Integrated geophysical and geological prospecting for magnetite in the ilmenite-bearing gabbroic rock of Purulia, West Bengal, India

Abstract

Mineral exploration in regions of limited bedrock exposure depends on the excellence of the predictive model yielded from geophysical and geological studies. In this aspect, the accuracy of the positions, shapes, and size of the concealed ore bodies is important for later resource evaluation. Commonly used magnetic susceptibility surveys to explore buried magnetite deposits often fail to resolve the boundary between magnetite ore, and host rocks when the host rock contains ilmenite, and/or magnetite as an accessory mineral. Electrical Resistivity Imaging (ERI), and Self-Potential (SP), are better substitutes to resolve the issue and delineate the positions and shapes of the ore bodies in gabbroic host-rock in Purulia district, West Bengal, India. The concealed magnetite ore body showed a sharp decrease in electrical resistivity value in the 2D ERI study, and a significant negative SP value was concurrent with the inferred concealed magnetite bodies, compared to the gabbroic host rock. Hence, the combined result of 2D ERI and SP indicate analogous negative anomalies to the inferred magnetite ore bodies, verified by the surface geological information and mineralogical studies. Such geophysical anomalies could be combined with field data to reconstruct magnetite ore body modeling, providing a practical approach to prospect buried magnetite ore bodies in basic host rocks.