The Bluesky Formation is a

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

unit of

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eig ...

age in the Western Canada Sedimentary Basin. It takes the name from the hamlet of

Bluesky Blue Sky, BlueSky or Bluesky may refer to: Places * Blue Sky, Colorado, U.S. *Bluesky, Alberta, Canada Science *Blue skies research (also called blue sky science), scientific research in domains where "real-world" applications are not immediate ...

, and was first described in Shell's ''Bluesky No. 1'' well by Badgley in 1952.

Lithology and Depositional Environment

The formation is composed of

mudstones Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' ...

, conglomerates and

sandstones Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) b ...

which can be quartzose or contain

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...

grains. Many of the Bluesky sandstones do not display bedding features although some low and moderate-angle large scale cross-bedding has been observed in some sections. The sediments were deposited in both marginally marine nearshore and fully marine offshore settings following a transgression of the ancient Moosebar Sea. Bluesky sediments are separated from Gething strata by a scoured or loaded contact and occasionally by a burrowed '' Glossifungites'' surface. The Bluesky Formation can be very porous and produces hydrocarbons in many areas across Western Canada. Heavy oil is produced from the Bluesky formation in the

Peace River The Peace River (french: links=no, rivière de la Paix) is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in th ...

area.

Distribution

The Bluesky Formation reaches a thickness of in the Pouce Coupe area, and thins out toward north and west. Thin sands can be found in the

area.

Relationship with other units

Although some early workers included the Bluesky Formation in the

Bullhead Group Bullhead Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin of northeastern British Columbia and western Alberta. It was first defined by F.H. McLearn in 1918 as the Bullhead Mountain Formation, but later ...

, it is usually classified as the basal unit of the Fort St. John Group. It is conformably overlain by the Wilrich Member of the Spirit River Formation and conformably underlain by the

Gething Formation Gething Formation is a stratigraphic unit of Lower Cretaceous ( Aptian) age in the Western Canada Sedimentary Basin. It is present in northeastern British Columbia and western Alberta, and includes economically important coal deposits. The forma ...

. Northeast of the town of

it was deposited

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...

on Mississippian limestone. It is equivalent with the

Glauconitic Sandstone Greensand or green sand is a sand or sandstone which has a greenish color. This term is specifically applied to shallow marine sediment that contains noticeable quantities of rounded greenish grains. These grains are called ''glauconies'' and c ...

of the

Mannville Group The Mannville Group is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin. It takes the name from the town of Mannville, Alberta, and was first described in the ''Northwest Mannville 1'' well by A.W. Nauss in 194 ...

in central and

southern Alberta Southern Alberta is a region located in the Canadian province of Alberta. In 2004, the region's population was approximately 272,017.Wabiskaw Member of the Clearwater Formation in the eastern part of

northern Alberta Northern Alberta is a geographic region located in the Canadian province of Alberta. An informally defined cultural region, the boundaries of Northern Alberta are not fixed. Under some schemes, the region encompasses everything north of the cen ...

Bitumen Deposits

The Bluesky deposit of bitumen comes from the "clean estuarine reservoir sands of the Cretaceous-age Bluesky Formation" in the

. Secondary production area is the Gething Formation. The combined Bluesky-Gething deposit is the primary target area for oil sands development in the Peace River area. There is a reservoir at about – below the surface. Heavy oil in the Peace River, produced from bitumen deposit is extracted using wells not by mining.

References

Stratigraphy of Alberta {{Canada-geologic-formation-stub