Bogotá Formation

The Bogotá Formation (, E_1-2b, 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.

Etymology

The formation was first described by Hettner in 1892,Acosta & Ulloa, 2002, p.59 then by Hubach in 1931, 1945 and 1957, and named in 1963 by Julivert after the Colombian capital Bogotá and its savanna.Montoya & Reyes, 2005, p.57

Description

Lithologies

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.Bayona et al., 2010, p.5McLaughlin, 1970, p.15 Fossil remains of '' Etaoya bacatensis'', named after Colombian geologist Fernando Etayo and the indigenous name for the Bogotá savanna, Bacatá,Villarroel, 1987, p.242 have been found in Ciudad Bolívar, close to the type locality of the Bogotá Formation.''Etayoa bacatensis''
at Fossilworks.org Additionally, macroflora of '' Palaeophytocrene hammenii'', named after Dutch botanist Thomas van der Hammen,Stull et al., 2012 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.Herrera et al., 2014, pp.204-209 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.Morón et al., 2013

Later analysis has found several other species, such as pleurodire turtles, found at the Doña Juana dump,Cadena, 2014, p.334 dyrosaurid mesoeucrocodylians, boid snakes, dipnoan fishes, frogs, lizards, sebecid crocodyliforms and 11 fossils of mammals.Bloch et al., 2008 The find of a derived snake in the Lower Eocene section of the formation represents the oldest New World record.Head et al., 2011 The finds of iguanians, including the fossil record of hoplocercines, and boine, caenophidian, and ungaliophiine snakes, indicate a tropical forest environment, present just before the Early Eocene Climatic Optimum (EECO).Head et al., 2012 The faunal distribution has been correlated to the '' Carodnia''-, '' Amphidolops''-, and '' Wainka''-bearing Peñas Coloradas Formation of the Golfo San Jorge Basin in Patagonia, Argentina.Woodburne et al., 2014, p.60

Stratigraphy and depositional environment

The Bogotá Formation, with a thickness of close to Tunja to near Bogotá,Bayona et al., 2013, p.8Guerrero Uscátegui, 1992, p.5 overlies the Cacho Formation and is overlain by the Regadera Formation. The age has been estimated to be Late Paleocene to Early Eocene.Montoya & Reyes, 2005, p.60 The middle part of the succession has been dated using detrital zircons at 56.2 ± 1.6 Ma.Bayona et al., 2012, p.104 The spread of ages based on zircons has been reported from 60.96 ± 0.7 to 53.6 ± 1.1 Ma.Bayona et al., 2012, p.103 The Bogotá Formation is laterally equivalent with the shales of the Socha Formation, the San Fernando Formation, the El Limbo Formation, Los Cuervos Formation,Figures Bayona et al.
/ref> and the fossil-rich Cerrejón Formation of La Guajira.

Outcrops

The Bogotá Formation is apart from its type locality, found in the synclinals of the Río Frío, Checua- Lenguazaque, Sesquilé, Sisga, Subachoque,Plancha 227, 1998 around Lake Suesca, in the Tenza Valley, and in the synclinals of Teusacá and Usme.Plancha 246, 1998Geological Map Bogotá, 1997 In the Usme Synclinal, the formation has a thickness of .Bayona et al., 2010, p.10 The campus of the Universidad La Javeriana has the Bogotá Formation as solid basement rock.García & Alfaro, 2001, p.5

The Bogotá Formation forms the footwall of the eastward compressional Chicamocha Fault, and the footwall of the westward thrusting Bogotá Fault.

Regional correlations

Itaboraian correlations

See also

* Geology of the Eastern Hills
* Geology of the Ocetá Páramo
* Geology of the Altiplano Cundiboyacense

Notes and references

Notes

References

Bibliography

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Maps

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External links

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{{DEFAULTSORT:Bogota Formation
Geologic formations of Colombia
Paleogene Colombia
Paleocene Series of South America
Eocene Series of South America
Casamayoran
Riochican
Itaboraian
Peligran
Selandian Stage
Thanetian Stage
Ypresian Stage
Fossiliferous stratigraphic units of South America
Paleontology in Colombia
Mudstone formations
Siltstone formations
Sandstone formations
Shale formations
Formations
Formations
Formations