Earth:Chorrera Formation

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Chorrera Formation
Stratigraphic range: Pliocene
(Montehermosan-Chapadmalalan)
~5–3 Ma
TypeGeological formation
UnderliesSubachoque Formation
OverliesGuadalupe Gp.
Thicknessup to 40 m (130 ft)
Lithology
PrimaryConglomerate
Location
Coordinates [ ⚑ ] : 4°55′30.0″N 74°06′22.6″W / 4.925°N 74.106278°W / 4.925; -74.106278
RegionBogotá savanna, Altiplano Cundiboyacense
Eastern Ranges, Andes
Country Colombia
Type section
Named forLa Chorrera waterfall
Named byHelmens & Hammen
LocationRío Frío, Subachoque/Tabio
Year defined1995
Coordinates [ ⚑ ] 4°55′30.0″N 74°06′22.6″W / 4.925°N 74.106278°W / 4.925; -74.106278
RegionCundinamarca
Country Colombia

The Chorrera Formation (Spanish: Formación Chorrera, N2ch) 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. The Chorrera Formation dates to the Neogene period; Pliocene epoch (Montehermosan to Chapadmalalan in the SALMA classification), and has a maximum thickness of 40 metres (130 ft).

Etymology

The formation was defined by Helmens and Van der Hammen in 1995 after the La Chorrera waterfall in Subachoque.[1]

Description

Lithologies

The Chorrera Formation consists of coarse to very coarse conglomerates.[1]

Stratigraphy and depositional environment

The Chorrera Formation unconformably overlies the Late Cretaceous Guadalupe Group. The formation is overlain by the Pleistocene Subachoque Formation. The age of the Chorrera Formation has been estimated to be Late Pliocene based on its stratigraphical position. The depositional environment is characterised by alluvial fans formed during the main phase of tectonic uplift of the Eastern Ranges in the Late Pliocene.[1] Dutch geologist Salomon Kroonenberg, who studied the Neogene uplift of the Eastern Andes in Colombia, defines the main stage of uplift between six and four million years ago. Other Dutch geologists Helmens, Van der Hammen and Hooghiemstra have pushed back this uplift phase to between 4.5 and 3 Ma.[2] The facies origin of the Chorrera Formation is comparable to the Marichuela Formation, outcropping on the eastern edge of the Bogotá savanna, yet different in stratigraphic position.[1] The deposition of sediments of the Chorrera Formation is time-equivalent with the explosive phase of the Paipa–Iza volcanic complex, active between 4.7 and 3.6 Ma,[3] and the Miocene to Late Pliocene Tilatá Formation.

Outcrops

Lua error in Module:Location_map at line 522: Unable to find the specified location map definition: "Module:Location map/data/Bogotá savanna" does not exist. The Chorrera Formation is found at its type locality in the synclinal of the Río Frío, east of Subachoque, Cundinamarca.[1]

See also

Featured article candidate Geology of the Eastern Hills
B-Class article Geology of the Ocetá Páramo
C-Class article Geology of the Altiplano Cundiboyacense

References

  1. 1.0 1.1 1.2 1.3 1.4 Montoya & Reyes, 2005, p.67
  2. Molnar, 2004, p.75
  3. Monsalve et al., 2011, p.120

Bibliography

  • Molnar, Peter. 2004. Late Cenozoic increase in accumulation rates of terrestrial sediment. Annual Review of Earth and Planetary Sciences 32. 67-89.
  • Monsalve, Maria Luisa; Nadia R. Rojas; Francisco A. Velandia P.; Iraida Pintor, and Lina Fernanda Martínez. 2011. Caracterización geológica del cuerpo volcánico de Iza, Boyacá - Colombia. Boletín de Geología 33. 117-130. Accessed 2017-02-25.
  • Montoya Arenas, Diana María, and Germán Alfonso Reyes Torres. 2005. Geología de la Sabana de Bogotá, 1–104. INGEOMINAS.

External links