Coalspur Formation
| Coalspur Formation Stratigraphic range: Maastrichtian to Danian |
|
|---|---|
| Type | Formation |
| Unit of | Saunders Group |
| Sub-units | Coalspur coal zone, Entrance conglomerate |
| Underlies | Paskapoo Formation |
| Overlies | Brazeau Formation |
| Thickness | Up to about 550 metres (1,800 ft) |
| Lithology | |
| Primary | Sandstone, siltstone, shale |
| Other | Coal, conglomerate, bentonite |
| Location | |
| Region |
 Alberta
|
| Country |
 Canada
|
| Type section | |
| Named for | Coalspur, Alberta |
| Named by | B.R. MacKay, 1949 |
The Coalspur Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in the foothills of southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous (Maastrichtian) to early Palaeocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It includes the economically important coal deposits of the Coalspur Coal Zone, as well as nonmarine plant and animal fossils.
The sediments of the Coalspur Formation were eroded from the Canadian Cordillera, and were transported eastward by river systems and deposited in fluvial channel and floodplain environments. The formation consists primarily of sandstones and siltstones, interbedded with mudstones and minor amounts of bentonite. Thick coal seams are present locally in the upper portion of the formation, especially in the Alberta Coal Branch area southeast of Hinton, Alberta. Near the Athabasca River the base consists primarily of conglomerate and is known as the Entrance Conglomerate.
The Coalspur Formation is part of the Saunders group. The K-Pg boundary has been identified within the formation at the base of the lowermost coal seam (the Mynheer seam), based on changes in the fossil pollen assemblage and the presence of an iridium anomaly. The boundary subdivides the Coalspur Formation into an upper member called the Coalspur coal zone which is of early Paleocene age, and an unnamed lower member of latest Cretaceous age.
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