Combination of electrical exploration methods in searching for ore-controlling structures in the Turuntaevskaya ore zone (Tomsk region)

Relevance. The prospects of expanding the mineral resource base are currently associated with the search for "hidden type" deposits, which do not have access to the surface. Such objects are characterized by large thicknesses of overlying sediments reaching 100 and more meters. Prospecting geophysical works in such conditions is not always effective due to incorrectly selected set of methods and non-observance of research stages. One of the possible ways to search for such objects is to identify the deep ore-controlling structure in small-scale prospecting and subsequent detailing of the section upper part by large-scale studies. Aim. To obtain new information about the Turuntaevskaya ore zone structure using a set of electrical exploration methods. The set allows extracting information from depths of several kilometers to the first hundreds meters. Methods. Magnetotelluric sounding, transient electromagnetic sounding, electrical resistivity tomography with measurement of induced polarization. Results and conclusions. According to magnetotelluric studies data, a conducting heterogeneity of lenticular shape was identified at the base of the ore zone. The roof depth of which is noted at 4 km. The identification of a hidden intrusive body of the Telbes magmatic complex at a depth from 2 to 3 km and with a width of 10 km is also a significant result. The authors use these geoelectric structures as depth criteria for mapping ore zones in the study area. The transient electromagnetic sounding method in the conditions of Turuntaevskaya ore zone, can be used to map the position ore-bearing Paleozoic rocks top, but does not allow solving the main geological problem – the search for ore objects. According to the data of electrical resistivity tomography with measurement of induced polarization, linear narrow zones of low electric resistivity associated with ore-controlling structures and confirmed by drilling are traced. These zones or their contacts are accompanied by linear anomalies of increased polarizability, which we associate with sulphide mineralization. In total, four extended ore-controlling structures of submeridional strike were identified, and the version of the existence of hollow-lying ore bodies was refuted. On the example of Turuntaevskaya ore zone it was shown that conductive heterogeneities identified by methods of magnetotelluric sounding and electrotomography at various stages of prospecting should be used as prospecting criteria in the search for new objects in the adjacent areas.