Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur Graph Search.
Concept
Bogotá Formation
Résumé
The Bogotá Formation (Formación Bogotá, E1-2b, Tpb, Pgb) is a geological formation of the Eastern Hills and Bogotá savanna on the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale and siltstone formation, with sandstone beds intercalated, dates to the Paleogene period; Upper Paleocene to Lower Eocene epochs, with an age range of 61.66 to 52.5 Ma, spanning the Paleocene–Eocene Thermal Maximum. The thickness of the Bogotá Formation ranges from near Tunja to near Bogotá. Fossils of the ungulate Etayoa bacatensis have been found in the Bogotá Formation, as well as numerous reptiles, unnamed as of 2017.
The formation was first described by Hettner in 1892, then by Hubach in 1931, 1945 and 1957, and named in 1963 by Julivert after the Colombian capital Bogotá and its savanna.
The Bogotá Formation consists mainly of grayish-red, locally purplish, commonly greenish-gray, generally poorly stratified mudstone and silty claystone. Lithic arenite sandstone lenses, ranging from fine- to medium-grained, generally friable and variegated, are local constituents. Carbonaceous material is present as thin beds of low-grade argillaceous coal, north of Bogotá. Fossil remains of Etaoya bacatensis, named after Colombian geologist Fernando Etayo and the indigenous name for the Bogotá savanna, Bacatá, have been found in Ciudad Bolívar, close to the type locality of the Bogotá Formation. Additionally, macroflora of Palaeophytocrene hammenii, named after Dutch botanist Thomas van der Hammen, and pollen of Foveotriletes margaritae, Proxapertites operculatus and Foveotricolpites perforatus have been found, used for dating the formation. Other pollen and flora, as Ulmoideipites krempii, Carpolithus, Anemocardium margaritae, and Hickeycarpum peltatum have been found in the Bogotá Formation. The abundant paleosols of the Bogotá Formation show an increase in chemical weathering across the Paleocene-Eocene (P-E) transition; the Paleocene–Eocene Thermal Maximum.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.