Facies and depositional environment of the uppermost Jurassic stromatoporoid biostromes in the Zagros Mountains of Iran

The uppermost Jurassic (Tithonian) stromatoporoid biostromes occur as horizontally extended, up to 2.5 m thick lenses in a shallow marine carbonate sequence in the northwestern part of the Zagros Mountains, Iran. Stromatoporoids, accompanied by corals and calcareous algae, form floatstone and rudstone textures. The initial establishment of these potential reef-building organisms may have been related to substrate stabilization, likely due to exposure events. The stromatoporoids show two types of growth forms. Columnar forms, including the new species Cladocoropsis lindstroemi, are enclosed in a micritic matrix in low-energy environments. Laminar-domical forms piled up their skeletons on other species, or formed bulbous structures by encrusting other organisms. This study is the first description of Mesozoic stromatoporoids from Iran.