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.

Palynological investigations, facies analysis and palaeoenvironmental interpretations from Late Palaeocene to Early Eocene lignites and associated sediments of Barmer, western India

“…Palynological studies in Rajasthan Basin (Fig. 2) have been made in Barmer (Bose, 1952;Jain et al, 1973;Naskar & Baksi, 1978;Tripathi, 1994Tripathi, , 1995Tripathi, , 1997Tripathi et al, 2003;Divya Srivastava, 2008;Tripathi et al, 2009), Jaisalmer (Lukose, 1974), Bikaner-Nagaur (Singh & Dogra, 1988;Kar, 1995Kar, , 1996Kar & Sharma, 2001;Tripathi et al, 2008) and Palana beds (Rao & Vimal, 1950, 1952Sah & Kar, 1974). Considering the theme of the present communication, the palynological studies previously conducted in Barmer Basin are discussed below.…”

“…Studies on lignite mine samples-Rock samples collected from open-cast lignite mine situated near Giral in Barmer were investigated palynologically by Tripathi et al (2003). The studied section is constituted by bentonite, shale and lignite sequences.…”

“…Palynological records from Palaeogene successions of Rajasthan (Fig. 2) are from Barmer (Bose, 1952;Jain et al, 1973;Naskar & Baksi, 1978;Tripathi, 1994Tripathi, , 1995Tripathi, , 1997Tripathi et al, 2003;Tripathi et al, 2009), Bikaner-Nagaur (Rao & Vimal, 1950, 1952Sah & Kar, 1974;Singh & Dogra, 1988;Kar, 1995Kar, , 1996Kar & Sharma, 2001;Tripathi et al, 2008) and Jaisalmer (Lukose, 1974).…”

“…The genus Acanthotricolpites, in all likelihood, also related to Nypa (Venkatachala et al, 1996) is profusely recorded in the Akli Assemblage. Fossil records show that different species of this genus produced pollen with a great morphological diversity Tripathi, 1994;Singh, 1999;Tripathi et al, 2003;Divya Srivastava, 2008). The genus Nypa, represented by one extant species (N. fruticans), is a mangrove palm growing in tidal mud flats fringing the tidal reaches of large fresh water rivers (Morley, 2000).…”