| 词条 | Golden Valley Formation |
| 释义 |
| name = Golden Valley Formation | image = | caption = | type = Geological formation | age = Late Paleocene-Early Eocene (Clarkforkian-Wasatchian) ~{{Fossil range|57|52}} | period = Eocene | prilithology = Claystone, mudstone, siltstone, sandstone | otherlithology = Lignite, conglomerate | namedfor = Golden Valley, North Dakota | namedby = Benson and Laird, 1947[1] | region = North Dakota | country = United States | coordinates = | unitof = Williston Basin | subunits = Bear Den Mb., Camels Butte Mb. | underlies = White River Group | overlies = Sentinel Butte Formation | thickness = up to {{convert|122|m|ft|-1}}[2] }} The Golden Valley Formation is a stratigraphic unit of Late Paleocene to Early Eocene age in the Williston Basin of North Dakota.[1] 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[1] and vertebrates,[3] as well as mollusk and insect fossils.[1][3] StratigraphyThe Golden Valley Formation is present as a series of outliers in western North Dakota.[4] It is underlain by the Sentinel Butte Formation and unconformably overlain by the White River Group.[5] It reaches thicknesses of up to {{convert|122|m|ft|-1}} and is subdivided into two members: the Bear Den Member (lower) and the Camels Butte Member (upper).[5] LithologiesThe base of the Bear Den Member consists of kaolinitic claystone, mudstone and sandstone that weather to white, light grey, orange, and purple.[5] These are overlain by grey or brownish carbonaceous sediments and, in some areas, a bed of lignite (the Alamo Bluff lignite).[1] In places the sequence is capped by a siliceous bed (the Taylor bed[1]) that represents a weathering surface or paleosol.[5] The Bear Den Member reaches a maximum thickness of about {{convert|15|m|ft|-1}}.[5] The Camels Butte Member consists of montmorillonitic[1] and micaceous claystone, siltstone, lignite, poorly cemented sandstone and conglomerate.[5][1] The upper part includes a massive fluvial sandstone that caps many of the major buttes in southwestern North Dakota.[5] The Camels Butte Member reaches a maximum thickness of about {{convert|107|m|ft|-1}}.[5] Depositional environmentThe Golden Valley Formation was deposited in a broad swampy lowland crossed by fluvial channels.[1] Deposition occurred during late Paleocene (Clarkforkian) to early Eocene (Wasatchian) time,[1] a period that spans the Paleocene-Eocene Thermal Maximum.[6] PaleontologyPlant 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.[1]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.[1][3] Invertebrate fossils include shells of freshwater mollusks such as Viviparus, Unio, Hydrobia, and Planorbis, and the wing casing of a crabid beetle.[1][3]References{{Portal|Earth sciences|North Dakota|Paleontology|Paleogene|Cenozoic}}1. ^1 2 3 4 5 6 7 8 9 10 11 Hickey, L.J. 1977. Stratigraphy and paleobotany of the Golden Valley Formation (early Tertiary) of western North Dakota. Geological Society of America, Memoir 150, 181 p. and 55 plates. {{ISBN|0-8137-1150-9}} 2. ^1 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 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. 4. ^{{cite web|last1=Bluemle|first1=John P. 1988|title=Generalized Bedrock Geological Map of North Dakota|url=https://www.dmr.nd.gov/ndgs/documents/Publication_List/pdf/MisMaps/MM-28.pdf|publisher=North Dakota Geological Survey, Miscellaneous Map 28|accessdate=2017-02-03}} 5. ^1 2 3 4 5 6 7 8 {{cite web|last1=Murphy|first1=Edward C. et al. 2009|title=North Dakota Stratigraphic Column|url=https://www.dmr.nd.gov/ndgs/documents/Publication_List/pdf/Strat-column-NDGS-(2009).pdf|publisher=North Dakota Geological Survey, Miscellaneous Series 91|accessdate=2017-02-06}} 6. ^{{cite journal|journal=Nature|volume=8|page=44|url=http://www.nature.com/ngeo/journal/v8/n1/full/ngeo2316.html|doi=10.1038/ngeo2316|author=Bowen, G.J. et al. 2015|title=Two massive, rapid releases of carbon during the onset of the Palaeocene–Eocene thermal maximum|year=2015}} 10 : Geologic formations of North Dakota|Paleogene geology of North Dakota|Mudstone formations|Siltstone formations|Sandstone formations of the United States|Coal formations|Conglomerate formations|Fluvial deposits|Fossiliferous stratigraphic units of North America|Paleontology in North Dakota |
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