earth science

Los Llanos Formation

Los Llanos 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 Los Llanos Formation rather than just read about it. In short: Los Llanos Formation is a geological formation in the La Rioja Province, northwestern Argentina whose strata date back to the Campanian stage of the Late Cretaceous. Los Llanos Formation over the years has been controversially described as ranging from Late Cretaceous to Miocene, but the Miocene succession was assigned to Las Mulitas Formation in 2019.

Key takeaways

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

Reference excerpt

Los Llanos Formation is a geological formation in the La Rioja Province, northwestern Argentina whose strata date back to the Campanian stage of the Late Cretaceous. Los Llanos Formation over the years has been controversially described as ranging from Late Cretaceous to Miocene, but the Miocene succession was assigned to Las Mulitas Formation in 2019. The formation rests on top of the Early Permian Los Sauces and Patquía Formations and in parts on Ordovician crystalline basement. The maximum thickness is estimated at 150 metres (490 ft). The sandstones and conglomerates of the formation were deposited ij a fluvial environment. The formation crops out in the Sanagasta geological park, where more than 90 titanosaurid nesting sites were discovered in Los Llanos Formation. The sites were encountered on top of areas characterized by hydrothermal activity as geysers and other vents, suggesting a preferred location for the incubation of the dinosaur eggs. Apart from fossil eggs, the formation has provided fossil flora and ostracods. The crocodyliform Llanosuchus, described in 2016 from the formation, was named after Los Llanos Formation.

Description

The Los Llanos Formation was first formally described by Bodenbender in 1911. The formation crops out in very localized patches in the south of La Rioja Province. Los Llanos Formation is found on the western and eastern slopes of the eponymous Sierra de Los Llanos, in the Sierra de Chepes, Sierra Ulapes, Sierra de Velasco and Sierra Brava. Between the original definition of "Los Estratos de Los Llanos" (Los Llanos Beds) by Bodenbender and later analysis during the twentieth century, a number of controversies arose. Rusconi (1936), Bordas (1941), Pascual (1954), Guiñazú (1962) and Zuzek (1978) assigned a Miocene age to the formation, based on mammal fossils found in the strata. This unit is presently known as the Las Mulitas Formation. The occurrence of typical Cretaceous charophytes confirms the assigned age for Los Llanos Formation. Los Llanos Formation unconformably overlies the Permian Los Sauces Formation in the Sierra de Velasco and the Permian Patquía Formation or Ordovician granitic basement in other places. The maximum recorded thickness in the Sanagasta Geologic Park is 4 metres (13 ft), while in the region of Tama the formation reaches an estimated thickness of 150 metres (490 ft). It comprises lightgrey and orange sandstones with basal conglomerate beds, deposited in a fluvial environment, which in the Sanagasta park is associated with hydrothermal activity. The more than 90 sauropod nests were found in direct association with these hydrothermal vents, suggesting a preferred incubation location of the mother dinosaurs.

Paleontological significance

The formation has provided fossilized nesting sites attributed to a titanosaurid dinosaur. Research conducted in 2015 by Hechenleitner et al. include a comparison with the Cretaceous Sanpetru Formation of Hațeg paleo-island in Romania, the Tremp Formation of the Spanish Pre-Pyrenees and the Boseong Formation of the Gyeongsang Basin in South Korea.

Fossil content The following fossils were reported from the formation:

Dinosaurs

Crocodyliformes

Oofossils

Invertebrates

Flora

See also List of dinosaur-bearing rock formations Allen Formation, Campanian to Maastrichtian fossiliferous formation of the Neuquén Basin Anacleto Formation, Campanian ooliferous formation of the Neuquén Basin Angostura Colorada Formation, Campanian to Maastrichtian fossiliferous formation of the North Patagonian Massif La Colonia Formation, Campanian to Maastrichtian formation of the Cañadón Asfalto Basin Colorado Formation, Campanian to Maastrichtian fossiliferous formation of the Colorado Basin Lago Colhué Huapí Formation, Campanian to Maastrichtian fossiliferous formation of the Golfo San Jorge Basin

