After the worldwide drastic Permo-Triassic event, a thick sequence of shallow-water carbonates, i.e. the Sefid Kuh Formation, was formed before the late Early Triassic. For the first time dasycladacean algae (Acicularia sp.) were found there, together with foraminifera which are typical of the Lower Triassic. A carbonate ramp is formed by several parasequences, each of them shallowing upwards and consisting of grainstones and packstones, being oolithic and/or pelJetoidal, mudstones being strongly affected by bioturbation ("Wurstelkalk", "vermicular Jlmestone"), crinoids ("Holocrinus sp."), packstone-tempestites, and algal boundstones. The Sefid Kuh limestone Formation as a whole is the product of a transgressison-regression cycle. According to conodont~ stratigraphical studies, this cycle set in at Spathian times and came to an end in ?Aegean/Bithynian times. This T-R-cycle is probably of eustatic nature, as comparisons with coeval sequences of the western Tethys realm show. Geodynamic considerations of R. BRANDNER result in the conclusion that in the area studied the northern Paleozoic Tethys ocean was entirely subducted already in Permo-Triassic times