Aikawa Volcanic Rock Member

Aikawa Volcanic Rock Member (Otuka, 1933) Tuzino et al., 2018

Invalid synonym: Aikawa Andesite, Aikawa Andesite and Pyroclastic Rocks Member, Torigoe Andesites

Type locality: Basen valley, Mabuchi river, Aikawa, Ninohe city, Iwate prefecture
Coherent formation
middle Miocene (15.9 Ma, U-Pb, 15.3 Ma, FT, 14.2 Ma, K-Ar)

Lithofacies: Basaltic andesite, Dacite
Lithofacies (Volcaniclastic rock facies): Volcanic breccia, Tuff breccia, Lapilli tuff
Lithofacies (Volcaniclastic rock facies, Minor): Conglomerate, Tuffaceous sandstone, Sandstone, Mudstone, Slump deposit
Lithofacies (Lava facies): Lava, Hyaloclastite
Lithofacies (Intrusive rock facies):

Source: around Aikawa, Ninohe city, Iwate pref.
Thickness: 0 - ca. 300 m
Upper limit: Conformity (Mainosawa Sandstone Member), Unconformity (Zyumonzi Formation, Horino Terrace Deposit)
Lower limit: Conformity (Itukamati Sandstone Member), Unconformity (Sikonai Siltstone Member, Sukohata Siliciclastic Rock Member

Suenomatuyama Formation
[ Upper ]
~~~~~~~~~~~~~~
Mainosawa Sandstone Member
--------------
Aikawa Volcanic Rock Member / Nakuidake Volcanic Rock Member
--------------
Itukamati Sandstone Member
--------------
Anausi Conglomerate Member
--------------
[ Lower ]

Shiratorigawa Group
[ Upper ]
~~~~~~~~~~~~~~
Suenomatuyama Formation
--------------
Kadonosawa Formation
--------------
Yotsuyaku Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Basen valley, Mabechi river, Aikawa, Ninohe city, Iwate pref.; Ishikiridokoro, Ninohe city, Iwate pref.; Nitadori, Ichinohe city, Ninohe county, Iwate pref.

Tuzino et al. (2018) Geology of the Ichinohe District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 161p. (in Japanese with English abstract 4p.)