Английская Википедия:Attawapiskat Formation
Шаблон:Short description Шаблон:Infobox rockunit
The Attawapiskat Formation is a geologic formation in Ontario. It preserves fossils dating back to the Silurian period.
Location
The Attawapiskat Formation encompasses a large portion of the Hudson Bay Basin. The formation remains visible from northern Ontario. A small portion of the formation does extend onto Nunavut territory.
Composition
It is widely believed that the formation originally deposited on a shallow rimmed shelf, followed by the development of barrier reefs into an nonlinear and uncoordinated "belt" around the Hudson Basin. Within the Hudson Bay Lowlands, the formation consists of dolomite and limestone rich in both coral and sponge. The formation is a haven for lithotopes, or media for sediments to deposit, with various types including:
- Mottled to Nodular Skeletal Wackestone
- Stromatoporoid-Coral Framestone
- Pelodial Intraclastic Bindstone
- Graded Oolitic Grainstone
The formation's depth reaches 62 meters at its deepest.
Fossil content
| Brachiopods | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Eocoelia | E. akimiskii | Inter-reef beds of the formation, on Akimiski Island.[1] | Over 300 specimens.[1] | ||
| Erilevigatella | E. euthylomata | [2] | |||
| Gypidula | G. akimiskiformis | [2] | |||
| Meristina | M. expansa | Ekwan River.[3] | Now deemed a junior synonym of Pentameroides septentrionalis. | ||
| Pentameroides | P. septentrionalis | Ekwan River and Attawapiskat River.[3] | |||
| Protanastrophia | P. repanda | [4] | |||
| Reticularia | R. septentrionalis | Ekwan River.[3] | Now deemed a junior synonym of Pentameroides septentrionalis. | ||
| Sapelnikovia | S. (=Reveroides) norfordi | Attawapiskat River.[3] | Now deemed a junior synonym of Pentameroides septentrionalis. | ||
| Trilobites | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Acidaspis | A. sp. | Ekwan River at portage at Strong Rapids.[5] | |||
| Chiozoon | C. cf. cowiei | Ekwan River at portage at Strong Rapids.[5] | |||
| Dicranopeltis | D. sp. | Ekwan River at portage at Strong Rapids.[5] | |||
| Ekwanoscutellum | E. ekwanensis | Limestone Island, Severn River.[5] | "Nested stacks of mostly inverted (concave-up) large sclerites, the majority of which are pygidia".[6] | A scutelluine. | |
| Meroperix | M. aquilonarius | Ekwan River at portage at Strong Rapids.[5] | [6] | A scutelluine. | |
| Opoa | O. sp. | Ekwan River at portage at Strong Rapids.[5] | |||
| Perryus | P. severnensis | Limestone Island, Severn River.[5] | Several cranidia, pygidia and disarticulated exoskeletons.[5] | An encrinurid. | |
| Stenopareia | S. sp. | Ekwan River at portage at Strong Rapids.[5] | [6] | An illaenid. | |
See also
References
- Шаблон:Cite web
- Ramdoyal, A., Nicolas, M.P.B. and Chow, N. 2013: Lithofacies analysis of the Silurian Attawapiskat Formation in the Hudson Bay Lowland, northeastern Manitoba; in Report of Activities 2013, Manitoba Mineral Resources, Manitoba Geological Survey, p. 144–155.
- Gass, Kenneth & Mikulic, Donald. (2011). Observations on the Attawapiskat Formation (Silurian) trilobites of Ontario, with description of a new encrinurine. Canadian Journal of Earth Sciences. 19. 589–596. 10.1139/e82-047.
Шаблон:Canada-geologic-formation-stub
Шаблон:Ontario-geo-stub
