Tungsten, barium and base metal mineralization in a layer of amphibolite in Mesoarchaean Ghattihosahalli belt, western Dharwar craton, Karnataka, India

Abstract

Scheelite together with barytes and base metals is found in a layer of para-amphibolite within the Mesoarchaean Ghattihosahalli schist belt in western Dharwar craton. Scheelite occurs as disseminated grains within the amphibolite layer which occurs at the interface between >3.34 Ga old sequence of ultramafic komatiite-komatiitic basalt and an overlying sequence of interbedded fuchsite quartzite, barytes, cherty quartzite and kyanite-sillimanite-quartz-sericite schist. This lithological assemblage is intruded by and co-folded with sheets of gneisses and granites of >3.0 Ga age (Peninsular gneiss). The source material of the mineralized amphibolite is probably derived from weathering of the underlying komatiitic basalt. The mineralization comprising of scheelite, barytes and basemetals in the amphibolite may have been formed by sea floor hydrothermal activity. The mineralized amphibolite is comparable in its geological setting and mineralization features to ∼3.8 Ga old Isua supracrustal belt of West Greenland. This new finding could be viewed as one of the oldest instances of Proto SEDEX-style base metal mineralization associated with barite deposits in the Indian shield.