Twitya Formation

The Twitya Formation is a geologic formation in Canada’s Northwest Territories. It mainly consists of cap carbonate rocks, shales and Sandstone-siltstone, with finely laminated mudstone and siltstones.^[1] It preserves fossils dating back to the Cryogenian period.^[3]

Twitya Formation
Stratigraphic range: Cryogenian 662.4 Ma[1] Pha. Proterozoic Archean Had. ↓
Type	Formation
Unit of	Hay Creek Group[1]
Underlies	Keele Formation
Overlies	Shezal Formation
Thickness	900 m (2,952 ft)[2]
Lithology
Primary	Cap carbonate
Other	Mudstone, Siltstone, Shale, Sandstone
Location
Region	Northwest Territories
Country	Canada

Dating

Using a combination of Re-Os geochronology and Os-Sr isotope dating at the base of the Twitya Formation, a date of 662±3 Ma has been recovered, placing the formation within the late Cryogenian.^[1]

Paleobiota

The Twitya Formation contains a small selection of discoidal and annunli forms, from Nimbia occlusa to tentative records of Irridinitus and Vendella.^[3]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

incertae sedis

Genus	Species	Notes	Images
Nimbia[3]	N. occlusa	Discoid organism.
Irridinitus (?)[3]	Irridinitus sp. (?)	Discoid organism, tentative assignment.
Vendella (?)[3]	Vendella sp. (?)	Discoid organism, tentative assignment. It is noted that it may be a junior synonym of Beltanelliformis.

See also

• Earth sciences portal
• Canada portal
• Paleontology portal

• List of fossiliferous stratigraphic units in Northwest Territories