Introducing Devsagar Sandstone Member: A revised stratigraphy of the Mesoproterozoic Chattisgarh basin, Central India

Abstract

Chandarpur–Raipur sequence in Chattisgarh basin is represented as siliciclastic-dominated Chandarpur Group and carbonate-dominated Raipur Group. Here, we introduce ‘Devsagar Sandstone Member’, the only sandstone-dominated member in the carbonate-dominated Charmuria Formation of Raipur Group, that marks a period of rapid siliciclastic deposition identifying a phase of forced regression between two carbonate platforms of Charmuria–Chandi formations, thereby indicating a drastic change in palaeogeography of Raipur Group. In addition, this study revised the litho-stratigraphy of Mesoproterozoic Chattisgarh basin to clarify the confusion raised due to the existence of different stratigraphy in different basinal parts and different nomenclature for the same lithologic units. Detailed geological mapping with facies analysis in the eastern part of the basin manifests the entire basin-fill succession as part of the Chattisgarh basin itself, rather than sub-dividing some parts as Baradwar sub-basin and Singhora proto-basin. Singhora Group deposited in Singhora proto-basin has already been presented as equivalent of Chandarpur Group. Here we propose, Bamandihi–Saradih–Raigarh formations of Raipur Group in Baradwar sub-basin, as lateral equivalent of Gunderdehi–Chandi–Tarenga formations of Raipur Group and Sarnadih–Nandeli formations of Kharsiya Group in Chattisgarh basin. Inferred depositional environment and tectonic setting of Chattisgarh basin support the lithostratigraphic revision, which will help in basin analysis as well as intrabasinal–interbasinal correlation in regional and global contexts.

Research highlights

• Devsagar Sandstone Member introduced as the only sandstone-dominated member in carbonate-dominated Charmuria Formation of Raipur Group.

• Devsagar Sandstone Member represents a tidal shelf in between two carbonate ramp platforms (Charmuria and Chandi), marking a period of rapid siliciclastic deposition and the only phase of forced regression in overall sea-level rising scenario of the carbonate-dominated Raipur Group.

• Stratigraphy of Chattisgarh basin revised. The entire Chattisgarh succession is represented as deposits of Chattisgarh basin only, without further subdivision into sub-basin and/or proto-basin, thus resolving the stratigraphic and basinal correlation problem.