Oguwa Formation, Chikanaga area (Cretaceous of Japan)

Where: Japan (33.3° N, 132.8° E: paleocoordinates 44.8° N, 125.1° E)

• local area-level geographic resolution

When: Oguwa Formation (Shimanto Group), Turonian (93.9 - 89.8 Ma)

• STRATIGRAPHIC RELATIONS: From the Oguwa Fm (Turonian) of the lower Shimanto Group and Shimanto Supergroup, overlying the Shimoono Fm (Middle and Upper Albian) and overlain by the Furushiroyama Fm (Coniacian). AGE: Turonian. STRATIGRAPHIC POSITION: List not specified to any part of the formation.

• formation-level stratigraphic resolution

Environment/lithology: offshore; siliciclastic sediments

• STRATIGRAPHY and STRUCTURE: The Shimanto Supergroup is a thick clastic sequence with minor basic volcanic rocks, chert and limestone. The Aptian, Albian, Turonian, and Conacian to Santonian strata are in fault contact with one another. The Lower Cretaceous, except for the Lower Aptian is regarded as rather deep offshore deposits, while the Upper Cretaceous as neritic, shelf deposits.
• SPECIFIC LITHOLOGY: Lithology, unknown, presumably siliciclastic. LITHIFICATION: No evidence for lithification.

Size class: macrofossils

Collection methods: COLLECTOR: Collector unknown. REPOSITORY: Repository unknown.

Primary reference: Y. Teraoka, I. Obata, and I. Mizuno. 1980. Stratigraphy of the Shimanto Supergroup in the Chikanaga area, west Shikoku, with special reference to the Miyakoan and Gyliakian Series. Bulletin of the Geological Survey of Japan 31(7):307-319 [A. Hendy/A. Hendy]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 65022: authorized by Austin Hendy, entered by Austin Hendy on 18.09.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Suspected to only include biostratigraphically important taxonomic groups (i.e. inoceramids and ammonoids). NOMENCLATURE: Not an authoritative publication, but using subgeneric and species-level designations.
Malacostraca
 Decapoda - Palinuridae
Linuparus aff. japonicus Nagao 1931 spiny lobster
Bivalvia
 Myalinida - Inoceramidae
 Lucinida - Lucinidae
Lucinoma ? sp. Dall 1901 clam
Gastropoda
 Sorbeoconcha - Naticidae
Gyrodes sp. Conrad 1860 moon snail
Cephalopoda
 Ammonitida - Acanthoceratidae
Romaniceras ? sp. Spath 1923 ammonite
Romaniceras cf. deverioides de Grossouvre 1889 ammonite
 Ammonitida - Collignoniceratidae
 Ammonitida - Desmoceratidae
Mesopuzosia sp. Matsumoto 1954 ammonite
 Ammonitida - Tetragonitidae
 Ammonitida - Nostoceratidae
Eubostrychoceras ? sp. Matsumoto 1967 ammonite
 Ammonitida - Scaphitidae
"Otoscaphites sp." = Yezoites, "Otoscaphites (Otoscaphites) puerculus" = Yezoites puerculus, "Otoscaphites (Hyposcaphites) cf. perrini" = Yezoites perrini
"Otoscaphites sp." = Yezoites ammonite
"Otoscaphites (Otoscaphites) puerculus" = Yezoites puerculus Jimbo 1894 ammonite
"Otoscaphites (Hyposcaphites) cf. perrini" = Yezoites perrini Anderson 1902 ammonite
 Nautilida - Nautilidae
Cymatoceras sp. Hyatt 1884 nautiloid
Echinoidea
 Spatangoida - Hemiasteridae