Guadalupian age of the Mizukoshi Formation, western Kyushu, Japan, based on radiolarians

抄録

This study revealed the radiolarian-based sedimentary age of the Mizukoshi Formation, a Permian siliciclastic deposit in western Kyushu, Japan. Radiolarians were recovered from four mudstone samples in this formation. The radiolarian assemblages contain abundant specimens of the genus Follicucullus. The assemblage in the upper part of the lower member includes Follicucullus scholasticus, F. porrectus, and Follicucullus sp. cf. F. ventricosus. The upper part of the upper member includes F. charveti, F. dilatatus, F. scholasticus, F. porrectus, and F. ventricosus. Based on these assemblages, the Mizukoshi Formation in the study area can be correlated with the F. scholasticus-F. ventricosus Zone and the lower part of the F. charveti-Albaillella yamakitai Zone, representing the middle to upper Guadalupian.