Vanguard Formation
| Vanguard Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Sub-units | Masefield Shale Roseray Formation Rush Lake Shale |
| Underlies | Mannville Group |
| Overlies | Shaunavon Formation |
| Thickness | up to 180 metres (590 ft)[1] |
| Lithology | |
| Primary | Shale, sandstone |
| Location | |
| Coordinates | Lua error in Module:Coordinates at line 489: attempt to index field 'wikibase' (a nil value). |
| Region | WCSB, Williston Basin |
| Country | Canada, United States |
| Type section | |
| Named for | Vanguard, Saskatchewan |
| Named by | Milner & Thomas |
| Year defined | 1954 |
Vanguard Formation (Canada) | |
The Vanguard Formation is a stratigraphical unit of Callovian to Oxfordian age in the Western Canadian Sedimentary Basin.
It takes the name from Vanguard, and was first defined by R.L. Milner and G.E. Thomas in 1954.[2]
Lithology
[edit | edit source]The Vanguard Formation is composed of calcareous shale with a median quartzose sandstone. [1]
Distribution
[edit | edit source]The Vanguard Formation Lateral reaches a maximum thickness of 180 metres (590 ft) in the Williston Basin along the Saskatchewan/Montana border.[1]
Relationship to other units
[edit | edit source]The Vanguard Formation is unconformably overlain by the Mannville Group and disconformably overlays the Shaunavon Formation.[1]
It is equivalent to the Ellis Group in Montana and North Dakota.
Subdivisions
[edit | edit source]In south-western Saskatchewan, Vanguard has group status, and includes the following subdivisions (of formation rank):
- Masefield Shale: calcareous shale
- Roseray Formation: quartzose glauconitic sandstone
- Rush Lake Shale: calcareous shale with Gryphaea and Kepplerites ammonite fossils