| Gun River Formation | |
|---|---|
| Stratigraphic range: Early Silurian (Llandovery) | |
| Type | Geological formation |
| Sub-units |
|
| 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.
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]
Color key
| Notes Uncertain or tentative taxa are in small text; |
| 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] | |||
| 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 rhynchonellid also 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. | |||
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