Ochiai Formation

Invalid synonym: Ochiai Conglomerate Formation

Coherent formation
Trough-fill deposit at the collision boundary between Oceanic arc of Paleo-Izu-Bonin arc (Ocean crust) and Honshu arc (Island arc)
Susugaya Trough deposit
early Pliocene (5.3 - 3.7 Ma)

Sedimentary facies: Marine
Sedimentary facies: Channel deposit
Metamorphic facies: Prehnite-Pumpellyite
Lithofacies: Clastic rocks
Sedimentary structures: Upward-fining

Thickness: 550 m
Lower limit: Conformity, partly unconformity (Jike Formation)

Hayato Subgroup
[ Upper ]
--------------
Ochiai Formation
~~~~~~~-------
Zike Formation
~~~~~~~-------
[ Lower ]

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

Distribution: Tanzawa mountains, Kanagawa pref.
Fossils: Foraminifera (Lepidocyclina nipponica)

Ishikawa et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.7, pp.291-304, DOI
Ueki et al. (2013) Geology of the Hachioji District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 137p. (in Japanese with English abstract 6p.)
Matsubara and Amano (2010) Jour. Geol. Soc. Japan, vol.116, no.3, pp.134-150 DOI
Oka et al. (1979) Geology of the Fujisawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 5p.)