Kozumi Shale Member

Type locality: Oginohama, Kozumi, Ishinomaki city, Miyagi prefecture
Coherent formation
Late Jurassic, Oxfordian - Kimmeridgian

Sedimentary facies: Marine
Sedimentary facies: Transgressive deposit
Lithofacies: Shale
Lithofacies (Middle): Sandy shale
Lithofacies (Lower): Sandstone
Lithofacies (Lower, Minor): Silty sandstone, Sandy shale
Sedimentary structures: Cross stratification, Ripple marks, Bioturbation

Thickness: ca. 100 - 200 m
Thickness (Shale): 50 - 100 m or thicker
Upper limit: Bottom of the horizon composed of 10 - 30 m thick medium sandstone and well foliaged shale
Upper limit: Transitional (Fukkiura Shale and Sandstone Member)
Lower limit: Conformity (Makinohama Sandstone Member)

Oginohama Formation
[ Upper ]
--------------
Fukkiura Shale and Sandstone Member
--------------
Kozumi Shale Member
--------------
Makinohama Sandstone Member
--------------
Kitsunesaki Sandstone and Shale Member
--------------
[ Lower ]

Ojika Group
[ Upper ]
~~~~~~~~~~~~~~
Ayukawa Formation
--------------
Oginohama Formation
--------------
Tsukinoura Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Oginohama - Kozumi pass - Yakeyamazaki - Tomarihama - Makinosaki - Aji island, Ishinomaki city, Miyagi pref.
Fossils (Ammonoids): Aspidoceras sp., Aulacostephanus (Pararasenia) sp., Discosphinctes cf. kiritaniensis, Lithacoceras onukii, Perisphinctes (Kranaosphinctes) cf. matsushimai, Perisphinctes (Perisphinctes) ozikaensis
Fossils (Shellfishes): Myophorella (Promyophorella) obsolete, Myophorella (Promyophorella) orientalis, Variamussium cf. habunokawense

Takizawa et al. (1987) Geology of the Yoriiso District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 74p. (in Japanese with English abstract 5p.)
Takizawa et al. (1984) Geology of the Ishinomaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 103p. (in Japanese with English abstract 7p.)
Takizawa et al. (1974) Geology of the Kinkasan District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 62p. (in Japanese with English abstract 5p.)