Polycyclic aromatic hydrocarbons in the Rudramata shale member of Jhuran Formation, Kachchh Basin, western India: Insights on provenance and thermal maturation

In the present study, samples from Rudramata Shale member of Jhuran Formation of the Kachchh Basin were evaluated based on the population distribution of polycyclic aromatic hydrocarbons (PAH). The PAHs present in the solvent extracts of the demineralized shale samples were identified with the aid of steady-state fluorescence emission (SSFE), synchronous fluorescence (SFS) and UV-visible absorption spectroscopy. Fourier-transformed infrared (FTIR) spectroscopy of powdered shale samples indicated the presence of clays along with aromatic and vinyl moieties in the bulk shale. Rock eval pyrolysis data of the bulk shale samples indicate their gas-prone and immature to overmature nature. Extracts of the shales exhibited presence of both 2–3 and 4–7 fused aromatic ring PAHs in synchronous fluorescence scan, viz., phenanthrene, benzo[a]pyrene and perylene. Useful insights on the provenance of source rock were obtained in the present study based on PAH signatures, and it was possible to infer the depositional environment of the Middle member (Rudramata Shale) of Jhuran Formation as a fluvial-dominated delta system with considerable terrestrial biogenic influence.