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Basalt Shale Unit

• Middle - lower crust of a Paleozoic volcanic island arc (Yakuno paleo-island arc) in the ocean
• Ophiolite originated from oceanic type, island-arc type and back-arc basin type oceanic crusts
• middle - late Permian (Radiolarians)
• Intruded by: Dolerite sills, Dykes

• Sedimentary facies: Marine
• Sedimentary facies (Oshima, Fukui pref.): Ocean floor crust
• Sedimentary facies (Ayabe, Kyoto pref.): Ocean floor crust
• Sedimentary facies (Yakuno, Kyoto pref.): Back-arc basin
• Sedimentary facies (Kamigori, Hyogo pref.): Island-arc crust
• Sedimentary facies (Ohara, Okayama pref.): Island-arc crust
• Lithofacies: Prehnite-Pumpellyite, Greenschist, Epidote-Amphibolite
• Lithofacies (Upper): Shale
• Lithofacies (Upper, Upper): Interbedded sandstone and shale, Conglomerate, Sandstone
• Lithofacies (Lower): Basalt lava, Pillow lava
• Lithofacies (Lower, Minor): Dolerite, Basalt hyloclastite, Tuff, Shale, Siliceous shale

• Thickness: 2,000 m or thicker
• Thickness (Upper): 1,000 m or thicker
• Thickness (Lower): 500 - 2,000 m or thicker
• Distribution (Width): ca. 1 - 3 km

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

• Distribution: Mount Karasugatake - Hoonji - Sabutani - Nishitanigawa river - Kitayama - Chihara - Umetani - Kashinokidai - Mount Himekamiyama - Tomioka - Inono, Fukuchiyama city, Kyoto pref.; Kuri town, Ayabe city, Kyoto pref.

Fossils (Radiolarians): Follicucullus sp.

• Kurimoto and Makimoto (1990) Geology of the Fukuchiyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 97p. (in Japanese with English abstract 5p.)