Palynology, palynofacies, and taphonomical studies of Kamthi Formation, (Godavari Graben), southern India: Implications to biostratigraphy, palaeoecology, and depositional environment

Abstract

The ambiguity regarding the age and palaeoecology of the Kamthi Formation is persisting for several years. In order to find the scientific answers to this problem, an integrated approach has been adopted on the samples collected from a 604 m thick sedimentary sequence (borehole) of the Kamthi Formation (late Permian), Godavari Graben. The compilation of detailed investigation includes the palynology, palynofacies and taphonomic studies, in order to establish the age, reconstructing the palaeoecology and inferring the environment of deposition. The palynological investigation indicates the presence of two informal palynoassemblages: the lower Palynoassemblage-A (Faunipollenites + Striasulcites), corresponds to the coarse-grained sandstone dominated basal part, and the Palynoassemblage-B (Densipollenites + striate bisaccates) occur in the upper fine-grained sandstone and shale dominated sequence. A detailed Gondwanan correlation of the palynoassemblages assign a late Permian age to the palynoflora: Palynoassemblage-A belongs to the Guadalupian age while Palynoassemblage-B corresponds to the Lopingian age.The dominance of glossopterids, peltasperms, conifers and Cordaites derived pollens indicate the presence of thick arborescent palaeovegetation. The rich cryptogam spore assemblage (algal, fillicopsid, and equisetopsid) constitute the opportunistic and rare component of the understorey flora. The present study suggests that the lycopsids along with few acritarchs make their appearance post-Guadalupian.The taphonomic studies infer that the palynoassemblages are greatly influenced by the structure of spores and pollen saccus. Further, the palynofacies analysis reveals a cyclic change in the environment fluctuating from unstable oxic to the stable anoxic environment. The occurrence of microscopic charcoal from the late Permian also suggests palaeo-wildfire events in the hinterland.