Yugashima Group

Type locality: Amagi road, Izu city, Shizuoka prefecture
Volcanic rocks
early - middle Miocene
Intruded by: Diorite porphyry, Quartz diorite porphyry, Dacite body
Correlation: Shiradagawa Volcanics?

Sedimentary facies: Submarine volano products
Lithofacies: Pigeonite series
Lithofacies (Upper): Quartz-bering andesite lava
Lithofacies (Upper, Minor): Tuff breccia, Pyroxene andesite
Lithofacies (Middle): Interbedded tuffaceous sandstone and mudstone
Lithofacies (Middle, Minor): Dacite pumice tuff
Lithofacies (Lower): Pyroxene andesite volcanic breccia, Tuff breccia
Lithofacies (Lower, Minor): Andesite lava, Tuff, Tuffaceous sandstone

Thickness: 3,500 m or thicker
Upper limit: Unconformity (Nekko Dacites, Uchiura Andesites, Shirakawa Basalts, Shirahama Group, Chokuro Andesites)

Yugashima Group
[ Upper ]
~~~~~~~~~~~~~~
Shuzenji White Tuffs
--------------
Yugashima Propylites
?--?--?--?--?-
[ Lower ]

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

Distribution: Amagi road, Izu city, Shizuoka pref.; Shimoda city, Shizuoka pref.; Sakurada - Akebushi - Matsuzaki - Shikura - Yoshida - Iwashina, Matsuzaki city, Kamo county, Shizuoka pref.; Nishina river, Yaenano - Osori, Isshiki, Nishiizu city, Kamo county, Shizuoka pref.; Kawazu river - Numanogawa river, Nashimoto, Kawazu city, Kamo county, Shizuoka pref.
Fossils (Shellfishes): Amussiopecten cf. praesignis, Chlamys kakisakiensis, Chlamys miurensis, Cryptopecten javanus?, Cryptopecten vesiculosus, Ctenoides sp., Decatopecten izuensis, Diraricella sp., Glycymeris rotunda, Haliotis sp., Lima cf. zushiensis, Monilea? sp., Ostrea sp., Patinopecten planicostulatus, Pleurotomaria yabei, Strombus sp., Suchium? sp., Terebratulina miurensis, Vasticardium sp., Venericardia crenulicostata, Veneridae
Fossils (Brachiopods): Asprella cf. djarianensis, Asprella tuberculosus, Terebratulina miurensis

Sawamura et al. (1970) Geology of the Shimoda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 41p. (in Japanese with English abstract 4p.)
Sawamura (1955) Shuzenji, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 47p. (in Japanese with English abstract 4p.)