View source for Subachoque Formation

{{short description|Geological formation in South America}}
{{other uses|Subachoque (disambiguation)}}
{{Infobox rockunit
| name           = Subachoque Formation
| period         = Pleistocene
| age            = [[Pleistocene|Early to Mid Pleistocene]]<br />~{{fossil range|2.5|1}}
| image          = 
| imagesize      = 
| caption        = 
| type           = [[Geological formation]]
| prilithology   = [[Shale]], [[lignite]]
| otherlithology = [[Sandstone]]
| unitof         = 
| subunits       = 
| underlies      = [[Sabana Formation]]
| overlies       = [[Tilatá Formation]]<br />[[Guadalupe Group|Guadalupe Gp.]]<br />[[Guaduas Formation|Guaduas Fm.]], [[Cacho Formation|Cacho Fm.]], [[Bogotá Formation|Bogotá Fm.]], [[Regadera Formation|Regadera Fm.]]
| thickness      = up to {{convert|150|m|ft|-1}}
| area           = 
| map            = Blakey Pleist - COL.jpg
| map_caption    = Paleogeography of the Pleistocene<br />{{small|by Ron Blakey}}
| location       =
| coordinates    = {{coord|4|57|17.3|N|74|13|07.5|W|display=inline,title}}
| region         = [[Bogotá savanna]], [[Altiplano Cundiboyacense]]<br />[[Cordillera Oriental (Colombia)|Eastern Ranges]], [[Andes]]
| country        = {{COL}}
| extent         = <!--{{convert||mi|km}}-->
| namedfor       = [[Subachoque]]
| namedby        = Helmens & [[Thomas van der Hammen|Hammen]]
| year_ts        = 1995
| location_ts    = Subachoque Synclinal
| coordinates_ts = {{coord|4|57|17.3|N|74|13|07.5|W|display=inline}}
| paleocoordinates_ts = 
| region_ts      = [[Cundinamarca Department|Cundinamarca]]
| country_ts     = {{COL}}
| thickness_ts   = <!--{{convert||m|ft|-1}}-->
}}
The '''Subachoque Formation''' ({{langx|es|Formación Subachoque}}, Q<sub>1su</sub>) is a [[formation (geology)|geological formation]] of the [[Bogotá savanna]], [[Altiplano Cundiboyacense]], [[Cordillera Oriental (Colombia)|Eastern Ranges]] of the [[Colombia]]n [[Andes]]. The formation consists mainly of sandy [[shale]]s and [[lignite]] with [[sandstone]] beds. The Subachoque Formation dates to the [[Quaternary]] period; [[Pleistocene|Early to Middle Pleistocene]] epoch (from approximately 2.5 to 1 Ma), and has a maximum thickness of {{convert|150|m|ft}}. It is the lowermost formation of the [[lacustrine]] and fluvio-glacial sediments of [[Lake Humboldt, Colombia|Lake Humboldt]].

== Etymology ==
The formation was first defined and named by Helmens and [[Thomas van der Hammen|Van der Hammen]] in 1995 after [[Subachoque]], [[Cundinamarca Department|Cundinamarca]].<ref name=Ingeominas_p69>Montoya & Reyes, 2005, p.69</ref>

== Description ==
=== Lithologies ===
The Subachoque Formation consists mainly of sandy [[shale]]s, some [[organic shale|organic]], with [[lignite]] and [[sandstone]] beds.<ref name=Ingeominas_p69/>

=== Stratigraphy and depositional environment ===
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 Formation|Guaduas]], [[Cacho Formation|Cacho]], [[Bogotá Formation|Bogotá]], and [[Regadera Formation]]s. The Subachoque Formation is overlain by other [[Quaternary]] deposits of [[Lake Humboldt, Colombia|Lake Humboldt]]. The age has been estimated to be [[Pleistocene|Early to Middle Pleistocene]] based on [[fission track]] analysis, with reported ages between 2.5 and 1 Ma.<ref name=Ingeominas_p71>Montoya & Reyes, 2005, p.71</ref> The depositional environment has been interpreted as [[lacustrine]] and fluvio-glacial with [[alluvial fan]]s.<ref name=Ingeominas_p69/>

