Geochemical Characteristics of Talcher Coal, India: Insights on Mode of Occurrence of Trace Elements and Palaeoenvironmental Condition

ABSTRACT Understanding the elemental concentration and distribution in coal has significant importance in assessing its mobility and behaviour during utilisation processes. The depositional environment of coal controls the concentrations of elements that can adversely affect human health and the environment. Thus, this study investigates the detailed mineralogy and elemental composition of Talcher coal, the largest coalfield in India, in order to gain insight into the mode of occurrence of elements and palaeodepositional conditions. The coal is enriched in detrital mineral matter and exhibits a high detrital/authigenic index. Quartz and kaolinite are abundant, while siderite, calcite, plagioclase, goethite, illite, dolomite, apatite, and Ti‐oxide have also been identified. This coal is enriched with Hg, Mo, Cr, and Th concerning the world hard coal. The Ti, Na, Cu, Cr, Rb, U, and Th have a strong association with silicate minerals. The Sr, K, Mg, Ca, and P exhibit both carbonate and phosphate affinities, whereas Fe, S, and Co are mostly associated with organic matter. Similarly, Mn, Ba, Ni, Zn, Pb, Cd, Mo, As, and Nb display both organic and inorganic affinities. The inorganic matters in coal are predominantly derived from intermediate rocks and have undergone strong weathering. Various elemental proxies suggest that the coal is formed predominantly in a freshwater depositional environment under a fluctuating oxygenating conditions. The Sr/Cu and Rb/Sr ratios have implied the prevalence of a warm humid climate with intermittent transitional warm to dry climatic conditions during coal formation. This research will be helpful in future palaeowetland research as well as understanding the behaviour of trace elements during coal utilisation.