earth science

Tiourarén Formation

Tiourarén 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 Tiourarén Formation rather than just read about it. In short: The Tiourarén Formation is a geological formation in the Agadez Region of Niger whose strata were originally thought to be Early Cretaceous. However, re-interpretation of the sediments showed that they are probably Middle or Late Jurassic (Bathonian-Oxfordian) in age.

Key takeaways

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

Reference excerpt

The Tiourarén Formation is a geological formation in the Agadez Region of Niger whose strata were originally thought to be Early Cretaceous. However, re-interpretation of the sediments showed that they are probably Middle or Late Jurassic (Bathonian-Oxfordian) in age. Other works suggested it reaches the Barremian. It is the uppermost unit of the Irhazer Group. Dinosaur remains & other vertebrates are among the fossils that have been recovered from the formation. Originally part of the "Argiles de l'Ihrazer", the Tiouaren Formation primarily comprises reddish to purple siltstones with occasional marls, limestones, and scarce channel sandstones.

Description

The formation comprises reddish, almost solid mudstones, which also shows grey and white streaks, probably caused by alternating oxidative and reducing environments. Stromatolites are intermittently found in calcareous layers, while indications of semi-arid to arid conditions such as desiccation cracks and caliche horizons have been reported. Other lithology includes green or grayish clays, marls, dolomite beds with chert, and phosphatic sandstone limestones. At Agadez this section is invaded by channels of coarse feldspathic sandstones with limestone nodules and fine, ripple-marked sandstones, featuring green and purple clays with intercalations of cherty limestone beds in the uppermost sequence. The sandstone component increases eastward, and the formation wedges out between the underlying Agadez Sandstones and the overlying Tegama Group. The formation suggests a low-energy setting with expansive floodplains, temporary shallow lake development, and calcrete horizon interchanged with swamps, with seasonal flooding from a meandering, shallow river system dominated by overbanked silt. Many sandstone channels are composed of reworked sand grain-sized pebbles of mudstone, supporting the view of a predominantly low-relief environment. This latter feature is suggested by the widespread occurrence freshwater ostracod accumulations and rarer unionid bivalve shells. Local sedimenst were very affected and influenced by large scale faulting.

The Early Cretaceous dating for the Tiouaren Formation was based on vertebrate fossil evidence, specially Mawsoniidae coelacanths (referred without evidence to Mawsonia lavocati), while other taxa like Hybodus? sp. and Lepidotes? sp., are either dubious or have a suggested wide temporal distribution and invertebrates (conchostracans and unionid bivalves), offer limited stratigraphic value. Recent report of an ash bed and other potentially datable beds near fossil bearing horizons opens the possibility of a future age calibration.

Fossil content

Bivalves

Fishes

Turtles "Turtle Bones" where quoted in the OR description of the unit.

Crocodylomorphs "Crocodiles" where quoted in the OR description of the unit.

Dinosaurs "Rare (in abundance) pterosaurs" where quoted in the OR description of the unit.

Plants

See also List of dinosaur-bearing rock formations Lists of fossiliferous stratigraphic units in Africa List of fossiliferous stratigraphic units in Niger Geology of Niger

References

Further reading A. F. d. Lapparent. 1960. Les Dinosauriens du "Continental intercalaire" du Saharal central [The dinosaurs of the "Continental Intercalaire" of the central Sahara]. Mémoires de la Société géologique de France, nouvelle série 39(88A):1-57 P. C. Sereno, A. L. Beck, D. B. Dutheil, H. C. E. Larsson, G. H. Lyon, B. Moussa, R. W. Sadleir, C. A. Sidor, D. J. Varricchio, G. P. Wilson, and J. A. Wilson. 1999. Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs. Science 286:1342-1347 P. C. Sereno, J. A. Wilson, H. C. E. Larsson, D. B. Dutheil, and H.-D. Sues. 1994. Early Cretaceous dinosaurs from the Sahara. Science 266(5183):267-271 F. Witzmann, O. Hampe, B. M. Rothschild, U. Joger, R. Kosma, D. Schwarz, and P. Asbach. 2016. Subchondral cysts at synovial vertebral joints as analogies of Schmorl's Nodes in a sauropod dinosaur from Niger. Journal of Vertebrate Paleontology 36(2):e1080719:1-11

Illustrations

Worked examples

Example 1 — a first encounter with Tiourarén Formation

Start with the simplest possible case. Write down what Tiourarén 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 Tiourarén 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 Tiourarén 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 Tiourarén Formation

In research: Tiourarén 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 Tiourarén 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: Tiourarén Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Agadez Region, Bathonian Stage, Fluvial deposits, so understanding it makes those chapters shorter.
In everyday life: Look for Tiourarén 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 Tiourarén Formation in 20 minutes

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

Frequently asked questions

What is Tiourarén Formation in simple terms?

Why does Tiourarén 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 Tiourarén 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 Tiourarén Formation.