The Subachoque Formation ( es, Formación Subachoque, Q_1su) is a geological formation of the

Bogotá savanna The Bogotá savanna is a montane savanna, located in the southwestern part of the Altiplano Cundiboyacense in the center of Colombia. The Bogotá savanna has an extent of and an average altitude of . The savanna is situated in the Eastern Ra ...

Altiplano Cundiboyacense The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. The altiplano corresponds to the ancient territory of the Muisca. The Alt ...

Eastern Ranges The Eastern Ranges is an Australian rules football team in the NAB League, the Victorian statewide under-18s competition. The club is a founding member of the competition (1992) and has produced several players for the Australian Football Le ...

of the Colombian

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

. The formation consists mainly of sandy

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

s and lignite with

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

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 . It is the lowermost formation of the

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

and fluvio-glacial sediments of

Lake Humboldt Lake Humboldt or Humboldt Lake is an endorheic basin lake in northern Churchill County and southern Pershing County in the state of Nevada in the United States. The lake has the name of Alexander von Humboldt, a German natural scientist. ...

Etymology

The formation was first defined and named by Helmens and Van der Hammen in 1995 after

Subachoque Subachoque is a municipality and town of Colombia in the Western Savanna Province, part of the department of Cundinamarca. The municipality is situated on the Bogotá savanna with the urban centre at an altitude of at a distance of from the c ...

, Cundinamarca.Montoya & Reyes, 2005, p.69

Description

Lithologies

The Subachoque Formation consists mainly of sandy

s, some

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product o ...

, with lignite and

beds.

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 The Tilatá Formation ( es, Formación Tilatá, N1t, Tpt) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of coarse to very coarse conglomerates and sands ...

and other parts unconformably the Cretaceous

Guadalupe Group The Guadalupe Group ( es, Grupo Guadalupe, K2G, Ksg) is a geological group of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The group, a sequence of shales and sandstones, is subdivided into three formations; Arenisca Dura, ...

and the Paleogene

Guaduas Guaduas () is a town in Colombia, in the Lower Magdalena Province department of Cundinamarca, about 117 km from Bogotá. It is an agricultural and tourist center of some importance with a population of about 41,000. Its name refers to a ...

Cacho Cacho may refer to: Dice Games * Cacho Alalay, a South American dice game popular in Bolivia * Dudo, a South American dice game popular in Chile, also known as Pico or Perudo Geology *Cacho Formation The Cacho Formation ( es, Formación Cacho, E1 ...

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish period and between 1991 and 2000, is the capital city of Colombia, and one of the largest ...

, and Regadera Formations. The Subachoque Formation is overlain by other Quaternary deposits of

. The age has been estimated to be Early to Middle Pleistocene based on

fission track Ion tracks are damage-trails created by swift heavy ions penetrating through solids, which may be sufficiently-contiguous for chemical etching in a variety of crystalline, glassy, and/or polymeric solids. They are associated with cylindrical d ...

analysis, with reported ages between 2.5 and 1 Ma.Montoya & Reyes, 2005, p.71 The depositional environment has been interpreted as

and fluvio-glacial with

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

Outcrops

The Subachoque Formation is found at its

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

in the western flank of the synclinal of

and in the western flank of the synclinal of

Guasca Guasca is a Colombian town and municipality in the Guavio Province, part of the Cundinamarca Department located approximately 55 km from Bogotá passing through the town of La Calera, Cundinamarca or 65 km passing through Sopó. Guasc ...

. The deposition of the Subachoque Formation postdates the main reverse movement of the

Bogotá Fault The Bogotá Fault ( es, Falla de Bogotá) is a major inactive slightly dextral oblique thrust fault in the department of Cundinamarca in central Colombia. The fault has a total length of , while other authors designate a length of , and runs along ...

.Geological Map Bogotá, 1997

Regional correlations

Notes

References

Bibliography

Maps

* *

External links

* {{cite LSA , last=Gómez , first=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_Plancha_5-09_del_Atlas_Geologico_de_Colombia_2015 , publisher=

Servicio Geológico Colombiano The Colombian Geological Survey (CGS) ( es, Servicio Geológico Colombiano; formerly known as INGEOMINAS) is a scientific agency of the Colombian government in charge of contributing to the socioeconomic development of the nation through research ...

, pages=1 , accessdate=2017-03-16 Geologic formations of Colombia Pleistocene Colombia Sandstone formations Shale formations Deltaic deposits Fluvial deposits Glacial deposits Lacustrine deposits Formations Geography of Cundinamarca Department Geography of Bogotá Muysccubun