Chikanaga Formation, Chikanaga area (Cretaceous of Japan)

Where: Japan (33.3° N, 132.8° E: paleocoordinates 43.4° N, 134.6° E)

• local area-level geographic resolution

When: Chikanaga Formation (Shimanto Group), Early/Lower Aptian (121.4 - 122.5 Ma)

• STRATIGRAPHIC RELATIONS: From the Chikanaga Fm (Lower Aptian) of the lower Shimanto Group and Shimanto Supergroup, overlain by the Kitanada Fm (Upper Aptian). AGE: Early Aptian. 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 65019: 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.
Show authors, comments, and common names
Cephalopoda
 Ammonitida - Douvilleiceratidae
Cheloniceras (Cheloniceras) shimizui, Cheloniceras (Cheloniceras) aff. minimus, Cheloniceras (Cheloniceras) aff. parinodum, Cheloniceras (Cheloniceras) sp.
Cheloniceras (Cheloniceras) sp. Hyatt 1903 ammonite
 Ammonitida -
"Hoplitaceae indet." = Hoplitoidea
"Hoplitaceae indet." = Hoplitoidea Douvillé 1890 ammonite