[ Top ] [ Japanese ]

Tokihariyama Formation Yamazaki, 1984

• Type locality: Nakamuragawa river, Okinoshima city, Oki county, Shimane prefecture
• Volcanic rocks
• Oligocene - early Miocene (26.0 - 18.1 Ma, FT)
• Intruded by: Tsuzurao Formation (Volcanic vent), Fuseko Basalt

• Sedimentary facies: Terrestrial, Freshwater
• Sedimentary facies (Lower, Minor): Turbidite
• Climate: Cool-temperate deciduous broad-leaved forest, Warm-temperate deciduous broad-leaved forest
• Lithofacies (Top): Andesite pyroclastic rocks
• Lithofacies (Top, Minor): Tuffaceous sandstone
• Lithofacies (Upper): Andesite lava, Hyaloclastite
• Lithofacies (Upper, Minor): Dacite lava, Andesite tuff breccia, Sandy tuff, Rhyolite pyroclastic rocks, Mudstone, Gravel-bearing mudstone
• Lithofacies (Lower): Rhyolite, Dacite lapilli tuff, Tuff, Tuff breccia
• Lithofacies (Lower, Minor): Rhyolite lava, Interbedded sandstone, mudstone and tuff
• Lithofacies (Basal, Minor): Conglomerate
• Sedimentary structures (Upper): Platy joints
• Sedimentary structures (Lower, Minor): Cross stratification, Parallel stratification, Slump structure, Graded bedding, Parallel stratification, Ripple marks

• Thickness: 450 - 1,000 m or thicker
• Upper limit: Unconformity (Kori Formation, Kama Basalt, Oku-kita Basalt, Shimoganya Basalt, Ganya Basalt), Abut unconformity (Tsuzurao Formation)
• Lower limit: Unconformity (Oki Metamorphic Rocks)

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

• Distribution: Uzuki - Togogawa river - Nakamuragawa river - Chikaishi - Korikawa river - Chikaishigawa river - Masugigawa river - Goka - Nakadani - Minamidani - Fuse - Oku, Okinoshima city, Oki county, Shimane pref.
• Fossils (Tokihariyama flora): Alnus sp., Betula cotanii, Betula konnoi, Carpinus protocordatus, Carpinus subcordata, Carpinus subyedoensis, Carpinus cf. stenophylla, Fagus cf. crenata, Hemitrapa sp., Juglans miochinensis, Metasequoia occidentalis, Pseudotsuga cf. tanai, Pterocarya asymmetrosa, Sequoia sp., Taiwania sp.

• Yamauchi et al. (2009) Geology of the Saigo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 118p. (in Japanese with English abstract 3p.)