Golden Valley Formation

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Golden Valley Formation
Stratigraphic range: Late Paleocene-Early Eocene (Clarkforkian-Wasatchian)
~57–52  Ma
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Type Geological formation
Sub-unitsBear Den & Camels Butte Members
Underlies White River Group
Overlies Sentinel Butte Formation
Thicknessup to 122 metres (400 ft) [1]
Lithology
Primary Claystone, mudstone, siltstone, sandstone
Other Lignite, conglomerate
Location
Coordinates 48°30′N102°42′W / 48.5°N 102.7°W / 48.5; -102.7
Approximate paleocoordinates 52°54′N82°12′W / 52.9°N 82.2°W / 52.9; -82.2
Region North Dakota
Country United States
Extent Williston Basin
Type section
Named for Golden Valley, North Dakota
Named byBenson & Laird [2]
Year defined1947
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Golden Valley Formation (the United States)
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Golden Valley Formation (North Dakota)

The Golden Valley Formation is a stratigraphic unit of Late Paleocene to Early Eocene age in the Williston Basin of North Dakota. [3] It is present in western North Dakota and was named for the city of Golden Valley by W.E. Benson and W.M. Laird in 1947. [2] It preserves significant assemblages of fossil plants [3] and vertebrates, [4] as well as mollusk and insect fossils. [3] [4]

Contents

History

The Golden Valley Formation was named in 1947. [2]

Between 1958–61, a large field expedition conducted by the Yale Peabody Museum recovered a plethora of crocodilian remains from the White Butte and Turtle Valley sites (collectively referred to as the South Heart Locality) within the Golden Valley Formation. [5] [6]

Stratigraphy

The Golden Valley Formation is present as a series of outliers in western North Dakota. [7] It is underlain by the Sentinel Butte Formation and unconformably overlain by the White River Group. [1] It reaches thicknesses of up to 122 metres (400 ft) and is subdivided into two members: the Bear Den Member (lower) and the Camels Butte Member (upper). [1]

Lithologies

The base of the Bear Den Member consists of kaolinitic claystone, mudstone and sandstone that weather to white, light grey, orange, and purple. [1] These are overlain by grey or brownish carbonaceous sediments and, in some areas, a bed of lignite (the Alamo Bluff lignite). [3] In places the sequence is capped by a siliceous bed (the Taylor bed [3] ) that represents a weathering surface or paleosol. [1] The Bear Den Member reaches a maximum thickness of about 15 metres (50 ft). [1]

The Camels Butte Member consists of montmorillonitic [3] and micaceous claystone, siltstone, lignite, poorly cemented sandstone and conglomerate. [1] [3] The upper part includes a massive fluvial sandstone that caps many of the major buttes in southwestern North Dakota. [1] The Camels Butte Member reaches a maximum thickness of about 107 metres (350 ft). [1]

Depositional environment

A Coryphodon: Restoration by Heinrich Harder Coryphodon.jpg
A Coryphodon : Restoration by Heinrich Harder

The Golden Valley Formation was deposited in a broad swampy lowland crossed by fluvial channels. [3] Deposition occurred during late Paleocene (Clarkforkian) to early Eocene (Wasatchian) time, [3] a period that spans the Paleocene-Eocene Thermal Maximum. [8]

Paleontology

Plant fossils collected from throughout the formation include floating and rooted aquatic plants such as Salvinia , Nelumbo and Isoetes , and lowland forest plants such as the ferns Onoclea and Osmunda , the conifers Glyptostrobus and Metasequoia , and the dicots Platanus and Cercidiphyllum . [3]

The vertebrate fossils have come primarily from the upper, early Eocene Camels Butte Member. They include the remains of mammals such as Coryphodon , Hyracotherium , Homogalax , Sinopa , Didymictis , Hyopsodus , Paramys and others; there are also remains of fish, amphibians, and reptiles such as Trionyx , Peltosaurus , and four genera of crocodilians. [3] [4]

Invertebrate fossils include shells of freshwater mollusks such as Viviparus , Unio , Hydrobia , and Planorbis , and the wing casing of a crabid beetle. [3] [4]

References

  1. 1 2 3 4 5 6 7 8 9 Murphy, Edward C. et al. 2009. "North Dakota Stratigraphic Column" (PDF). North Dakota Geological Survey, Miscellaneous Series 91. Retrieved 2017-02-06.{{cite web}}: CS1 maint: numeric names: authors list (link)
  2. 1 2 3 Benson, W.E. and Liard, W.M. (1947). Eocene of North Dakota. Geological Society of America Bulletin, vol. 60, pp. 1166–1167.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 Hickey, 1977
  4. 1 2 3 4 Jepsen, G.L. 1963. Eocene vertebrates, coprolites, and plants in the Golden Valley Formation of western North Dakota. Geological Society of America Bulletin, vol. 74, pp. 673–684.
  5. ↑ Jepsen, Glenn L. (1963). "Eocene Vertebrates, Coprolites, and Plants in the Golden Valley Formation of Western North Dakota" . Geological Society of America Bulletin. 74 (6): 673. doi:10.1130/0016-7606(1963)74[673:EVCAPI]2.0.CO;2. ISSN   0016-7606.
  6. ↑ Cossette, A. P.; Tarailo, D. A. (2024). "Crocodylian diversity during the early Eocene climatic optimum in the Golden Valley Formation of North Dakota, U.S.A." Journal of Vertebrate Paleontology. e2403579. doi: 10.1080/02724634.2024.2403579 .
  7. ↑ Bluemle, John P. 1988. "Generalized Bedrock Geological Map of North Dakota" (PDF). North Dakota Geological Survey, Miscellaneous Map 28. Retrieved 2017-02-03.{{cite web}}: CS1 maint: numeric names: authors list (link)
  8. ↑ Bowen, G.J. et al. 2015 (2015). "Two massive, rapid releases of carbon during the onset of the Palaeocene–Eocene thermal maximum". Nature. 8 (1): 44. Bibcode:2015NatGe...8...44B. doi:10.1038/ngeo2316.{{cite journal}}: CS1 maint: numeric names: authors list (link)

Bibliography

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