Geochemistry and Tectonic Significance of Late Archaean-Early Proterozoic Metabasalts from Bacheli, Bastar District, Madhya Pradesh

The fine grained, massive metabasalts of Bacheli-Kirandul areas, Bastar district, M.P., characterized by a greenschist facies mineral assemblage have been studied for their major, trace and REE geochemical distribution pattern. On Jensen's AFM Plot and diagrams of relatively immobile elements; these metabasalts fall in the tholeiitic basalts to basaltic andesite field.

Large scatter in Na₂O/K₂O, K/Rb and RblSr ratios suggest to alteration effects, while high MgO content ascribes to the oxidative diagenesis. Relatively immobile and HFSE element discriminant diagrams point to an island arc/convergent plate setting. The depletion in Nb and Ta relative to Th and LREE in these samples may be relict from a previous tectonic event.

Inferences drawn from geochemical tectonic discriminant diagrams have been evaluated in the light of additional geological data, and an ensialic rift setting for these volcanics is envisaged.