Earlie Formation

The Earlie Formation is a stratigraphic unit of Middle Cambrian age in the Western Canada Sedimentary Basin that is present beneath the plains of Alberta and eastern Saskatchewan.[1][2] It was named for Earlie Lake in the County of Vermilion River, Alberta, by D.C. Pugh in 1971, who described the type section based on data from an oil well drilled in that area.[1][3]

Earlie Formation
Stratigraphic range: Upper
TypeFormation
UnderliesPika Formation, Deadwood Formation
OverliesBasal sandstone unit
ThicknessUp to 172 metres (565 ft)[1]
Lithology
PrimarySiltstone, sandstone, shale
Location
Coordinates53°10′49″N 110°25′47″W
RegionCanadian Rockies
Country Canada
Type section
Named forEarlie Lake, Alberta
Named byD.C. Pugh[1]

Lithology

The Earlie Formation consists of interbedded glauconitic siltstones and fine-grained sandstones and shales.[1][3] The presence of glauconite indicates that the sediments were deposited in a marine environment.[4]

Deposition and stratigraphic relationships

The Earlie Formation underlies the plains of Alberta and eastern Saskatchewan. It rests conformably on the unnamed basal sandstone unit that was deposited on the Precambrian rocks of the North American Craton at the start of a marine transgression of that area. It is overlain by the Pika Formation or, in areas where the Pika is not present, by the Deadwood Formation. It thickens to the west where it grades into the Mount Whyte, Cathedral, Stephen, and lower Pika Formations; the upper Eldon formation is age-equivalent.[5] It thins eastward to zero in Saskatchewan.[2][3][6]

Trilobite biostratigraphy supports an age in the upper Wuliuan (Ehmaniella Zone, lower to upper Altiocculus subzone)[7]

References
  1. Pugh, D.C. 1971. Subsurface Cambrian stratigraphy in southern and central Alberta. Geological Survey of Canada, Paper 70-10.
  2. Slind, O.L., Andrews, G.D., Murray, D.L., Norford, B.S., Paterson, D.F., Salas, C.J., and Tawadros, E.E., Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin (Mossop, G.D. and Shetsen, I., compilers), Chapter 8: Middle Cambrian and Early Ordovician Strata of the Western Canada Sedimentary Basin". Retrieved 2023-05-30.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN 0-920230-23-7.
  4. Chafetz, H.S. and Reid, A. 2000. Syndepositional shallow-water precipitation of glauconitic minerals. Sedimentary Geology, vol. 136, p. 29-42.
  5. Handkamer, Neal M.; Ichaso, Andrei; Pratt, Brian R.; Mángano, M. Gabriela; Buatois, Luis A. (2023). "Systematics and biostratigraphy of a new trilobite fauna collected from the subsurface Earlie Formation (Wuliuan Stage, Miaolingian Series, Cambrian) in southwestern Saskatchewan". Canadian Journal of Earth Sciences. doi:10.1139/cjes-2023-0003. S2CID 258813643.
  6. Alberta Geological Survey, 2013. "Alberta Table of Formations; Alberta Energy Regulator". Retrieved 1 May 2018.
  7. Handkamer, Neal M.; Ichaso, Andrei; Pratt, Brian R.; Mángano, M. Gabriela; Buatois, Luis A. (2023). "Systematics and biostratigraphy of a new trilobite fauna collected from the subsurface Earlie Formation (Wuliuan Stage, Miaolingian Series, Cambrian) in southwestern Saskatchewan". Canadian Journal of Earth Sciences. doi:10.1139/cjes-2023-0003. S2CID 258813643.
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