[ Top ] [ Japanese ]

Furukuchi Formation Iizuka, 1924

The upper part of Kusanagi Formation had been included in Furukuchi Formation.

• Type locality: Furukuchi, Tozawa city, Mogami county, Yamagata prefecture
• Coherent formation
• late Miocene - Pliocene
• Correlation: Kitamata Formation, Kamabuchi Formation
• Intruded by: Rhyolite, Dacite

• Sedimentary facies: Marine (Shellfishes)
• Sedimentary facies (Minor): Lava dome
• Lithofacies: Mudstone
• Lithofacies (Minor): Siltstone, Acidic tuff, Tuffaceous sandstone
• Lithofacies (Minor, Lava dome): Rhyolite, Dacite

• Thickness: 500 - 600 m
• Upper limit: Transitional (Noguchi Formation)
• Lower limit: Conformity (Kusanagi Formation)

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

• Distribution: Furukuchi, Tozawa city, Mogami county, Yamagata pref.; Komata - Kogawauchi - Yachinosawa - Takasaka - Nishikawa - Nishikori, Mamurogawa city, Mogami county, Yamagata pref.; Oashizawa, Sakekawa city, Mogami county, Yamagata pref.
• Fossils: Fish scales, Sponges (Sagarites chitanii)
• Fossils (Shellfishes): Ancistrolepis mogamiensis, Chlamys akitana, Chlamys miyatokoensis, Conchocele bisecta, Fulgoriara (Psephaea) pervostiana, Lucinoma cf. acutilineata, Natica janthostoma, Neptunea sp., Nucula ijirii, Panomya beringiana, Psephaea striata, Serripes makiyamai, Thyasira bisecta, Thyasira nipponica
• Fossils (Foraminifera): Cribrostomoides subglolosum, Cyclamina cancellata, Cyclammina japonica, Cyclammina pusilla, Globigerina bulloides, Globigerina cf. quinqueloba, Globigerina woodi, Globigerinita glutinata, Globigerinoides immaturus, Globoquadrina altispira, Martinottiella communis
• Fossils (Radiolarians): Spongodiscus spp., Thecosphaera japonica
• Fossils (Nannofossils): Braarudosphaera bigelowii, Calcidiscus leptoporus, Calcidiscus macintyrei, Coccolithus pelagicus, Dictyocaccites perplexus, Dictyococcites productus, Discoaster bergrenii, Discoaster brouweri, Discoaster intercalaris, Discoaster pentaradiatus, Discoaster quinqueramus, Discoaster variabilis, Helicosphaera carteri, Neosphaera coccolithomorpha, Pyracyclus inversus, Reticulofenestra gelida, Reticulofenestra haquii, Reticulofenestra minuta, Reticulofenestra minutula, Reticulofenestra pseudoumbilica, Sphenolithus abies, Sphenolithus heteromorphus, Sphenolithus neoabies, Sphenolithus cf. verensis

• Moriya et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.8, pp.389-404 DOI
• Moriya et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.1, pp.1-15 DOI
• Tsuchiya (1989) Geology of the Osawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 6p.)