Igami Formation

Type locality: Nara prefecture
Coherent formation
Miocene

Sedimentary facies (Upper): Fluvial
Sedimentary facies (Middle): Fluvial
Sedimentary facies (Lower): Marine
Sedimentary facies (Upper): Meandering river
Sedimentary facies (Middle): Meandering river
Sedimentary facies (Lower): Shoreface of storm-dominant shelf
Lithofacies (Upper): Sandstone
Lithofacies (Upper, Minor): Silt
Lithofacies (Middle): Interbedded sandstone and mudstone
Lithofacies (Middle, Minor): Conglomerate, Lignite
Lithofacies (Lower): Sandstone, Conglomerate
Lithofacies (Lower, Minor): Silt, Lignite
Sedimentary structures (Upper): Cross stratification, Parallel stratification
Sedimentary structures (Middle): Cross stratification, Parallel stratification, Ripple foliation
Sedimentary structures (Lower): Cross stratification

Thickness (Upper): 30 - 300 m
Thickness (Middle): ca. 50 m
Thickness (Lower): 250 m or thinner

Yamagasu Group
[ Upper ]
~~~~~~~~~~~~~~
Nakataro Formation
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Igami Formation
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Shioi Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Igami - Nagano - Shioi - Kuroiwa - Mount Yoroidake - Mount Sumitsukayama - Mount Kurosoyama - Mount Kogoyama, Soni city, Uda county, Nara pref., ., Shikizu, Mitsue city, Uda county, Nara pref.; Mount Oborayama - Toro - Yachi - Ishinahara, Misugi town, Tsu city, Mie pref.
Fossils (Shellfishes): Chlamys sp., Dosinia sp., Glycymeris sp., Lucinoma sp., Macoma sp., Tectonatica sp., Turritella sp., Yoldia sp.

Nishioka et al. (2001) Geology of the Sakurai District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 141p. (in Japanese with English abstract 5p.)
Nishioka et al. (1998) Geology of the Nabari District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 72p. (in Japanese with English abstract 5p.)