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Trincheras Formation
Trincheras Formation
Stratigraphic range: Early Aptian; ~120–115 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Villeta Group
Sub-units	Anapoima Mb., El Tigre Mb.
Underlies	Socotá Fm., El Peñón Fm.
Overlies	Murca Fm., La Naveta Fm., Útica Fm.
Thickness	up to 1,260 m (4,130 ft)
Lithology
Primary	Shale
Other	Sandstone, limestone
Location
Coordinates	4°30′13″N 74°36′22″W / 4.50361°N 74.60611°W
Region	Altiplano Cundiboyacense; Eastern Ranges, Andes
Country	Colombia
Type section
Named for	Quebrada Trincheras
Named by	Cáceres & Etayo
Location	Apulo
Year defined	1969
Coordinates	4°30′13″N 74°36′22″W / 4.50361°N 74.60611°W
Region	Cundinamarca
Country	Colombia
	; Paleogeography of Northern South America; 120 Ma, by Ron Blakey

The Trincheras Formation (Spanish: Formación Trincheras, Kitr) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cretaceous period; Early Aptian epoch and has a maximum thickness of 1,260 metres (4,130 ft). The formation, deposited in a marine platform environment, part of a transgressive cycle, hosts ammonite, bryozoan, mollusc and echinoid fossils.

Etymology

The formation was defined and named in 1969 by Cáceres and Etayo after Quebrada Trincheras, Apulo, Cundinamarca.^[1]

Description

Lithologies

The Trincheras Formation has a maximum thickness of 1,260 metres (4,130 ft),^[2] and is characterised by a sequence of claystones with intercalated limestones and sandstones. Fossils of the ammonites Heinzia sp., Pseudohaploceras sp., Heminautilus etheringtoni, Cheloniceras sp. and bryozoans, molluscs and echinoids have been found in the Trincheras Formation.^[3]

Stratigraphy and depositional environment

The Trincheras Formation is the lowermost unit of the Villeta Group,^[4] and conformably overlies the Murca, La Naveta and Útica Formations. The formation is overlain in a transitional pattern by the Socotá and El Peñón Formations.^[2] The Trincheras Formation is subdivided into the El Tigre and Anapoima Members. The age has been estimated to be Early Aptian. Stratigraphically, the formation is time equivalent with the fossiliferous Paja Formation of Boyacá and the Las Juntas Formation.^[5] The formation has been deposited in a marine well oxygenated platform environment.^[3] In terms of sequence stratigraphy, this phase was transgressional.^[5]

Outcrops

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Type locality of the Trincheras Formation to the southwest of the Bogotá savanna

The Trincheras Formation is apart from its type locality in Apulo, found near La Mesa and Anapoima,^[3] in the Villeta Anticlinal, the Murca-Guayabal-Nimaima Anticlinal and along the roads between Pacho and La Palma and Útica-La Peña.^[2] The formation also crops out around San Joaquín east of La Mesa,^[6] and on the right bank of the Bogotá River near Apulo.^[7]

The reverse Bituima Fault thrusts the Trincheras Formation on top of the Güagüaquí Group,^[6] while the Bogotá River Fault laterally displaces the formation near Anapoima.^[7]

Regional correlations

Cretaceous stratigraphy of the central Colombian Eastern Ranges
Age	VMM	Guaduas-Vélez		W Emerald Belt		Villeta anticlinal		Chiquinquirá- Arcabuco	Tunja- Duitama	Altiplano Cundiboyacense		El Cocuy
Maastrichtian	Umir	Córdoba		Seca		eroded		Guaduas				Colón-Mito Juan
Maastrichtian				Umir				Guadalupe
Campanian				Córdoba
Campanian				Oliní
Santonian	La Luna	Cimarrona - La Tabla										La Luna
Coniacian		Oliní				Villeta	Conejo		Chipaque
Coniacian		Güagüaquí	Loma Gorda	undefined			La Frontera
Turonian		Güagüaquí	Hondita	La Frontera	Otanche		La Frontera
Cenomanian	Simití	hiatus		La Corona			Simijaca					Capacho
Cenomanian				Pacho Fm.			Hiló - Pacho	Churuvita	Une			Aguardiente
Albian				Hiló			Hiló - Pacho	Chiquinquirá	Tibasosa	Une		Aguardiente
Albian	Tablazo			Tablazo			Capotes - La Palma - Simití	Simití		Une		Tibú-Mercedes
Aptian	Tablazo			Capotes			Socotá - El Peñón	Paja		Fómeque		Tibú-Mercedes
	Paja			Paja	El Peñón		Trincheras					Río Negro
						La Naveta
Barremian
Hauterivian					Muzo					Cáqueza	Las Juntas
Hauterivian	Rosablanca				Muzo			Ritoque			Las Juntas
Valanginian				Ritoque	Furatena	Útica - Murca		Rosablanca	hiatus		Macanal
Valanginian				Rosablanca	Furatena			Rosablanca			Macanal
Berriasian	Cumbre			Cumbre				Los Medios			Guavio
Berriasian	Tambor			Arcabuco				Cumbre			Guavio
Sources

References

^ Acosta & Ulloa, 2002, p.39
^ ^a ^b ^c Acosta & Ulloa, 2001, p.23
^ ^a ^b ^c Acosta & Ulloa, 2002, p.40
^ Acosta & Ulloa, 2001, p.22
^ ^a ^b Villamil, 2012, p.168
^ ^a ^b Plancha 227, 1998
^ ^a ^b Plancha 246, 1998

Bibliography

Acosta Garay, Jorge E.; Ulloa Melo, Carlos E. (2002), Mapa Geológico del Departamento de Cundinamarca - 1:250,000 - Memoria explicativa, INGEOMINAS, pp. 1–108, retrieved 2017-06-05
Acosta Garay, Jorge; Ulloa Melo, Carlos E. (2001), Geología de la Plancha 208 Villeta - 1:100,000 (PDF), INGEOMINAS, pp. 1–84, retrieved 2017-06-05
Villamil, Tomas (2012), Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia, Society for Sedimentary Geology (SEPM), pp. 161–216

Maps

Ulloa, Carlos; Acosta, Jorge (1998), Plancha 208 - Villeta - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Ulloa, Carlos E; Rodríguez, Erasmo; Acosta, Jorge E. (1998), Plancha 227 - La Mesa - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Acosta, Jorge E.; Ulloa, Carlos E. (1998), Plancha 246 - Fusagasugá - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06