Twitya Formation
| Twitya Formation | |
|---|---|
| Stratigraphic range: Cryogenian | |
| 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 |
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]
Dating
[edit]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
[edit]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
|
Notes Uncertain or tentative taxa are in small text; |
incertae sedis
[edit]| Genus | Species | Notes | Images |
|---|---|---|---|
| Nimbia[3] |
|
Discoid organism. |  |
| Irridinitus (?)[3] |
|
Discoid organism, tentative assignment. | |
| Vendella (?)[3] |
|
Discoid organism, tentative assignment. It is noted that it may be a junior synonym of Beltanelliformis. |
See also
[edit]
References
[edit]- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.
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- ^ a b c d Rooney, Alan D.; Macdonald, Francis A.; Strauss, Justin V.; Dudás, Francis Ö.; Hallmann, Christian; Selby, David (7 January 2014). "Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth". Proceedings of the National Academy of Sciences. 111 (1): 51–56. doi:10.1073/pnas.1317266110.
- ^ Narbonne, G; Aitken, J (May 1995). "Neoproterozoic of the Mackenzie Mountains, northwestern Canada". Precambrian Research. 73 (1–4): 101–121. doi:10.1016/0301-9268(94)00073-Z.
- ^ a b c d e Hofmann, H. J.; Narbonne, G. M.; Aitken, J. D. (1990). "Ediacaran remains from intertillite beds in northwestern Canada". Geology. 18 (12): 1199. doi:10.1130/0091-7613(1990)018<1199:ERFIBI>2.3.CO;2.