Gabbro Unit

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Gabbro 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
early Permian (275 - 241 Ma, K-Ar; 285 Ma, Rb-Sr)

Sedimentary facies: Marine
Sedimentary facies: Ocean floor crust
Lithofacies: Hornblende clinopyroxene gabbro
Lithofacies (Minor): Hornblende gabbro, Amphibolite

Distribution (Width): ca. 0.3 - 2 km
Upper limit: Unconformity (Arima Group)
Lower limit: Thrust fault (Fuchigaki Formation)

Kyoto pref.
[ Upper ]
/--/--/--/--/-
Maizuru Metamorphic Rocks
/--/--/--/--/-
[ Lower ]

Asago, Hyogo pref.
[ North ]
/--/--/--/--/-
Middle sheet
/--/--/--/--/-
Lower sheet
/--/--/--/--/-
[ South ]

Yakuno Complex
[ Upper ]
/--/--/--/--/-
Basalt Shale Unit
/--/--/--/--/-
Gabbro Unit
/--/--/--/--/-
[ Lower ]

South zone
[ Upper ]
/--/--/--/--/-
Yakuno Complex
/--/--/--/--/-
[ Lower ]

Maizuru Belt
[ North ]
/--/--/--/--/-
North zone
/--/--/--/--/-
Central zone
/--/--/--/--/-
South zone
/--/--/--/--/-
[ South ]

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

Distribution: Mount Eboshiyama - Fukuchiyama - Sandanike park - Yasui - Hoonji - Nukata - Makikawa river - Mount Karasugatake - Hatakenaka - Inono - Iwai - Musochi, Fukuchiyama city, Kyoto pref.; Iden town - Yuragawa river - Hattagawa river - Ankokuji town - Takakura town, Ayabe city, Kyoto pref.

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.)
Kimura et al. (1989) Geology of the Ayabe District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 104p. (in Japanese with English abstract 5p.)