Age and depositional environment of the Upper Bhuban Formation of Champhai area (Eastern Mizo hills) India - A palynological approach

Abstract

Palynological analysis of outcropping claystone, shale and alternation of sandstone -siltstone, Upper Bhuban Formation from Champhai, eastern Mizoram, India has been attempted. In all total 47 genera and 60 species are recognised in the assemblage. Of these 8 genera and 11 species are represented by pteridophytic spores and 27 genera and 35 species belong to angiospermic pollen, 6 genera and 6 species to gymnospermous pollen, fungal remains are also encountered. Some significant constituents of the assemblage are Dictyophyllidites, Pteridacidites, Polypodiisporites, Lycopodiumsporites, Compositoipollenites, Polygonacidites, Malvacearumpollis, Hibisceapollenites, Cupuliferoipollenites, Alnipollenites, Engelhardtioidites, Pinuspollenites, Piceaepollenites and Podocarpidites. Quantitative dominance of angiospermous pollen is a conspicuous feature of the assemblage. The recorded palynological assemblage indicates the prevalence of wet semi evergreen type of vegetation with warm and humid tropical-temperate climate with plenty of rainfall during sedimentation. On the basis of comparison of the present assemblage with the palynoassemblages known from Indian Tertiary sediments. An Upper Miocene age has been assigned to the Tertiary sediments of Champhai area of Mizoram.