Fluvial architecture of Early Permian Barakar rocks of Korba Gondwana basin, eastern-central India

摘要

The Early Permian Barakar Formation of the Korba basin represents repeated deposition of fining upward sequences of coarse to medium grained sandstone, fine grained sandstone-shale, shale and coal. The sandstones are channel, sheet like, multistory, and profusely cross-bedded. The shale beds are lens as well sheet like and laminated; coal facies is thin to moderately thick and shows splitting. Paleocurrent analysis suggests a northwesterly paleoslope during Barakar sedimentation. However, the deflection of paleoslope towards northeast in the eastern part of the basin supports the existence of a watershed in the depositional area. The Barakar paleochannel were 4.05 m deep and 176 m wide (single channel) with an average sinuosity of 1.27. The average flow velocity and sediment load during flood stage are in the order of 1.77 m/s and 4.15. These results indicate bed-load (braided) to mixed load nature of the Barakar streams of the Korba basin. The study suggests that the Early Permian braided Barakar streams deposited the coal measure sequence subsequent to deglaciation in a northwesterly slopping paleovalley. The basin floor was highly uneven marked by the presence of a basement high in the northwestern part that bifurcates the paleo-streams into northwestern and northeastern branches.