Ellis Group

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Ellis Group
Stratigraphic range: Bajocian-Oxfordian
Type Geological formation
Sub-units Swift Formation
Rierdon Formation
Sawtooth Formation
Underlies Mannville Group
Overlies Rundle Group, Shaunavon Formation
Thickness up to 150 metres (490 ft)[1]
Lithology
Primary Shale, sandstones
Other Siltstone, limestone
Location
Region WCSB
Country  Canada
Type section
Named for Fort Ellis
Named by A.C. Peale, 1893

The Ellis Group is a stratigraphical unit of Bajocian-Oxfordian age in the Western Canadian Sedimentary Basin.

It takes the name from Fort Ellis, Montana, and was first described in outcrop in the Rocky Creek Canyon by .C. Peale in 1893.[2]

Lithology[edit]

The Ellis Group is composed of shale and sandstones deposited in marine and transitional environment. [1]

Hydrocarbon production[edit]

Oil is produced from the Sawtooth Formation in south-eastern Alberta.

Distribution[edit]

The Ellis Group Lateral occurs in the sub-surface in southern Alberta and northern and central Montana.[1] It is typically 80 metres (260 ft), but thickens on either side of the Sweetgrass Arch and reaches up to 150 metres (490 ft) in south-eastern Alberta.

Subdivisions[edit]

The Ellis Group includes the following formations, from top to bottom:

Sub-unit Age Lithology Max.
Thickness
Reference
Swift Formation Oxfordian marine shale, transitional shale, siltstone and sandstone 41 m (130 ft) [3]
Rierdon Formation Bathonian to Callovian marine shale and limestone 60 m (200 ft) [4]
Sawtooth Formation Bajocian to Bathonian quartzose sandstone with shale 41 m (130 ft) [5]
Piper Formation Middle Jurassic sandy limestone (top)
papery shale
siltstone and shale
grey limestone
white gypsum (base)
23 m (80 ft) [6]

Relationship to other units[edit]

The Ellis Group is unconformably overlain by the shale and sandstone of the Mannville Group and rests on the carbonates of the Rundle Group. It grades westwards to the Fernie Group shale, and eastwards to shale, sandstones and limestone of the Vanguard Formation and Shaunavon Formation.[1]

References[edit]

  1. ^ a b c d Lexicon of Canadian Geologic Units. "Ellis Group". Retrieved 2010-01-01. 
  2. ^ Peale, A.C., 1893. The Paleozoic section in the vicinity of Three Forks, Montana. United States Geological Survey, Bulletin 110, p.9-56.
  3. ^ Lexicon of Canadian Geologic Units. "Swift Formation". Retrieved 2010-01-03. 
  4. ^ Lexicon of Canadian Geologic Units. "Rierdon Formation". Retrieved 2010-01-03. 
  5. ^ Lexicon of Canadian Geologic Units. "Sawtooth Formation". Retrieved 2010-01-03. 
  6. ^ Lexicon of Canadian Geologic Units. "Piper Formation". Retrieved 2010-01-03.