Source rock potential, thermal maturity, and depositional environment of the Ordovician Ra’an Shale Member, central Saudi Arabia

•Three main lithofacies were identified in the Ordovician Ra’an Shale.•Elemental analysis indicates anoxic marine conditions during deposition.•Microscopic investigation reveals various pore systems.•Ra’an Shale exhibits kerogen types III and II/III, with a poor/fair HC potential.•Maturity parameters indicate mainly an immature source rock sequence.•Weathering index indicates high weathering rates, causing TOC reduction.