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Gun River Formation

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

Gun River Formation
Stratigraphic range: Early Silurian (Llandovery)
TypeGeological formation
Sub-units
  • Lachute Member
  • Innomée Member
  • Sandtop Member
  • Macgilvray Member
UnderliesMenier Formation[1]
OverliesMerrimack Formation[1]
Thickness85 to 100 meters[1]
Location
Region Quebec
Country Canada
Type section
Named bySchuchert and Twenhofel[1]
Year defined1910[1]

Description edit

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 edit

Vertebrates edit

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.
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

References edit

  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.


 

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