Delineation of gold mineralization near Lawa village, North Singhbhum Mobile Belt, India, using electrical resistivity imaging, self-potential and very low frequency methods

摘要

North Singhbhum Mobile Belt (NSMB), India, is almost 200 km long elongated zone. The region has stretched out shear zones that are in E-W direction with a complex history of lithology, structure, metamorphism and tectonic settings, which closely mirrors other gold producing orogenic metamorphic mobile belts. The study area, Lawa village, is located in Nimdih Block of Seraikella-Kharsawan district, Jharkhand, India. Detailed Electrical resistivity tomography (ERT), Self-Potential (SP) and Very Low Frequency Electromagnetic (VLF-EM) surveys were carried out to investigate appropriate conducting zones associated with Cu-U mineralization for gold exploration. Apparent resistivity pseudo sections obtained and compared with the current density pseudo sections of VLF data achieved from K-H filtering technique and SP anomaly curves to mark out considerable lateral extension of prospective source. Conventional filtering methods cannot help in eliminating non-linear and non-stationary noises that contaminated the VLF-EM data, obtained from the field. To regain signals with significant geologic information, we have used empirical mode decomposition (EMD) technique. Results obtained show an excellent correlation between ERT and VLF profiles marked by low resistivity, high current density zones. This correlation indicates that the conducting features have shallow depth and are steeply dipping with a strike along E-W direction. However, SP anomaly curves were not clear enough to harmonize with the above result. This study boosts the scope of further geo-electrical and EM investigations in this region to explore appropriate target locations for gold exploration, which may be later, utilized on a significant scale for commercial purposes. (C) 2019 Elsevier B.V. All rights reserved.