The Pabdeh-Asmari Boundary Facies in Kuh e-Asmari Section: Evidence for Unconformable Ruplian-Chattian Boundary in Iran

The uppermost layers of the Pabdeh Formation in Kuh e-Asmari section consist of microbial (tufa and stromatolite) facies interpreted to have been deposited in a lacustrine environment. These deposits are unconformably overlain by basal anhydrite and transitional zone of the Asmari and Pabdeh Formations. The transitional zone is correlated with the lower Asmari (with a basal unconformity or correlative conformity) in the Gachsaran No. 31 and Aghajari No. 61 wells and in Kuh e-Mish, Shahzadeh Abdullah, Tang-Sorgh and Rag-Sefid surface sections. Therefore the basal anhydrite and transitional zone should be considered as a part of the Asmari Formation. The drastic facies change near the Pabdeh and Asmari contact is due to thrust-loading, relative sea-level changes and climatic variations close to Ruplian-Chattian boundary.