OM-18 - Omagari Formation, Tokomuro district: Late Oligocene, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Carditida - Carditidae
R category
VA category
R category
Bivalvia - Protobranchia - Sareptidae
R category
Bivalvia - Protobranchia - Yoldiidae
R category
Bivalvia - Protobranchia - Nuculidae
R category
Acila cf. praedivaricata Nagao and Huzioka 1941
VA category
Acila brevis Nagao and Huzioka 1941
C category
see common names

Geography
Country:Japan
Coordinates: 42.8° North, 143.7° East (view map)
Paleocoordinates:44.4° North, 140.2° East (Wright 2013)
Basis of coordinate:based on nearby landmark
Geographic resolution:small collection
Time
Period: Paleogene Epoch: Oligocene
Stage: Chattian 10 m.y. bin: Cenozoic 4
Key time interval: Late Oligocene
Age range of interval: 27.3 - 23.04 m.y. ago
Stratigraphy
Formation:Omagari
Stratigraphic resolution:bed
Stratigraphy comments: STRATIGRAPHIC RELATIONS: From Omagari Fm of the Ombetsu Gp, which overlies the Shakubetsu Fm of the Urahaoro Gp (Early Oligocene) and is overlain by the Charo Fm of the Ombetsu Gp (Late Oligocene). THICKNESS: From bed with unit 60-160 m thick. AGE: Late Oligocene based on molluscan biostratigraphy. STRATIGRAPHIC POSITION: Unknown position within formation.
Lithology and environment
Primary lithology: lithified conglomeratic sandstone
Includes fossils?Y
Lithology description: SPECIFIC LITHOLOGY: Conglomerate sandstone. LITHIFICATION: Assumed to be lithifed on the basis of figured specimens and age.
Environment:coastal indet.
Geology comments: ENVIRONMENT: Coastal marine, siliciclastic environment.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Collection methods:field collection
Reason for describing collection:taxonomic analysis
Collection method comments: COLLECTOR: Presumably S. Yui (c. 1975). REPOSITORY: Probably Tohoku University, Japan.
Taxonomic list comments:COVERAGE: Exhaustive for gastropoda, bivalvia and scaphopoda. NOMENCLATURE: Authoritative publication, using moderately recent nomenclature, subgenus and species level designations.
Metadata
Database number:70616
Authorizer:A. Hendy Enterer:A. Hendy
Research group:marine invertebrate
Created:2007-03-29 19:56:58 Last modified:2025-02-22 15:12:02
Access level:authorizer only Released:2007-03-29 19:56:56
Creative Commons license:CC0
Reference information

Primary reference:
23698. Y. Honda. 1989. Paleogene molluscan faunas from the Kushiro Coal Field, Eastern Hokkaido. Tohoku University, Science Report, 2nd series 60(1):1-137 [A. Hendy/A. Hendy]