Biodiversity of a Permian temperate forest: A case study from Handapa area, Talcher Basin, Odisha, India

Abstract:

A palaeofloristic study and geochemical analysis of a Permian section in Handapa area of Talcher Basin, Odisha, India has been undertaken. Fourteen hundred and sixty-seven (1467) specimens of plant megafossils with sixty-five (65) varied species have been recorded from the studied fossiliferous horizons. This is one of the rich reports in the world with such a large number of species from a Lower Gondwana exposure. The specimens are preserved as impressions on compact, fine-grained, pinkish-brown shales. The investigated megafloral assemblage comprises five groups of both pteridophytes (Equisetales: Schizoneura, Equisetaceous stems; Sphenophyllales: Trizygia; Filicales: Neomariopteris, Dizeugotheca) and gymnosperms (Ginkgoales: Rhipidopsis; Glossopteridales: Glossopteris, Gangamopteris) along with stem axis, fructifications, and scale leaves. The genus Glossopteris dominates the assemblage by constituting more than 88% and 54 different species. The lithology of the fossiliferous horizon as well as the megaforal assemblage define the studied sediments to be of Lower Kamthi/Raniganj Formation of Late Permian (Lopingian). The occurrence of Gangamopteris is the first report of this genus from the Lower Kamthi/Raniganj Formation of the Talcher Basin, as well as from the Son-Mahanadi Master Basin. The studied sediments were devoid of any structured palynomorphs. However, palynological study places the Handapa sediments in P-T boundary with ample presence of fungal remains along with cuticular structures and degraded organic matter. Biomarker (n-alkane) analysis indicates an increased contribution from aquatic macrophytes as well as microbial organic matter in the sedimentary environment, however, the overall biomarker composition and distribution suggests an increased thermal maturity of the studied samples.