earth science

Wynniatt Formation

Wynniatt Formation is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Wynniatt Formation rather than just read about it. In short: The Wynniatt Formation is a geologic formation in Nunavut, and is a part of the wider Shaler Supergroup. It preserves enigmatic fossils in a shallow marine environment, dating back to the Middle to Late Tonian period, around 850 Ma - 760 Ma.

Key takeaways

Wynniatt Formation belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Wynniatt Formation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Wynniatt Formation from memory before moving on to harder problems.

Reference excerpt

The Wynniatt Formation is a geologic formation in Nunavut, and is a part of the wider Shaler Supergroup. It preserves enigmatic fossils in a shallow marine environment, dating back to the Middle to Late Tonian period, around 850 Ma - 760 Ma.

Geology The Wynniatt Formation, which is a part of the larger Shaler Supergroup, can be found outcropping in the Minto Inlier of Victoria Island. It is unconformably overlain by the sabkha-style evaporite and marine carbonate Kilian Formation, whilst it is conformably underlain by the sulphate evaporite and marine carbonate Minto Inlet Formation.

Members The formation is composed of four informal members, which are as follows, in stratigraphic order (lowest to highest):

Lower Carbonate Member: This member, which ranges between 85–130 m (279–427 ft) in thickness, is primarily composed of lime mudstone in its lower section, with small amounts of black shales, chert nodules, intra-clast breccias found throughout. In its middle section, the lime mudstone layers give way to cross-stratified grainstone, which is inter-bedded with lime mudstone and minor shales. Into the upper section of the member, the grainstone transitions into inter-bedded stromatolitic dolostone and black silty-shale. Using Re–Os dating, this member roughly correlates to the Snail Spring Formation. Black Shale Member: This member, which ranges between 10–200 m (33–656 ft) in thickness, is dominated by dark-gray siltstone and silty-shale, with clasts throughout. Near the contact to the Lower Carbonate Member can be found inter-bedded stromatolitic dolostones and dololutite. Further towards the top there can also be found thin- to medium-thick beds of ripple-topped quartz arenite. Using Re–Os dating, this member roughly correlates to the Snail Spring Formation. Stromatolite Carbonate Member: This member, which ranges between 160–320 m (520–1,050 ft) in thickness, is predominately composed of stromatolitic dolostone, with inter-bedded inter-clast grainstone and mudstone throughout, which themselves contain rip-up clasts and breccia units. Dololutite can also be found within the member, and ranges from being parallel-laminated to microbially laminated in nature. Using Re–Os dating, this member roughly correlates to the Ram Head Formation. This member is also notably fossiliferous in nature. Upper Carbonate Member: This member, which ranges between 110–380 m (360–1,250 ft) in thickness, is primarily composed of black calcareous shale, which is nodular in nature in its lower sections, and is overlain by thin-bedded sandy-quartz. The upper section of the member sees the shales and sandy-quartz give way to thick, inter-bedded stromatolitic dolostone and cross-bedded intra-clast grainstone, with cross-bedded quartz–arenite and microbially laminated lime mudstone found throughout. Using Re–Os dating, this member roughly correlates to the upper Ram Head Formation.

Dating Using Re–Os geochronology on black shale layers within the Wynniatt Formation, a large date range was recovered. Samples from the lower sections of the formation yielded a date of 849±48 Ma, whilst samples from near the middle of the formation yielded a date of 761±41 Ma, restricting the age of deposition for the formation between 849 Ma and 761 Ma.

Palaeoenvironments Due to the large thickness of the Wynniatt Formation and its informal members, it also has a notably wide range of environments, mostly shallow in nature, inferred from the rocks and minerals found within each member, which are as follows, based on Rainbird et al., 1996:

Lower Carbonate Member: This member is inferred to be a periodically exposed inter-tidal mudflat. Black Shale Member: This member is inferred to that of a shallow marine environment, which was sub-tidal to inter-tidal in nature with layers of microbial mat. Stromatolite Carbonate Member: This member is inferred to have been an extensive shelf-marginal reef complex, which itself is overlain by deposits of lagoons and a back-reef algal flat. Upper Carbonate Member: This member is inferred to have undergone cycles of shallow sub-tidal to inter-tidal.

Taphonomy The Wynniatt Formation is unique in that is has a Burgess Shale-type preservation, with organisms being preserved as carbonaceous films on the surface of a rock. Notably, this would mean that if there were any metazoan organisms present at the time, they too would have been preserved, as seen by the many animal fossils in younger BST sites, such as the Burgess Shale, but only various unicellular and multicellular algae forms have been preserved in the Wynniatt Formation, suggesting there were metazoans had not evolved by 800 Ma, and giving a possible soft maximum age for their appearance.

Paleobiota The Wynniatt Formation contains a small collection of algae-like fossils dating back to the Tonian, ranging from the classic Tawuia, to enigmatic forms such as Osculosphaera, and the fungi-like Tappania.

Illustrations

Worked examples

Example 1 — a first encounter with Wynniatt Formation

Start with the simplest possible case. Write down what Wynniatt Formation claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Wynniatt Formation before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Wynniatt Formation ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Wynniatt Formation

In research: Wynniatt Formation appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Wynniatt Formation in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Wynniatt Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dolomite formations of Canada, Geologic formations of Nunavut, Lagerstätten, so understanding it makes those chapters shorter.
In everyday life: Look for Wynniatt Formation outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Wynniatt Formation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Wynniatt Formation means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Wynniatt Formation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Wynniatt Formation in simple terms?

Why does Wynniatt Formation matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Wynniatt Formation?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Wynniatt Formation.