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Zukawa Sandstone Member (Mochizuki, 1928) Sumi et al., 1989

Invalid synonym: Zukawa Formation

Correlation: Yabuta Formation, Junicho Formation

• Type locality: Zukawa, Takaoka city, Toyama prefecture
• Coherent formation
• early - late Pliocene
• Interfingered: Omma Sandstone member

• Sedimentary facies: Marine
• Depth of water (Upper): Upper shallow
• Depth of water (Lower): Lower shallow
• Lithofacies (Upper): Gravel-bearing sandstone
• Lithofacies (Upper, Minor): Conglomerate
• Lithofacies (Lower): Calcareous sandstone
• Sedimentary structures: Parallel stratification, Cross stratification
• Paleocurrent: to Northeast - East

• Thickness: ca. 150 - 250 m or thicker
• Upper and lower members are transitional with the boundary at the basement of Ikarabe 2 tephra (IK2)
• Upper limit: Unconformity (Itaya Sandstone and Siltstone Member)
• Lower limit: Unconformity (Yachi Formation, Otogawa Formation)

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

• Distribution: Zukawa - Ikarabe, Takaoka city, Toyama pref.; Horakuji, Oyabe city, Toyama pref.
• Fossils (Calcareous nannofossils): Braarudosphaera bigelowii, Coccolithus pelagicus, Discolithina japonica, Gephyrocapsa spp., Helicosphaera carteri, Helicosphaera hyalina, Helicosphaera sellii, Rhabdosphaera stylifera, Reticulofenestra sp., R. spp., Sphenolithus abies, Syracosphaera pulchra
• Fossils (Zukawa fauna, Shellfishes): Acesta goliath, Acila (Truncacila) insignis, Anadara (Andara) cf. amicula, Anisocorbula venusta, Anomia chinensis, Antiplanes contraria, Arca boucardi, Astarte hakodatensis, Astarte (Tridonta) alaskaensis, Astarte (Tridonta) borealis, Bittium sp., Boreoscala greenlandica, Buccinum sp., Cadella luburica, Callista (Ezocallista) brevisiphonata, Callithaca adamsi, Calyptraea yokoyamai, Cancellaria (Sydaphera) spengleriana, Cardiomya gouldianaCetoconcha sp., Chlamys (Chlamys) cosibensis, Chlamys (Chlamys) farreri, Chlamys (Leochlamys) tanassevitschi, Chlamys (Swiftopecten) swiftii, Clinocardium fastosum, Crassatella (Indocrassatella) oblongata, Crassostrea sp., Crenella yokoyamai, Crithe cotamago, Cryptobranchia kuragiensis, Cryptonatica clausa, Cryptonatica janthostoma, Cryptonatic ajanthostomoides, Cycladicama cumingii, Cyclocardia ferruginea, Cymatiidae gen. et sp. indet, Enida japonica, Ennucula niponica, Entodesma sp., Euspira sp., Ezocallista brevisiphonata, Felaniella ohtai, Felaniella usta, Ginebis crumpii, Glycymeris (Glycymeris) nipponica, Glycymeris (Glycymeris) yessoensis, Glycymeris (Tucetilla) pilsbryi, Homalopoma amussitatum, Irus? sp., Lepeta caeca pacifica, Limatula (stabilima) japonica, Limatula vladivostokensis, Lima vulgatula, Limopsis (Crenulilimopsis) cretata, Limopsis (Enpleconia) cumingi, Limopsis oblonga, Limopsis tokaiensis, Liocyma fluctuosa, Lunatia pila, Macoma (Macoma) calcarea, Macoma (Macoma) contabulata, Macoma (Macoma) incongrua, Macoma (Macoma) nipponica, Mactridae gen. et sp. indet, Megacardita ferruginosa, Megacrenella columbiana, Mercenaria stimpsoni, Miodontiscus nakamurai, Miodontiscus prolongatas nakamurai, Mitrella (Mitrella) bicincta, Mizuhopecten poculum, Mizuhopecten tokyoensis hokurikuensis, Mizuhopecten yessoensis yokoyamae, Modiolus difficilis, Monia macroschisma, Monia umbonata, Myadora japonica, Mya (Mya) cuneiformis, Mytilus sp., Nassarius (Zeuxis) caelatus, Naticidae gen. et sp. indet, Nemocardium samarangae, Neptunea (Golikovia) cf. nikkoensis, Neptunea (Neptunea) insularis, Neverita (Glossaulax) didyma, Nipponoacmaea sp., Niveotectura pallida, Nuculana (Nuculana) pernula, Nuculana (Thestyleda) yokoyamai, Ocinebrellus sp., Olivella spretoides, Ophiodermella kakumensis, Ophiodermella ogurana, Ostrea sp., Panomya nipponica, Panopea japonica, Pecten (Notovola) albicans, Peronidia zyonoensis, Polynemamussium intuscostatum, Portlandia (Megayoldia) thraciaeformis, Profulvia kurodai, Pteropurpura sp., Puncturella nobilis, Reticunassa sp., Retusa (Coleophysis) succincta, Ringicula (Ringiculina) yokoyamai, Rissolina (Rissolina) costulata, Searlesia japonica, Securella sp., Serpulorbis cf. medusae, Solen sp., Spisula (Mactromeris) grayana, Spisula (Mactromeris) vogi, Suavodrilla declivis, Sulcerato callosa, Swiftopecten swiftii, Tachyrhychus onoyamai, Tachyrhynchus venustellus, Thracia kakumana, Thracia kamayasikiensis, Thyasiratokunagai, Tridonta alaskensis, Tridonta borealis, Trophon (Boreotrophon) candelabrum, Turcica coreensis, Turritella (Neohaustator) saishuensis etigoensis, Turritella (Neohaustator) saishuensis motidukii, Turritella (Neohaustator) saishuensis saishuensis, Umbonium (Suchium) akitanum, Venericardia ferruginea orbicularis, Venericardia myogadaniensis, Venericarida (Megayoldia) ommaensis, Yabepecten tokunagai, Yoldia (Cnesterium) notabilis
• Tephra: Shizukudani Tuff Bed (SZp = T3), Ikarabe 1 Buff Bed (IK1), Ikarabe 2 Tuff Bed (IK2)

• Amano et al. (2012) Jour. Geol. Soc. Japan, vol.118, no.12, pp.810-822 DOI
• Sumi et al. (1989) Geology of the Isurugi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 118p. (in Japanese with English abstract 5p.)