Sedimentation pattern and tectonic evolution of the Proterozoic Singhbhum Basin in the eastern Indian shield

Abstract

The Proterozoic Singhbhum Basin (PSB) located on the flank of an Archaean platform (ca. 3400 Ma) is a distinct lithotectonic unit of the Singhbhum crustal province of the eastern Indian shield. The present contribution traces the evolution of this basin filled by volcanics-dominated submarine supracrustals and sedimentary formations. The Proterozoic Singhbhum Basin has been identified to be a marginal basin evolved in a back-arc setting. An axial volcanic belt manifesting MOR-like basaltic eruptions divided the basin into two domains with parallel but distinct sedimentation patterns. An asymmetry in sedimentation pattern and source polarity are documented in litho-as-semblages and REE distribution patterns of cover rocks in the basinal domain flanking the southern platform. Prevailing tectonics strongly controlled the mechanism of sedimentation which, coupled with the volcanic history of the basin, indicates its riftogenic character. Progressive lithospheric stretching successively produced picritic volcanics and MOR-type basalts along the axial zone of the basin, being related to a stretching factor of ≥ 2. Continental margin rifting ultimately resulted in an oceanic transition as supported also by available geophysical data. The evolution of the Proterozoic Singhbhum Basin in its broad perspective was controlled by subduction-related processes.