The Permian–Triassic boundary section at Baghuk Mountain, Central Iran: carbonate microfacies and depositional environment

Abstract Sections at Baghuk Mountain, 45 km NNW of Abadeh (Central Iran), have excellent exposures fossiliferous marine Late Permian to Early Triassic sedimentary successions. Detailed bed-by-bed sampling enables the analysis microfacies changes three successive rock units across Permian–Triassic boundary. The Hambast Formation is mainly result biogenic carbonate production. Its dominated by biogen-rich and bioturbated nodular limestones, indicating a well-oxygenated aphotic dysphotic environment. biogen-dominated factory in ceased simultaneously with main mass extinction pulse, which marked sharp contact between Hambast-Formation overlaying Member (= ‘Boundary Clay’). clay silt deposits some beds show only few signs bioturbation or relics benthic communities. Claraia Beds are characterised partly microbially induced production, indicated frequent microbialite structures. depositional environment does not provide evidence large amplitude sea level subaerial exposure during boundary interval. deposition Mountain sediments took place deep shelf environment, most time below storm wave base.