The Marichuela Formation (, N_1m) is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the

Bogotá savanna The Bogotá savanna is a savanna#Savanna ecoregions, 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 si ...

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. (Do not confuse with The Altiplano or the Altiplano Nariñense, both fur ...

Eastern Ranges The Eastern Ranges is an Australian rules football team that currently competes in the Talent League, the Victorian statewide under-18s competition. History Inaugural playing squad (1992) Honours *Premiers (2): 2002, 2013 *Runners-up (6): 199 ...

of the

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. The formation consists of coarse to very coarse conglomerates. The Marichuela Formation dates to the

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

period;

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

Early Pliocene Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...

epochs, and has a maximum thickness of .

Etymology

The formation was defined by Helmens and Van der Hammen in 1995 and named after the Marichuela neighbourhood of

Usme Usme is the 5th locality of the Bogotá, Capital District, Capital District of Bogotá, capital city of Colombia. Usme is located in the south of Bogotá, bordering to the north the localities of San Cristóbal, Bogotá, San Cristóbal, Rafael Ur ...

.Montoya & Reyes, 2005, p.65 Part of the Marichuela Formation had been included in the Conos de Tunjuelo, defined by Julivert in 1961.Suna Hisca, s.a., p.45

Description

Lithologies

The Marichuela Formation consists of coarse to very coarse conglomerates.

Stratigraphy and depositional environment

The Marichuela Formation unconformably overlies the Cretaceous rocks of the

Guadalupe Group The Guadalupe Group (, 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, Plaeners and Areni ...

. The age has been estimated to be

.Montoya & Reyes, 2005, p.67 The depositional environment has been interpreted as

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 Semi-arid climate, semiar ...

s, caused by earthquakes or heavy rains.Montoya & Reyes, 2005, p.66

Outcrops

The Marichuela Formation is apart from its type locality in the

Synclinal, the valley of the

Tunjuelo River The Tunjuelo or Tunjuelito River is a river on the Bogotá savanna and a left tributary of the Bogotá River. The river, with a length of originates in the Sumapaz Páramo and flows northward through the Usme Synclinal to enter the Colombian capit ...

, found in the synclinals of Neusa, Sisga and La Calera.

Regional correlations

Notes

References

Bibliography

* *

Maps

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 The Colombian Geological Survey (CGS) (; formerly known as INGEOMINAS) is a scientific Government agency, agency of the Colombian government in charge of contributing to the socioeconomic development of the nation through research in basic and ap ...

, pages=1 , accessdate=2017-03-16 Geologic formations of Colombia Neogene Colombia Messinian Tortonian Miocene Series of South America Pliocene Series of South America Montehermosan Huayquerian Conglomerate formations Alluvial deposits Formations Geography of Cundinamarca Department Geography of Bogotá