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Aratani Formation Nakagawa and Tahara, 1991

• Volcanic rocks
• Miocene (15.7 Ma, K-Ar)
• Intruded by: Basalt - Andesite dykes

• Sedimentary facies (AT-1): Submarine pyroclastic cone
• Lithofacies (Top): Sandstone
• Lithofacies (Upper, AT-2): Basaltic andesite lapilli tuff, Tuff
• Lithofacies (Upper, AT-2, Minor): Andesite volcanic breccia
• Lithofacies (Middle): Mudstone, Siltstone
• Lithofacies (Lower): Tuffaceous sandstone
• Lithofacies (Lower, Minor): Rhyolite pumiceous lapilli tuff, Tuff
• Lithofacies (Basal, AT-1): Andesite lapilli tuff, Tuff, Volcanic conglomerate
• Sedimentary structures (AT-1): Graded bedding, Parallel stratification

• Source (AT-2): middle reaches of Takasugawa river, Fukui pref.
• Source (AT-1): Amasugo, Fukui city, Fukui pref.
• Mode of eruption (AT-1): Phreatomagmatic
• Thickness: 300 m or thicker
• Thickness (AT-2): 100 m
• Thickness (AT-1): 200 m or thicker
• Upper limit: Unconformity (Ichinose Rhyolite)
• Lower limit: bottom of AT-1
• Lower limit: Transitional (Kunimi Formation)

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

• Distribution: Amasugo - Aratani town - Takasu town - Mera town, Fukui city, Fukui pref.
• Fossils (Shellfishes): Acila cf. submirabilis, Acmaea sp., Anadara (Anadara) ogawai, Anisocorbula sp., Boreotrophon osawanoensis, Callista sp., Calyptraea tuburg, Cerithidea sp., Chama sp., Chelyconus tokunagai, Chlamys (Chlamys) nisataiensis, Clinocardium andoi, Crepidula cf. nidatoriensis, Cryptopecten yanagawaensis, Cultellus (Clutellus) izumoensis, Cyclocardia siogamensis, Diodora minoensis, Dosinia (Kaneharaia) kannoi, Elaeocyma (Splendrilla) sp., Euclino balantium, Euspira meisensis, Fissidentalium (Fissidentalium) yokoyamai, Fusinum sp., Glossaulax didyma coticazae, Glycymeris rhynchonelloides, Glycymeris (Veletuceta) cf. cisshuensis, Gobraeus, Kaneharaia kannoi, Katelysia sp., Limatula (Limatula) sp., Liracassis japonica, Lucinoma actilineata, Macoma (Macoma) incongrua, Macoma (Macoma) optiva, Megasurcula yokoyamai, Minolia sp., Mizuhopecten kimurai murayamai, Mizuhopecten kimurai tiganouraensis, Modiolus sp., Mytilus sp., Naticidae, Neogenella itoi, Nipponocrassatella osawanoensis, Nitidotellina sp., Oliva cf. osawanoensis, Olivella sp., Onustus matsuoi, Panomya simotomensis, Panopea nomurae, Paphia (Paphia) suzuensis, Phacosoma nomurai, Rapana niuensis, Saccella (Saccella) saikaiensis, Saccostrea sp., Saxidomus sp, Securella yokoyamai, Sinum (Sinum) ineptum, Siphonalia ikebei, Siratoria cf. siratoriensis, Solen sp., Spisula sp., Tellinella osafunei, Teredo sp., Thracia watanebei, Thyasira sp., Turritella (Hataiella) shatai, Vasticardium ogurai, Venus (Ventricoloidea) sp., Yoldia (Cnesterium) cf. ensifera akeyoensis
• Fossils (Foraminifera): Myogypsina kotoi kotoi, Operculina complanata japonica

• Kano et al. (2007) Geology of the Fukui District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 68p.