Palynology of Permian-Triassic sequence in Iria Nala, Tatapani-Ramkola Coalfield, India

Abstract

The Permian-Triassic sediments exposed along Iria Nala in the northern part of Tatapani-Ramkola Coalfield have been palynologically analysed. The palynological assemblage includes 42 genera and on the basis of quantitative dominance three assemblage zones have been distinguished in ascending order: (i) Densipollenites magnicorpus zone, (ii) Crescentipollenites fuscus zone and (iii) Falcisporites stabilis zone. The first two palynoassemblage zones are restricted to the coal, carbonaceous shale, sandstone sequence (= Raniganj Formation) which is overlain by a khaki shale bed rich in Schizoneura gondwanensis.The lithological succession above this bed contains greyish/khaki green splintery shale and sandstone (=Panchet Formation). These shales have yielded the third palynoassemblage zone marked by Falcisporites stabilis, Playfordiaspora cancellosa and Klausipollenites schaubergeri. The Permian - Triassic boundary lies above the Schizoneura gondwanensis bed between the second and third palynozones. The transition is marked by the decline in the frequency of Crescentipollenites followed with the increase of non-striate group represented by Falcisporites. The onset of Triassic sedimentation is also marked by the presence of khaki shales which closely compares with the Panchet (Lower Triassic) sediments of the type area. Thus, the transition of palynoflora from Late Permian to Early Triassic is gradual and broadly conforms with the lithological changes. There appears to be a continuous sedimentation between the Permian and Triassic periods in this part of Tatapani-Ramkola Basin.