Palynological investigation and environmental interpretation on Akli Formation (Late Palaeocene) from Barmer Basin, western Rajasthan, India

Abstract

Akli Formation of Barmer Basin, mainly a claystone, shale and lignite sequence, is divided into two members viz.., Thumbli Member and Kapurdi Fuller's earth Member. Palynological studies on samples from the Thumbli Member exposed near Barmer, western Rajasthan were carried out and a rich palynological assemblage constituted by dinoflagellate cysts, fungal remains, pteridophytic spores and angiospermic pollen was recorded from shale and lignite samples. The assemblage is dominated by angiospermic pollen which are assigned to the families Arecaceae, Liliaceae, Oleaceae, Caesalpiniaceae, Rubiaceae, Meliaceae, Myricaceae, Onagraceae and Lamiaceae. Palynotaxa having affinity with Arecaceae are abundant indicating deposition of sediments in coastal environment. Many pteridophytic spores and abundant fungal remains in the assemblage indicate warm and humid climate with high precipitation. Presence of dinoflagellate cysts indicates marine influence.

Most of the families represented in the assemblage are presently confined to tropical to subtropical areas. Considering the high frequency of Nypa/Nypa-like pollen in the assemblage it is inferred that sediments were deposited in an area which was fringed by thick vegetation of mangrove chiefly constituted by Nypa.