Stratigraphy and petroleum geology of Central-East Iran

This study integrates field observations with seismic and well data, including structural, sedimentological, palaeontological interpretations and geochemical analyses to characterize the petroleum system elements of Central-East Iran. The sedimentary record of this province reflects a complex tectonic evolution, spanning from Gondwanan stability through Neo-Tethyan rifting and Cimmerian orogenesis, to Cenozoic intra-arc and intermountain basin development driven by Neotethyan subduction and the Arabian–Eurasian collision. The only proven system is Cenozoic, sourced from and trapped within the Oligo-Miocene Qom Formation. Hydrocarbons are generated by organic-rich mudstones in the Qom c- and e-members. Fractured shallow-marine limestones in the Qom e-member are the main reservoirs sealed by evaporites in the uppermost Qom Formation or base of the Upper Red Formation. Despite discoveries such as Alborz and Sarajeh, exploration has not been commercial due to discontinuous source rocks, poor seals, and structural complexity during the late Neogene. The Palaeozoic–Mesozoic successions host key components of the petroleum system, including source rocks such as the Upper Devonian–Lower Carboniferous Shishtu Formation and the Lower–Middle Jurassic Shemshak Group, along with reservoir carbonates of the Middle Permian Jamal Formation. Hydrocarbon generation likely occurred prior to the Cenozoic, resulting in a temporal mismatch with the formation of structural traps.