Petrographic characteristics and carbon isotopic composition of Permian coal: Implications on depositional environment of Sattupalli coalfield, Godavari Valley, India

► These coals have a fluvial deposition as supported by increasing ash yield and a low (< 1%) CaO content. ► Coal formation initiated under oxic condition followed by increased water cover in the paleomire. ► Carbon isotope data of coal and associated sediments indicate their terrestrial source. ► This contention is also revealed in petrography, gelification and tissue preservation indices. ► Vitrinite has enhanced the ∂13C as revealed by their correlation (r = 0.849).