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Iriomote Formation
- Coherent formation
- Miocene (14.9 - 13.5 Ma, Nannofossils)
- Sedimentary facies: Marine, Brackish
- Sedimentary facies: Transgressive lag, Tidal, Sandy mudflat, Muddy mudflat
- Depth of water: Shallow, Intertidal, Offshore - shelf facing open sea
- Lithofacies: Sandstone, Interbedded sandstone and mudstone
- Lithofacies (Minor): Mudstone intercalating coal beds
- Sedimentary structures: Trough cross-stratification, Hummocky cross-stratification, Paralle stratification, Wave-formed ripples, Lenticular stratification, Wavy stratification
- Thickness: Approximately 700 m
- Upper limit: Unconformity (Ryukyu Group)
- Lower limit: Unknown
- Yaeyama Group (Iriomote island)
- [ Upper ]
- ~~~~~~~~~~~~~~
- Iriomote Formation
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- [ Lower ]
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Hoshisuna beach - Cape Nishi, Iriomote island, Okinawa pref.; Uchibanare island, Okinawa pref.
- Fossils: Bivalves (Amussiopecten yabei (Nomura)), Corals, Bryozoa, Echinoids
- Fossils (Nannofossils): Cyclicargolithus floridanus, Sphenolithus heteromorphus
- Fossils (Trace fossils): Ophopmorpha nodosa, Thalassinoides suevicus, Macaronichnus sp., Scolicia isp., Gryochorte comosa, Phycosiphon incertum, Planolites isp., Skolithos linearis
- Kotake et al. (2013) Jour. Geol. Soc. Japan, vol.119, no.11, pp.701-713 DOI