The Application Of Controlled Source Audio-frequency Magnetotelluric In Lushi County Of Henan Province Hydrology Geological Structure Survey

Since the invention of CSAMT at seventies of last century, it has became animportant means of electromagnetic exploration and widely used by many countries.In the hydrogeology investigation, especially the exploration of deep geothermalstructure, the conventional electrical already cannot satisfy the needs of practical work.Controlled source audio magnetotelluric sounding method of artificial field sourcewith high power, has the characteristics of stable signal, signal-to-noise ratio, strongpenetration ability, probing depth, is a kind of effective artificial sourceelectromagnetic exploration method.Lushi county is located in the joint part of mainland China two first-ordertectonic units, the Lushi basin is a basin of a small Intermountain fault, basin formedin the Cenozoic, filling the Neogene and quaternary lake facies of Paleogene,continental clastic sedimentary rocks, with geothermal mineralization conditionsuperior.The hydro geological geophysical survey work, Lushi County of HenanProvince area deep hydrogeological structure, adopts the controlled source audiofrequency magnetotelluric sounding method, according to the situation of distributionof electrical measurement, infer the workspace section domain since the basinbasement top2000meters below the surface within the interface, the fracture positionand occurrence.In the full collection of the geology, hydrology geology, geophysical and otherbasic data, field use GDP-32produced by American Zonge company ofmultifunctional electrical meter. This work is to complete the controlled source audiofrequency magnetotelluric method (CSAMT) of9profiles. The total length of theprofile10650m, physical measuring point355. Observation frequency specified underthe excitation of the electric field and the orthogonal magnetic field, into theimpedance, and the calculated impedance apparent resistivity and phase, is used forthe analysis of inversion of magnetotelluric sounding technique class.In order to petrophysical parameters as the basis, combined with the regionalgeological data and accessories of existing geothermal resources prospecting workthrough this field controlled source, initially revealed the work area profile domainbasin basement undulation shape and approximate depth, inferred the possible faultlocation and occurrence element.