Wheeler Shale

Wheeler Shale
Stratigraphic range: Middle Cambrian
~507 Ma
↓

Elrathia kingii, famed trilobite of the Wheeler Shale.
Type Geological formation
Thickness 100–200 m (330–660 ft)
Lithology
Primary Calcareous shale
Other Mudstone, shaley limestone and limestone
Location
Coordinates 39°15′N 113°20′W / 39.25°N 113.33°W / 39.25; -113.33
Region House Range and Drum Mountains, Millard Co., west Utah
Country United States
Type section
Named for House Amphitheater (Geographic feature and type locality)
Named by Charles Doolittle Walcott

The Wheeler Shale (named by Charles Walcott) is a Cambrian (c. 507 Ma) fossil locality world famous[1] for prolific agnostid and Elrathia kingii trilobite remains (even though many areas are barren of fossils)[2] and represents a Konzentrat-Lagerstätten. 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.[3] As such, the Wheeler Shale also represents a Konservat-Lagerstätten.[4]

Together with the Marjum Formation and lower Weeks Formation, the Wheeler Shale forms 490 to 610 m (1,610 to 2,000 ft) of limestone and shale exposed in one of the thickest, most fossiliferous and best exposed sequences of Middle Cambrian rocks in North America.[5]

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.[6] 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.[6]

Taphonomy and sedimentology

Asaphiscus wheeleri, Cambrian, Wheeler shale, Utah

.

Emeraldella brocki an arthropod From the Burgess Shale

Detailed work recognises a number of ~10 m thick lagerstätten sequences in the formation, each of which formed at a sea-level high stand[7] in deep water.[8] The lagerstätte were deposited by turbidities and mudslides onto an oxygenated sea floor.[7] The productive layers comprise mud and clay particles, with a tiny fraction of wind-blown quartz.[9]

Stratigraphy

The Wheeler Shale spans the Ptychagnostus atavus[10] and uppermost-Middle Cambrian Bolaspidella trilobite zones (See House Range) for full stratigraphy).

Fauna

Incomplete list of the fauna of the Wheeler Shale:[6][11][12][13][14][15][16] (Note: the preservation of hard bodied trilobite remains and soft bodied animals seems to be mutually exclusive within particular horizons.)[4][17]


Protista

Arthropoda

Arachnomorpha

Trilobita

Brachiopoda

Chordata

Cnidaria

Mollusca

Echinodermata

Porifera

Priapulida

Unclassified

References

  1. ↑ Johnson, Kirk; Troll, Ray (2007), Cruising the fossil freeway: An epoch tale of a scientist and an artist on the ultimate 5,000-Mile paleo road trip, Golden, CO.: Fulcrum Publishing, ISBN 978-1-55591-451-6
  2. ↑ Robert R. Gaines; Mary L. Droser (2003), "Paleoecology of the familiar trilobite Elrathia kingii: An early exaerobic zone inhabitant" (pdf), Geology, 31 (11): 941–4, Bibcode:2003Geo....31..941G, doi:10.1130/G19926.1
  3. ↑ Robert R. Gaines; Derek E.G. Briggs; Zhao Yuanlong (2008), "Cambrian Burgess Shale–type deposits share a common mode of fossilization", Geology, 36 (10): 755–758, doi:10.1130/G24961A.1
  4. 1 2 Gaines, R; Kennedy, M; Droser, M (2005), "A New Hypothesis for Organic Preservation of Burgess Shale Taxa in the Middle Cambrian Wheeler Formation, House Range, Utah", Palaeogeography Palaeoclimatology Palaeoecology, 220: 193–205, doi:10.1016/j.palaeo.2004.07.034
  5. ↑ Robison, R.A. (1964), "Late Middle Cambrian faunas from western Utah", Journal of Paleontology, 38 (3): 510–566
  6. 1 2 3 Gunther, L.F.; Gunther, V.G. (1981), "Some Middle Cambrian Fossils of Utah", Brigham Young University Geology Studies, 28: 1–81
  7. 1 2 Brett, C. E.; Allison, P. A.; Desantis, M. K.; Liddell, W. D.; Kramer, A. (2009). "Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah". Palaeogeography Palaeoclimatology Palaeoecology. 277: 9–33. doi:10.1016/j.palaeo.2009.02.010.
  8. ↑ Halgedahl, S. L.; Jarrard, R. D.; Brett, C. E.; Allison, P. A. (2009). "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". Palaeogeography Palaeoclimatology Palaeoecology. 277 (1–2): 34–56. doi:10.1016/j.palaeo.2009.02.011.
  9. ↑ Gaines, R. R.; Kennedy, M. J.; Droser, M. L. (2005). "A new hypothesis for organic preservation of Burgess Shale taxa in the middle Cambrian Wheeler Formation, House Range, Utah". Palaeogeography, Palaeoclimatology, Palaeoecology. 220: 193. doi:10.1016/j.palaeo.2004.07.034.
  10. ↑ Lieberman, B. S. (2003). "A New Soft-Bodied Fauna: the Pioche Formation of Nevada". Journal of Paleontology. 77 (4): 674–690. ISSN 0022-3360. doi:10.1666/0022-3360(2003)077<0674:ANSFTP>2.0.CO;2.
  11. ↑ Briggs, D.E.G.; Robison, R.A. (1984), Exceptionally preserved nontrilobite arthropods and Anomalocaris from the Middle Cambrian of Utah, The Paleontological Institute, The University of Kansas
  12. ↑ Photos of Wheeler Shale fossils from UC Berkeley
  13. ↑ Rigby, J.K. (1978), "Porifera of the Middle Cambrian Wheeler Shale, from the Wheeler Amphitheater, House Range, in western Utah", Journal of Paleontology, 52 (6): 1325–1345, doi:10.2307/1303938
  14. ↑ Utah's Cambrian Life from University of Kansas Natural History Museum
  15. ↑ Cambrian fossils from Utah by the University of Utah
  16. ↑ Comprehensive treatment from The Virtual Fossil Museum
  17. ↑ Gaines, Robert R.; Droser, Mary L.; Kennedy, Martin J. (2001), "Taphonomy of soft-bodied preservation and ptychopariid Lagerstätte in the Wheeler Shale (Middle Cambrian), House Range, USA; controls and implications", PaleoBios, 21 (Suppl.2): 1–55
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