The Characterization of Metamorphic Facies of Metabasalts of Hutti Greenstone Belt

Abstract

The Hutti greenstone belt, containing several promising gold deposits is predominantly composed of metavolcanics represented by basalt with minor felsic volcanics and metasediments. Basalt has undergone regional metamorphism as indicated by the presence of characteristic metamorphic mineral assemblage of plagioclase, amphibole and chlorite. Electron microprobe studies are carried out on these minerals to study the chemistry and the mineral reactions in the rock. The analytical data indicate that plagioclase is andesine, amphibole is magnesio-hornblende and chlorite is ripidolite.

The mineralogical assemblage, the chemistry and in particular the co-existence of hornblende and chlorite in metabasalt indicates a metamorphic grade 'transition between greenschist and amphibolite facies'.