International Journal of Coal Geology 224 (2020) 103485 Contents lists available at ScienceDirect International Journal of Coal Geology journal homepage: www.elsevier.com/locate/coal Palaeoenvironmental reconstruction and evidence of marine influence in Permian coal-bearing sequence from Lalmatia Coal mine (Rajmahal Basin), T Jharkhand, India: A multi-proxy approach ⁎ Runcie P. Mathews , S. Suresh K. Pillai, M.C. Manoj, Shailesh Agrawal Birbal Sahni Institute of Palaeosciences, 53 University Road, Lucknow 226007, India ARTICLE INFO ABSTRACT Keywords: Lalmatia coal-bearing sequences belong to the Barakar Formation (Permian) of Lower Gondwana. The well- Permian coal-bearing sequence developed coal-bearing sequences (approx. 52 m) exposed along the mine section have been studied to un- Glossopteris derstand the depositional environment. Along with this, a cuticle study was performed to understand the pa- Biomarkers laeoclimate with the help of the stomatal index. The distribution of n–alkanes (n–C15 to n–C31) suggests major Stable carbon isotope higher plant and algal dominant source input, although variations are seen in the relative input. Steranes Stomatal index identified include C regular sterane and 4-Methylsteranes. The Pr/Ph ratio varied from 0.43 to 4.26. Warm Palaeoclimate 29 temperate to subtropical palaeoclimate with fresh to brackish water bodies, and reducing oxygen-poor en- vironment were inferred from the Rb/Sr, Sr/Cu, Th/U, Sr/Ba, V/(V+Ni). Mean δ13C value measured is −23.0‰ ± 0.60‰ for coal and −22.6‰ for shale. These values are well correlated with typical δ13C values of the Permian coal and shale. The stomatal index of Glossopteris leaves (280 million years) was taken into account, and it showed a value of 10.7 that assumes a higher level of atmospheric CO2 during the Barakar Formation (Artinskian age). The result also shows that Permian taxon Glossopteris can be used for CO2–proxy during Permian age. The geochemical evidence suggests that towards the middle part (middle coal seam) of the studied section, the depositional milieu was under a marine-influenced marginal condition. The geochemical studies and carbon isotopic ratios unequivocally suggest that fluctuating climatic conditions existed during the deposition of the Lalmatia coal-bearing sequence. 1. Introduction degradation, biomarkers provide highly convincing signatures re- flecting past environments than other proxies (Zhang et al., 2014, Climate is the supreme factor controlling the floral composition as 2016a). Besides this, inorganic geochemical parameters also provide plant families respond to the change in environmental factors. The highly useful information regarding past environmental shifts. Ac- dominance or absence of plant communities is directly related to the cordingly, various methods are applied to differentiate past sedimen- temperature and moisture conditions and thus to the climatic varia- tary realms. Elemental composition is an important parameter that can tions. Hence, the determination of palaeofloral composition can provide provide indications of geodynamic and palaeoclimatic conditions (Fu clues to the change in environmental factors that occurred during se- et al., 2018). However, quantitative analysis of major and trace ele- dimentation (Hautevelle et al., 2006). The latest developments in the ments is the most commonly accepted and applied method across basins macromolecular analysis of organic matter demonstrated the im- (Liu and Zhou, 2007; Dai et al., 2016; Zhang et al., 2016b; Wang et al., portance of biomarker compounds in the palaeoclimate reconstruction 2017; Fu et al., 2018). Consequently, the occurrence and composition of (Castañeda and Schouten, 2011). Although, the OM is affected by trace elements in coal have been studied extensively (Dai et al., 2015, various alterations after the deposition causing transformations in the 2016, 2017, 2018). Similarly, one of the robust proxies which can re- C=H bonds and functional groups, the carbon skeletal structures of flect the variation of the carbon cycle in local to regional level isthe biomarker compounds are indestructible. Hence, in the sedimentary stable carbon isotopic ratio (δ13C) (Chen et al., 2014; Aggarwal et al., record, these compounds are well upheld for geological ages (Peterson 2019). Considering the morphological aspects, various studies have et al., 2007). Due to this source specificity and resistance to shown that the quantitative estimation of the stomatal number of fossil ⁎ Corresponding author. E-mail address: [email protected] (R.P. Mathews). https://doi.org/10.1016/j.coal.2020.103485 Received 18 December 2019; Received in revised form 12 April 2020; Accepted 12 April 2020 Available online 15 April 2020 0166-5162/ © 2020 Elsevier