Abstract

A limestone block in the Shirokawa-Nomura area of western Shikoku (Japan) is interpreted to have been originated as a Panthalassan seamount, and is assigned to the northern part of the Southern Chichibu Terrane. The Late Permian foraminiferal fauna from this block is composed of 33 species, and is characterized by Nanlingella? sp., three unidentified species of Staffellidae, Paraglobivalvulina mira, Dagmarita chanakchiensis, Paradagmarita sp., and Partisania sp. Among them, four unidentified species are systematically described and discussed. Although this fauna is indeterminately either Wuchiapingian or Changhsingian, it is clearly Late Permian in age by comparison with Late Permian faunas in the Tethyan regions, and by the complete absence of neoschwagerinids, verbeekinids, and schwagerinids, which became extinct by the end of Middle Permian time. The limestone block in the Shirokawa-Nomura area is clearly distinguished from Upper Permian shelf limestones from the Kurosegawa, Southern Kitakami, and Maizuru terranes by its lithology and by the complete absence of the foraminifer Colaniella, one of the most important index genera in Upper Permian strata throughout the Tethyan and peri-Gondwana regions.

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