The Paleoproterozoic Supracrustal Kolhan Group in Singhbhum Craton, India and the Indo-African Supercontinent

The 2.0 Ga supracrustal Kolhan Group to the south of Chaibasa in Singhbhum Craton, eastern India is a shale-dominated succession deposited in continental rift setting. It begins with thin plane- and cross-bedded red and purple sandstones consisting of ferric oxide-rich quartz arenite with beds/lenses of conglomerates deposited in shallow, ephemeral braided streams. The thick and extensive shale deposited in lacustrine environment overlies the sandstone. The shale succession consisting of thin and even bedded shale and silty shale contains lenticular bodies of finely laminated thin-bedded limestones and manganese-rich interval towards the basal part. It lacks subaerial exposure and tidal features and at places exhibits small wave ripples on bed surfaces.

Petrography, geochemistry and CIA values of Kolhan siliciclastics, suggest passive margin tectonic setting, an intensely weathered low-relief provenance dominantly composed of granitoid rocks and a warm and humid palaeoclimate. Based on similarities in age, lithology, petrography, depositional environment and type of mineralization, the Kolhan Group in Singhbhum Craton is correlated with manganese bearing Wyllies Poort Formation of the Soutpansberg Group, northeast Kaapvaal Craton, South Africa. This correlation suggests the two cratonic blocks may formerly have been juxtaposed and represents the sundered fragments of an Archean Craton.