Implications of Retrograde Metamorphism for Gold Mineralisation in the Greenstone Belts of Northern Dharwar Craton, Karnataka, India

Gold mineralisation in the Archaean Hutti, Mangalur and Gadag greenstone belts of the northern Dharwar craton is characterised by hydrothermal wall-rock alterations with ubiquitous presence of chlorite, sericite/muscovite, biotite, carbonates, sulphides and quartz veins indicating greenschist facies mineral assemblages. Such wall-rock alterations associated with gold mineralisation in these belts post-date the peak of regional metamorphism and are retrograde with respect to regional metamorphism. There is a salient relationship between gold mineralisation and retrograde greenschist facies metamorphism in these belts.