We investigated the Changhsingian Stage in six sections in the area of Julfa (Aras Valley) for their lithology (petrography and carbonate facies), geochemistry (stable isotopes), conodonts and ammonoids. Revision of the biostratigraphy led to the separation of ten Changhsingian conodont zones and eight ammonoid zones. This refined scheme serves as a basis for studies on the proximate causes of the end-Permian mass extinction. The detailed subdivision of the Changhsingian by means of ammonoids has some potential for the correlation of sections within the Tethyan realm. However, ammonoids have only rarely been used for the correlation of the Transcaucasian/Iranian with the Chinese sections, but nevertheless they played a role in discussions about the completeness or incompleteness of the central Tethyan sections. This resulted in the statement that the Iranian assemblages represent only the lower part of the Changhsingian. Correlation of the Late Permian ammonoid successions in Iran and China reveals major problems, which are rooted in the significant differences of the assemblages on the family level. The morphological differences demonstrate that, in terms of sutural development (notching of individual lobes), the Tethyan forms are even more advanced than the Chinese forms.

Keywords