Archaean greenstone belts of the Eastern Baltic and the Southern Indian shields - a comparative study

Abstract

A comparative study of the Archaean geenstone belts of the same time span (3.3 Ga to 2.5 Ga) in the Dharwar era ton of southern India and the eastern Baltic shield of Karelia, USSR, shows some significant differences in their evolutionary trend Whereas detrital sedimentary rocks occur throughout the stratigraphic succession in the southern Indian shield, they are restricted to the upper part of the sequence in the eastern Baltic shield. Chemogenic sediments (banded iron- and manganese-formations and carbonate rocks), dominant constituents in the Dharwar belts are poorly developed in the Baltic shield. Stromatolites are absent in the Baltic greenstone belts, but occur in profusion in the Dharwar belts. Bimodal/polymodal volcanic assemblages, together with immature sediments in the Baltic shield, point to an island arc setting, whereas association of both mature and immature sediments with bimodal volcanics in the Dharwar belts favours a back-arc environment.