Project-scale prospectivity analysis for unconformity-related uranium deposits in the Badami Group of the western Kaladgi basin, India

Abstract

Developing successful exploration strategies for finding new ore deposits is a major challenge for exploration geologists, particularly, for concealed deposits in terranes with thick sediment cover. Proterozoic unconformity-related uranium deposits occur at, below, or above, unconformable contacts between Archean and Paleoproterozoic crystalline basement and siliciclastic sediments of middle or later Proterozoic age, often at locations where fault systems cut across either one or both of the geologic units that lie above and below the unconformity. The present study implements project-scale prospectivity analyses to identify drilling targets in the Badami Group of the western Kaladgi basin, India. Topographic profiles; field observations of breccia and lineaments; surface and sub-surface sampling; petrography and geochemistry; drill-core lithologs; and interpreted aeromagnetic anomalies were used to build a generalized local geological model of unconformity-related uranium deposits in the study area. Based on the geological model and a generalised mineral systems model, hydrothermal alteration, proximity to lineaments, proximity to unconformity surface, and anomalous uranium content on the surface and in the groundwater were identified as key project-scale targeting criteria. Seven high-priority drilling targets were mapped based on expert driven prospectivity analysis constrained by a GIS-based fuzzy prospectivity modelling. Out of these, four target areas coincide with the targets identified by the Atomic Minerals Directorate (AMD) of India based on their independent investigation. The three new targets from this study are recommended as targets for detailed exploration and drilling. In addition to this, about eight additional low priority targets were identified for follow-up exploration activities. This paper demonstrates that the prospectivity mapping methods can be applied at the project scale. The strategy demonstrated in this study can be used for exploration targeting in similar basins like the western Kaladgi basin that are structurally less disturbed.