Carboniferous ammonoids from the Kawai Limestone of the Akiyoshi Belt, eastern Hiroshima Prefecture, SW Japan

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1 Jour. Geol. Soc. Japan, Vol. 118, No. 8, p , August 2012 JOI: JST.JSTAGE/geosoc/ doi: /geosoc Carboniferous ammonoids from the Kawai Limestone of the Akiyoshi Belt, eastern Hiroshima Prefecture, SW Japan Abstract Masayuki Ehiro, Osamu Nishikawa and Isao Nishikawa The Tohoku University Museum, Sendai , Japan Mineral Industry Museum, Graduate School of Technology and Resource Science, Akita University, Akita , Japan Otsu , Yuki, Jinsekikogen-cho, Jinseki-gun, Hiroshima , Japan Two Late Carboniferous (late Bashkirian Moscovian) ammonoids, Diaboloceras sp. and Pseudoparalegoceratidae gen. et sp. indet., are described from the Kawai Limestone of the Akiyoshi Belt, eastern Hiroshima Prefecture. This is the first record of Carboniferous ammonoids from the central part of the Akiyoshi Belt. These ammonoids and previously reported foraminiferans and brachiopods show that the age of the Kawai Limestone ranges from Late Carboniferous to Middle Permian. Fossil data indicate that the Kawai Limestone consists of three repetitions of an Upper Carboniferous to Middle Permian stratigraphic sequence. The Carboniferous Permian limestones, sporadically exposed as inliers, along the southern margin of the Akiyoshi Belt in Hiroshima Prefecture are possibly constituents of a large seamount-reef complex. Keywords: Carboniferous ammonoid, Diaboloceras, Kawai Limestone, Akiyoshi Belt, Hiroshima Prefecture Corresponding author; M. Ehiro, ehiro@m.tohoku.ac.jp, 1984; Kanmera et al., 1990,, 1974; Sano and Kanmera, 1988; Sano et al., 2000; Fig. 1A 2 Fig. 1B;, 1996;, The Geological Society of Japan Fig. 1, 2000, 1979 Fig Yanagida and Nishikawa1984 Fig. 2 AsselianSakmarian

2 Fig.. (A) Index map showing the large limestone bodies in the Akiyoshi Belt of the Chugoku District, southwest Japan, and (B) geologic sketch map of the eastern part of Hiroshima Prefecture (simplified from Teraoka et al., 1996, and Matsuura et al., 2002) Fig. 2 NNW SSE Yanagida and Nishikawa1984 Fig mm 3 Fig IGPS coll. cat. no ;

3 Fig.. Geologic map of the Kawai area, Fuchu City, eastern Hiroshima Prefecture. The geologic map is simplified from Sada et al. (1979). Fossil data are from Sada et al. (1979) and Yanagida and Nishikawa (1984). Fig. 3-1, 2 D 20 mm 6 7 UD D 50% 11.5 mm no V first umbilical lobeu 1 second umbilical lobeu 2 2 lobe Fig 3-1d WocklumeriaEpiwocklumeriaSoliclymenia Schistocetatidae Diaboloceras ParalegocerasWelleritidae Winslowoceras Eowellerites Welleritidae 2 Schistocetatidae DiabolocerasMiller and Furnish, 1940 ParalegocerasHyatt, mm, Nassichuk, 1975 Paralegoceras Diaboloceras UD/D U 2 V 20 mm U 2 Diaboloceras Diaboloceras Bashkirian Moscovian Kullmann, 2009Paralegoceras Moscovian Nishida1971 Paralegoceras Diaboloceras? sp. Nassichuk IGPS coll. cat. no ; Fig mm 15 mm Fig. 3-3c Pseudoparalegoceratidae Phaneroceras Pseudoparalegoceras Pseudoparalegoceratidae gen. et sp. indet. BashkirianKasimovian Kullmann, , Nishida, 1971;, 2007 Diaboloceras BashkirianMoscovian Yanagida and Nishikawa 1984 AsselianSakmarian 1979 Triticites? sp. 200 m Pseudofusulina

4 Fig.. Ammonoid fossils from the Kawai Limestone. 1, Diaboloceras sp. (IGPS coll. cat. no ). 2, Diaboloceras sp. (IGPS coll. cat. no ) 3, Pseudoparalegoceratidae gen. et sp. indet. (IGPS coll. cat. no ). 1a and 2a, lateral views. 1b and 2b, ventral views. 1c, cross section. 1d, external suture line (part). 3a, lateral view. 3b, ventral view. 3c, internal suture line. Scale bars are 10 mm unless otherwise specified. sp m ProfusulinellaPseuodstaffella, 1979 NNW SSE 20 km 10 km 1962, 1964, 1965 Fig. 1B Hase, A., 1962, Geol. Rep. Hiroshima Univ., no.12, Hase, A., 1964, Geological Map of Hiroshima Prefecture, 1: 200,000 and Explanatory Text, Naigai Map Co., Hase, A., 1965,,,

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