Conodont biostratigraphy of a Carboniferous–Permian boundary section in siliceous successions of pelagic Panthalassa revealed by X-ray computed microtomography

Pelagic deep-sea siliceous successions in accretionary complexes preserve precious records of a vast deep seafloor that is now lost due to plate subduction. Microfossils are the key means age assignment these successions, but poor preservation tectonic deformation and metamorphism at subduction zone hamper biostratigraphic records. X-ray computed microtomography, while not widely used studies until now, allows us visualize fossils impossible or difficult extract from host rocks preservation. In this study, we applied method on conodonts pelagic chert–claystone succession Okoshizawa, Iwaizumi Town, Northeast Japan, using laboratory-based microscope. This work first close look conodont biostratigraphy across Carboniferous–Permian boundary Panthalassa. We identified including ten species as zonal markers intensely studied areas such around East European Platform Midcontinent United States. Based occurrence conodonts, section Okoshizawa was correlated lower Moscovian middle Artinskian. Confirmation Artinskian diagnostic Panthalassa strengthens their role global indicators. By identifying more numerous specimens compared conventional hydrofluoric acid dissolution method, were able obtain information about faunal characteristics The dominant taxa changed Streptognathodus Mesogondolella Asselian, probably reflecting an ecological takeover by latter waters.