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Orose Formation

• Type locality: Orose, Oshu city, Iwate prefecture
• Volcanic rocks
• Miocene

• Sedimentary facies: Marine
• Lithofacies: Tuff breccia, Tuffaceous sandstone, Tuff, Shale

• Thickness: 400 m
• Upper limit: Unconformity (Mizuyama Formation, Kunimiyama Andesite)
• Lower limit: Conformity (Maekawa Formation)

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

• Distribution: Orose, Oshu city, Iwate pref.; Maekawa river, Isawa river - Shitomae river - Kanayama creek - Hondera creek - Iwai river, Oshu city, Iwate pref.; Mount Kogurumi - Mount Takahino, Oshu city, Iwate pref.
• Fossils: Shellfishes, Foraminifera
• Fossils (Shellfishes): Anadara cfr. amicula, Arca? sp., Argobuccinum sp., Batillaria sp., Benthovoluta sp., Chlamys cfr. heteroglyptus, Clinocardium shiobaraense, Dentalium yokoyamai, Dosinia cfr. japonica, Dosinia kaneharai, Glycymeris oinouyei, Glycymeris vestioides, Limopsis sp., Lora? sp., Lucinoma otukai, Macoma calcarea, Macoma cfr. tokyoensis, Mactra kurikoma, Mya sp., Nassarius sp., Neverita sp., Nuculana sp., Ostrea sp., Panope japnica?. Peronidia protovenulosa, Polinices sp., Schizothaerus? sp., Siphonalia sp., Tellina protovenulosa, Tracia genbinna, Trachycardium narusawaense, Venericardia sp., Venus cfr. securis
• Fossils (Foraminifera): Angulogerina kughesi, Anomalia glabrata, Biloculinella globula, Bolivina decussata, Buccella inusilata, Buliminella elegantissima tenuis, Cassidulina cf. orientale, Cassidulina sublimbata, Cibicides akerianus, Cibicides lobatulus, Cibicides pseudoungerianus, Cibicides cf. refulgens, Discopulvinulina orbicularis, Discopulvinulina stachi, Discorbis opercularis, Discorbis subopercularis, Elphidium advenum, Elphidium cf. eligoense, Elphidium fax, Elphidium jenseni, Eponides haidingeri, Eponides nipponicus, Eponides umbonatus, Fissurina semimarginata, Fissurina orbignyana, Globigerina apertura, Globigerina bulloides, Globigerina conglomerata, Globigerina parabulloides, Globigerina trilocularis, Globigerinoides conglobutus, Globigerinoides immatuus, Globigerinoides oblinquus, Globigerinoides ruber, Globigerinoides sacculifer, Globoquadruba pozonensis, Guttulina sp., Hanzawaia nipponica, Hastigerina siphonifera, Lagena sulcata laevicostata, Oolina costata, Oolina melo, Quinqueloculina sawanensis, Robulus orbicularis, Rotalia beccarii aomoriensis, Rotalia nipponica, Rotalia takanabensis, Spiroplectammina cf. higuchii, Triloculina trigonula, Uvigerina nitidula

• Kitamura (1965) Yakeishi-dake, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 40p. (in Japanese with English abstract 8p.)