Minamihirasawa Formation

Minamihirasawa Formation (Fujioka, 1950) Shikano et al., 2011

Type locality: Minamihirasawa, Oga city, Akita prefecture
Coherent formation
early Pliocene (5 - 3.6 Ma)

Sedimentary facies: Turbidite
Lithofacies: Tuffaceous mudstone, Siltstone
Lithofacies (Minor): Acidic tuff, Tuffaceous sandstone
Paleocurrent: Northwest

Thickness: 15 - 160 m
Upper limit: Top of Minamihirasawa Tuff
Upper limit: Conformity (Nishimizuguchi Formation), Onlap unconformity (Kitaura Formation)
Lower limit: Bottom of the mudstone bed intercalated by many tuffaceous sandstone beds
Lower limit: Conformity (Funakawa Formation, Shinzan Diatomaceous Mudstone Member)

Minamihirasawa Formation
[ Upper ]
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Minamihirasawa Tuff
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Main part
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[ Lower ]

Oga peninsula, Akita pref.
[ Upper ]
~~~~~~~~~~~~~~
Shibikawa Formation
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Wakimoto Formation
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Kitaura Formation
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Nishimizuguchi Formation
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Minamihirasawa Formation
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Funakawa Formation
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[ Lower ]

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

Distribution: Minamihirasawa - Kanegawa - Yumoto - Nomura - Kitaura, Oga city, Akita pref.
Fossils: Sponges (Makiyama chitanii), Radiolarians, Calcareous nannofossils, Diatoms
Fossils (Plants, Pollen): Fagus sp., family Taxodiaceae
Fossils (Foraminifera): Globigerina bulloides, Globigerinita glutinata, Globorotalia humerosa, Globorotalia cf. ikebei, Globorotalia orientalis, Miliammina echigoensis, Neogloboquadrina (Globoquadrina) asanoi, Neogloboquadrina kagaensis, Neogloboquadrina pachyderma, Orbulina bilobata, Orbulina universa
Tephra: Minamihirasawa Tuff (ca. 3.0 Ma)

Kano et al. (2011) Geology of the Toga and Funakawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 127p. (in Japanese with English abstract 4p.)