Mapping of alteration zones associated with uranium mineralization using joint analysis of quasi 3D ERT with gravity anomaly near Kutni, South Purulia Shear Zone, India

Abstract

In the eastern part of India, South Purulia Shear zone (SPSZ) forms an elementary feature of Tamar-Porapahar lineament that trends in approximately E-W direction. In terms of Uranium mineralization prospects, SPSZ contributes a significant fraction when it comes to exploration. For a detailed investigation of subsurface characteristics, a quasi 3D resistivity survey using multi-electrode Schlumberger array configuration was performed near Kutni village in South Purulia Shear Zone (SPSZ). For this approach, we carried out measurements at various parallel profiles perpendicular to the strike in the area, to achieve the spatial resistivity distribution beneath the subsurface. Interpretation of the electrical resistivity tomography (ERT) results shows the presence of a conducting body at a depth of approximately 25-30 m that dips in the north direction and has a continuous extent in the E-W direction. Such low resistivity regions in 2D resistivity sections, when compared with gravity results, the outcome was in concurrence with low-density zones. These low resistivity and low gravity anomaly zones may correspond to the hydrous Uranium altered regions. Two more multi-electrode Schlumberger profiles were taken parallel to the strike direction near the exposed outcrop that showed the presence of anomalous zones. The integrated approach of geophysical methods used in this paper improves the likelihood of target location and helps in successfully deciphering the dimension of the geological features present beneath the surface.