南部北上帯の上部石炭系長岩層産コリスティテス型腕足類とその古生物地理学的意義

抄録

Four choristitid brachiopod species were found in the Upper Carboniferous (Moscovian) limestone of the Nagaiwa Formation in the Nagaiwa area, South Kitakami Belt, northeast Japan: Choristites mosquensis Fischer de Waldheim, Choristites jigulensis (Stuckenberg), Parachoristites sp. A, and Parachoristites sp. B. All these species are Boreal-type brachiopods, distributed throughout the Upper Carboniferous (Bashkirian) to lowest Permian (Asselian) of northern and western Russia, central Asia, and Northwest to Northeast China. Therefore, the occurrence of the present choristitid brachiopods suggests that the South Kitakami area was part of the continental shelf along the eastern margin of North China (Sino-Korea) during the Late Carboniferous.