Joli Fou Formation
Encyclopedia
The Joli Fou Formation is a stratigraphical
unit of middle Albian
age
in the Western Canadian Sedimentary Basin
. It takes the name from the Joli Fou Rapids on the Athabasca River
, and was first described in an outcrop along the river, 8 kilometres (5 mi) downstream from Joli Fou Rapids, by RTD Wickenden in 1949.
with minor sandstone
lenses. The shale is non-calcareous, dark grey, while the sandstone lenses are fine to minor medium grained, quartzose or micaceous. In central Saskatchewan, the unit contains glauconitic
sandstone and mudstone
interbeds.
. It occurs throughout the Western Canadian Sedimentary Basin, from the Rocky Mountain Foothills to south-central Saskatchewan.
. It is overlain by the Viking Formation
(disconformably
in south-eastern Saskatchewan) and conformably underlain by the upper Mannville Group
(Grand Rapids Formation in north-eastern Alberta, Pelican Formation in southern Alberta).
It is equivalent to the lower Ashville Formation
in southern Manitoba
, the Skull Creek Shale in North Dakota
and parts of the Blackleaf Formation in northern Montana
.
In south-eastern Alberta, the base of the Formation contains the Cessford Sand marker, consisting of sandstone, siltstone and mudstone.
The Joli Fou Formation was previously referred to as the Pelican Shale, but renamed in 1949 to avoid confusion with the overlying Pelican Sandstone beds.
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
unit of middle Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
age
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...
in the Western Canadian Sedimentary Basin
Western Canadian Sedimentary Basin
The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...
. It takes the name from the Joli Fou Rapids on the Athabasca River
Athabasca River
The Athabasca River originates from the Columbia Glacier of the Columbia Icefield in Jasper National Park in Alberta, Canada...
, and was first described in an outcrop along the river, 8 kilometres (5 mi) downstream from Joli Fou Rapids, by RTD Wickenden in 1949.
Lithology
The Joli Fou Formation is composed of shaleShale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
with minor sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
lenses. The shale is non-calcareous, dark grey, while the sandstone lenses are fine to minor medium grained, quartzose or micaceous. In central Saskatchewan, the unit contains glauconitic
Glauconite
Glauconite is an iron potassium phyllosilicate mineral of characteristic green color with very low weathering resistance and very friable.It crystallizes with a monoclinic geometry...
sandstone and mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
interbeds.
Distribution
The Joli Fou Formation is 33 metres (108.3 ft) thick at its type section, and reaches up to 61 metres (200.1 ft) in southern SaskatchewanSaskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
. It occurs throughout the Western Canadian Sedimentary Basin, from the Rocky Mountain Foothills to south-central Saskatchewan.
Relationship to other units
The Joli Fou Formation is the basal (oldest) formation of the Colorado GroupColorado Group
The Colorado Group, also called the Colorado shale, is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.It was first described in the Rocky Mountains front ranges of Colorado by A. Hague and S.E...
. It is overlain by the Viking Formation
Viking Formation
The Viking Formation is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.It takes the name from the town of Viking, Alberta, and was first described in the Viking-Kinsella oil field by Dowling in 1919.-Lithology:...
(disconformably
Unconformity
An unconformity is a buried erosion 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 of time before deposition of the younger, but the term is used to describe...
in south-eastern Saskatchewan) and conformably underlain by the upper Mannville Group
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...
(Grand Rapids Formation in north-eastern Alberta, Pelican Formation in southern Alberta).
It is equivalent to the lower Ashville Formation
Ashville Formation
The Ashville Formation is a geological formation in Saskatchewan and Manitoba whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation....
in southern Manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
, the Skull Creek Shale in North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
and parts of the Blackleaf Formation in northern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
.
In south-eastern Alberta, the base of the Formation contains the Cessford Sand marker, consisting of sandstone, siltstone and mudstone.
The Joli Fou Formation was previously referred to as the Pelican Shale, but renamed in 1949 to avoid confusion with the overlying Pelican Sandstone beds.