References

Bibliography Chiesa, Jorge (2019), "Estratigrafía, paleontología y paleoambientes del Plioceno de la región Cuyo de Argentina (San Luis, Mendoza, San Juan y La Rioja)", Opera Iilloana, 52: 287–347 Hechenleitner, E. M (2017), Dinosaurios saurópodos de la Formación Los Llanos (Cretácico, La Rioja, Argentina): ocurrencia, caracterización sistemática y tafonómica, bioestratigrafía, análisis paleoambientales y sus implicancias geológico-regionales (PhD thesis), Universidad Nacional de La Plata, pp. 1–161 De Sosa Tomas, Andrea; Carignano, Ana Paula; Fiorelli, Lucas Ernesto; Hechenleitner, E. Martín (2017), Carofitas del cretácico tardío de la Formación Los Llanos, La Rioja - Reporte preliminar, V Jornadas de las Ciencias de la Tierra "Dr. Eduardo Musacchio", pp. 34–36, ISBN 978-987-1937-79-0 Fiorelli, Lucas E.; Leardi, Juan M.; Hechenleitner, E. Martín; Pol, Diego; Basilici, Giorgio; Grellet-Tinner, Gerald (2016), "A new Late Cretaceous crocodyliform from the western margin of Gondwana (La Rioja Province, Argentina)", Cretaceous Research, 60: 194–209, Bibcode:2016CrRes..60..194F, doi:10.1016/j.cretres.2015.12.003, hdl:11336/43823 Hechenleitner, M. E.; Fiorelli, L.E.; Grellet-Tinner, G.; Leuzinger, L.; Basilici, G.; Taborda, J. R. A.; de la Vega, S. R.; Bustamante, C. A. (2016), "A new Upper Cretaceous titanosaur nesting site from La Rioja (NW Argentina), with implications for titanosaur nesting strategies", Palaeontology, 59 (3): 433–446, Bibcode:2016Palgy..59..433H, doi:10.1111/pala.12234, hdl:11336/44234 Hechenleitner, E. Martín; Grellet Tinner, Gerald; Fiorelli, Lucas E. (2015), "What do giant titanosaur dinosaurs and modern Australasian megapodes have in common?" (PDF), PeerJ, 3:e1341: 1–32, retrieved 2018-05-24 Carignano, Ana Paula; Hechenleitner, E. Martín; Fiorelli, Lucas Ernesto (2013), "Hallazgo de ostrácodos (Crustacea) Cretácicos continentales en la Formación Los Llanos, localidad de Tama, La Rioja", Ameghiniana, 50: R39, retrieved 2020-06-19 Grellet-Tinner, G.; Fiorelli, L. E. (2010), "A new Argentinean nesting site showing neosauropod dinosaur reproduction in a Cretaceous hydrothermal environment", Nature Communications, 1 (3): 1–8, Bibcode:2010NatCo...1...32G, doi:10.1038/ncomms1031, hdl:11336/68592, PMID 20975685 Bodenbender, G (1911), "Constitución geológica de la parte meridional de La Rioja y regiones limítrofes", Boletín de la Academia Nacional de Ciencias, 19: 2–11

Illustrations

Worked examples

Example 1 — a first encounter with Los Llanos Formation

Start with the simplest possible case. Write down what Los Llanos 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 Los Llanos 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 Los Llanos 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 Los Llanos Formation

In research: Los Llanos 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 Los Llanos 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: Los Llanos Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Campanian Stage, Conglomerate formations of Argentina, Cretaceous Argentina, so understanding it makes those chapters shorter.
In everyday life: Look for Los Llanos 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 Los Llanos Formation in 20 minutes

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

Frequently asked questions

What is Los Llanos Formation in simple terms?

Why does Los Llanos 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 Los Llanos 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 Los Llanos Formation.