== Outcrops ==
{{Location map | Bogotá savanna
| width   = 250
| lat_deg = 4.954799
| lon_deg = -74.218754
| label   = 
| float = left
| position = right
| mark = Yellow pog.svg
| marksize = 12
| caption = Type locality of the Subachoque Formation on the northwestern Bogotá savanna
}}
The Subachoque Formation is found at its [[type locality (geology)|type locality]] in the western flank of the synclinal of [[Subachoque]] and in the western flank of the synclinal of [[Guasca]].<ref name=Ingeominas_p69/> The deposition of the Subachoque Formation postdates the main [[thrust fault|reverse movement]] of the [[Bogotá Fault]].<ref name=MapaGeoBogota>Geological Map Bogotá, 1997</ref>

{{clear}}

== Regional correlations ==
{{Stratigraphy of the Llanos Basin}}

== See also ==
{{Portal|Colombia|Geology}}
:{{icon|GAN}} [[Eastern Hills, Bogotá#Geology|Geology of the Eastern Hills]]
:{{icon|B}} [[Ocetá Páramo#Geology|Geology of the Ocetá Páramo]]
:{{icon|C}} [[Altiplano Cundiboyacense#Geology|Geology of the Altiplano Cundiboyacense]]

== Notes ==
{{reflist|group=note}}

== References ==
{{reflist|30em}}

=== Bibliography ===
* {{citation |last1=Montoya Arenas |first1=Diana María |last2=Reyes Torres |first2=Germán Alfonso |year=2005 |title=Geología de la Sabana de Bogotá |publisher=[[INGEOMINAS]] |pages=1–104}}

==== Maps ====
* {{citation |last1=Buitrago |first1=José Alberto |last2=Terraza M. |first2=Roberto |author3-link=Fernando Etayo |last3=Etayo |first3=Fernando |year=1998 |title=Plancha 228 - Santafé de Bogotá Noreste - 1:100,000 |url=https://drive.google.com/open?id=0BwFQPMJEi17QTlNraVVZZ2ZCY0E |publisher=[[INGEOMINAS]] |pages=1 |accessdate=2017-06-06}}
* {{citation |last=Various |first=Authors |year=1997 |title=Mapa geológico de Santa Fe de Bogotá – Geological Map Bogotá – 1:50,000 |url=http://seisan.sgc.gov.co/RSNC/Mapa_Geo.pdf |publisher=[[INGEOMINAS]] |pages=1 |accessdate=2017-03-16}}

== Further reading ==
* {{citation |last=Guerrero Uscátegui |first=Alberto Lobo |year=1992 |title=Geología e Hidrogeología de Santafé de Bogotá y su Sabana |publisher=Sociedad Colombiana de Ingenieros |pages=1–20}}

== External links ==
* {{citation |last1=Gómez |first1=J. |last2=Montes |first2=N.E. |last3=Nivia |first3=Á. |last4=Diederix |first4=H. |year=2015 |title=Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000 |url=https://www.researchgate.net/publication/309533589 |publisher=[[Servicio Geológico Colombiano]] |pages=1 |accessdate=2017-03-16}}

[[Category:Geologic formations of Colombia]]
[[Category:Pleistocene Colombia]]
[[Category:Sandstone formations]]
[[Category:Shale formations]]
[[Category:Deltaic deposits]]
[[Category:Fluvial deposits]]
[[Category:Glacial deposits]]
[[Category:Lacustrine deposits]]
[[Category:Altiplano Cundiboyacense|Formations]]
[[Category:Geography of Cundinamarca Department]]
[[Category:Geography of Bogotá]]