• Source: Subachoque Formation

The Subachoque Formation (Spanish: Formación Subachoque, Q1su) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists mainly of sandy shales and lignite with sandstone beds. The Subachoque Formation dates to the Quaternary period; Early to Middle Pleistocene epoch (from approximately 2.5 to 1 Ma), and has a maximum thickness of 150 metres (490 ft). It is the lowermost formation of the lacustrine and fluvio-glacial sediments of Lake Humboldt.




Etymology


The formation was first defined and named by Helmens and Van der Hammen in 1995 after Subachoque, Cundinamarca.




Description






= Lithologies

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The Subachoque Formation consists mainly of sandy shales, some organic, with lignite and sandstone beds.




= Stratigraphy and depositional environment

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The Subachoque Formation is the lowermost of the lagunal and alluvial sequence of the Bogotá savanna. In parts, it conformably overlies the Tilatá Formation and other parts unconformably the Cretaceous Guadalupe Group and the Paleogene Guaduas, Cacho, Bogotá, and Regadera Formations. The Subachoque Formation is overlain by other Quaternary deposits of Lake Humboldt. The age has been estimated to be Early to Middle Pleistocene based on fission track analysis, with reported ages between 2.5 and 1 Ma. The depositional environment has been interpreted as lacustrine and fluvio-glacial with alluvial fans.




Outcrops



The Subachoque Formation is found at its type locality in the western flank of the synclinal of Subachoque and in the western flank of the synclinal of Guasca. The deposition of the Subachoque Formation postdates the main reverse movement of the Bogotá Fault.




Regional correlations



Legend
group
important formation
fossiliferous formation
minor formation
(age in Ma)
proximal Llanos (Medina)
distal Llanos (Saltarin 1A well)




See also



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




Notes






References






= Bibliography

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Montoya Arenas, Diana María; Reyes Torres, Germán Alfonso (2005), Geología de la Sabana de Bogotá, INGEOMINAS, pp. 1–104



Maps

Buitrago, José Alberto; Terraza M., Roberto; Etayo, Fernando (1998), Plancha 228 - Santafé de Bogotá Noreste - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Various, Authors (1997), Mapa geológico de Santa Fe de Bogotá – Geological Map Bogotá – 1:50,000 (PDF), INGEOMINAS, p. 1, retrieved 2017-03-16




Further reading


Guerrero Uscátegui, Alberto Lobo (1992), Geología e Hidrogeología de Santafé de Bogotá y su Sabana, Sociedad Colombiana de Ingenieros, pp. 1–20




External links


Gómez, J.; Montes, N.E.; Nivia, Á.; Diederix, H. (2015), Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000, Servicio Geológico Colombiano, p. 1, retrieved 2017-03-16

Kata Kunci Pencarian:

• Subachoque Formation
• Subachoque
• Subachoque (disambiguation)
• Chorrera Formation
• Tilatá Formation
• Tunjuelo Formation
• Eastern Hills (Bogotá)
• Sabana Formation
• List of Muisca toponyms
• Honda Group, Colombia