Wynniatt Formation

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Wynniatt Formation
Stratigraphic range: Tonian 848+-49–761+-41 Ma
Type Geological Formation
Sub-unitsMember 1, 2, 3 and 4
UnderliesKilian Formation [2]
OverliesBoot Inlet Formation [2]
Thickness500 - 800 m (1,640 - 2,624 ft)
Lithology
Primary Dolomite
Other Mudstone, Siltstone, Quartz arenite, Sandstone, Limestone, Gabbro
Location
Region Nunavut
Country Canada

The Wynniatt Formation is a geologic formation in Nunavut. It preserves enigmatic fossils dating back to the Middle to Late Tonian period, around 850 Ma - 760 Ma. [3]

Contents

Paleoenviroments

Due to the large thickness of the Wynniatt Formation, it is broken up into 4 Members, simply named "Member" 1 - 4, and from the rocks contained within these 4 members, a rough idea of what the paleoenvironments may have looked across the formation are as follows: [2]

- Member 1 : Periodically exposed inter-tidal mudflat.

- Member 2 : Shallow sub-tidal to inter-tidal with layers of microbial mat, and is also the fossil bearing member. [3]

- Member 3 : Extensive shelf-marginal reef complex, which itself is overlain by deposits of lagoons and a back-reef agal flat.

- Member 4 : Cycles of shallow sub-tidal to inter-tidal.

Paleobiota

After Butterfield, 2005. [3]

Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
GenusSpeciesNotesImages
Cheilofilum
  • C. hysteriopsis
Enigmatic 1.2mm long filamentous organism.
Chuaria
  • Chuaria sp.
Enigmatic fossil, possibly synonymous with Tawuia.
Clavitrichoides
  • Clavitrichoides sp.
Enigmatic filamentous organism, most material from this formation are possibly less well preserved Cheilofilum.
Osculosphaera
  • Osculosphaera sp.
Enigmatic filamentous organism.
Plicatosphaeridium
  • P. impostor
Enigmatic filamentous organism.
Tappania
  • Tappania sp.
Acanthomorph acritarch.
Tappania plana (Greyson Formation, Belt Supergroup).jpg
Tawuia
  • Tawuia sp.
Enigmatic fossil, possibly an alga.
Tawuia and epibionts.png

See also

References

  1. ↑ van Acken, David; Thomson, Danielle; Rainbird, Robert H.; Creaser, Robert A. (October 2013). "Constraining the depositional history of the Neoproterozoic Shaler Supergroup, Amundsen Basin, NW Canada: Rhenium-osmium dating of black shales from the Wynniatt and Boot Inlet Formations". Precambrian Research. 236: 124–131. doi:10.1016/j.precamres.2013.07.012.
  2. 1 2 3 Rainbird, R. H.; Jefferson, C. W.; Young, G. M. (April 1996). "The early Neoproterozoic sedimentary Succession B of northwestern Laurentia: Correlations and paleogeographic significance". Geological Society of America Bulletin. 108 (4): 454–470. doi:10.1130/0016-7606(1996)108<0454:TENSSB>2.3.CO;2.
  3. 1 2 3 Butterfield, Nicholas J. (June 2005). "Reconstructing a complex early Neoproterozoic eukaryote, Wynniatt Formation, arctic Canada". Lethaia. 38 (2): 155–169. doi:10.1080/00241160510013231.
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