Mapping of Greenstone Belts using Aeromagnetic Data in Eastern Dharwar Craton, India

The Eastern Dharwar Craton (EDC) in southern India comprises several thin, linear N–S and NW–SE trending greenstone belts that hold rich economic mineral deposits, surrounded by gneisses and granites of different ages. Very long, linear, high-frequency, high-amplitude magnetic anomalies trending along the E–W, NE–SW, ENE–WSW, NW–SE and N–S directions associated with several sets of dike swarms, fault shears and fractures forming a rhombic pattern over the granite-gneissic terrain in the western part of EDC hindered the recognition of these thin, linear belts. The N–S strike of the belts inthe low-magnetic latitudes posed another limitation to demarcate these zones. A comprehensive relook into the regional aero-magnetic data using the prevailing interpretation techniques through diverse approaches helped identify the feeble magnetic signatures due to known narrow zones and enabled us to map hitherto unknown belts, namely Kurnool and Lattavaram–Atmakuru. 2.5D GM-SYS modelling has been carried out to delineate the vertical disposition of known belts that reaffirmed the existence of newly inferred belts. Isolated magnetic anomalies are also modelled for source-body parameters.