The geology of the Rengali Province: implications for the tectonic development of northern Orissa, India

Abstract

The Rengali Province in northern Orissa, India is a distinct lithological, structural and metamorphic belt bound by major shear zones between the Singhbhum Province and the northern Eastern Ghats Belt and the NE part of the Bhandara Province. The Rengali Province comprises an amphibolite facies sequence of intercalated basement gneiss and meta-volcanosedimentary lithologies. Deformation is characterised by a variation in strain from relatively low for much of the central and NE part of the belt to a strongly deformed zone south of the intra-province Riamal Shear Zone. Geochronological constraints suggest dextral displacement along the bounding Kerajang and Barakot Shear Zones occurred prior to ca. 980 Ma and D 2 within the Eastern Ghats Belt, and post the Meso-Neoproterozoic metamorphism within the Sausar and Gangpur Groups, which may have once represented a single contiguous belt. Deformation associated with the dextral displacement of the Singhbhum Province relative to the Bhandara Province resolved the Rengali Province as a distinct and comparatively high-strain belt which accommodated large-scale dextral shearing at amphibolite facies conditions. Progressive shearing and later reactivation associated with late retrogression was confined to the southern margin of the Rengali Province along the Kerajang Fault Zone. The latest brittle reactivation along the Kerajang Fault Zone deforms the Ib River and Talchir Permo-Triassic coal sequences.