Quantitative stratigraphic correlation of Tethyan conodonts across the Smithian-Spathian (Early Triassic) extinction event

Three small-scale extinctions occurred in the Early Triassic with one of them recognized close to the Smithian-Spathian boundary. In the last two decades, the end-Permian mass extinction as well as the subsequent recovery have been intensively studied throughout the Tethys region, but correlations within the Lower Triassic are difficult due to conodonts endemism. Here we use paleontological and geochemical methods to document a high-resolution biostratigraphy of the Smithian-Spathian boundary interval from two sections of Oman. In combination with previously published data from both South-Central Europe and South China, a quantitative stratigraphic correlation has been achieved with 7 conodont UA Zones recognized using the unitary association method. Based on conodonts and carbonate carbon isotope data, the Smithian-Spathian boundary is identified in the interval from UAZ4 to UAZ5 close to the last occurrence of Nv. pingdingshanensis in Oman and South China, and within the range of P. inclinata, Ns. planus, Pl. regularis, and Pl. corniger in South-Central Europe. UAZ7 fauna displays a clear diachronism as it starts from South China, arrives a bit later in Oman and even later in western Tethys. Pollan gardenae and Icriospathodus zaksi are reported from Oman for the first time and thus expand the geographical distribution of these rarely reported species.