The El Peñón Formation (, Kipe) is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the

Altiplano Cundiboyacense The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. (Do not confuse with The Altiplano or the Altiplano Nariñense, both fur ...

Eastern Ranges The Eastern Ranges is an Australian rules football team that currently competes in the Talent League, the Victorian statewide under-18s competition. History Inaugural playing squad (1992) Honours *Premiers (2): 2002, 2013 *Runners-up (6): 199 ...

of the

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. The formation consists of calcareous shales and siltstones and dates to the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

period; Late Aptian epoch and has a measured thickness at its type section of .

Ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

fossils have been found in the formation, deposited in a shallow marine platform environment.

Etymology

The formation was defined and named in 1982 by Ulloa after El Peñón, Cundinamarca.

Description

Lithologies

The El Peñón Formation has at is type section a thickness of , and is characterised by a sequence of calcareous

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s and

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

s. The middle part of the sequence contains

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

.Acosta & Ulloa, 2001, p.29 Fossils of the ammonites '' Cheloniceras sp.'' and '' Epicheloniceras sp. aff. carlosacostai'' have been found in the El Peñón Formation.Acosta & Ulloa, 2002, p.42

Stratigraphy and depositional environment

The El Peñón Formation, part of the

Villeta Group The Villeta Group () is a group (geology), geological group of the Cordillera Oriental (Colombia), Eastern Ranges of the Colombian Andes, to the west of the Altiplano Cundiboyacense. The group, a sequence of shales, limestones and sandstones, is s ...

, conformably overlies the

Trincheras Formation The Trincheras Formation (, Kitr) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cr ...

and is conformably overlain by the Capotes Formation.Acosta & Ulloa, 2001, p.30 The age has been estimated to be Late Aptian. Stratigraphically, the formation is time equivalent with the Tablazo Formation and a lateral facies equivalent of the

Socotá Formation The Socotá Formation (, Kis) is a formation (geology), geological formation of the Altiplano Cundiboyacense, Cordillera Oriental (Colombia), Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous sandstones a ...

.Acosta & Ulloa, 2001, p.16 The formation has been deposited in a

shallow marine Shallow water marine environment refers to the neritic marine environment between the shore and the shelf break. This environment is characterized by oceanic, geological and biological conditions, as described below, and water in this environmen ...

platform environment. In the Late Aptian, central Colombia was dominated by shallow marine carbonate platform environments.Villamil, 2012, p.164

Outcrops

The El Peñón Formation, restricted to Cundinamarca, is locally found around its type locality, between Bituima and Guayabal de Síquima,Plancha 227, 1998 and along the road from

Villeta Villeta is a city of Paraguay in the Central Department, on the banks of Paraguay River. It is an important industrial center and port. Toponymy The city was founded on March 5, 1714, by Juan Gregorio Bazán de Pedraza, with the original name ...

to Sasaima.Acosta & Ulloa, 2001, p.27

References

Bibliography

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Maps

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External links

* {{DEFAULTSORT:El Penon Formation Geologic formations of Colombia Cretaceous Colombia Lower Cretaceous Series of South America Aptian Stage Shale formations Shallow marine deposits Formations Formations