Inorganic geochemical attributes of Jaintia Hills coals, India: Implications for paleo-depositional conditions

Abstract

The Paleogene coal deposits of the Jaintia Hills of Meghalaya have undergone examinations by various researchers, primarily focusing on organic petrography and geochemistry and highlighting the rank, type, and grade, with perspectives on potential utilization. However, the genesis of these coals has received limited attention from the researchers. This research article addresses this gap by conducting a comprehensive examination of the geochemical and mineralogical aspects of these coals. Coal samples from two coal seams at nine locations in the Sampar coalfield in Jaintia Hills were collected and studied. The samples are subjected to X-ray fluorescence spectroscopy, X-ray diffraction analyses, Fourier transform infrared spectroscopy, proximate, and ultimate analysis to study geochemical and mineralogical composition and ash yield. The study utilizes various geochemical proxies based on the inorganic constituents, providing insights into the paleo-depositional conditions and contributing to a deeper understanding of the unique characteristics of Meghalayan coals. The research indicates that these coals were formed in coastal swamps and lagoons on stable platforms, experiencing minimal tectonic activity, influenced by seawater incursions. These coals were deposited in reducing to significantly reducing conditions and warm and humid to semi-arid climatic conditions. No signature of a geothermally active fluid has been recorded.