Ashiro Mudstone Member

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Ashiro Mudstone Member

Invalid synonym: Ashiro Formation

Type locality: Ashiro, Higashimiyoshi city, Miyoshi county, Tokushima prefecture
Coherent formation
Izumi sedimentary basin
Forearc basin associated with strike-slip fault related to Median Tectonic Line
Late Cretaceous, middle Campanian
Interfingered: Hiketa Formation

Sedimentary facies: Lower submarine fan, Sedimentary basin floor
Sedimentary facies: Low-density turbidity current sheet flow
Sedimentary facies: Turbidite
Lithofacies: Mudstone
Lithofacies (Minor): Sandstone, Felsic tuff

Thickness: 800 - 1,000 m
Upper limit: Bottom of the sandstone-dominant horizon including thick sandstone beds
Upper limit: Conformity (Nagoro Sandstone Member)
Lower limit: Transitional (Unpenji Sandstone Member)

Takikubo Formation
[ Upper ]
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Ashiro Mudstone Member
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Unpenji Sandstone Member
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Ebisukui Mudstone Member
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Tanono Sandstone Member
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Minoura Sandstone and Mudstone Member
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[ Lower ]

Main facies (Sanuki mountains, Tokushima pref.)
[ Upper ]
'''''''/,,,,,,
Bandodani Formation
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Higaidani Formation
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Horita Formation
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Takikubo Formation
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[ Lower ]

Izumi Group
[ North ]
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Northern marginal facies
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Main facies
~~~~~~~~~~~~~~
Southern facies
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[ South ]

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

Distribution: Ashiro - Kuzukago - Uchino - Nakanomine - Dodoro - Sadayasu, Higashimiyoshi city, Miyoshi county, Tokushima pref.; Kunigino - Shioiri - Mount Daisenzan, Manno city, Nakatado county, Kagawa pref.
Fossils: Ammonoids (Baculites sp.), Gastropods, Trace fossils (Archaeozoastera isp.)
Fossils (Bivalves): Inoceramus balticus, Propeamussium sp.

Noda et al. (2021) Geology of the Ikeda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 150p. (in Japanese with English abstract 5p.)