Hiki Alternation

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Hiki Alternation (Iketani and Horie, 1982)

Invalid synonym: Egenoya Formation, Yamadagaya Formation

Type locality: Hiki, Omaezaki city, Shizuoka prefecture
Coherent formation
middle Miocene - Pliocene
Correlation: lower Horinouchi Alternation

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

Thickness: 300 - 400 m or thicker
Lower limit: Conformity (Ogane Mudstone)

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: Hiki - Sakura - Uenohara, Omaezaki city, Shizuoka pref.
Fossils: Sponges (Sagarites chitanii), Calcareous nannofossils
Foraminifera (Foraminifera): Globigerina nepenthes, Globorotalia tumida plesiotumida, Globorotalia tumida tumida
Tephra: Hk

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.)