Magnetic characteristics of a part of Closepet Granite, Eastern Dharwar Craton

Abstract

The exposed granite gneissic complex to the west of Cuddapah basin in Eastern Dharwar Craton (EDC) is studied to understand the magnetic character of various plutons in this region with more emphasis on a part of Closepet Granite (CG). The NW–SE trending plutons in this region show gradual decrease in magnetic intensities from southwest to northeast; CG in the southwest corner of the study area have high mafic content, and there onwards show a depletion in mantle enrichment towards NE. Parts of the CG namely, the main mass and northern intrusions separated by a gap zone are differentiated based on magnetic character deduced by processing the aeromagnetic data. Reduced to the pole (RTP) and its upward continued maps revealed NNW trending eastward convex anomaly highs inferring the magnetic nature of CG due to Porphyritic Monzogranite (PMG). Gap zone is identified to be structurally significant, bounded by deep ENE faults and inferred to be associated with PMG at relatively deeper levels. 2.5D modelling of magnetic anomaly profile substantiated our qualitative analysis of magnetic anomalies over CG, inferring magnetic and non-magnetic units of CG. Known shear zones running north–south are identified with a few inferred shears revealed from magnetic data interpretation within CG.