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Josoji Formation (Tai, 1952) Ministry of International Trade and Industry, 1967

• Type locality: Josoji, Matsue city, Shimane prefecture
• Coherent formation
• early - middle Miocene (16 - 14 Ma)
• Correlation: Otsu Formation, Kuri Formation, Kawai Formation
• Intruded by: Gabbro - Quartz diorite - Dolerite - Porphyrite sills, laccolith

• Sedimentary facies: Shallow marine
• Sedimentary facies: Submarine volcano by the felsic volcanisum
• Sedimentary facies: Feeder dikes, Submarine pyroclastic flow deposits, Lava dome
• Depth of water: Continental margin - middle Continental slope (Foraminifera)
• Depth of water: Bathyal (Foraminifera)
• Lithofacies: Rhyolitic lava, Rhyolitic hyaloclastite, Volcanic breccia, Pumice tuff, Shale
• Lithofacies (Minor): Pyroxene andesite lava, Andesite reworked deposits, Tuffaceous sandstone
• Sedimentary structures: Slump structures, Graded bedding, Parallel stratification, Cross stratification, Imbricate structure, Convolute lamination, Columnar joints
• Paleocurrent: from Southwest to Northeast

• Source (Rhyolite): Katae bay, Tasumi, Mount Shinyama
• Source (Andesite): Shichirui bay, Morokui
• Thickness: 100 - 1,600 m
• Thickness (Andesite): 100 - 150 m
• Thickness (Submarine pyroclastic flow, A unit): Several - 20 m
• Upper limit: Transitional (Ushikiri Formation), Unconformity (Hinomisaki Terrace Deposit)
• Lower limit: Bottom of black shale dominated horizon
• Lower limit: Conformtiy (Koura Formation)

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

• Distribution: Josoji - Mount Asahiyama - Mount Shinyama, Matsue city, Shimane pref.; Hoda - Chikumi - Mitsu - Sozu, Mihonoseki town, Matsue city, Shimane pref.; Sakaura - Cape Hinomisaki - Ketakake - Sagiura - Uryu - Mount Hnatakasen - Mount Obunesan - Ichihatayakushi, Izumo city, Shimane pref.
• Fossils: Whales (family Balaenopteridae), Fish (Scales, Bones), Starfish (Astrophiura? sp.)
• Fossils (Shellfishes): Acesta aff. amaxaenisa, Acesta cf. smithi, Bathyamussium sp., Megayoldia sp., Nuculana sp., Palliolum sp., Portlandia sp., Propeamussium cf. tateiwai, Solemya sp., Yoldia sp.
• Fossils (Foraminifera): Ammodiscus incortus, Ammonia tochigiensis, Ammphicoryna scalaris sagamiensis, Bathysiphon? sp., Bolivina sp., Brizalina rgentea, Brizalina marginata masudai, Bulimina striata, Cibicides cf. floridanus, Cibicides malloryi, Cribrostomoides cf. crassimaargo, Cyclammina cancellata, Cyclammina cf. ezoensis, Cyclammina japonica, Cyclammina orbicularis, Cyclammina pusilla, Discammina cf. compressa, Discammina cf. emaciata, Epistominella pulchella, Epistominella shimanensis, Eponides subpraecinctus, Fursenkoina ishikiensis, Globigerina angustiumbilicata, Globigerina falconensis, Globigerina praebulloides praebulloides, Globigerina weissi, Globigerinita glutinata, Globobulimina pyrula, Globoquadrina cf. immaturus, Globoquadrina cf. venezuelana, Globorotalia birnageae, Globorotalia continuosa, Globorotalia quinifalcata, Globorotalia siakensis, Gyroidina orbicularis, Gyroidinoides shinjiensis, Haphlofragmoides cf. compressum, Haphlofragmoides renzi, Hastilina bradyi, Hopkinsina sp., Lagena sulcata, Lenticulina nikobarensis, Lituolidae gen. et sp. indet., Martinottiella communis, Martinottiella nodulosa, Nonionella miocenica, Plectina nipponica, Proteonina sp., Sigmoilopsis schlumbergeri, Sphaeroidina compacta, Spiroplectammina sp., Spirosigmoilinella compressa, Textularia sp., Torchammina sp., Uvigerina akitaensis, Uvigerina subperegrina, Valvulineria masudai
• Deposits: Kuroko massive sulfide deposit (Wanibuchi mine, Utouge mine, Sagi mine)

• Kano (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.781-803 DOI
• Nomura et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.2, pp.95-109 DOI
• Sakai et al. (2013) Jour. Geol. Soc. Japan, vol.119, no.4, pp.285-299 DOI
• Sato et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.8, pp.439-450 DOI
• Tanaka and Nomura (2009) Jour. Geol. Soc. Japan, vol.115, no.6, pp.261-265 DOI
• Utada (2007) Jour. Geol. Soc. Japan, vol.113, no.8, pp.438-453 DOI
• Kano et al. (1998) Geology of the Taisha District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 58p. (in Japanese with English abstract 3p.)
• Kano et al. (1994) Geology of the Matsue District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 126p. (in Japanese with English abstract 5p.)
• Kano et al. (1991) Geology of the Imaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 79p. (in Japanese with English abstract 5p.)
• Kano and Nakano (1986) Geology of the Etomo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 30p. (in Japanese with English abstract 3p.)
• Kano and Nakano (1985) Geology of the Mihonoseki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 28p. (in Japanese with English abstract 3p.)
• Kano and Yoshida (1985) Geology of the Sakaiminato District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)