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.

Geology The Blueflower Formation can be found outcropping in the Wernecke Mountains in Canada, and is a part of the wider Rackla Group. It is overlain by the Risky Formation, whilst it is unconformably underlain by the dolostone Gametrail Formation. 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.

Members 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.

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.

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.

Dating The base of the Blueflower Formation has been dated using Re–Os Dating, whilst the upper layers have been dated based on the fossil material. Using samples from the base of the formation, the recovered dates were and , placing the lower layers within the Avalon assemblage. Meanwhile, various fossils collected from rocks higher up in the formation are noted to be akin to formations placed within the White Sea and Nama assemblages, with the tentative proarticulate Windermeria correlating these layers to the White Sea assemblage.

Paleobiota Unlike most other Ediacaran formations, the Blueflower Formation is unique in that is preserves shallow and deep-marine environments, and as it correlates with other Avalonian formations such as those in Newfoundland and Labrador, it allowed scientists to figure out whether the Ediacaran Biota started out in deep-marine environments before making their way into shallower waters. The forms that can be found across the formation are the familiar Petalonamae such as Charniodiscus, including juvenile petalonamids from the Lower Member, and from the Upper Member tubular forms such as Annulatubus, and the enigmatic Windermeria.

A recent paper also describes White Sea aged fossils within the lower sections of the formation, with the fossiliferous rocks being notably enriched in Carbon-13, an enrichment which has only been found in rocks dating to and , placing them within the Avalon assemblage and pushing their appearance some 7 million years before the White Sea assemblage begins, and includes organisms such as the olgunid Funisia and the proarticulate Dickinsonia. It is also the first example of White Sea assemblage organisms not only being found in a deep-water environment, but also the first example of several organisms being found within Laurentia.

Bilaterian

GenusSpeciesEnvironmentNotesImagesKimberella K. quadrataDeep-waterMollusc-like organism, first record in Laurentia and outside of Australia.

Porifera

GenusSpeciesEnvironmentNotesImagesFunisia F. dorotheaDeep-waterOlgunid tubular organism, first record in Laurentia and outside of Australia.

Petalonamae

GenusSpeciesEnvironmentNotesImagesCharniodiscusCharniodiscus sp.Frondose organism.PteridiniumPteridinium sp.Frondose organism, originally reported as Inkrylovia.Swartpuntia (?)Swartpuntia (?) sp.Deep-waterFrondose organism.Juvenile FrondsArborea ? Charniodiscus ? Trepassia ?Shallow-waterJuvenile frondose organisms, exact genus affinities unknown.

Proarticulata

GenusSpeciesEnvironmentNotesImagesWindermeriaW. aitkeniShallow-waterElongated motile organism.DickinsoniaDickinsonia sp.Deep-waterOval motile organism, with glided reflection. First record in Laurentia.

Trilobozoan

GenusSpeciesEnvironmentNotesImagesRugoconites (?)Rugoconites (?) spShallow-waterTri-lobed organism, too poorly preserved for confident assignment.

Cnidarian

GenusSpeciesEnvironmentNotesImagesEdiacariaE. flindersiDiscoid organism.KullingiaKullingia sp.Discoidal organism.

incertae sedis

GenusSpeciesEnvironmentNotesImagesAnnulatubusA. flexuosusShallow-waterTubular organism. AspidellaA. terrinovicaShallow and Deep-waterDiscoid organism.AulozoonA. soliorumDeep-waterSessile, tubular organism, first record in Laurentia and outside of Australia.CyclomedusaCyclomedusa sp. C. davidiDiscoid organism.EoandromedaE. octobrachiataEight-armed radial organism, first record in Laurentia.HiemaloraH. pleiomorphusDiscoid organism, possibly holdfasts of petalonamids.MedusinitesM. asteroidesDeep-waterDiscoidal organism. Specimens described in Evans et al, 2026 notably bear stalk-like structures.SekwiaS. excentriaDiscoid organism.SekwitubulusS. annularisShallow and Deep-waterTubular organism.

Flora

GenusSpeciesEnvironmentNotesImagesBeltanelliformisB. brunsaeShallow-waterCyanobacterial colony.Vendotaenia (?)Vendotaenia (?) sp.Shallow-waterRibbon-like organism.

Ichnogenera

GenusSpeciesEnvironmentNotesImagesArchaeonassaArchaeonassa sp.Burrows.GordiaG. marinaBurrows.HelminthoidichnitesHelminthoidichnites sp.Shallow and deep-waterBurrows.HelminthopsisHelminthopsis sp. H. abeli H. irregularisShallow-waterBurrows.KimberichnusKimberichnus sp.Deep-waterFeeding traces of Kimberella.PlanolitesP. monatanusShallow and deep-waterBurrows.TorrowangeaTorrowangea sp.Burrows.

Undescribed

GenusSpeciesEnvironmentNotesImagesproblematicum???Deep-waterRibbon-like fossils, affinities unknown.tubicolous organism???Deep-waterAnnulated tubular fossils, which may be flexible in nature, affinities unknown.unnamed frond specimen???Shallow-waterFrond-like fossils. Previously reported as Rugoinfractus, although was instead considered a body fossil and not a trace fossil, affinities unknown.segmented problematicum???Shallow-waterSegmented fossil, appears to be trilobate. Probable Arboreomorpha???Deep-waterSegmented fossil, bears similarities to the arboreomorphs. “petaloids”???Deep-waterSegmented petaloid fossils, which are either assignable to Pteridinium, Windermeria, and Inkrylovia. New taxon????Deep-waterFossil with two anchor-shaped structures arising from a central division, and bears similarities to Parvancorina. Is noted to possibly be a new genus.

See also

List of fossiliferous stratigraphic units in Northwest Territories

References