earth science

San Cassiano Formation

San Cassiano 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 San Cassiano Formation rather than just read about it. In short: San Cassiano Formation (Anisian-Carnian) is a geologic formation located on the Southern Alps (Northeast Italy) in the Dolomites. These Triassic dolomites are considered to be a classic example of ancient carbonate platforms.

Key takeaways

San Cassiano 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 San Cassiano Formation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of San Cassiano Formation from memory before moving on to harder problems.

Reference excerpt

San Cassiano Formation (Anisian-Carnian) is a geologic formation located on the Southern Alps (Northeast Italy) in the Dolomites. These Triassic dolomites are considered to be a classic example of ancient carbonate platforms. As the allochthonous elements in the Shale strata (Cipit boulders) show a good preservation, fossils and microbialites contained in these elements are useful in detailed geochemical analyses.

History Research on the San Cassiano Formation started in the 19th century with the works of Nicolas de Saussure and the stratigraphic works of Leopold von Buch and Alexander von Humboldt. By the late 19th century Richthofen and von Mojsisovics had already acknowledge the reefal origin of these mountains.

Geological background

The landscape of the Dolomites is dominated by Triassic carbonates, deposited from the Anisian to the Carnian. In the Lower Carnian (Julian) the percentages of carbonates increments due to the diminishing eustatic sea-level change. The last part of the reefal evolution is the development of patch reefs constituted by colonial corals (Scleractinia). Large areas of the reefs of the Dolomites suffered karstic erosion due to sea regression in the Anisian. A new transgression in the Carnian permitted new carbonate platforms to develop in swallow basins.

Stratigraphy The San Cassiano Formation overlays the Wengen Formation (a volcanic flysch sequence); the limit between this two formations is arbitrary; usually considered as the first carbonate strata in the volcaniclastic sequence. The San Cassiano Formation shows a variable thickness from 300 m to 500 m; it was described by Ogilvie in 1893, and it has two Members. The Inferior Member is constituted by an intercalated sequence of shale, limestone, volcaniclast (pseudoflysch) and marl; deposited from the Late Ladinian (Mid Triassic) to Early Carnian (Superior Triassic). The Superior Member is a sequence of pseudoflysch, marl, limestone and mudrock (in this strata some Cipit Boulders occur). This sequence was deposited from during the Middle Carnian. The strata are very similar in both members; they are divided by biostratigraphic criteria based in the aon zone (Inferior Member) and aonoides and austracum zones (Superior Member). Dürrenstein Dolomite (a massive dolomite unit) overlies the San Cassiano Formation.

Paleoenvironment In the 20th century the research in San Cassiano Formation was mostly focused in the study of facies analysis. The paleoenvironments represented in San Cassiano Formation are as follows: Reefal environments consisting of patch reefs; shallow marginal basin; carbonate platform; continental slope; and deep basin.

Facies The facies identified in San Cassiano Formation:

1. Volcaniclastic sandstones with cross bedding and clastic turbidites (pseudoflysch) 2. (a) Patch reefs with 10 m to 20 m in length and 10 m of thickness, generally with significant diagenetic alteration (b) Sequences of intercalated sediments influenced by volcanic activity and near carbonate platforms. Fossiliferour limestones, fossiliferous marl alternated with dismicrits, algal mats, oolit banks, fine to coarse grain size sandstones with cross bedding (c) Cyclic tidalites, massive dolomites, laminated algal mats, reworked ooliths 3. (a) Dolomitic massive carbonates presenting evidence of karstification (solution cavities, residual sediments and limonite crusts) (b) Stratified marine debris 4. (Muds or carbonate sediments interrupted by volcanic or carbonate turbidites) (a) Cipit Boulders consisting mostly of algal biolites, corals, pellets and micrites (microbialites) (b) Clay sediments with stratified oolites, oncolites, tuffites, turbidites and calcarenites with abundant gastropod and bivalve shells (c) Tuffites up to 300 m in thickness with sorted strata of calcirudites, calcarenites and Cipit Boulders. Most of the faunal elements are allochthonous (d) Mudrock and limestone with fine bedding, intercalated with fine grain turbidite and sporadic calcarenite turbidites These facies are interpreted as the next deposit environments:

1. Volcanic islands and formations 2. Reefal environment near to cost line: (a) patch reefs (b) A sequence of variable sediments intercalates with patch reefs (c) Back reef area of the carbonate platform 3. Carbonate platform 4. Basin: (a) Cipit Boulders (b) Marginal shallow basin (c) continental slope (300 m) (d) deep basin

Biota The Patch reefs from Valle di Rimbianco present a diverse fauna of fossilized calcitic sponges (Porifera), corals (Cnidaria), bivalves and gastropods (Mollusca), Brachiopoda and Echinodermata. Large parts of the basin are not fossiliferous. In the deep basin and continental slope facies the fauna consists only of ammonites and pseudoplanktonic bivalves, beside of allochthonous elements eroded from the carbonate platform (Cipit Boulders).

Geochemistry The facies that present less diagenetic alteration are the Cipit Boulders. The microbialites contained in these elements show a very good preservation and therefore are very useful as geochemical proxies to determine paleoenvironmental conditions of the carbonate platform. The carbonate platform itself suffered intense karstification and dolomitization, because of these alterations the fossils in this facies cannot be used in geochemical analysis.

References

Illustrations

Worked examples

Example 1 — a first encounter with San Cassiano Formation

Start with the simplest possible case. Write down what San Cassiano 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 San Cassiano 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 San Cassiano 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 San Cassiano Formation

In research: San Cassiano 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 San Cassiano 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: San Cassiano Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dolomites, Geologic formations of Italy, Lagerstätten, so understanding it makes those chapters shorter.
In everyday life: Look for San Cassiano 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 San Cassiano Formation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what San Cassiano 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 San Cassiano Formation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is San Cassiano Formation in simple terms?

Why does San Cassiano 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 San Cassiano 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 San Cassiano Formation.