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Toyagamine Formation (Kanehara, 1940) Kobayashi et al., 1986

Invalid synonym: Toyagamine Andesite

• Type locality: Wada river, Obiro - Sodeyama, Uonuma city, Niigata prefecture
• Volcanic rocks
• late Miocene (6.4 Ma, K-Ar)

• Lithofacies: Augite hypersthene hornblende dacite lava, Augite hypersthene hornblende andesite volcanic breccia, Tuff breccia, Lava
• Lithofacies (Exotic blocks of Tsunagi Formation): Siltstone

• Thickness: 100 - 500 m or thicker
• Upper limit: Unconformity (Kawaguchi Formation)
• Lower limit: Unconformity (Nishimyo Formation)

• Distribution: Wada river, Obiro - Sodeyama, Uonuma city, Niigata pref.; Fukuyama river - Mount Toyagamine, Uonuma city, Niigata pref.
• Fossils (Diatoms, Exotic blocks): Actinocyclus ellipticus, Actinocyclus ingens var. ingens, Actinocyclus octonarius, Actinoptychus senarius, Actinoptychus splendens, Cocconeis californica, Cocconeis vitrea, Coscinodiscus endoi, Coscinodiscus marginatus, Coscinodiscus perforatus, Coscinodiscus vetustissimus, Crucidenticula nicobarica, Crucidenticula punctata, Cyclotella striata, Cymatosira aff. loreziana, Denticulopsis hustedtii, Denticulopsis hyalina, Denticulopsis praedimopha, Grammatophora sp., Hyalodiscus spp., Ikebea tenuis, Mediaria splendida, Melosira sol, Navicula sp., Neodelphineis pelagica, Nitzschia challengeri, Paralia sulcata, Plagiogramma sp., Rhizosolenia spp., Rouxia californica, Rouxia peragalli, Rosstella mediopunctata, Stephanopyxis turris, Symbolophora sp., Synedra cfr. jouseana, Thalassionema hirosakiensis, Thalassionema nitzschioides, Thalassiosira grunowii, Thalassiosira leptopus, Thalassiothrix longissima

• Takahashi et al. (2004) Geology of the Suhara District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 80p. (in Japanese with English abstract 4p.)
• Kobayashi et al. (1991) Geology of the Nagaoka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 132p. (in Japanese with English abstract 6p.)
• Yanagisawa et al. (1986) Geology of the Ojiya District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 177p. (in Japanese with English abstract 6p.)