Archaean Shelf-Facies and Stromatolite Proliferation in Dharwar Supergroup, North Kanara District, Karnataka

The stromatolitic cherty dolomite of KaIche is a lithostratigraphic equivalent of the carbonate rocks of the Joldhal Formation of Archaean age. Morphotypes suggest development in subtidal to lower intertidal zone of the Dharwar seas. Some of the forms observed near Kalche are comparable to the domical forms observed near Kumsi in the Shimoga schist belt and Vanivilaspura in the Chitradurga schist belt. The morphotypes observed in these regions contrast with the actively and passively branched columnar stromatolites observed near Dodguni and Bhimasamudra in the Chitradurga schist belt where the stromatolites evolved in an intertidal environment. Diversity of morphotypes of stromatolites appears to have occurred in the Archaean itself, although such diversity appears to have attained stratigraphic significance by the middle Proterozoic.