CONODONT ZONATION, MICROFACIES ANALYSIS, AND δ13CCARB EXCURSIONS ACROSS THE PERMIAN-TRIASSIC BOUNDARY IN A SHALLOW SHOAL SETTING (YANGOU, JIANGXI PROVINCE), SOUTH CHINA

Conodont chrono-biostratigraphy is crucial for the studies on the Permian-Triassic (P-Tr) mass extinction and provides high-resolution timescale for revealing event sequences across the Permian-Triassic boundary (PTB) in South China. Growing evidence shows that various geochemical proxies and redox conditions exhibit water-depth gradients during this critical interval. When compared with well-studied deeper water facies section, conodont biostratigraphy from shallow platform facies PTB section remains poorly studied due to rarity of conodont fossils in shallower water settings. Here, we present our new conodont zonation across the PTB from a shallow ooid shoal setting, the Yangou section, which is located ~30 km northeast of Leping County, Jiangxi Province, South China, and was situated at the eastern part of the Lower Yangtze Platform during the P-Tr transition. In Yangou, a total of six types of carbonate microfacies (MF) are recognized based on field observation and detailed petrologic analysis, including: MF 1 (ooid grainstone), MF 2 (ooid-bioclast packstone), MF 3 (ooid wackestone), MF 4 (bioclast wackestone), MF 5 (bioclast-peloid micrite), and MF 6 (laminated micrite). Of these, the first two types of microfacies predominate the entire succession in Yangou, indicating a typical shallow, high-energy ooid shoal setting. Besides, five important conodont species: Hindeodus praeparvus (Kozur), H. parvus (Kozur et Pjatakova), H. typicalis (Sweet), Isarcicella lobata (Perri et Farabegoli), and I. turgita (Kozur, Mostler and Rahimi-Yazd) are also identified, and the H. praeparvus, H. parvus, and I. lobata Zones are established. These conodont zones are comparable with their counterparts from the GSSP Meishan section and those from western Paleo-Tethyan sections. Two δ¹³C_carb negative shifting excursions from Yangou correlate well with the same excursions derived from the P-Tr transition in the Meishan section.