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Ronji Formation (Suzuki, 1938) Nakano et al., 2002

Invalid synonym: Ronji Mudstone Member, Machi Formation, Junidaira Formation, Yahagi Formation, Oshidashi Formation, Hodai Formation, Erabatake Formation, Kamikusukawa Formation, Irinotaira Formation, Sakainomiya Formation, Senmi Formation, Otagiri Formation, Sanganji Formation, Ichinose Formation, Zenkojionsen Formation, Hatayama Formation, Iimori Formation, Funakubo Formation, Hirosaki Formation, Oubayama Formation

It was defined as a member of Ogawa Formation.

• Type locality: Hotama creek, Ronji, Nagano city, Nagano prefecture
• Coherent formation
• late Miocene - early Pliocene
• Correlation: Yanagisawa Formation

• Sedimentary facies: Marine, Brackish
• Sedimentary facies: Open sea
• Sedimentary facies: Turbidite
• Climate: Subtropical, Warm temperate
• Water temperature: Cold ocean current
• Depth of water: Bathyal, Abyssal
• Lithofacies: Sandstone, Sandy mudstone
• Lithofacies (Minor): Interbedded sandstone and mudstone, Lignite
• Lithofacies (Basal): Pumice tuff
• Sedimentary structures: Parallel stratification, Graded bedding, Sole marks, Convolute stratification, Slump structures, Ripple marks, Hummocky cross-stratification
• Paleocurrent: Northwest

• Thickness: ca. 150 - 2,000 m
• Upper limit: Conformity (Gonda Formation, Tanogashira Formation, Takafu Formation), Unconformity (Hijiriyama Andesite, Akada Formation, Yanagisawa Mudflow Deposit)
• Lower limit: Conformity, partly transitional (Nodaira Member), Conformity (Nishikyo Formation), Abut unconformity (Susobana Formation)

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

• Distribution: Ronji - Tatara - Zenkojionsen - Kunimi - Kawago - Kusazaki - Ikadaira - Habu - Iimori - Wakabayashi - Utabi, Nagano city, Nagano pref., Sumeragi, Nakajo, Nagano city, Nagano pref.; Yamakamijo - Yamahokari - Ojima - Somuro, Shinshushinmachi town, Nagano city, Nagano pref.; Fukatanisawa creek, Kinasa, Nagano city, Nagano pref.; Susohanagawa river, Nagano city, Nagano pref.; Omachi city, Nagano pref.; Kuwanokizawa creek - Sakainomiya - Mount Oubayama, Omachi city, Nagano pref.
• Fossils: Whales (Mysticeti), Fish (Bones), Crabs (Callianassa yagii, Neptunus ozawai), Bryozoans, Trace fossils (Pipe rocks)
• Fossils (Zenkojionsen fauna): Anadara amicula, Anodonta sp., Buccinum shinanoense, Clinocardium shinjiense, Corbicula cf. sandaiformis, Cristaria? sp., Dosinia japonica troscheli, Dosinia (Kaneharaia) kaneharai, Eunaticina festiva, Fusitriton oregonensis, Glycymeris yamasakii, Lucinoma mochizuki, Macoma tokyoensis, Mercenaria chitaniana, Mercenaria yokoyamai, Mya donaciaeformis, Mya japonica, Mytilus grayanus, Nassarius nakamurai, Ostrea gigas, Panope japonica, Perondia sp., Saxidomus purpuratus, Schizothaerus keenae, Serripes makiyama, Spisula sachalinensis, Spisula cf. voyi, Tectonatica janthostomoides, Turritella saishuensis, Volsella difficilis
• Fossils (Chausuyama flora): Acer cfr. diabolicum?, Acer polymorphum, Acer polymorphum miocenum, Acer rufinerve, Acer rubrum, Acer sinense, Acer trilobalum, Alnus japonica, Bambusium yadakeides, Betula brongniaris, Carpinus sp., Camellia sp., Castanea ungeri, Celtis cfr. mississippiensis, Cephalotaxus sp., Cinnamonum cfr. polymorphum, Cyperites sp., Dicksonia cf. microlepia, Diospyros? sp., Dryophyllum? sp., Equisetum sp., Euonymus japonicus, Fagus americana, Fatsia sp., Ficus tiliaefolia, Ficus truncata, Fraxinus sp., Glyptostrobus europaeus, Hedera sp., Laurus sp., Meliosma sp., Myrica lignitum, Nephrodium sp., Onoclea sensibilis, Osmunda lignitum, Oyperites sp.., Phyllites sp., Planera ungeri, Populus balsamoides, Pteridium aquilinum, Pterocarya japonica, Quercus dentata, Rhododendron dilatatum, Rhus sp., Rosa sp., Salix sp., Sasa cfr. bambusium yadakeides, Sequoia cfr. sempervirens, Sequinoia sp., Smilax sp., Taxodium distichum miocenum, Trachycarpus sp., Ulmus longifolia?, Zelkova sp.
• Fossils (Shellfishes): Anadara amicula, Haplophragmoides sp., Mercenaria sp., Ostrea sp., Patinopecten sp.
• Fossils (Echinoids): Echinarachnius microthyroide, Echinarachnius naganoensis, Ophiura sarsii sarsii
• Fossils (Foraminifera): Cyclammina pusilla, Epistominella pulchella, Globigerina incompta, Globigerina pachyderma, Globigerina cf. woodi, Haplophragmoides cf. evoluta, Haplophragmoides cf. subglobosum, Martinottiella bradyana tarukiensis, Nonion pompilioides, Uvigerina sp.
• Tephra: Kns10, Kns20

• Tanabe (2015) Jour. Geol. Soc. Japan, vol.121, no.8, pp.265-278, DOI
• Nagamori et al. (2003) Geology of the Togakushi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 109p. (in Japanese with English abstract 3p.)
• Nakano et al. (2002) Geology of the Shiroumadake District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 105p. (in Japanese with English abstract 5p.)
• Kato et al. (1989) Geology of the Omachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 7p.)
• Kato and Akahane (1986) Geology of the Nagano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 120p. (in Japanese with English abstract 5p.)