Wasatch Formation
Stratigraphic range: Early Eocene
(Clarkforkian-Bridgerian)
(typically Wasatchian)
~56.8–46.2 Ma
Clinker-bed breccia from the Wasatch Formation (Wyoming)
TypeFormation
Sub-unitsSee text
UnderliesGreen River & Fowkes Formations, Santa Fe Group
OverliesFort Union, Williams Fork, Torrejon & Evanston Formations
ThicknessVariable, up to 1,500 m (4,900 ft)
Lithology
PrimaryMudstone, shale, siltstone, sandstone
OtherClaystone, lignite
Location
Coordinates41°12′N 108°48′W / 41.2°N 108.8°W / 41.2; -108.8
Approximate paleocoordinates46°00′N 92°36′W / 46.0°N 92.6°W / 46.0; -92.6
Region Colorado
 Idaho
 Montana
 Wyoming
 Utah
Country United States
ExtentPowder River, Green River, Wind River, Bighorn, Piceance & Uinta Basins
Type section
Named forWasatch Range
Named byHayden
LocationEcho Canyon, Summit County & Weber Canyon, Ogden, Utah
Year defined1873
Coordinates40°53′N 110°58′W / 40.88°N 110.97°W / 40.88; -110.97 (Echo Canyon)
41°08′09″N 111°54′14″W / 41.13583°N 111.90389°W / 41.13583; -111.90389 (Weber Canyon)
RegionUtah
Wasatch Formation is located in the United States
Wasatch Formation
Wasatch Formation (the United States)
Wasatch Formation is located in Wyoming
Wasatch Formation
Wasatch Formation (Wyoming)

The Wasatch Formation (Tw)[1] is an extensive highly fossiliferous geologic formation stretching across several basins in Idaho, Montana Wyoming, Utah and western Colorado.[2] It preserves fossils dating back to the Early Eocene period. The formation defines the Wasatchian or Lostcabinian (55.8 to 50.3 Ma), a period of time used within the NALMA classification, but the formation ranges in age from the Clarkforkian (56.8 to 55.8 Ma) to Bridgerian (50.3 to 46.2 Ma).

Wasatch fauna consists of many groups of mammals, including numerous genera of primates, artiodactyls, perissodactyls, rodents, carnivora, insectivora, hyaenodonta and others. A number of birds, several reptiles and fish and invertebrates complete the diverse faunal assemblages. Fossil flora and ichnofossils also have been recovered from the formation.

The formation, first named as Wasatch Group in 1873 by Ferdinand Vandeveer Hayden, was deposited in alluvial, fluvial and lacustrine environments and comprises sandstones, siltstones, mudstones and shales with coal or lignite beds representing wet floodplain settings.

The Wasatch Formation is an unconventional tight gas reservoir formation in the Uinta and Piceance Basins of Utah and the coal seams of the formation are mined in Wyoming. At the Fossil Butte National Monument, the formation crops out underlying the Green River Formation. In the Silt Quadrangle of Garfield County, Colorado, the formation overlies the Williams Fork Formation.[3]

Description

Definition

The Wasatch Formation was first named as the Wasatch Group by Ferdinand Vandeveer Hayden in the 1873 edition of his original 1869 publication titled "Preliminary field report of the United States Geological Survey of Colorado and New Mexico: U.S. Geological and Geographical Survey of the Territories", based on sections in the Echo and Weber Canyons, of the Wasatch Mountains.[4] In the language of the native Ute people, Wasatch means "mountain pass" or "low pass over high range."[5][6] According to William Bright, the mountains were named for a Shoshoni leader who was named with the Shoshoni term wasattsi, meaning "blue heron".[7]

Outcrops

View of Fossil Butte with the Wasatch Formation outcropping in the lower areas

At the base of Fossil Butte are the bright red, purple, yellow and gray beds of the Wasatch Formation. Eroded portions of these horizontal beds slope gradually upward from the valley floor and steepen abruptly. Overlying them and extending to the top of the butte are the much steeper buff-to-white beds of the Green River Formation, which are about 300 feet (91 m) thick. The Wasatch Formation ranges from about 3,000 feet (910 m) in the western part of the Uinta Basin, thinning to 2,000 feet (610 m) in the east.[8] In the Silt Quadrangle of Garfield County, Colorado, the formation overlies the Williams Fork Formation.[3] The formation is exposed in the Desolation and Gray Canyons pertaining to the Colorado Plateau in northeastern Utah,[9] and in Flaming Gorge National Recreation Area at the border of southwestern Wyoming and northeastern Utah.[10]

