Not to be confused with the Emigrant Formation, a different formation of a similar age.
Emigrant Springs Formation
Formation
Age[1]
PeriodCambrian
PrilithologyCalcisiltite
OtherlithologyMudstone, Calcilutite, Calcarenite
RegionNevada
CountryUnited States
SubunitsSee: Members
UnderliesDunderberg Formation
OverliesPatterson Pass Shale

The Emigrant Springs Formation (Also known as the Emigrant Springs Limestone) is a geologic formation in Nevada. It preserves fossils dating back to the Cambrian period.

Geology

The Emigrant Springs Formation is predominately composed of various carbonate rocks, and is overlain by the Dunderberg Formation, whilst it is underlain by the Patterson Pass Shale. It also contains three members, which are as follows, in ascending stratigraphic order (lowest to highest):

Members

  • Member A: This member is the thinnest, only getting up to 256 ft (78 m) thick, and is composed of medium-gray, thin to medium-bedded calcisiltite and calcilutite, with breccia's in the upper beds of the member.[1]
  • Member B: This member is the thickest, getting up to 1,509 ft (460 m) thick, and is dominated by light-olive-gray, yellowish or pink calcisiltite, which contains silt-sized quartz grains. At the base of this member, there are also mudstones present, transitioning to medium-light-gray, thin to thick-bedded calcisiltite and calcilutite above.[1]
  • Member C: This member can get up to 495 ft (151 m) thick, and is primarily composed of medium-gray oolitic calcarenite, calcilutite and calcisiltite.[1]

Paleobiota

The Emigrant Springs Formation contains a small number of trilobites,[1] and a collection of conodonts, and various molluscs.[2]

Arthropoda

Arthropoda
GenusSpeciesNotesImages
Coosina[1]
  • Coosina sp.
Ptychoparid trilobite.
Blountia[1]
  • Blountia sp.
Ptychoparid trilobite.
Crepicephalus[1]
  • Crepicephalus sp.
Ptychoparid trilobite.
Tricrepicephalus[1]
  • Crepicephalus sp.
Ptychoparid trilobite.
Pemphigaspis[1]
  • Pemphigaspis sp.
Ptychoparid trilobite.
Elrathia[2]
  • E. alapyge
Ptychoparid trilobite.
Cedaria (?)[1]
  • Cedaria (?) sp.
Ptychoparid trilobite.
Meteoraspis (?)[1]
  • Meteoraspis (?) sp.
Ptychoparid trilobite.
Baltagnostus[2]
  • Baltagnostus sp.
  • B. eurypyx
Diplagnostid agnostid.
Hypagnostus[2]
  • Hypagnostus sp.
Diplagnostid agnostid.
Pseudagnostus[1]
  • Pseudagnostus sp.
Agnostid trilobite.
Utagnostus[1]
  • U. trispinulus
Agnostid trilobite.
Kymagnostus (?)[1]
  • Kymagnostus (?) sp.
Agnostid trilobite.
Lejopyge[2][1]
  • L. calva
Ptychagnostid agnostid.
Ptychagnostus[2]
  • Ptychagnostus sp.
  • P. aculeatus
Ptychagnostid agnostid.
Glaphyraspis[1]
  • Glaphyraspis sp.
Trilobite.
Cheliacephalus[1]
  • Cheliacephalus sp.
Trilobite.
Aphelaspis[1]
  • Aphelaspis sp.
Trilobite.

Chordata

GenusSpeciesNotesImages
Hertzina[2]
  • H. bisulcata
Furnishinid paraconodont.
Westergaardodina[2]
  • W. muelleri
Westergaardodinid paraconodont.
Furnishina[2]
  • F. asymmetrica
  • F. furnishi
  • F. bicarinata
Furnishinid paraconodont.
Distacodus[2]
  • D. palmeri
Distacodontid conodont.
Oneotodus[2]
  • O. tenuis
Protopanderodontid tenuis.

Lophotrochozoa

GenusSpeciesNotesImages
Helcionella[2]
  • Helcionella sp.
Helcionellid mollusc.
Scenella (?)[2]
  • Scenella (?) sp.
Scenellid mollusc.
Canthylotreta[3]
  • C. crista
Acrotretid brachiopod.
Lingulella[2]
  • Lingulella sp.
Obolid brachiopod.
Livnarssonia[2]
  • L. ophirensis
Brachiopod.
Paterina[2]
  • Paterina sp.
Brachiopod.

See also

References

  1. ^ Kellogg, Harold E. (1963). "Paleozoic Stratigraphy of the Southern Egan Range, Nevada". Geological Society of America Bulletin. 74 (6): 685. doi:10.1130/0016-7606(1963)74[685:PSOTSE2.0.CO;2]
  2. ^ Clark, David L. & Robison, Richard A. (1969). "Oldest Conodonts in North America". Journal of Paleontology. 43 (4): 1044–1046. ISSN 0022-3360
  3. ^ Streng, Michael & Holmer, Lars E. (January 2006). "New and poorly known acrotretid brachiopods (Class Lingulata) from the Cedaria-Crepicephalus zone (late Middle Cambrian) of the Great Basin, USA". Geobios. 39 (1): 125–154. doi:10.1016/j.geobios.2004.10.004