ammonites

G. spiralis, Greyson Shale, Montana - Walter et. al 1990: Neoproterozoic, Montana

Where & when
Geology
Taphonomy & methods
Metadata & references
Geography
Country:United States State/province:Montana
Coordinates: 46.5° North, 111.3° West (view map)
Paleocoordinates:46.5° North, 111.2° West
Basis of coordinate:based on nearby landmark
Geographic resolution:outcrop
Time
Key time interval:Neoproterozoic
Age range of interval:1000.0 - 542.0 m.y. ago
Stratigraphy
Formation:Greyson Shale
Stratigraphic resolution:bed
Stratigraphy comments: The fossil bearing strata discussed are in a monotonous (repeating) sequence of the described lithology. It should be noted that a lagoonal setting is rejected as there is no evidence for a barrier in this portion of the section. However, the environment is thought to be a ""protected"" offshore setting.
Lithology and environment
Primary lithology:gray,green lithified "shale"
Secondary lithology: lithified siltstone
Includes fossils?Y
Lithology description: slightly greenish gray shale, muddy siltstone, and laminae and thinbeds of very fine-grained sandstone (below storm wave base).
Environment:offshore ramp
Taphonomy
Collection methods and comments
Collection methods:field collection
Reason for describing collection:taxonomic analysis
Collection method comments: Strata containing fossils is thought to be 1500 to 1300 MA old based on paleomagnetic data (Elston, 1984).
Metadata
Database number:10306
Authorizer:M. Patzkowsky Enterer:P. Borkow
Modifier:C. Visaggi Research group:marine invertebrate
Created:2001-04-03 12:04:00 Last modified:2004-03-11 14:25:09
Access level:the public Released:2001-04-03 12:04:00
Reference information
Primary reference:
3827 M. R. Walter, D. U. Rulin, and R. J. Horodyski. 1990. Coiled carbonaceous megafossils from the Middle Proterozoic of Jixian (Tianjin) and Montana. American Journal of Science 290-A:133-148 [M. Patzkowsky/P. Borkow]