Macroscopic charcoal remains as evidence of wildfire from late Permian Gondwana sediments of India: Further contribution to global fossil charcoal database

Abstract

Although there have been numerous reports of the occurrence of charcoal from the Indian Permian sediments (Kashmir and the Domodar Basin), here we report a new occurrence of charcoal from the Lopingian sediments of Central India, which is evidence of wildfire occurrence in the Permian of Gondwana and an addition to the global fossil charcoal database. Charcoal, a product of incomplete combustion of vegetation, is extensively reported from the Permian sediments of southern and northern hemisphere. Numerous reports have been generated from palaeobotanical and petrographical aspects of Gondwana sediments of India but the presence of macroscopic fossil charcoal has been somewhat overlooked until the past few years by many researchers, though the fusinite (charcoal equivalent term in petrographical studies) from many coalfields of Indian Gondwana has been attributed to pyrogenitic origin. Our study was carried out on macroscopic charcoal fragments retrieved from an exploratory drill core MBKW-3 from Mand-Raigarh Coalfield in the central part of the Mahanadi Basin, eastern India. The analysis involved Scanning Electron Microscopy for study of anatomical features and reflecting microscopy for estimation of the temperature of fire of charcoal formation where the inertinite reflectance data (average of 3.33%) indicate that these charcoals are formed at a temperature above 500°C. Palynomorph composition and their probable botanical affinity indicate that gymnosperms were the major type of vegetation that contributed to fuel load for wildfire while pteridophytes constituted a minor proportion. The palynological data reveal the predominance of arborescent vegetation over herbaceous elements. Fusinite reflectance data indicate that these charcoals are formed at a temperature in excess of 500°C. The almost unabraded edges of these charcoals, their high degree of preservation, and an assorted assemblage of different sizes clearly indicate their hypoautochtonous nature.