B.V. All rights reserved. R.P. Mathews, et al. International Journal of Coal Geology 224 (2020) 103485 Fig. 1. The transgression of Tethys through Khemgaon of Sikkim till Northern Bihar and present day Jharkhand (after Chatterjee and Hotton, 1986; Moore and Scotese, 2012). plant leaves (i.e, the stomatal index and density analysis) can be effi- magmatism during the Gondwana period and beneath the trap lays the caciously correlated to the palaeoatmospheric fluctuationsMcElwain, ( unclassified Triassic sediments underlain by Barakar and Talchir for- 1998; Wagner et al., 2005). Thus, in addition to the geochemical mations. The N–S aligned lower Gondwana exposures are encountered parameters microscopic investigation of cuticles is also considered as an extensively covering Bengal Basin, North Bengal, and Purnea. The essential tool to decipher past climates (Stace, 1965; Cutler, 1982; sampling is done in the Lalmatia Coal mine, Boarijor Tehsil, Godda Kovach and Dilcher, 1984; Upchurch Jr., 1995). District, Jharkhand State, India. Lalmatia Coalfield/mine (Earlier called Several studies have been done on the coal-bearing sequences of the as Rajmahal Open Cast Mine) occupies around 15 sq. km and is ex- Rajmahal Basin particularly on the morpho-taxonomical (Feistmantel, plored by the Central Mine Planning and Design Institute. The block is 1880; Singh et al., 1987; Bajpai and Maheshwari, 1991; Maheshwari located between latitudes 25° 1' 12" and 25° 3' 15" N and Longitude 87° and Bajpai, 1992; Srivastava and Pant, 2002), palynology (Tripathi and 21' 0" and 87° 24' 0" E (Fig. 2a). Hura, Pachwara, Chuperbita, Brahmani Ray, 2005; Tripathi et al., 2010), petrological (Roy et al., 1983; and Mahuagarhi are the five coal fields of the Rajmahal Gondwana Madabhushi, 1990; Singh, 1992), molecular composition and hydro- Basin. Towards the northern part of the Rajmahal Basin coal seams of carbon potential (Tewari et al., 2016, 2017) aspects. Earlier studies approximately 78 m thickness are encountered in the Lalmatia Coal have shown possible marine influences at various localities in the lower mine (Hura Coal-field). The age of this sedimentary sequence is as- Gondwana basins of India as given in Fig. 1 (e.g. Shah and Sastry, 1975; signed as Artinskian (280 Ma). Intercalated shales yielding plant fossils Chatterjee and Hotton, 1986; Venkatachala and Tiwari, 1988; Ahmad (Maheshwari and Bajpai, 1992) are very thick in some places and divide and Khan, 1993). Reports of marine incursions during Gondwana are the seam into three parts: referred to as seams L−I, L−II, and L−III based on Eurydesma–Productus–Conularia. Apart from this, reports of (Raja Rao, 1987). A total of eight workable coal seams are present in marine incursions are reported from Daltonganj (Dutta, 1965), Umaria the Lalmatia coal mine. The seams are bottom to top as seam I, II marine beds (Sinor, 1923), Subansiri (Sahni and Dutta, 1959), Ma- (bottom), II (top), III, IV, IX, X and VI. Seams II (bottom), II (top) and III hendragardh (Ghosh, 1954), Badhaura of Western Rajasthan (Mishra merge and split within the area to form various combinations. Max- et al., 1961; Shah, 1963) in India. The other evidence of marine in- imum coal reserves (95%) are found in seam II (bottom), II (top) and III cursion during Permian is from sedimentary nodules, invertebrate (95%). Towards the western periphery of the basin, the sedimentary faunas, Acritarch (Leiosphaerid and Foveofusa), coastal–marine, and rocks of Talchir Formation are encountered. Karharbari Formation Cruzianaichno–facies (Seilacher, 1964). Recently, Goswami (2008) has succeeds above encompass conglomerates, grits and carbonaceous pointed out marine incursions in Mahanadi Basin from trace fossils sandstones. In most of the areas, Archean rocks form the basement and wave ripples and acritarchs. In the present study, multi–proxy analyses it is overlain by the coal-bearing formation (Barakar). The general have been done to know the OM source, depositional conditions, pa- stratigraphical succession exposed in the Rajmahal area, eastern laeoclimatic scenario and its variations during the period of formation Jharkhand is given in Table 1 (after Ball, 1877; Raja Rao, 1987; of Permian Lalmatia coal–bearing sequences. More importantly, this is Sengupta, 1988; Tiwari and Tripathi, 1995; Ghose et al., 1996; Tripathi the first attempt from the Indian context to study palaeoenvironment et al., 2013). The litholog of the studied section from the Lalmatia coal and marine influence based on multiple proxies (biomarker, plant fos- mine showing three coal seams (upper, middle and bottom) is given in sils, stable carbon isotope, and geochemical records) of Gondwana se- Fig. 2b. diments along with the stomatal index of Glossopteris leaves.