McMurray Formation

McMurray Formation Stratigraphic range: late Barremian to Aptian PreЄ Є O S D C P T J K Pg N
Outcrop along the Athabasca River, c. 1900
Type	Geological formation
Unit of	Mannville Group
Sub-units	Upper, Middle and Lower Member
Underlies	Clearwater Formation (Wabiskaw Member)
Overlies	Banff Formation, Wabamun Formation
Area	140,000 km2 (54,000 sq mi)[1]
Thickness	up to 60 metres (200 ft)[2]
Lithology
Primary	Sandstone
Other	Siltstone
Location
Named for	Fort McMurray
Named by	F.H. McLearn,1917
Coordinates	56°46′24″N 111°24′13″W / 56.77328°N 111.40374°W / 56.77328; -111.40374 (McMurray Formation)
Region	north-eastrn  Alberta
Country	Canada

The McMurray Formation is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.

It takes the name from Fort McMurray, and was first described in the outcrop occurring on the banks of the Athabasca River (5 kilometres (3.1 mi) north of Fort McMurray) by F.H. McLearn in 1917.^[3]

Lithology

The McMurray Formation consists of fine grained quartzitic bitumenous sand and sandstone.

Three members were described inside the McMurray Formation, and can be differentiated in outcrops (to a lesser degree in the sub-surface):

• Lower Member: conglomeratic sandstone, present only in depressions formed in the underlying Devonian limestone.
• Middle Member: massive well sorted, fine grained oil saturated sand in the base, with inclined beds of thick rippled sandstone and thin shaley siltstone partings in the top.
• Upper Member: horizontal, argillaceous very fine grained sandstone with oil saturation

Oil/gas production

McMurray Formation mined in Syncrude's Mildred Lake mine site

Bitumen is produced from the McMurray Formation in the Athabasca Oil Sands by open pit mining and from the sub-surface with SAGD techniques. East of Fort McMurray, it contains water instead of bitumen.

Distribution

The McMurray Formation reaches a maximum thickness of 60 metres (200 ft) in the Athabasca Oil Sands. It thins out towards the west and south. It is completely eroded north of the outcrop area.

Relationship to other units

The McMurray Formation is conformably overlain by the Wabiskaw Member of the Clearwater Formation and rests unconformably on Paleozoic limestone beds of the Banff Formation, Wabamun Formation or Winterburn Formation. The McMurray Formation is equivalent with the Ostracod Beds of the Mannville Group in central Alberta, with the Dina Member in the Lloydminster area and the Gething Formation of western and northern Alberta and northeastern British Columbia. In some interpretations it is considered part of the Mannville Group.

References

1. ^ Alberta Geological Survey. "Alberta Oil Sands". http://www.ags.gov.ab.ca/energy/oilsands/alberta_oil_sands.html. Retrieved 2009-03-02. 
2. ^ Lexicon of Canadian Geological Units. "McMurray Formation". http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:009513. Retrieved 2009-02-28. 
3. ^ McLearn, F.H., 1917. Athabasca River section, Alberta. Geological Survey of Canada Summary Report 1916, p. 145-151.