Unit Name: Blueflower Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Ediacaran (635 - 542 ma)
Age Justification: Biostratigraphy. The Blueflower Formation carries an Ediacaran fauna, and is latest Proterozoic (Aitken, 1989b).
Province/Territory: Northwest Territories
Originator: Aitken, 1989b.
Type Locality:
The type section of the Blueflower Formation is at latitude 63° 25' 25'' N and longitude 128° 25' 00'' W (Aitken, 1989b).
Distribution:
Central Mackenzie Mountains. The formation is 450 m thick at the type secion in the Sekwi Brook area (Aitken, 1989b).
Lithology:
The Blueflower Formation is a recessive weathering unit consisting mainly of fissile shale and lesser, non-fissile mudstone that are dark grey to black, partly silty, partly pyritic, and partly calcareous. The mudrocks weather grey to black and brown. The dominant, dark grey shale and mudstone are interrupted by sandstone beds that are mainly thin and fine or very fine grained, with some units of medium and thick, coarse grained beds. Many of the sandstone beds have turbidite characteristics. Near the base are several units of ribbon-bedded limestone (Aitken, 1989b).
Fossils:
Hofmann (1981) reports the bodyfossils Inkrylovia sp. (a pteridiniid), and Sekwia excentrica (a medusoid), and the trace fossils Gordia sp., Torrowangea sp., and several problematica. A specimen of Pteridinium sp. was found in the basal unit of the formation (Aitken, 1989b).
Relationship:
The Blueflower Formation overlies the Gametrail Formation of the Windermere Supergroup with apparent conformity, and is conformably and gradationally overlain by the Risky Formation. Because of its position below redbeds near the Precambrian-Cambrian boundary, its turbiditic character, and a small content of quartz granules in some beds, the Blueflower is very probably a correlative of part of the 'Grit unit' of Selwyn Basin (Gabrielse et al., 1973). It appears to be a distal facies of the 'Grit unit' (Aitken, 1989b, 1991).
History:
The formation is named after Blueflower Mountain, a prominent peak in the area, elevation 7541 feet, latitude 63 ° 20' 04'' N; longitude 128° 19' 16'' W, overlooking Natla River to the south (Aitken, 1989b).
References:
Aitken, J.D., 1989b. Uppermost Proterozoic Formations in Central Mackenzie Mountains, Northwest Territories; Geological Survey of Canada, Bulletin 368, 26 pp.
Aitken, J.D., 1991. The Ice Brook Formation and Post-Rapitan, Late Proterozoic Glaciation, Mackenzie Mountains, Northwest Territories; Geological Survey of Canada, Bulletin 404, 43 pp.
Gabrielse, H., Blusson, S.L., and Roddick, J.A., 1973. Geology of the Flat River, Glacier Lake and Wrigley Lake map-areas, District of Mackenzie and Yukon Territory; Geological Survey of Canada, Memoir 366 (Parts I and II), 421 p.
Hofmann, H.J., 1981, First record of a Late Proterozoic faunal assemblage in the North American Cordillera; Lethaia, v. 14, p. 303--310.
Source: GSC file of geological names; T.E. Bolton and J. Dougherty (compiler)
Contributor: Michael Pashulka
Entry Reviewed: No
Name Set: Lithostratigraphic Lexicon
LastChange: 31 Mar 2011