Extent

Map of the Powder and Wind River and Bighorn Basins
Map of the Green River Basin
Map of the Uinta and Piceance Basins

The Wasatch Formation is found across six states in the northwestern United States, from Montana[11] and Idaho in the north across Utah[12] and Wyoming to Colorado in the southwest. The formation is part of several geologic provinces; the eponymous Wasatch uplift, Uinta uplift, Green River, Piceance, Powder River, Uinta and Paradox Basins and the Colorado Plateau sedimentary province and Yellowstone province.[13]

In Montana, the formation overlies the Fort Union Formation and is overlain by the White River Formation.[14] There is a regional, angular unconformity between the Fort Union and Wasatch Formations in the northern portion of the Powder River Basin.[15]

Subdivision

Generalized stratigraphy of the Wasatch Formation

Many local subdivisions of the formation exist, the following members have been named in the literature:[13]

Member States Lithologies Notes
Alkali Creek Tongue Wyoming Mudstones and sandstones [16]
Atwell Gulch Colorado Sandstones and mudstones [17]
Bullpen Wyoming
Cathedral Bluffs Tongue Colorado, Wyoming Mudstones and sandstones [16]
Chappo Wyoming
Cowley Canyon Utah
Desertion Point Tongue Wyoming
Hiawatha Colorado, Utah, Wyoming
Kingsbury Conglomerate Wyoming Feldspathic conglomerates [18][19]
Knight Utah, Wyoming
La Barge Wyoming
Lookout Mountain Conglomerate Wyoming Conglomerates
Luman Tongue Wyoming [20]
Main Body Wyoming Mudstones [16][21]
Molina Colorado Sandstones [17]
Moncrief Wyoming Feldspathic conglomerates [18]
New Fork Tongue Wyoming
Nightingale Wyoming
Niland Tongue Colorado, Wyoming
Ramsey Ranch Wyoming
Red Desert Tongue Wyoming
Renegade Tongue Colorado, Utah
Shire Colorado Sandstones and mudstones [17]
Tunp Wyoming

Lithologies and facies

In the Fossil Basin at the Fossil Butte National Monument, Wyoming, the Wasatch Formation consists primarily of brightly variegated mudstones with subordinate interbedded siltstones, sandstones, and conglomerates and represents deposition on an intermontane alluvial plain.[22] In Mesa County, Colorado, the formation comprises interbedded purple, lavender, red, and gray claystones and shales with local lenses of gray and brown sandstones, conglomeratic sandstones, and volcanic sandstones that are predominantly fluvial and lacustrine in origin.[23] Along the western margin of the Powder River Basin, the Wasatch Formation contains two thick conglomeratic members (in descending order, the Moncrief Member and Kingsbury Conglomerate Member).[24]

The Molina Member of the formation is a zone of distinctly sandier fluvial strata. The over- and underlying members of the Molina are the Atwell Gulch and Shire members, respectively. These members consist of infrequent lenses of fluvial-channel sandstones interbedded within thick units of variegated red, orange, purple and gray overbank and paleosol mudstones.[17]

The Molina Member represents a sudden change in the tectonic and/or climatic regimes, that caused an influx of laterally-continuous, fine, coarse and locally conglomeratic sands into the basin. The type section of the Molina is located near the small town of Molina on the western edge of the basin and is about 90 metres (300 ft) thick. These sandy strata of the Molina Member form continuous, erosion-resistant benches that extend to the north of the type section for approximately 25 kilometres (16 mi). The benches are cut by canyons or "gulches", from which the Atwell Gulch and Shire Gulch members get their names. The Molina forms the principle target within the Wasatch Formation for natural gas exploration, although it is usually called the "G sandstone" in the subsurface.[17]

Provenance

Detrital zircons collected from the middle part of the formation in the Powder River Basin of Wyoming, where the Wasatch Formation reaches a thickness of more than 1,500 metres (4,900 ft) were gathered for U-Pb geochronological analysis. The detrital zircon age spectrum ranged from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. The 2900 Ma age peak is consistent with the age of Archean rocks at the core of the Bighorn Mountains. The sparse Proterozoic grains were likely derived from the recycling of Paleozoic sandstone units. The analysis concluded that the Wasatch sandstone is a first cycle sediment, the Archean core of the Bighorn uplift was exposed and shedding sediment into the Powder River Basin during time of deposition of the Wasatch Formation and the Powder River Basin Wasatch detrital zircon age spectra are distinct from the coeval Willwood Formation in the Bighorn Basin west of the Bighorn Mountains.[25] Cobbles and pebbles in the Wasatch are rich in feldspathic rock fragments, with individual samples containing as much as 40 percent,[26] derived from erosion of the Precambrian core of the Bighorn Mountains.[24] Part of the feldspar has been replaced by calcite cement.[27] Glauconite is present in the Wasatch, although always in volumes of less than 1 percent of the grains. It most probably was derived from the nearby, friable, glauconite-bearing Mesozoic strata of the eastern Bighorn Mountains.[18]

