The Nahanni Formation is a

stratigraphical 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: lithostrati ...

unit of

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in Fra ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the

Western Canadian Sedimentary Basin The Western Canadian Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ...

. It takes the name from

Nahanni Butte Nahanni Butte ( ; Slavey language: Tthenáágó "strong rock") is a "Designated Authority" in the Dehcho Region of the Northwest Territories, Canada. The community is located at the confluence of the Liard River, Liard and South Nahanni Rivers i ...

, a prominent ridge at the confluence of the

South Nahanni River The South Nahanni River is a major tributary of the Liard River, located roughly west of Yellowknife in the Northwest Territories of Canada. It is the centerpiece of Nahanni National Park Reserve. It flows from the Mackenzie Mountains in the wes ...

and

Liard River The Liard River of the North American boreal forest flows through Yukon, British Columbia and the Northwest Territories, Canada. Rising in the Saint Cyr Range of the Pelly Mountains in southeastern Yukon, it flows southeast through British Co ...

, and was first described in outcrop on the south face of the mountain by C.O. Hage in 1945.Hage, C.O., 1945. Geological reconnaissance along the lower Liard River, British Columbia, Yukon and Northwest Territories. Geol. Surv. Can., Paper 45-22.

Lithology

The Nahanni Formation is composed of

dolomitic Dolomite () is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite. An alternative name sometimes used for the dolomiti ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

Petroleum geology

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

is produced from the Nahanni Formation in the Mackenzie River Valley.

Paleontology

The Nahanni Formation contains paleofauna composed of

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

s and

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

Distribution

The Nahanni Formation reaches a maximum thickness of at

, and has typical thickness of . It occurs from the Franklin Mountains in the north to north-eastern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

in the south.

Relationship to other units

The Nahanni Formation is conformably overlain by the

Fort Simpson Formation The Fort Simpson Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin. It takes the name from the settlement of Fort Simpson, and was first described in well Briggs Turkey Lake No. 1 (located south-east ...

in the west and by the

Horn River Formation The Horn River Formation (also ''Horn River Shale'') is a stratigraphic unit of Devonian (early Givetian to late Frasnian) age in the Western Canadian Sedimentary Basin. It is a thick sequence of marine sediments that was first described in out ...

in the east. It overlays the

Headless Formation The Headless Formation is a Formation (geology), geologic formation in Northwest Territories. It preserves fossils dating back to the Devonian Period (geology), period. See also * List of fossiliferous stratigraphic units in Northwest Territorie ...

diachronically and transitionally, with younger deposits occurring in the west. It is equivalent to the upper part of the

Hume Formation The Hume Formation is a geologic formation in the Northwest Territories, Canada. It preserves fossils dating back to the Devonian period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation ma ...

in the Mackenzie River area, as well as the Lonely Bay Formation,

Pine Point Formation The Pine Point Formation is a stratigraphical unit of Givetian age in the Western Canadian Sedimentary Basin. It takes the name from Pine Point, a promontory (and former townsite) on the south shore of the Great Slave Lake, west of Fort Resolut ...

and Little Buffalo Formation in the

Great Slave Lake Great Slave Lake (french: Grand lac des Esclaves), known traditionally as Tıdeè in Tłı̨chǫ Yatıì (Dogrib), Tinde’e in Wıìlıìdeh Yatii / Tetsǫ́t’ıné Yatıé (Dogrib / Chipewyan), Tu Nedhé in Dëne Sųłıné Yatıé (Chi ...

area. In

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 cent ...

it corresponds to the

Keg River Formation The Keg River Formation is a stratigraphic unit of Givetian age in the Western Canada Sedimentary Basin. Description It takes the name from the Keg River, a tributary of the Peace River, and was first described in the California Standard Steen ...

References

{{Western Canadian Sedimentary Basin, Liard_River=yes Stratigraphy of British Columbia Stratigraphy of the Northwest Territories Givetian Stage Devonian southern paleotropical deposits