Blueflower Formation
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| Blueflower Formation | |
|---|---|
| Stratigraphic range: Ediacaran | |
| Type | Formation |
| Unit of | Rackla Group |
| Sub-units | Lower and Upper Member |
| Underlies | Risky Formation |
| Overlies | (Unconformably) Gametrail Formation |
| Lithology | |
| Primary | Siliciclastic |
| Other | Limestone, Mudstone, Siltstone, Sandstone |
| Location | |
| Region | Northwest Territories |
| Country | Canada |
The Blueflower Formation is a geologic formation in the Northwest Territories, and is a part of the Rackla Group. It preserves fossils dating back to the Ediacaran period, in both shallow and deep-water environments.
Members
The Blueflower Formation can be found outcropping in the larger Rackla the Wernecke Mountains in Canada. It is overlain by the Riskey Formation,[1] whilst it is unconformably underlain by the dolostone Gametrail Formation.[2] The formation is also unique in preserving both deep-water and shallow-water environments. The shallow-water sections are primarily composed of siliciclastic rocks, with sandy-carbonates throughout, and is also fossiliferous in nature, meanwhile the deep-water sections are split into three members.[1]
The deep-water sections of this formation are composed of three members, two of which are informally named, which are as follows in stratigraphic order (lowest to highest):
- Yuletide Member: This member is primarily composed of inter-bedded conglomerate, sandstone and siltstone.[2]
- Disk Member: This member is dominated by black shales, which is inter-bedded with siltstone, sandstone, and authigenic carbonate lenses and nodules. This member is also fossiliferous in nature, containing a number of discoidal forms such as Aspidella, which give the member its informal name.[2]
- Upper Member: This member is predominately composed of sandstones, containing coarse-grained trough- and tabular-cross-bedded rocks, all of which is inter-bedded with shales.[2]
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