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 members
Underlies	Clearwater Formation (Wabiskaw Member)
Overlies	Waterways Formation, Banff Formation, Wabamun Formation
Area	140,000 km2 (54,000 sq mi)
Thickness	up to 60 metres (200 ft)
Lithology
Primary	Sand, Sandstone
Other	Silt, mud, coal
Location
Coordinates	56°46′24″N 111°24′13″W / 56.77328°N 111.40374°W / 56.77328; -111.40374 (McMurray Formation)
Region	Alberta
Country	Canada
Type section
Named for	Fort McMurray
Named by	F.H. McLearn,1917

The McMurray Formation is a stratigraphic unit of Early Cretaceous age (late Barremian to Aptian stage) of the Western Canada Sedimentary Basin in northeastern Alberta. It takes the name from Fort McMurray, and was first described in the outcrops exposed along the banks of the Athabasca River, 5 kilometres (3.1 mi) north of Fort McMurray, by F.H. McLearn in 1917. It is a well-studied example of fluvial to estuarine sedimentation, and it is economically important because it hosts most of the vast bitumen resources of the Athabasca Oil Sands region.

The McMurray Formation consists of fine- to coarse-grained quartzitic sand and sandstone, interbedded with lesser amounts of silt, mud, clay and, less commonly, thin coal beds. The sands are very loose and friable, unless they are partially or fully cemented with bitumen, calcite or, rarely, quartz.

Three members have been defined within the McMurray Formation. They can be differentiated in outcrops and, to a lesser degree, in the subsurface:

The McMurray Formation outcrops along the Athabasca and Clearwater Rivers near Fort McMurray, in the Athabasca Oil Sands of northeastern Alberta, where it averages about 60 metres (200 ft) thick. It thins eastward into Saskatchewan where, in most areas, it is devoid of bitumen. It has been removed by erosion north of the Athabasca Oil Sands area.