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Komasuzawa Formation (Kitamura et al., 1972) Kudo, 2005

Invalid synonym: northwest part of Ichinowatari Formation

• Type locality: Komasu creek, Fukamochi, Towada city, Aomori prefecture
• Sub-type locality: Omonai river, Okuse, Towada city, Aomori prefecture
• Coherent formation
• Miocene (6.8 - 6.4 Ma, Diatoms)

• Sedimentary facies: Shallow marine
• Sedimentary facies: Submarine pyroclastic flow deposit
• Lithofacies: Pumice lapilli tuff, Tuffaceous sandstone
• Lithofacies (Minor): Mudstone, Conglomerate, Welded tuff
• Sedimentary structures: Planar cross-stratification, Trough cross-stratification

• Thickness: ca. 300 m
• Upper limit: Interfingered (Tsukihiyama Volcanics), Interfingered, partly unconformity (Togawa Formation), Unconformity (Horyokita Lava, Hakkoda-Takatoge Pyroclastic Flow Deposit, Hakkoda 1st-stage Pyroclastic Flow Deposit, Towada Okuse Pyroclastic Flow Deposit)
• Lower limit: Conformity (Dochi Formation), Unconformity (Itadome Formation)

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

• Distribution: Komasu creek, Fukamochi, Towada city, Aomori pref.; Omonai river, Okuse, Towada city, Aomori pref.; Mise - Nakayashiki - Myotan creek, Towada city, Aomori pref.
• Fossils: Sponges (Spicules)
• Fossils (Plants): Alnus cf. hirsuta, Acer cf. subpictum, Acer Iwaii, Fagus paleocrenata, Fagus protojaponicus
• Fossils (Diatoms): Actinoptychus senarius, Actinoptychus splendens, Aulacoseira spp., Amphora sp., Cavitatus jouseanus, Cocconeis californica, Cocconeis costata, Cocconeis vitrea, Coscinodiscus marginatus, Coscinodiscus radiatus, Coscinodiscus spp., Clavicula polymorpha, Denticulopsis hyalina, Denticulopsis simonsenii, Hemiaulus polymorphus (= Eucampia sp.), Grammatophora spp., Hyalodiscus obsoletus, Ikebea tenuis, Melosira sol, Nitzschia grunowii, Nitzschia rolandii, Odontella aurita, Poralia sulcta, Plagiogramma staurophorum, Proboscia barboi, Pseudopyxilla americana, Rhabdonema japonicum, Rouxia californica, Thalassionema hirosakiensis, Thalassionema nitzschioides, Thalassiosira marujamica, Thalassiosira nidulus, Thalassiosira temperei, Thalassiosira spp., Thalassiothrix longissima

• Kudo (2005) Geology of the Towada District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 79p. (in Japanese with English abstract 3p.)