Research And Application Of CSAMT In The Metal Mineral Exploration

In recent years，the Controlled Source Audio-frequency MagnetoTellurics (CS-AMT) with exploration depth, anti-interference ability and high efficiency, especiallyagainst a high-impedance shield and stratigraphic formations sensitive to low resistan-ce, etc.,was relatively rapid development as a method of electrical prospecting,andhad been successfully applied in geophysical engineering, metal mineral exploration,geothermal exploration and oil and gas field exploration. It sloved many practicalproblems, and had a very broad application prospects.It was one of the importantmethods in the field of geophysical exploration.CSAMT was an artificial source frequency domain sounding methods,whichdeveloped on the basis of magnetotelluric method(MT) and audio magnetotelluricmethod (AMT). It was, based on a finite ground wire for the field source, anelectromagnetic sounding method while observing electrical, magnetic field sourceparameters in certain distance away from the center of the field source.The horizontal electric dipole source transmited skywave,formation wave andground wave to the surrounding. Due to the difference in wave processes, at a certainmomentnear the ground,a horizontally polarized plane wave is formed whichpropagating almost vertically downwards. These three waves propagated in thesubsurface, interactd with the underground medium, was received by groundobservation point. This was the physical premises of CSAMT to solve geologicalproblems.The theoretical basis of CSAMT was described in this paper by from Maxwell’sequations deduced to the electromagnetic wave equation. From this basis,differentelectric and magnetic formulas in different diatance was deduced by electromagneticwave from the horizontal electric dipole source, and finally got the basic formula ofCSAMT(apparent resistivity and apparent phase formula formula).On the basis of theoretical research on CSAMT, a detailed and in-depth researchhad being carried out on the influence of technology of CSAMT method, mainly donein-depth research on proximity effect and static effect, and their produced, theconsequences and how to do a correction,respectively. Then the skin effect and the wave field region division was discussd which has a direct relationship to theproximity effect.Through in-depth study,the CSAMT’s conclusion was used to guide the work offield data collection, determine the emission and reception of dipole-dipole size,improve the quality of data collection, avoid some of the interference. Through thoseresearch, a smaller dipole used to explorate the shallow target, whereas a larger dipoleused to explorate the deeper target. Finally, combineing with indoor processing, datainversion and interpretation of inference summarized a set of applicable to the explor-ation of metal minerals technology, which provided the basis for the next CSAMTpractical exploration.At the instance of the CSAMT method applying in metal mineral exploration, theCSAMT method can effectively reflect the differences in the underground ground,divided differences in the presence of electric rock. In the combining with the existinggeological and geophysical data, the underground anomalies was concluded, and thusguided to further work. Examples show that the CSAMT method can achieve betterresults in metal mineral exploration, which was a good exploration methods at presentto guide metal mineral exploration...