Joint Three-Dimensional Interpretation of AMTS and RMT-C Tensor Data in a Region Promising the Discovery of Primary Diamond Sources (Karelian Isthmus)

Abstract

—The paper presents the techniques and results of the joint interpretation of AMTS and RMT-C tensor data in the area of the Karelian Isthmus near the village of Yablonovka, promising the discovery of primary diamond sources. Earlier, according to drilling data, fluid-cataclastic breccias, fluidolites, were identified here, which, according to modern geological concepts, can be primary diamond sources. The site is located in the marginal part of the Pash-Ladoga rift zone and is characterized by a complex three-dimensional structure. Under these conditions, in the presence of a system of multidirectional faults, the joint interpretation of the AMTS and RMT-C tensor data was performed within a 3D model of the medium. To reduce the inversion execution time, an approach and a procedure for transforming the RMT-C data obtained in the intermediate zone of a controlled source to sounding curves corresponding to the plane wave model are proposed. The transformed RMT-C apparent resistivity curves were also used to correct the static shifts of the AMTS curves. A joint 3D inversion was performed taking into account the relief. The resulting model is in good agreement with the geological data obtained from the wells previously drilled near the work site. The geoelectric sections show zones of relatively increased resistivity, which may be associated with fluidolites. The developed approaches to the joint 3D interpretation of AMTS and RMT-C tensor data and the obtained information about the structure and properties of the basement rocks, rocks hosting fluidolites, and overlying sedimentary deposits, can be used in prospecting works for diamonds on the Karelian Isthmus and adjacent territories.