Wheeler Shale Explained

Type:Geological formation
Period:Cambrian
Age:
Middle Cambrian
~
Prilithology:Calcareous shale
Otherlithology:Mudstone, shaley limestone and limestone
Namedfor:House Amphitheater (Geographic feature and type locality)
Namedby:Charles Doolittle Walcott
Region:House Range and Drum Mountains, Millard Co., west Utah
Country:United States
Coordinates:39.25°N -113.33°W
Thickness:100-

The Wheeler Shale (named by Charles Walcott) is a Cambrian ( 507 Ma) fossil locality world-famousfor prolific agnostid and Elrathia kingii trilobite remains (even though many areas are barren of fossils)and represents a Konzentrat-Lagerstätte. Varied soft bodied organisms are locally preserved, a fauna (including Naraoia, Wiwaxia and Hallucigenia) and preservation style (carbonaceous film) normally associated with the more famous Burgess Shale. As such, the Wheeler Shale also represents a Konservat-Lagerstätten.

Together with the Marjum Formation and lower Weeks Formation, the Wheeler Shale forms 490to of limestone and shale exposed in one of the thickest, most fossiliferous and best exposed sequences of Middle Cambrian rocks in North America.

At the type locality of Wheeler Amphitheater, House Range, Millard County, western Utah, the Wheeler Shale consists of a heterogeneous succession of highly calcareous shale, shaley limestone, mudstone and thin, flaggy limestone. The Wheeler Formation (although the Marjum & Weeks Formations are missing) extends into the Drum Mountains, northwest of the House Range where similar fossils and preservation are found.

Taphonomy and sedimentology

Detailed work recognises a number of ~10 m thick lagerstätten sequences in the formation, each of which formed at a sea-level high stand[1] in deep water.[2] The lagerstätte were deposited by turbidities and mudslides onto an oxygenated sea floor.[1] The productive layers comprise mud and clay particles, with a tiny fraction of wind-blown quartz.[3]

Stratigraphy

The Wheeler Shale spans the Ptychagnostus atavus[4] and uppermost-Middle Cambrian Bolaspidella trilobite zones (See House Range for full stratigraphy).

Fauna

See main article: Burgess Shale-type fauna. Incomplete list of the fauna of the Wheeler Shale:[5] [6] [7] [8] (Note: the preservation of hard bodied trilobite remains and soft bodied animals seems to be mutually exclusive within particular horizons.)

Protista

Arthropoda

Dinocaridida

Trilobita

Brachiopoda

Chordata

Cnidaria

Mollusca

Echinodermata

Porifera

Priapulida

Unclassified

Notes and References

  1. Allison. C. E.. P. A.. Desantis. Liddell. Kramer . M. K.. W. D.. A.. Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah. Palaeogeography, Palaeoclimatology, Palaeoecology. 277. 9–33. 2009. Brett. 1–2. 10.1016/j.palaeo.2009.02.010. 2009PPP...277....9B .
  2. Brett . S. L. . R. D.. C. E.. Jarrard. P. A. . Geophysical and geological signatures of relative sea level change in the upper Wheeler Formation, Drum Mountains, West-Central Utah: A perspective into exceptional preservation of fossils. Allison. Palaeogeography, Palaeoclimatology, Palaeoecology. 277. 1–2. 34–56 . 2009. Halgedahl . Susan Halgedahl. 10.1016/j.palaeo.2009.02.011. 2009PPP...277...34H .
  3. Gaines . R. R. . Kennedy . M. J. . Droser . M. L. . A new hypothesis for organic preservation of Burgess Shale taxa in the middle Cambrian Wheeler Formation, House Range, Utah . 10.1016/j.palaeo.2004.07.034 . Palaeogeography, Palaeoclimatology, Palaeoecology . 220 . 193–205 . 2005 . 1–2 . 2005PPP...220..193G .
  4. Lieberman . B. S.. A New Soft-Bodied Fauna: the Pioche Formation of Nevada. Journal of Paleontology. 77. 4. 674–690. 2003. 0022-3360. 10.1666/0022-3360(2003)077<0674:ANSFTP>2.0.CO;2. 130145927.
  5. http://www.ucmp.berkeley.edu/cambrian/house.html Photos of Wheeler Shale fossils from UC Berkeley
  6. http://www.kumip.ku.edu/cambrianlife Utah's Cambrian Life from University of Kansas Natural History Museum
  7. http://www.earth.utah.edu/utahfossil.html Cambrian fossils from Utah by the University of Utah
  8. http://www.fossilmuseum.net/Cambrian-Explosion/Utah-Cambrian-Explosion.htm Comprehensive treatment from The Virtual Fossil Museum
  9. Pates . Stephen . Lerosey-Aubril . Rudy . Daley . Allison C. . Kier . Carlo . Bonino . Enrico . Ortega-Hernández . Javier . 2021-01-19 . The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian) . PeerJ . en . 9 . e10509 . 10.7717/peerj.10509 . 2167-8359 . 7821760 . 33552709 . free .
  10. Lerosey‐Aubril . Rudy . Ortega‐Hernández . Javier . 2022 . Zhang . Xi‐Guang . A new lobopodian from the middle Cambrian of Utah: did swimming body flaps convergently evolve in stem‐group arthropods? . Papers in Palaeontology . en . 8 . 3 . 10.1002/spp2.1450 . 250076505 . 2056-2799.
  11. Pates . Stephen . Wolfe . Joanna M. . Lerosey-Aubril . Rudy . Daley . Allison C. . Ortega-Hernández . Javier . 2022-02-09 . New opabiniid diversifies the weirdest wonders of the euarthropod stem group . Proceedings of the Royal Society B: Biological Sciences . 289 . 1968 . 20212093 . 10.1098/rspb.2021.2093 . 8826304 . 35135344.
  12. Foster . John R. . Howells . Thomas F. . Sroka . Steven D. . 2022 . First record of the chancelloriid Allonnia from the middle Cambrian Wheeler Formation (Drumian, Miaolingian) of western Utah . PaleoBios . en . 39 . 4 . 10.5070/P939455661 . 251544727 . 0031-0298. free .
  13. Nanglu. Karma. Caron. Jean-Bernard. Conway Morris. Simon. Cameron. Christopher B.. 2016-07-07. Cambrian suspension-feeding tubicolous hemichordates. BMC Biology. 14. 56. 10.1186/s12915-016-0271-4. 1741-7007. 4936055. 27383414 . free .

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