The presence of the Kingsbury Conglomerate at the base of the Wasatch Formation indicates that tectonic activity in the immediate vicinity of the Powder River Basin was intensifying. The conglomerate consists of Mesozoic and Paleozoic rock fragments. The lack of Precambrian fragments indicates that the metamorphic core of the Bighorn Mountains had not been dissected by this early deformation.[19] Deformation in the upper part of the formation has been interpreted as the result of the last phase of uplift during the Laramide orogeny.[28]

Correlations

The basal part of the Wasatch Formation is equivalent to the Flagstaff Formation in the southwest part of the Uinta Basin.[29] The Wasatch Formation is correlated with the Sentinel Butte and Golden Valley Formations of the Williston Basin.[30][31]

Paleontological significance

The Wasatch Formation is the defining formation for the Wasatchian, ranging from 55.8 to 50.3 Ma, within the NALMA classification. The Wasatchian followed the Clarkforkian stage (56.8-55.8 Ma) and is defined by the simultaneous first appearance of adapid and omomyid euprimates, hyaenodontid creodonts, perissodactyls and artiodactyls.[32] The deposits of the formation were laid down during a period of globally high temperatures during the Paleocene-Eocene Thermal Maximum (PETM). Mean annual temperatures were around 25 °C (77 °F) and temperature variations were minimal during this time.[33]

At the Fossil Butte National Monument, the Wasatch Formation preserved ichnofossils attributed to arthropods and described as Lunulichnus tuberosus.[34] Trace fossils are common within the upper part of the Main Body Member. These traces occur in three distinct alluvial depositional settings: flood basin/alluvial plain, crevasse splay, and fluvial channel. Flood basin deposits (dominated by alluvial paleosols with pronounced color variegation) are characterized by common Planolites, rare Skolithos and small, meniscate plug-shaped burrows, possibly Celliforma.[35]

Crevasse splay deposits (current-rippled to planar laminated, fine-grained sandstone to siltstone) are characterized by a mixed assemblage of vertical (Arenicolites, Skolithos, unwalled sinuous shafts, shafts with discoidal lenses of sediment), sub-vertical (Camborygma and Thalassinoides) and horizontal (Scoyenia, Rusophycus, Taenidium, Planolites and Palaeophycus) burrows. Large, vertically oriented burrows (Camborygma, cf. Ophiomorpha, Spongeliomorpha and Thalassinoides) are the dominant forms within fluvial channel deposits.[35]

Fossil content

Among the following fossils have been found in the formation:[2]

Mammals

Primates
Artiodactyls
Perissodactyls
Hyaenodonta
Acreodi
Carnivora
Cimolesta
Dinocerata
Erinaceomorpha
Eutheria
Ferae
Glires
Insectivora
Leptictida
Lipotyphla
Macroscelidea
Multituberculata
Pantodonta
Pholidota
Placentalia
Soricomorpha
Taeniodonta
Theriiformes

Birds

Reptiles

Amphibians

Fish

Invertebrates

Bivalves
Gastropods
Mollusks

Flora

Ichnofossils

Herbivore expansion

The mammal fauna of the formation is part of the fourth phase of herbivore expansion spanning about 115 Ma from the Aptian to Holocene,[118] and correlated with the Wind River and Wilcox Formations of the United States and the Laguna del Hunco Formation of Argentina.[119]

Economic geology

Petroleum geology

The Wasatch Formation is a tight gas reservoir rock in the Greater Natural Buttes Field in the Uinta Basin of Utah and Colorado. The formation is characterized by porosity ranging from 6 to 20% and permeability of up to 1 mD. Based on 409 samples from the Wasatch Formation, average porosity is 8.75 percent and average permeability is 0.095 mD.[8] The production rates after 2 years are 100–1,000 mscf/day for gas, 0.35–3.4 barrel per day for oil, and less than 1 barrel per day for water. The water:gas ratio ranges from 0.1 to 10 barrels per million standard cubic feet, indicating that free water is produced along with water dissolved in gas in the reservoir.[120] Oil in the Bluebell-Altamont Field in the Uinta Basin and gas in the Piceance Creek Field in the Piceance Basin are produced from the Wasatch Formation.[121]

