Evolution of the proterozoic rift margin sediments - North Singhbhum Mobile Belt, Jharkhand-Orissa, India

The Proterozoic North Singhbhum Mobile Belt (NSMB), a Proterozoic rift basin, registered a complex interplay of tectonism and sedimentation. The siliciclastic sedimentary succession developed along the southern margin of the NSMB offers a deep insight into the changing pattern of sedimentation in response to crustal dynamism along a rift margin. Stratigraphic, sedimentologic, structural and tectonic studies of the Proterozoic sedimentary succession (Bisrampur Formation) indicate deposition in a series of half-grabens developed successively along the margin of the rift basin under the influence of lithospheric stretching. Analyses of the sedimentary facies attributes and the architecture of the studied sedimentary succession, and paleocurrent patterns indicate filling of the half-grabens by Archean basement-derived siliciclastic sediments in an alluvial fan-fan-delta environment. The structural elements developed in these sediments and neighboring rock units suggest that deformation and final collapse of the half-graben basins took place during a terminal orogeny. On the basis of an integrated analysis of the dataset generated in the present study and the database available in published work, a comprehensive evolutionary model of the North Singhbhum Mobile Belt is reconstructed. (C) 2007 Elsevier B.V. All rights reserved.