivities of the early-time and the late-time wereconnected together by the turning point. The result shows that the inverse spline method is feasible and the method alsolays a foundation for initial model construction in the TEM automatic inversion.展开更多
基金supported by Sino Probe Project(Sino Probe-09-02,201011079)Development Project of National Key Scientific Equipment(No.ZDYZ2012-1-05)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA14050100)
文摘To test the performance of the Chinese whole-surface electromagnetic prospecting （SEP） system, system integrations, instrument performances, and large-scale production viabilities in Liaoning province and Inner Mongolia were measured via extensive field tests. Resultant electric fields, magnetic fields, apparent resistivities, impedance phases, and inversion profiles compared favorably with results of commercial equipment from other countries. The inversion results agreed well with the geologic information from boreholes. Field tests showed that the SEP system is stable, reliable, lightweight, and easy to operate, making it suitable and ready for real-field exploration.
文摘The depth of upper fault point is the key data for ascertaining the active age of a buried fault on a plain. The difference of depth obtained from same fault may be dozens to several hundred meters when using different geophysical methods. It can result in the absolutely opposite conclusions when judging fault activity. Because of a lack of an artificial earthquake source with wide band and high central frequency, many kinds of methods have to be used together. The higher the frequency of the artificial earthquake wave, electromagnetic wave and sonic wave, the higher the resolution. However the attenuation is also very fast and the exploration depth is very shallow. The reverse is also true. The frequency of artificial seismic waves is in the tens of Hz. Its exploration depth is big and the resolution is poor. The frequency of radar electromagnetic waves is about a million Hz, indicating that the resolving power is better, but the exploration depth is very shallow. However, the acoustic frequency is thousands of Hz, its resolving power is better than that of the artificial earthquake method and the exploration depth is larger than that of the radar method. So it is suitable for extra shallow exploration in the thick deposit strata of the Quaternary. The preliminary results detected using the high frequency acoustic method in extra shallow layers indicates that previous inferences about some fault activity in the eastern part of the North China plain may need to be greatly corrected.
文摘The present paper investigates the application of high resolution magnetic survey to detecting igneous bodies. The slight difference in magnetism between igneous bodies and their surrounding rocks is measured first and then the magnetic survey data are processed to determine whether there exist igneous bodies by analog among several measuring lines, and finally the modified Marquart inversion was used to determine the occurrence and distribution of the igneous bodies.
文摘A ground magnetic survey was conducted on the Kusi mineral prospect, Papua New Guinea, to provide insights into the magnetic properties of the mineralisation and help define drill targets for an exploration programme. The results of the survey suggest three distinct magnetic zones： （1） a magnetic high zone covering the northern portion of the survey area; （2） a northeast-southwest trending magnetic low zone occupying the southern portion and （3） a possible buried intrusive body separating the magnetic high from the low magnetic zone. The results of the survey suggest that drilling is concentrated on the zone of low magnetic response, and the periphery of the interpreted intrusion is adjacent to the contact to the limestone defining the mineralisation style of the two zones. A further ground magnetic survey is required to determine the western limits of the low magnetic zone.
基金Project 40344022 supported by National Natural Science Foundation of China
文摘A convenient numerical calculation method (inverse spline interpolation) for all-time apparent resistivity intransient electromagnetic method (TEM) is proposed in this paper. Characteristic of early and late normalized inductiveelectromotive force was investigated. According to the turning point, the transient process is divided into the earlyphase, the turning point, and the late phase. Afterwards, apparent resistivity is obtained through inverse spline interpo-lation in the early and the late phases, respectively. Finally, the resistivities of the early-time and the late-time wereconnected together by the turning point. The result shows that the inverse spline method is feasible and the method alsolays a foundation for initial model construction in the TEM automatic inversion.
