Late Carboniferous brachiopod Plicatiferina from Nishiamada, Fukui Prefecture, central Japan, and its tectonic implications

抄録

A new occurrence of the Late Carboniferous productoid brachiopod species, Plicatiferina borealica Kalashnikov, is described from a sequence of alternating metamorphosed limestone and subordinate metamorphosed felsic tuff, mudstone and sandstone at Nishiamada, Fukui Prefecture, central Japan. Plicatiferina is a typical Boreal-type genus, distributed in the Upper Carboniferous and lowest Permian of Arctic Canada, Arctic Russia, and the northern and southern Urals. The fossilbearing sequence at Nishiamada is assigned to the Late Carboniferous (Kasimovian?), and is correlated with the Unazuki metamorphic rocks of the Hida Belt, central Japan. The occurrence of a Boreal-type brachiopod at Nishiamada suggests that the original calcareous and volcaniclastic sediments of the Unazuki metamorphic rocks were deposited in a shallow sea on and around the eastern North China (Sino-Korea) during the Late Carboniferous.