Evidence of the Permian marginal marine sedimentation recorded in sub-surface drill cores, Lower Gondwana successions, southern India

Evidence of marine influences within the Permian Barakar Formation of the Pranhita-Godavari (P-G) Basin and its age equivalent, the Kommugudem Formation of the Krishna-Godavari (K-G) Basin, are previously investigated from the outcrop studies. The present work carefully documents the signatures of tidal and wave influences from the Early Permian rocks, solely based on excellently preserved subsurface drill core samples from both the basins. Tidalites, represented by laterally accreted tidal bundles, tidal rhythmites, tidal beddings, oppositely directed strata bundles, and double mud drapes, are preserved within the sandstone-mudstone heterolithic rocks, signifying deposition predominantly in an upper subtidal-intertidal setting. Association of wave-generated structures with the tidalites are indicative of open marine waves, interacting with the tides in the upper subtidal to intertidal region. Records of such tidal and wave processes unambiguously point to the significant marine influence within the continental setup during the Lower Gondwana sedimentation in both the P-G and the K-G basins during the Early Permian time, which indicates a regional encroachment of the sea onto the land.