As of May 2019, tight gas from the Wasatch Formation and underlying Mesaverde Group has been produced more than 1.76 trillion cubic feet (TCF) of gas from over 3,000 wells in the Uinta Basin, mostly from the Natural Buttes gas field in the eastern part of the basin. In the Piceance Basin, the Mesaverde Group and Wasatch Formation produced more than 7.7 TCF from over 12,000 wells, mostly from the central part of the basin.[122]

Mining

Coal

Coal is mined from the Wasatch Formation in Wyoming. Together with the Fort Union Formation, the Wasatch Formation represents the thickest coal bed deposits in the state.[123]

Uranium

Main article: Uranium mining in Wyoming

The fluvial sandstones contain uranium roll front deposits. The formation is the main producer of uranium in the state.[124] Ore zones contain uraninite and pyrite. Oxidized ores include uranophane, meta-autunite, and phosphuranylite.[125]

Wasatchian correlations

Wasatchian correlations in North America
Formation Wasatch DeBeque Claron Indian Meadows Pass Peak Tatman Willwood Golden Valley Coldwater Allenby Kamloops Ootsa Lake Margaret Nanjemoy Hatchetigbee Tetas de Cabra Hannold Hill Coalmont Cuchara Galisteo San Jose Ypresian (IUCS) • Itaboraian (SALMA)
Bumbanian (ALMA) • Mangaorapan (NZ)
Basin Powder River
Uinta
Piceance
Colorado Plateau
Wind River
Green River
Bighorn		 Piceance
Colorado Plateau


Wind River



Green River





Bighorn		 Williston Okanagan Princeton Buck Creek Nechako Sverdrup Potomac GoM Laguna Salada Rio Grande North Park Raton Galisteo San Juan
Wasatch Formation is located in North America
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation
Wasatch Formation (North America)
Country  United States  Canada  United States  Mexico  United States
Copelemur
Coryphodon
Diacodexis
Homogalax
Oxyaena
Paramys
Primates
Birds
Reptiles
Fish
Insects
Flora
Environments Alluvial-fluvio-lacustrine Fluvial Fluvial Fluvio-lacustrine Fluvial Lacustrine Fluvio-lacustrine Deltaic-paludal Shallow marine Fluvial Shallow marine Fluvial Fluvial
Wasatchian volcanoclastics

