Palynostratigraphy, dating and correlation of coal bearing and associated sediments in Mamakannu area, Godavari Graben, Andhra Pradesh, India

Abstract

Palynological investigations carried out in Bore core MMK-19 from Mamakannu area, Lingala-Koyagudem coal belt, Godavari sub-basin have revealed presence of five distinct palynoassemblages. The oldest Palynoassemblage-I is demarcated by the dominance of Callumispora with monosaccate pollen taxa Parasaccites. Palynoassemblage-II is characterised by dominance of monosaccate Parasaccites and non-striate disaccate Scheuringipollenites along with striate disaccates chiefly, Striatopodocarpites and Faunipollenites. Palynoassemblage-III shows dominance of non-striate disaccates, viz. Scheuringipollenites and Ibisporites along with subdominance of striate disaccates, viz. Striatopodocarpites and Faunipollenites. Early Permian age has been assigned to Palynoassemblage-I, II and III belonging to Lower Karharbari, Upper Karharbari and Barakar respectively. Palynoassemblage IV is exemplified by dominance of Faunipollenites and Striatopodocarpites along with striate disaccate Crescentipollenites and monosaccate taxa Parasaccites. Youngest palynoassemblage, i.e. Palynoassemblage-V is demarcated by the dominance of Crescentipollenites alongwith sub dominance ofFaunipollenites and Striatopodocarpites. Late Permian (Raniganj Formation) age has been assigned to Palynoassemblage-IV and Palynoassemblage-V. These two palynoassemblages also show the appearance of some younger forms, viz. Lundbladispora, Falcisporites, Playfordiaspora and Densoisporites which are significant taxa of Early Triassic. Presence of Parasaccites in high percentage alongwith striate disaccates in Palynoassemblage-IV suggests that the climate towards the end of the Permian time tended to become colder. This evidence supports the contention of a third glacial phase during Late Permian/Early Triassic time. The presence of the Lower Raniganj palynoflora has been demarcated in lithologically designated Barren Measures Formation.