El Peñón Formation Explained

El Peñón Formation
Period:Aptian
Age:Late Aptian
~
Type:Geological formation
Prilithology:Calcareous shale
Otherlithology:Siltstone, gypsum
Unitof:Villeta Group
Underlies:Capotes Formation
Overlies:Trincheras Formation
Thickness:more than 381m (1,250feet)
Map:Blakey 120Ma - COL.jpg
Coordinates:5.2536°N -74.3411°W
Region:Altiplano Cundiboyacense
Eastern Ranges, Andes
Namedfor:El Peñón
Namedby:Ulloa
Year Ts:1982
Location Ts:El Peñón
Coordinates Ts:5.2536°N -74.3411°W
Region Ts:Cundinamarca
Thickness Ts:381m (1,250feet)

The El Peñón Formation (Spanish; Castilian: Formación El Peñón, Kipe) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of calcareous shales and siltstones and dates to the Early Cretaceous period; Late Aptian epoch and has a measured thickness at its type section of 381m (1,250feet). Ammonite 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 381m (1,250feet), and is characterised by a sequence of calcareous shales and siltstones. The middle part of the sequence contains gypsum.[1] Fossils of the ammonites Cheloniceras sp. and Epicheloniceras sp. aff. carlosacostai have been found in the El Peñón Formation.[2]

Stratigraphy and depositional environment

The El Peñón Formation, part of the Villeta Group, conformably overlies the Trincheras Formation and is conformably overlain by the Capotes Formation.[3] The age has been estimated to be Late Aptian.[2] Stratigraphically, the formation is time equivalent with the Tablazo Formation and a lateral facies equivalent of the Socotá Formation.[4] The formation has been deposited in a shallow marine platform environment.[2] In the Late Aptian, central Colombia was dominated by shallow marine carbonate platform environments.[5]

Outcrops

The El Peñón Formation, restricted to Cundinamarca, is locally found around its type locality,[2] between Bituima and Guayabal de Síquima,[6] and along the road from Villeta to Sasaima.[7]

See also

Geology of the Eastern Hills

Geology of the Ocetá Páramo

Geology of the Altiplano Cundiboyacense

References

Bibliography

Maps

Notes and References

  1. Acosta & Ulloa, 2001, p.29
  2. Acosta & Ulloa, 2002, p.42
  3. Acosta & Ulloa, 2001, p.30
  4. Acosta & Ulloa, 2001, p.16
  5. Villamil, 2012, p.164
  6. Plancha 227, 1998
  7. Acosta & Ulloa, 2001, p.27