Incidence of Gold in Subgreenschist to Greenschist Facies Metabasalt of Bhowali, Nainital District, Uttaranchal

Abstract

Mesoproterozoic metavolcano-sedimentary sequence in and around Bhowali-Khairna area, Uttaranchal, constitute mostly metabasalts with quartzites, phyllites and variegated slates, referable to Bhimtal Formation. Our study was centred on metabasalts and the rocks occurring in close spatial association with them. Detailed petro-mineralogical and SEM-EDS studies have revealecl the presence of gold which we report here for the first time. Of the two types of metabasalts viz., massive, crudely foliated type and foliated type, both showing mineralogical assemblages of subgreenschist facies and greenschist facies respectively, gold is commonly found in the foliated type and rarely in the massive type. Presence of gold as tiny grains in disseminated fashion suggest that widespread hydrothermal activity caused precipitation of gold after the rocks had witnessed peak metamorphism.