Oyori Mudstone

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Oyori Mudstone Tsuchi, 1961

Invalid synonym: Oyori Silt

Type locality: Oyori, Makinohara city, Shizuoka prefecture
Coherent formation
middle Miocene - Pliocene
Contemporaneous heterotopic facies (Upper): Hagima Conglomerate
Correlation: Tamari Formation
Correlation (Upper - Middle): Ogane Mudstone
Correlation (Lower): Yokobuna Mudstone

Sedimentary facies: Marine
Sedimentary facies: Forearc basin (Sagara-Kakegawa Basin) deposit
Depth of water: upper part of Middle bathyal (600 - 1,000 m)
Lithofacies: Mudstone
Lithofacies (Minor): Sandstone

Thickness: 300 - 600 m
Upper limit: Conformity (Hagima Conglomerate, Horinouchi Alternation)
Lower limit: Conformity (Sugegaya Alternation, Hirugaya Alternation)

Sagara Group (Western part)
[ Upper ]
--------------
Hagima Conglomerate
--------------
Oyori Mudstone
--------------
Hirugaya Alternation
--------------
Sugegaya Alternation
~~~~~~~~~~~~~~
[ Lower ]

Sagara Group (Central part)
[ Upper ]
--------------
Hiki Alternation
--------------
Ogane Mudstone
--------------
Sagara Alternation
--------------
Yokobuna Mudstone
~~~~~~~~~~~~~~
[ Lower ]

Sagara Group (Eastern part)
[ Upper ]
--------------
Omaezaki Alternation
--------------
Sagara Alternation
--------------
Susuki Mudstone
--------------
Jitogata Alternation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Oyori - Shirai - Shinden, Makinohara city, Shizuoka pref.; Niino - Nanatsuyama, Omaezaki city, Shizuoka pref.
Fossils: Sponges (Sagarites chitanii), Calcareous nannofossils
Fossils (Shellfishes): Amussiopecten praesignis, Cardium? egregium, Chione casinaeformis, Clementia iizukai, Conus sp., Crassatellites pauxillus, Crassostrea gigas, Glycymeris nipponica, Glycymeris vestita, Melongena miranda, Meretrix chinensis, Pleurotoma subdeclivis, Urosalpinx birileffi, Valuta hirugayensis, Venericardia panda, Venus ozawai
Fossils (Foraminifera): Globorotalia tumida plesiotumida, Globorotalia tumida tumida, Pulleniatina sp., Sphaeroidinella dehiscens dehiscens
Tephra: Sa

Sugiyama et al. (1988) Geology of the Omaezaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 153p. (in Japanese with English abstract 6p.)