USGS Mesozoic loc. 20734: Callovian, Alaska
collected by D.L. Minard 1946

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Trigoniida - Myophorellidae
Vaugonia doroschini (Eichwald 1871)
original and current combination Trigonia doroschini
see common names

Geography
Country:United States State/province:Alaska
Coordinates: 59.7° North, 153.2° West (view map)
Paleocoordinates:31.5° North, 86.8° West
Basis of coordinate:based on nearby landmark
Time
Period:Jurassic Epoch:Middle Jurassic
Stage:Callovian 10 m.y. bin:Jurassic 5
Key time interval:Callovian
Age range of interval:165.30000 - 161.50000 m.y. ago
Stratigraphy
Formation:Chinitna Member:Tonnie Siltstone
Stratigraphy comments: Callovian, 260 to 290 m (850-950 ft) above base of Tonnie Siltstone member of Chinitna Formation
Lithology and environment
Primary lithology:concretionary,brown,gray sandy siltstone
Secondary lithology:fine,gray,green sandstone
Lithology description: Massive arenaceous dark-gray to brownish-gray siltstone constitutes most of the Tonnie Siltstone Member. The siltstone weathers brownish gray to red brown and contains numerous small yellowishbrown-weathering limestone concretions that occur in parallel bands and at random throughout the section. Sandstone is present as thin interbeds in the siltstone, generally being fine grained and greenish gray. A more massive sandstone unit is present at the base of most sections. An unusual feature of the section on Chisik Island is a basal channel conglomerate of cobbles and boulders, mainly volcanic rock types. The Chisik Island section also contains numerous thin beds of volcanic ash.
Environment:marine indet.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils,mesofossils
Collection methods and comments
Reason for describing collection:taxonomic analysis
Museum repositories:USNM
Collectors:D.L. Minard Collection dates:1946
Metadata
Database number:139582
Authorizer:G. Stanley Enterer:H. Shepherd
Created:2013-02-14 07:09:52 Last modified:2013-02-13 14:09:52
Access level:the public Released:2013-02-14 07:09:52
Creative Commons license:CC BY
Reference information

Primary reference:
40842. T. P. Poulton. 1979. Jurassic Trigoniid Bivalves from Canada and Western United States of America. Geological Survey of Canada Bulletin 282 [G. Stanley/H. Shepherd/H. Shepherd]