Stratigraphical implications of Tertiary palynological succession in north-eastern and western India

Abstract

Cretaceous and Tertiary sedimentary rocks are found overlying a Precambrian granite basement or occasionally the Sylhet Trap (Late Jurassic) in north-east India whereas in Kutch, western India, the Tertiary rocks rest on the Deccan Trap and its derivatives. In north-east the Tertiary succession is almost complete whereas in Kutch the Early and Middle Palaeocene and Late Eocene sediments are missing. More than 150 spores and pollen genera' are described from the Tertiary sediments but except about 20 all are long ranging. The Early Tertiary palynological succession in north-east and Kutch is more or less similar and all the marker taxa are found simultaneously in the equivalent formations in both the regions. In north-east India, throughout the Tertiary succession, the pteridophytic spores are found in abundance whereas in Kutch they are found in meagre percentage. The distribution of marker taxa throughout the Tertiary has been shown with the help of a chart. It is assumed that during Palaeocene to Eocene the plants grew in tropical, coastal swamps whereas from Oligocene onwards the deposition was mostly riverine in the eastern region.