[BCG08-P02] Rhaetian (Late Triassic) conodont biostratigraphy of the Panthalassa Ocean and the final extinction of conodonts at the end of the Triassic
Keywords:Late Triassic, biostratigraphy, conodont, bedded chert, Mino belt, Panthalassa Ocean
Here we present 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 (Hori, 1992; Sugiyama, 1997). Based on the stratigraphic distributions of marker species, four conodont zones were defined: the Mocina bidentata Zone, the Misikella hernsteini Zone, the M. posthernsteini zone, and the M. ultima zone, in ascending order. These conodont zones are comparable to the standard Late Norian and Rhaetian conodont zones of western Tethys. The Norian/Rhaetian boundary in the study section is tentatively placed between the last occurrence of a Norian radiolarian species (Betraccium deweveri) and the first occurrences of Rhaetian conodont species (M. posthernsteini). The intercalibrated conodont—radiolarian biostratigraphy from the section accurately calibrates the radiolarian zones in Japan with standard chronostratigraphic stages and substages.