Palynostratigraphical studies on subsurface Tertiary sediments in Upper Assam Basin, India

Abstract

The present paper incorporates the results of palynostratigraphical investigations of subsurface Tertiary sediments from six bore-holes in the Upper Assam Basin, India. A total of 87 palynofossil genera and 120 species belonging to pteridophytic spores, gymnospermous and angiospermous pollen. Fungal spores and ascostromata and dinoflagellate cysts are recorded. The distributional pattern of palynotaxa demonstrates the reliability of palynofloral assemblages in the demarcation of different litho-units as well as for long distance correlation. The recorded palynofloral assemblages are compared with the previous reported assemblages from the north-eastern region. Qualitative and quantitative analyses of the palynoflora indicate the presence of lowland subtropical rain forest during Palaeogene times. However, in Neogene it shows distinct development of montane vegetation. Palaeoenvironmental condition of deposition of these sediments is also inferred.