Uranium potential of concealed E-W shear through geophysical data guided exploration in Khetri sub-basin - a case study from Karoi area, Rajasthan, India

Uranium potential of Khetri sub-basin of North Delhi Fold Belt (NDFB), especially South Khetri sub-basin, is widely established through exploration over the years. Metasedimentary sequence of the sub-basin is subjected to polyphase deformation with coaxial NNE-SSW to NE-SW two phases followed by a later phase of E-W trend. Ground and heliborne geophysical data were of immense use in the interpretation of mineralisation locales. Analysis of heliborne magnetic data brought out an E-W trending lineament which is well reflected from ground magnetic data over a small area adjoining Karoi village. Higher charge ability in ground induced polarisation survey and conductor interpreted through heliborne electromagnetic data in the vicinity also follow this trend. Follow up sub-surface drilling intercepted strike persistent significant uranium mineralisation in boreholes drilled over a strike length of approximately 1.2 km along the concealed E-W shear below the soil covered area around Karoi. Encouraging exploration results of the area provide scope to probe further strike and dip extent on the lineament. Presence of uranium mineralisation along E-W shear coinciding with the last phase of deformation also points towards the possibility of post-deformational mineralisation or remobilisation episodes. (author)