INTEGRATED GEOPHYSICAL EXPLORATION APPLIED IN SPATIAL POSITIONING OF IRON DEPOSIT

Taking Maogongpu iron mine in Fushun, Liaoning Province, as the object, the study carries out the high-precision gravity and magnetic survey, with non-equidistant, non-equal-ratio IP sounding and wide-audio-frequency magnetotelluric(MT) sounding in key areas. The survey adopts small point distance of 5 m for key sections, and large point distance of 20 m for other sections in single profile. The maximum interval of non-equal-ratio pole distance induced polarization(IP) sounding is less than 200 m, and the widest frequency of wide-audio-frequency MT sounding is 0.1 Hz. The gravity and magnetic data are processed by multi-software, multi-parameter and multi-method, with multiple transition maps for comprehensive research and selection of effective key areas. Conventional sounding methods with unconventional parameters are applied in key areas. Besides, multi-parameter and multi-method data processing and inversion methods are used to accurately characterize the deep electrical characteristics, which are finally verified by drilling project. The results show that the high-precision gravity survey can assist high-precision magnetic survey with iron deposit exploration. The gravity anomaly can better represent the surface projection position of anomaly geological body. Electromagnetic sounding is an effective method for vertical division. Parameters such as resistivity and polarizability of IP sounding can be used to classify and detect the boundary of alteration, structure and rock mass better. The multiple electrical parameters of IP sounding can make up for the shortage of single electrical parameters of MT sounding, and help to identify water body, polymetallic mineralization, altered body, structure and fracture zone. The working procedure from region to area, from area to point and from point to depth is effective. The drilling results show that the integrated methods have a good performance in the iron deposit exploration, especially in the determination of spatial occurrence parameters of iron orebody, such as buried depth, dip direction, dig angle and shape. A set of effective iron deposit exploration technology model is established with this method.