Fluid Inclusion Characteristics of Basemetal Mineralization in Southern Part of Aladahalli - Nuggihalli Schist Belt, Western Dharwar Craton, Karnataka, India

Abstract

Aladahalli-Nuggihalli Schist belt of Karnataka in Western Dharwar Craton is well known for its remobilized volcanic exhalative type base-metal mineralization. The schist belt comprises metamorphosed mafic-ultramafic rock assemblage, traversed by quartz veins. The study area belonging to the southern extension of the schist belt is chosen on the basis of bipolar aero-magnetic anomaly (magnetic high) and higher order EM channels (4th, 5th and 6th) along with favourable geological conditions for mineralization. Lithology of the area includes metabasics (dominant) and meta-ultramafics intricately associated with pegmatite dykes and quartz veins. Subsurface mineral exploration programmes carried out in Aladahalli belt shows a close link between the quartz veins and sulphide mineralisation. Fluid inclusion study has been carried out on quartz samples from these veins to characterise the composition and P – T condition of entrapment of fluid inclusions. Three contrasting types of fluid inclusions are reported suggesting moderate to low salinity hydrothermal fluid pertaining to shallow-level epithermal condition.