Evidence of recurrent wildfire from the Permian coal deposits of India: Petrographic, scanning electron microscopic and palynological analyses of fossil charcoal

• Published in: Palaeoworld Vol. 29; no. 4; pp. 715 - 728
• Main Authors: Murthy, Srikanta, Mendhe, Vinod Atmaram, Kavali, Pauline Sabina, Singh, Vikram Partap
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2020
• Subjects: Auranga Coalfield; Damodar Basin; Fire temperature; Fossil charcoal; Wildfire; Fossil charcoal; Auranga Coalfield; Wildfire; Fire temperature; Damodar Basin
• ISSN: 1871-174X
• DOI: 10.1016/j.palwor.2020.03.004

In India hitherto fossil charcoal has been reported from Kashmir, Damodar Basin, and Mahanadi Basin. This work documents recurrent Cisuralian wildfire based on the occurrence of fossil charcoal from India. The authors used petrographical, palynological and SEM studies to analyze the anatomy of charred wood fragments and temperature of their formation. The fossil charcoal has been retrieved from the Cisuralian coal bearing subsurface sediments of Lower Barakar Formation (Artinskian) from Auranga Coalfield of Damodar Basin. Evidences of recurrent wildfire have been observed by the occurrence of charcoal at four levels of clastic sediments in Borehole 2N. The charcoal was subjected to petrographical, palynological and SEM studies to understand the burning temperature, fuel source and plant anatomy respectively. Petrographic studies indicate high frequency of semifusinite vis-à-vis fusinite having reflectance values ranging from 2.87% to 4.1%. The majority of the fusinite reflectance values fall in the range of 2.9%–3.5% indicating the temperature of formation of these charcoals to be at approximately 500°C. High temperature is also indicated by homogenization of cell walls under SEM. They also reveal fungal infestation and degradation in all charcoal samples. Moderate to high degree of preservation of charcoal indicates lesser transportation/post-depositional degradation suggesting a hypo-autochthonous nature. The botanical affinity of recovered spores and pollen suggest that the hinterland was dominated by gymnosperms and sub-dominated by filicopsids, sphenopsids, and lycopsids which contributed to the fuel source.