Gun River Formation

Geologic formation in Quebec, Canada

Gun River Formation

Stratigraphic range: Early Silurian (Llandovery)
Type| Geological formation
Sub-units|

* Lachute Member
* Innomée Member
* Sandtop Member
* Macgilvray Member

Underlies| Menier Formation[1]
Overlies| Merrimack Formation[1]
Thickness| 85 to 100 meters[1]
Location
Region| Quebec
Country| Canada
Type section
Named by| Schuchert and Twenhofel[1]
Year defined| 1910[1]

The Gun River Formation is a geologic formation in Quebec. It preserves fossils dating back to the early Silurian period.

## Description

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The formation is divided into 4 members (from the base up): the Lachute, Innommée, Sandtop and Macgilvray members. The formation was deposited some 40–80 km offshore from the stable Laurentian craton, underwater at depths of 30 to 60 meters.[1]

## Fossil content

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### Vertebrates

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Color key
| Taxon | Reclassified taxon | Taxon falsely reported as present | Dubious taxon or junior synonym | Ichnotaxon | Ootaxon | Morphotaxon

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| Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.
Conodonts

Genus | Species | Presence  | Material | Notes | Images
Anticostiodus | A. fahraeusi | Anticosti Island.[2] |  |  |
A. boltoni | Anticosti Island.[2] |  |  |
Icriodella | I. deflecta |  |  | Probably instead belongs to the Jupiter Formation.[1] |

### Invertebrates

[edit]

Brachiopods

Genus | Species | Presence  | Material | Notes | Images
Brachyprion |  | Sandtop and Macgilvray Members.[1] |  | A strophomenid.  |
Coolinia |  | Sandtop and Macgilvray Members.[1] |  |  |
Fenestrirostra | F. glacialis | Lowermost part of the formation.[3] |  | A rhynchonellidalso found in the Merrimack Formation.  |
F. pyrrha | Lachute Member.[1] |  | A rhynchonellid.  |
'Gotatrypa' | 'G.' sp.  | Innommée Member.[1] |  |  |
Hyattidina |  | Sandtop to Macgilvray Members.[1] |  | An athyrid.  |
Joviatrypa |  | Uppermost Macgilvray Member.[1] |  |  |
Kulumbella | K. xacta | Upper Macgilvray Member.[4][5] |  | A pentamerid.  |
Mendacella |  | Innommée Member.[1] |  | A dalmanellid.  |
Meristina |  | Innommée Member.[1] |  |  |
Pentamerus | P. palaformis | Top of the formation (uppermost Macgilvray Member).[1][4] |  | Also found in the Jupiter Formation.  |
Stegerhynchus |  | [1] |  |  |
Stricklandia | S. gwelani | Top of the formation (Macgilvray Member).[1][4] |  | Also found in the Jupiter Formation.  |
S. sp.  | Innommée Member.[4] | A509 (7 broken valves on a slab).[4] | Also found in the uppermost Merrimack Formation.  |
Sypharatrypa | S. sp.  | Innommée Member.[1] |  |  |
Bryozoans

Genus | Species | Presence  | Material | Notes | Images
Phaenopora | P. superba |  |  | Also found in the Becscie Formation.[6] |
Ptilodictya | P. canadensis |  | USNM 143039.[6] |  |
P. sulcata |  | USNM 143039, 143050; YPM 3063/98, 3063/104.[6] |  |
Corals

Genus | Species | Presence  | Material | Notes | Images
Acidolites | A. arctatus | [7] |  | A heliolitid.  |
Brachyelasma |  | [1] |  |  |
Crassilasma |  | [1] |  |  |
Helicelasma |  | [1] |  |  |
Palaearaea |  | Cap aux Goélands (Uppermost Macgilvray Member).[1] | Small colonies.[1] | The only rugosan coral known from the formation, also found in the Menier formation.  |
Paleofavosites | P. capax |  | Multiple colonies.[8] | A tabulate coral.  |
Crinoids

Genus | Species | Presence  | Material | Notes | Images
Dendrocrinus |  | [1] |  |  |
Eumyelodactylus |  | Macgilvray Member.[1] |  |  |
Laurocrinus |  | Macgilvray Member.[1] |  |  |
Stupatocrinus |  | Macgilvray Member.[1] |  |  |
Graptolites

Genus | Species | Presence  | Material | Notes | Images
Paraclimacograptus | P. cf. innuitus | Deeper water facies of the Sandtop Member.[1] |  |  |
Sponges

Genus | Species | Presence  | Material | Notes | Images
Camptodictyon |  | [1] |  | A stromatoporoid.  |
Clathrodictyon |  | [1] |  | A stromatoporoid.  |

## See also

[edit]

* Earth sciences portal
* Canada portal
* Paleontology portal

* List of fossiliferous stratigraphic units in Quebec

## References

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1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae Copper, Paul; Long, Darrel G. F.; Jin, Jisuo (2012). "The Early Silurian Gun River Formation of Anticosti Island, eastern Canada: A key section for the mid-Llandovery of North America". Newsletters on Stratigraphy. 45 (3): 263. doi:10.1127/0078-0421/2012/0024. ISSN 0078-0421.
2. ^ a b Zhang, Shunxin; Barnes, Christopher R. (July 2000). "Anticostiodus, a new multielement conodont genus from the Lower Silurian, Anticosti Island, Quebec". Journal of Paleontology. 74 (4): 662–669\. doi:10.1666/0022-3360(2000)074<0662:AANMCG>2.0.CO;2. ISSN 0022-3360. S2CID 59056082.
3. ^ Jin, Jisuo; Caldwell, W. G. E.; Copper, Paul (March 1990). "Evolution of the Early Silurian rhynchonellid brachiopod Fenestrirostra in the Anticosti Basin of Quebec". Journal of Paleontology. 64 (2): 214–222\. doi:10.1017/s0022336000018370. ISSN 0022-3360. S2CID 132248649.
4. ^ a b c d e Jin, Jisuo; Copper, Paul. "Late Ordovician and Early Silurian pentamerid brachiopods of Anticosti Island, Québec, Canada". Palaeontographica Canadiana.
5. ^ Jin, Jisuo; Copper, Paul (May 1998). "Kulumbella and Microcardinalia (Chiastodoca) new subgenus, Early Silurian divaricate stricklandiid brachiopods from Anticosti Island, eastern Canada". Journal of Paleontology. 72 (3): 441–453\. doi:10.1017/s0022336000024185. ISSN 0022-3360. S2CID 132809506.
6. ^ a b c "Larger Cryptostome Bryozoa of the Ordovician and Silurian, Anticosti Island, Canada". www.jstor.org. SEPM Society for Sedimentary Geology. JSTOR 1300852. Retrieved 2022-09-18.
7. ^ Dixon, O. A. (January 1986). "The heliolitid coral Acidolites in Ordovician–Silurian rocks of eastern Canada1". Journal of Paleontology. 60 (1): 26–52\. doi:10.1017/S002233600002148X. ISSN 0022-3360. S2CID 130759173.
8. ^ Lee, Dong-Jin; Noble, James P. A. (July 1990). "Reproduction and life strategies in the Paleozoic tabulate coral Paleofavosites capax (Billings)". Lethaia. 23 (3): 257–272\. doi:10.1111/j.1502-3931.1990.tb01452.x. ISSN 0024-1164.

* Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 25 March 2022. Retrieved 17 December 2021.

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