Early Precambrian basic rocks of India

Abstract

Precambrian rocks are widely exposed in the Indian Shield, which forms the majority of peninsular India (Figure 15.1). Although radiometric dating of these rocks is not very comprehensive, they range from crystalline basement rocks as old as 3.8 Ga in the Singhbhum craton to widespread supracrustal sequences, and dykes intruding crystalline basement which are only 0.9 Ga old. Archaean and early Proterozoic igneous and meta-igneous rocks comprise a large proportion of the exposed Precambrian Indian Shield basement. Basic igneous and meta-igneous rocks occur in all of the three major cratonic nuclei in the Indian Shield. Detailed geochemical data are rather sparse for many of these occurrences, and this review concentrates on those regions (primarily the Dharwar craton; Figure 15.1) for which a reasonable body of petrological and chemical data are available.