Archaean stromatolites from the Chitradurga schist belt, Dharwar Craton, South India

Abstract

Stromatolites have been found in the cherty dolomite member of the Vanivilas Formation of the Chitradurga Group belonging to > 2600 Ma old Archaean Dharwar Supergroup, South India. They occur in the Bhimasamudra, Marikanve and Dodguni areas of the Chitradurga schist belt. The stromatolites of the Bhimasamudra and Marikanve areas are described here for the first time. The stromatolites of Bhimasamudra consist of cylindrical and terete columns, as well as pseudocolumns with concave tops developed on a wavy base. Coalescence of columns and γ-type branching have been noticed. The Marikanve stromatolites are stratiform, often grading into pseudocolumnar and dome-shaped types. Naked stromatolite columns showing β-type and markedly divergent branching are found in the Dodguni area. The Bhimasamudra and Dodguni stromatolites probably developed in an intertidal environment and the Marikanve ones in a subtidal environment.