Horseshoe Canyon Formation
Horseshoe Canyon Formation | |
---|---|
Stratigraphic range: Maastrichtian ~[1] | |
Type | Geological formation |
Unit of | Edmonton Group |
Underlies | Whitemud Formation |
Overlies | Bearpaw Formation |
Thickness | 227 m (745 ft)[2] |
Lithology | |
Primary | Sandstone |
Other | Shale, coal |
Location | |
Coordinates | 51°25′24″N 112°53′18″W / 51.42333°N 112.88833°W |
Region | Alberta Western Canadian Sedimentary Basin |
Country | Canada |
Type section | |
Named for | Horseshoe Canyon |
Named by | E.J.W. Irish, 1970 |
The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta.[3][4] It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230 metres (750 ft) thick. It is of Late Cretaceous age, Campanian to early Maastrichtian stage (Edmontonian Land-Mammal Age), and is composed of mudstone, sandstone, carbonaceous shales, and coal seams. A variety of depositional environments are represented in the succession, including floodplains, estuarine channels, and coal swamps, which have yielded a diversity of fossil material. Tidally-influenced estuarine point bar deposits are easily recognizable as Inclined Heterolithic Stratification (IHS). Brackish-water trace fossil assemblages occur within these bar deposits and demonstrate periodic incursion of marine waters into the estuaries.
The Horseshoe Canyon Formation crops out extensively in the area around Drumheller, as well as farther north along the Red Deer River near Trochu and along the North Saskatchewan River in Edmonton.[3] It is overlain by the Battle, Whitemud, and Scollard formations.[4] The Drumheller Coal Zone, located in the lower part of the Horseshoe Canyon Formation, was mined for sub-bituminous coal in the Drumheller area from 1911 to 1979, and the Atlas Coal Mine in Drumheller has been preserved as a National Historic Site.[5] In more recent times, the Horseshoe Canyon Formation has become a major target for coalbed methane (CBM) production.
Dinosaurs found in the Horseshoe Canyon Formation include Albertavenator, Albertosaurus, Anchiceratops, Anodontosaurus, Arrhinoceratops, Atrociraptor, Epichirostenotes, Edmontonia, Edmontosaurus, Hypacrosaurus, Ornithomimus, Pachyrhinosaurus, Parksosaurus, Saurolophus, and Struthiomimus. Other finds have included mammals such as Didelphodon coyi, non-dinosaur reptiles, amphibians, fish, marine and terrestrial invertebrates and plant fossils. Reptiles such as turtles and crocodilians are rare in the Horseshoe Canyon Formation, and this was thought to reflect the relatively cool climate which prevailed at the time. A study by Quinney et al. (2013) however, showed that the decline in turtle diversity, which was previously attributed to climate, coincided instead with changes in soil drainage conditions, and was limited by aridity, landscape instability, and migratory barriers.[6]
Oil/gas production
The Drumheller Coal Zone has been a primary coalbed methane target for industry. In the area between Bashaw and Rockyford, the Coal Zone lies at relatively shallow depths (about 300 metres) and is about 70 to 120 metres thick. It contains 10 to 20 metres of cumulative coal, in up to 20 or more individual thin seams interbedded with sandstone and shale, which combine to make an attractive multi-completion CBM drilling target. In total, it is estimated there are 14 trillion cubic metres (500 tcf) of gas in place in all the coal in Alberta.
