ABSTRACT The present investigation reports the detailed saturated and aromatic biomarker distributions in seven Early Permian coal samples using the conventional gas chromatography–mass spectrometry (GC–MS) and comprehensive GC × GC–time‐of‐flight (ToF)–MS techniques to reveal new insights into organic matter (OM) source, deposition conditions, and thermal maturity. The coal samples from the Karharbari and Barakar Formations of the Ib‐Valley Basin, Odisha, India, reveal a predominance of intermediate chain‐length n ‐alkanes (51.83%–63.61%) and low odd‐over‐even carbon preference (OEP = 0.31–1.91), likely suggesting OM derivation from aquatic plants and/or terrestrial shrubs/herbs. The identification of saturated bicyclic (C 16 –C 18 ), tricyclic (abietane, norabietane, 4β(H)‐19‐norisopimarane), and tetracyclic diterpanes (16β(H)‐phyllocladane, 16β(H)‐ ent ‐kaurane, 16α(H)‐ ent ‐kaurane, norkaurane), along with isohexyl alkylnaphthalenes, retene, tetrahydroretene, and bisnorsimonellite in the aromatic fraction, suggests a significant contribution from Glossopteris flora and/or primitive conifers. High abundances of C 29 regular steranes and diasteranes further support the contribution from terrestrial swamp vegetation. Redox‐sensitive parameters, including pristane/phytane ratios, Pr/ n ‐C 17 versus Ph/ n ‐C 18 , alkylated dibenzothiophenes, dibenzofurans, and methyltrimethyltridecylchromans (MTTCs), with MTTC index values of 0.32–0.58 and α‐/γ‐MTTC ratios of 0.61–2.10, reflect peat accumulation under fluctuating oxic–anoxic conditions within a marginal marine environment. Thermal maturity assessments based on biomarker parameters, such as C 31 17β(H),21β(H)‐homohopane, C 29 diasterane/sterane ratios, methylphenanthrene indices, and methyldibenzothiophene isomer ratios, suggest that the coals have attained peak catagenetic maturity, with estimated equivalent vitrinite reflectance values ranging from 0.57% to 0.68%. These molecular‐level insights provide a comprehensive understanding of the origin, depositional environment, and maturation history of Early Permian coals from the Ib‐Valley Basin.
Ghosh et al. (Mon,) studied this question.