earth science

Macanal Formation

Macanal 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 Macanal Formation rather than just read about it. In short: The Macanal Formation or Macanal Shale (Spanish: (Formación) Lutitas de Macanal, Kilm, K1m) is a fossiliferous geological formation of the Altiplano Cundiboyacense and Tenza Valley in the Eastern Ranges of the Colombian Andes. The predominantly organic shale formation dates to the Early Cretaceous period; Berriasian to Valanginian epochs and has a maximum thickness of 2,935 metres (9,629 ft).

Key takeaways

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

Reference excerpt

The Macanal Formation or Macanal Shale (Spanish: (Formación) Lutitas de Macanal, Kilm, K1m) is a fossiliferous geological formation of the Altiplano Cundiboyacense and Tenza Valley in the Eastern Ranges of the Colombian Andes. The predominantly organic shale formation dates to the Early Cretaceous period; Berriasian to Valanginian epochs and has a maximum thickness of 2,935 metres (9,629 ft). The Macanal Formation contains numerous levels of fossiliferous abundances. Bivalves, ammonites and fossil flora have been found in the formation. The formation is a source rock for oil and gas in the Eastern Cordillera Basin and adjacent Llanos Basin foothills and provides emeralds in the vicinity of Macanal, after which the formation is named.

Etymology The formation was defined and named in 1979 by Rodríguez and Ulloa after Macanal, Cundinamarca. The name Macanal is either derived from the Muysccubun word Macana, meaning garrote, or from the Macana palm tree.

Description

Lithologies

The Macanal Formation has a maximum thickness of 2,935 metres (9,629 ft), and is characterised by a sequence of micaceous organic shales, with calcite veins and gypsum occurrences intercalated in the formation. The Macanal Formation contains high values of TOC. In the Eastern Cordillera Basin and the adjacent foothills of the Llanos Basin, the Macanal Formation is a source rock for oil and gas. In the vicinity of Macanal, the formation provides emeralds.

Stratigraphy and depositional environment The Macanal Formation, a unit of the Cáqueza Group, concordantly overlies the Guavio, Santa Rosa, Ubalá, Chivor and Batá Formations, and is concordantly overlain by the Las Juntas Formation. The age has been estimated to be Berriasian to Valanginian. Stratigraphically, the formation is time equivalent with the Mercedes, Tambor, Rosablanca, Murca and La Naveta Formations. The formation has been deposited in a shallow marine environment in an enclosed basin, with as provenance areas the Santander High and the Guiana Shield. The Macanal Formation is part of the syn-rift sequence of eastern Colombia.

Fossil content The Macanal Formation contains numerous levels of fossiliferous abundances. Bivalves, ammonites and flora have been found in the formation. Ammonites of Substeueroceras cf. mutabile, Sarasinella cf. hondana, Subalpinites sp., Berriasela sp., Neocomites cf. wichmanni, Olcostephanus sp., Olcostephanus cf. atherstoni, Favrella cf. colombiana, Acanthodiscus sp. have been registered in the formation, as well as bivalves of Corbis (Sphaera) cf. corrugata, Trigonia cf. hondana, Trigonia (Buchotrigonia) cf. abrupta, Trigonia (Notoscabrotrigonia) cf. tocaimaana, and Exogyra cf. boussingaulti. Analysis of the deformation registered in ammonite fossils has helped in understanding the tectonic history of the Llanos foothills of the Eastern Ranges.

Outcrops

The Macanal Formation is apart from its type locality in the Batá River canyon, found in the Cravo Sur anticline, east of the Ocetá Páramo, in the Desespero Synclinal in the southern and northern parts of Labranzagrande, around Páez and Campohermoso, in the eastern part of Gama, bordering the Guavio Reservoir, and in the Servitá Synclinal, west of Villavicencio. The Macanal Formation crops out along the road between Bogotá and Villavicencio and is there heavily fractured and folded. The Macanal Formation is the most extensive formation around Cáqueza, and Gachalá, Cundinamarca. The Pajarito Fault thrusts the Macanal Formation on top of the Fómeque Formation to the east of Lake Tota, and the Chámeza Fault thrusts the Macanal Formation on top of the overlying Las Juntas Formation around Chámeza, Casanare. The Ubaque Fault forms the contact between the Fómeque Formation and the Macanal Formation, while the Las Mercedes Fault puts the Quetame Group in contact with the Macanal Formation near Quetame, as does the San Juanito Fault. The Servitá Fault forms the contact between the Guatiquía Redbeds and the Macanal Formation, and the Upín Fault, part of the same system puts the Macanal Formation in contact with the Tertiary Palmichal Group. At this contact, brines are extracted from the formation.

Regional correlations

Legend group important formation fossiliferous formation minor formation (age in Ma) proximal Llanos (Medina) distal Llanos (Saltarin 1A well)

Illustrations

Worked examples

Example 1 — a first encounter with Macanal Formation

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

In research: Macanal 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 Macanal 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: Macanal Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Altiplano Cundiboyacense, Berriasian Stage, Colombian emeralds, so understanding it makes those chapters shorter.
In everyday life: Look for Macanal 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Macanal Formation in 20 minutes

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

Frequently asked questions

What is Macanal Formation in simple terms?

Why does Macanal 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 Macanal 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 Macanal Formation.