Biostratigraphy
The timeline below follows syntheses presented by Arbour et al. 2009, Cullen et al. 2013[7] Larson et al. 2010,[8] Williamson & Carr 2002, Claessens & Loewen 2015,[1] and Funston & Currie (2016).[9]
Dinosaurs
Ankylosaurs
Ankylosaurids reported from the Horseshoe Canyon Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Units 2-4 |
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E. longiceps |
Unit 2 |
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E. tutus |
Walter Coombs (1971) synonymised Anodontosaurus lambei with E. tutus. However, recent studies suggest that Anodontosaurus is distinct enough from Euoplocephalus to be placed in its own genus and species.[10][12] Furthermore, all Horseshoe Canyon Formation ankylosaurine specimens were suggested to be reassigned to Anodontosaurus.[11] |
Maniraptors
Maniraptors reported from the Horseshoe Canyon Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
A. curriei |
Frontals, type specimen |
A troodontid |
||||
A. borealis |
Upper unit 4 |
Limb bones, type specimen |
An alvarezsaurid |
|||
A. pennatus [9] |
Unit 1 [9] |
Partial skeleton and skull, type specimen [9] |
A caenagnathid.[9] | |||
A. marshalli |
Upper unit 4 |
Partial skull, type specimen |
A dromaeosaurid | |||
E. curriei[14] |
Unit 1 |
Partial skeleton, type specimen |
A caenagnathid |
Marginocephalians
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Marginocephalians reported from the Horseshoe Canyon Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
A. ornatus |
Units 1 & 2 |
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A. brachyops |
Units 1 & 2 |
"Complete skull."[15] |
||||
E. xerinsularis |
Unit 5 |
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M. cerorhynchus[16] |
Isolated braincase AMNH 5244.[16] |
AMNH 5244 was probably left by an indeterminate leptoceratopsid. | ||||
P. canadensis |
Upper unit 1 |
Ceratopsids | ||||
P. lakustai |
Lower unit 1 |
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S. edmontonense |
Unit 1 |
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"Almond Formation" ceratopsid |
Unnamed |
Upper Unit 1, Horseshoe Canyon Formation, 72.2-71Ma ago).[17] |
Misidentified as Anchiceratops, it is actually a new species, probably the same as a new Pentaceratops-like form from the Almond Formation of Wyoming [18] |
Ornithomimids
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Ornithomimids reported from the Horseshoe Canyon Formation | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
D. brevitertius |
An ornithomimid |
|||||
O. currelli |
Junior synonym of O. edmontonicus | |||||
O. edmontonicus |
Units 1-4 |
Several specimens, type specimen |
An ornithomimid | |||
Unnamed |
Unit 4 |
An ornithomimid |
Ornithopods
Ornithopods reported from the Horseshoe Canyon Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
E. regalis |
Units 1-2 |
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H. altispinus |
Units 4-5 |
"[Five to ten] articulated skulls, some associated with postcrania, isolated skull elements, isolated postcranial elements, many individuals, embryo to adult."[19] |
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P. warreni |
Unit 3 |
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S. osborni |
Unit 4 |
"Complete skull and skeleton, [two] complete skulls."[19] |
Tyrannosaurs
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Theropods reported from the Horseshoe Canyon Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
A. arctunguis |
Junior synonym of A. sarcophagus |
|||||
A. sarcophagus |
Units 2-5 |
Several skeletons and partial skeletons, type specimen |
A tyrannosaurid | |||
D. sp.[20] |
Bonebed, Toothmarks on Saurolophus and Edmontosaurus |
A tyrannosaurid. A specimen of Edmontosaurus regalis and Saurolophus osborni have toothmarks from a species of Daspletosaurus.[20] |
Other Animals
Mammals
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Mammals reported from the Horseshoe Canyon Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
D. coyi |
Other Reptiles
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Reptiles reported from the Horseshoe Canyon Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
S. mccabei |
"a skull, partial lower jaws, and partial postcranial skeleton" |
An alligatoroid |
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C. albertensis |
"partial skeleton with partial skull" |
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L. ultimus |
"a partial skeleton" |
a plesiosaur of uncertain classification |
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B. morrinensis |
"nearly complete shell" |
Fish
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Fish reported from the Horseshoe Canyon Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
H. armaserratus |
See alsoReferences
Bibliography
|
- Geologic formations of Alberta
- Cretaceous Alberta
- Maastrichtian Stage of North America
- Late Cretaceous North America
- Upper Cretaceous Series of North America
- Western Canadian Sedimentary Basin
- Sandstone formations
- Shale formations
- Coal formations
- Fluvial deposits
- Tidal deposits
- Reservoir rock formations
- Source rock formations
- Fossiliferous stratigraphic units of North America
- Paleontology in Alberta