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Sikonai Siltstone Member (Otuka, 1934) Matsubara, 1995
Invalid synonym: Sikonai Alternation Beds, Kagitori Sandstone
Invalid synonym (Upper): Kadonosawa Tuffaceous Sandstone Member, Kagitori Sandstone and Siltstone Member
- Type locality: Shiratori river, Tate bridge - Anaushi bridge, Ninohe city, Iwate prefecture
- Coherent formation
- early Miocene (17.0 - 14.6 Ma, Diatoms)
- Sedimentary facies: Open sea
- Sedimentary facies (Upper): Open sea (Foraminifera)
- Sedimentary facies (Middle): Closed bay (Foraminifera)
- Sedimentary facies (Lower): Offshore, Mud floor
- Climate (Upper): Cold temperate
- Depth of water: Bathyal
- Lithofacies: Siltstone
- Lithofacies (Minor): Tuff, Pumice lapilli tuff, Lapilli tuff
- Lithofacies (Upper): Siltstone, Sandstone
- Lithofacies (Middle): Tuff
- Lithofacies (Lower): Claystone, Siltstone
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Shiratori river, Tate bridge - Anaushi bridge, Ninohe city, Iwate pref.; Kitadate, Ichinohe city, Ninohe county, Iwate pref.; Kamidate - Kokarumai, Karumai city, Kunohe county, Iwate pref.
- Fossils: Desmostylus sp., Whales (family Kentriodontidae), Foraminifera (Bolivina spp.)
- Fossils (Upper, Shiobara-Yama fauna):
- Fossils (Lower, Shikonai fauna):
- Fossils (Diatoms): Crusidenticula kanayae (= Denticulopsis kanayae), Denticulopsis lauta
- Tephra: Zarame (Goma) Tuff, Nimaigumi Tuff, Kagitori Tuff
- Tuzino et al. (2018) Geology of the Ichinohe District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 161p. (in Japanese with English abstract 4p.)
- Yamanoi et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.2, pp.114-117 DOI