[BCG07-07] Upper Triassic (Rhaetian) conodont biostratigraphy of the Panthalassa Ocean and the final extinction of conodonts at the end-Triassic
Keywords:Triassic, Jurassic, Chert, Panthalassa Ocean, Conodont, Extinction
Here we present the Upper Norian to Rhaetian conodont biostratigraphy of an Upper Triassic bedded chert succession from the Mino belt, central Japan, where the radiolarian biostratigraphy has been investigated. Based on the stratigraphic distributions of marker species, four conodont zones are defined: the Mockina bidentata, Misikella hernsteini, M.posthernsteini, and M. ultimazones (in stratigraphic order). The conodont biostratigraphy established here calibrates the radiolarian zones in Japan with standard chronostratigraphic stages and substages, which allow us to compare the bio- and chemostratigraphicdata of other Triassic-Jurassic boundary sections from different areas in Tethys and Panthalassa oceans.Our analysis suggests that the final extinction of conodonts was asynchronous: the group first tried to take refuge from shallow water to open marine environments before becoming extinct.