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Yoshiwara Formation Shiba et al., 1989
- Coherent formation
- Trough basin-fill deposit at the collision boundary between Izu-Bonin-Mariana arc and Southwest - East Japan island arc
- Back-arc basin volcanic activity at the back-arc basin of Izu-Bonin-Mariana arc
- late Miocene - Pliocene
- Sedimentary facies: Marine
- Lithofacies: Tuffaceous sandstone, Sandstone-dominant interbedded sandstone and mudstone
- Lithofacies (Minor): Mudstone, Mudstone-dominant interbedded sandstone and mudstone
- Sedimentary structures: Slump structures
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Shizuoka pref.
- Fossils (Foraminifera): Globigerinoides obliquus obliquus, Globoquadrina altispira, Globorotalia juanai, Globorotalia miozea conoidea, Globorotalia tumida plesiotumida, Neogloboquadrina acostaensis, Pullenialina primalis, Sphaeroidinellopsis seminulina, Sphaeroidinellopsis subdehiscens
- Sugiyama and Shimokawa (1990) Geology of the Shimizu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 103p. (in Japanese with English abstract 8p.)