Uppermost Permian to Lower Triassic conodont biostratigraphy and carbon isotope records from Southern Armenia

Abstract

The Southern Armenia region is critical for studying biostratigraphy, chemostratigraphy, sedimentology, and environmental events during the Permian-Triassic transition. However, conodont data of previous studies are either outdated or lacking a detailed examination in terms of their classification and stratigraphic distribution, precluding a precise correlation of the strata and events with other Tethyan localities. This study presents an updated conodont taxonomy and biostratigraphy for the uppermost Permian to Lower Triassic from three sections in Southern Armenia. Eleven conodont zones are recognized in ascending order: the Clarkina bachmanni, C. nodosa, C. yini, C. hauschkei, Hindeodus praeparvus, H. parvus, Isarcicella staeschei, Is. isarcica, H. postparvus, H. sosioensis, and Neospathodus dieneri zones. These conodont zones, integrated with high-resolution carbonate carbon isotopic records, facilitate robust correlations between the Armenian sections and other well-studied Tethyan sections, particularly those in Iran and South China. The Permian-Triassic boundary is tentatively placed just above the basal microbialite unit of the Karabaglyar Formation, marked by the first occurrence of Hindeodus parvus and significant carbon isotope excursions. However, further studies are needed due to the limited preservation of conodonts within these microbialites. In the absence of index conodonts, the Induan-Olenekian boundary is inferred to lie just above a maximum regressive surface, marked by a distinct lithological change, and immediately below the P2 peak of the carbon isotope excursion in the Early Triassic.