El Peñón Formation
The El Peñón Formation (Spanish: 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 381 metres (1,250 ft). Ammonite fossils have been found in the formation, deposited in a shallow marine platform environment. EtymologyThe formation was defined and named in 1982 by Ulloa after El Peñón, Cundinamarca.[1] DescriptionLithologiesThe El Peñón Formation has at is type section a thickness of 381 metres (1,250 ft),[2] and is characterised by a sequence of calcareous shales and siltstones. The middle part of the sequence contains gypsum.[3] Fossils of the ammonites Cheloniceras sp. and Epicheloniceras sp. aff. carlosacostai have been found in the El Peñón Formation.[1] Stratigraphy and depositional environmentThe El Peñón Formation, part of the Villeta Group, conformably overlies the Trincheras Formation and is conformably overlain by the Capotes Formation.[4] The age has been estimated to be Late Aptian.[1] Stratigraphically, the formation is time equivalent with the Tablazo Formation and a lateral facies equivalent of the Socotá Formation.[5] The formation has been deposited in a shallow marine platform environment.[1] In the Late Aptian, central Colombia was dominated by shallow marine carbonate platform environments.[6] OutcropsThe El Peñón Formation, restricted to Cundinamarca, is locally found around its type locality,[1] between Bituima and Guayabal de Síquima,[7] and along the road from Villeta to Sasaima.[2] Regional correlations
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