Wasatchian fauna

Wasatchian flora
Volcanic Yes No Yes No Yes No Yes No Yes No

See also

References

  1. ^ Shroba & Scott, 2001, p.3
  2. ^ a b Wasatch Formation at Fossilworks.org
  3. ^ a b Shroba & Scott, 2001, p.18
  4. ^ Wasatch - USGS
  5. ^ Wasatch County - Utah History Encyclopedia
  6. ^ Van Cott, 1990, p.390
  7. ^ Bright, 2004, p.549
  8. ^ a b Nelson & Hoffman, 2009, p.8
  9. ^ Stratigraphy of the Desolation Canyon and Gray Canyon
  10. ^ Stratigraphy of Flaming Gorge National Recreation Area
  11. ^ Wasatch Formation - Montana - USGS
  12. ^ Wasatch Formation - Utah - USGS
  13. ^ a b Wasatch "Group" - USGS
  14. ^ Widmayer, 1977, p.18
  15. ^ Widmayer, 1977, p.105
  16. ^ a b c Roehler, 1991, B16
  17. ^ a b c d e Lorenz et al., 1996, p.3
  18. ^ a b c Whipkey et al., 1991, D15
  19. ^ a b Widmayer, 1977, p.11
  20. ^ Luman Tongue Member at Fossilworks.org
  21. ^ Main Body Member at Fossilworks.org
  22. ^ Gunnells et al., 2016, p.984
  23. ^ Carrara, 2000, p.8
  24. ^ a b Whipkey et al., 1991, D1
  25. ^ Anderson et al., 2017
  26. ^ Whipkey et al., 1991, D5
  27. ^ Whipkey et al., 1991, D11
  28. ^ Shroba & Scott, 2001, p.23
  29. ^ Sanborn, 1981, p.259
  30. ^ Widmayer, 1977, p.19
  31. ^ Pocknall, 1987, p.30
  32. ^ Anemone & Dirks, 2009, p.116
  33. ^ Pocknall, 1987, p.172
  34. ^ a b Zonneveld et al., 2006, p.90
  35. ^ a b c d e f g h i j k l m n Zonneveld et al., 2006, p.88
  36. ^ a b c d e f g h i j k l m n o p q r s Smith & Holroyd, 2003
  37. ^ a b c d Covert & Hamrick, 1993
  38. ^ a b Bown & Rose, 1987
  39. ^ a b c d e f g h i j k l m n o p q r s t u v West & Dawson, 1973
  40. ^ a b c d e f g h i j k l Gazin, 1962
  41. ^ a b c d Muldoon & Gunnell, 2002
  42. ^ 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 af ag ah ai aj ak al am an ao Alroy, 2002
  43. ^ Honey, 1988
  44. ^ a b c Gunnell et al., 2016, p.991
  45. ^ 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 af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br Gunnell & Bartels, 2002
  46. ^ a b c d Gunnell, 1994
  47. ^ Beard, 1988
  48. ^ a b c Gunnell et al., 2016, p.992
  49. ^ a b c Holroyd & Strait, 2008
  50. ^ Bown, 1979
  51. ^ a b Gunnell et al., 2016, p.990
  52. ^ a b c d e f g h i Clyde et al., 1997
  53. ^ a b c d Holroyd & Rankin, 2014
  54. ^ Gazin, 1942
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  57. ^ a b c d e f g h i j k l m n o p q Strait et al., 2016
  58. ^ a b c d e f g h i j k l Foster, 2001
  59. ^ Roehler, 1991
  60. ^ a b c d e f g h i j k l m n o p q r s t u v Gazin, 1965
  61. ^ Scott & Fox, 2005
  62. ^ a b c d Gunnell et al., 2016, p.1003
  63. ^ Stucky & Krishtalka 1990
  64. ^ a b Krishtalka & Stucky, 1985
  65. ^ Stucky & Covert, 2014
  66. ^ Gunnell et al., 2016, p.1004
  67. ^ Gingerich, 1991
  68. ^ Zonneveld & Gunnell, 2003
  69. ^ a b c d e f g h i j k l m n o West, 1973
  70. ^ a b c Dorr, 1978
  71. ^ a b Froehlich, 2002
  72. ^ a b Gunnell et al., 2016, p.1000
  73. ^ a b Gunnell et al., 2016, p.1001
  74. ^ Polly, 1996
  75. ^ a b Morlo & Gunnell, 2003
  76. ^ a b c Gunnell et al., 2016, p.998
  77. ^ a b c Gunnell, 1998
  78. ^ Gingerich, 1982
  79. ^ a b c d e Gunnell et al., 2016, p.995
  80. ^ a b c d e f g h i Zonneveld et al., 2000
  81. ^ Guthrie, 1971
  82. ^ Roehler, 1987
  83. ^ a b c Gunnell et al., 2016, p.989
  84. ^ Gazin, 1956
  85. ^ Scott et al., 2002
  86. ^ Bown & Schankler, 1982
  87. ^ a b Gunnell et al., 2016, p.987
  88. ^ Secord, 2008
  89. ^ a b c d e Savage et al., 1972
  90. ^ a b Gunnell et al., 2016, p.999
  91. ^ a b c d e Korth, 1984
  92. ^ a b c d e f Black & Sutton, 1984
  93. ^ Anemone et al., 2012
  94. ^ a b c Rose, 1981
  95. ^ Gunnell et al., 2016, p.985
  96. ^ Hamrich & Covert, 1991
  97. ^ a b c Gunnell et al., 2016, p.994
  98. ^ a b Lucas, 1998
  99. ^ Thewissen, 1990
  100. ^ Williamson & Lucas, 1992
  101. ^ Schoch & Lucas, 1981
  102. ^ Gunnell et al., 2016, p.984
  103. ^ Schoch, 1986
  104. ^ Wetmore, 1931
  105. ^ Stidham, 2014
  106. ^ a b c d e f g h i Smith & Gauthier, 2013
  107. ^ Hay, 1908
  108. ^ Sullivan, 1979
  109. ^ Hutchison, 1991
  110. ^ a b c Dorr & Steidtmann, 1970
  111. ^ a b c d Divay & Murray, 2016
  112. ^ a b c d e f g h i j k l m n o p q r Brown, 1962
  113. ^ Manchester, 2002
  114. ^ a b c Yen, 1948
  115. ^ a b c Wilf, 2000
  116. ^ a b c d e f g h i j k l m n o Wilf et al., 2006
  117. ^ Manchester et al., 1999
  118. ^ Labandeira, 2006, p.421
  119. ^ Labandeira, 2006, p.434
  120. ^ Nelson & Hoffman, 2009, p.5
  121. ^ Sanborn, 1981, p.260
  122. ^ Drake II et al., 2019, p.1
  123. ^ Wyoming's Coal Geology - Wyoming State Geological Survey
  124. ^ Langden, 1973
  125. ^ Heinrich, 1958

Bibliography

Wasatch publications

Geology publications

Maps
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Quadrangle maps
Other maps

Paleontology publications

Categories