Influence of continental rifting on sedimentation and its provenance and geodynamic implications: An example from late Paleoproterozoic Chandil Formation, eastern India

The Paleoproterozoic-Mesoproterozoic boundary is associated with onset of supercontinental cycle and global thermal perturbation. In the Singhbhum cratonic province, the 1600 Ma felsic volcanics and metasedimentary successions of the Chandil Formation conformably overlies the mafic volcanic and volcaniclastic successions of the Dalma Formation. Unlike the Dalma Formation and the underlying Singhbhum Group of rocks, the sedimentary facies and provenance characterization of the Chandil Formation has been long overdue. Herein we present sedimentary facies and geochemical characterization of the Chandil Formation. The Chandil Formation has been divided into three distinct sedimentary facies associations: the bottommost trough cross-stratified, poorly sorted and texturally immature, coarse- to medium-grained sandstone-shale facies association formed in a fluvial setting. The overlying fine-grained, well-sorted and well-rounded sandstones of the sandstone-siltstone-mudstone (volcanic ash) facies association is characterized by aeolian dunes and pinstripe laminations, and thus formed in an aeolian environment. The medium-grained, moderately sorted, cross-bedded sandstones of the topmost facies association bear alternate thick-thin sandy foresets that are bounded by mudstone drapes and hummocky-cross stratification, indicating a marine depositional setting. The Chandil sedimentation pattern is remarkably similar to the very well-known and 1000 million years younger Potsdam Group clastics, USA that formed in an intracratonic rift setting with similar sedimentary facies characteristics. Comparative provenance studies of the clastic rocks of the Chandil Formation and the lowermost Potsdam Group reveal that the protoliths of both rock successions were arkosic to litharenitic composition. Trace element studies of the sedimentary units of both rock successions confirm the provenance interpretation and indicate reworking of early rift and/or granitic basement rocks. The similarities between these sedimentary successions including sedimentary facies, basin development, and geochemical trends, although differing in age by ca. 1 billion years, indicate overwhelming influence of provenance on sediment generation, transportation and deposition that muted other controlling factors of sedimentation like paleoclimate, changes to Earth magmatism and consequent changes in tectonic regime etc. Sedimentological and geochemical analysis, following the methodology adopted in this paper, from other sedimentary successions will help to infer the interplay between contemporary basin tectonics and consequent sedimentation. Our analyses further indicate major terrestrial sedimentation, higher continental freeboard and felsic magmatism around 1600 million years in the Singhbhum craton similar to the adjoining Cuddapah basin (Dharwar), Pranhita-Godavari basin (Bastar) in the southern Indian block, in the Central Indian Tectonic Zone, and in the Vindhyan basin of the north Indian block.