Conejo Formation

Conejo Formation Stratigraphic range: Turonian-Santonian ~90–83.6 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Villeta Group
Underlies	Guadalupe Group
Overlies	La Frontera Formation
Thickness	up to 1,022 m (3,353 ft)
Lithology
Primary	Sandstone, shale
Other	Limestone
Location
Coordinates	5°35′40.7″N 73°12′59.6″W / 5.594639°N 73.216556°W / 5.594639; -73.216556Coordinates: 5°35′40.7″N 73°12′59.6″W / 5.594639°N 73.216556°W / 5.594639; -73.216556
Region	Altiplano Cundiboyacense Eastern Ranges, Andes
Country	Colombia
Type section
Named for	El Conejo Hill
Named by	Renzoni
Location	Toca, Boyacá
Year defined	1981
Coordinates	5°35′40.7″N 73°12′59.6″W / 5.594639°N 73.216556°W / 5.594639; -73.216556
Region	Cundinamarca, Boyacá
Country	Colombia
Paleogeography of Northern South America 90 Ma, by Ron Blakey

The Conejo Formation (Spanish: Formación Conejo, K₂C, Kscn) is a fossiliferous geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The uppermost unit of the Villeta Group, a sequence of shales and sandstones dates to the Late Cretaceous period; Turonian, Coniacian and Santonian epochs, and has a maximum thickness of 1,022 metres (3,353 ft).

Etymology[]

The formation was named in 1967 and published in 1981 by Renzoni, named after El Conejo Hill in Pontezuela, Toca, Boyacá, west of the .^[1][2]

Description[]

Lithologies[]

The Conejo Formation is characterised by a sequence of calcareous sandstones, containing ammonites, shales and the uppermost part sandstone and limestone banks.^[3] In the Conejo Formation, fossils of , , , , , , , , , Heterohelix globulosa, Heterohelix reussi, , Hedbergella sp., and the ammonites , and Codazziceras scheibei have been found.^[4][5][6]

Stratigraphy and depositional environment[]

The Conejo Formation is the uppermost unit of the Villeta Group.^[7] It overlies the La Frontera Formation and is overlain by the Guadalupe Group. The age has been estimated on the basis of ammonites to be ranging from Turonian to Santonian.^[8] Stratigraphically, the lower part of the formation is time equivalent with the upper part of the Chipaque,^[8] and Loma Gorda Formations.^[7]

Outcrops[]

Type locality of the Conejo Formation on the Altiplano Cundiboyacense

The type locality of the Conejo Formation is located close to El Conejo Hill in Pontezuela, Toca, Boyacá.^[2] Other outcrops of the Conejo Formation have been noted in Cucaita,^[4][5] the urban areas of Boyacá and Ventaquemada, around the Puente de Boyacá, south of Pesca, west of Siachoque,^[9] surrounding Chiquinquirá and Ubaté,^[10] between Chivatá and Oicatá,^[2] east of Paipa,^[11] west of Tibacuy,^[12] north and south of Albán, southeast of Cachipay, east of Anolaima, and San Antonio del Tequendama, Cundinamarca.^[13]

Regional correlations[]

Cretaceous stratigraphy of the central Colombian Eastern Ranges

Age	Paleomap	VMM	Guaduas-Vélez		W Emerald Belt		Villeta anticlinal		Chiquinquirá- Arcabuco	Tunja- Duitama	Altiplano Cundiboyacense		El Cocuy
Maastrichtian							eroded		Guaduas
									Guadalupe
Campanian
					Oliní
Santonian			-
Coniacian			Oliní				Villeta	Conejo		Chipaque
				Loma Gorda	undefined			La Frontera
Turonian				Hondita	La Frontera
Cenomanian			hiatus					Simijaca
					Pacho Fm.			Hiló - Pacho		Une
Albian					Hiló						Une
								Capotes - -
Aptian					Capotes			Socotá - El Peñón	Paja		Fómeque
		Paja			Paja	El Peñón		Trincheras
							La Naveta
Barremian
Hauterivian												Las Juntas
		Rosablanca							Ritoque
Valanginian					Ritoque		- Murca		Rosablanca	hiatus		Macanal
					Rosablanca
Berriasian												Guavio
					Arcabuco
Sources

See also[]

Geology of the Eastern Hills

Geology of the Ocetá Páramo

Geology of the Altiplano Cundiboyacense

References[]

Bibliography[]

• Acosta, Jorge E., and Carlos E. Ulloa. 2002. Mapa geológico del Departamento de Cundinamarca 1:250,000 - Memoria Explicativa, 1–108. INGEOMINAS.
• Acosta Garay, Jorge, and Carlos E. Ulloa Melo. 2001. Geología de la Plancha 208 Villeta - 1:100,000, 1–84. INGEOMINAS. Accessed 2017-03-16.
• Luque, Javier; Stéphane Hourdez, and Olev Vinn. 2015. A new fossil bristle worm (Annelida: Polychaeta: Aphroditiformia) from the late Cretaceous of tropical America. Journal of Paleontology 89. 257–261. Accessed 2017-04-04.
• Montoya Arenas, Diana María, and Germán Alfonso Reyes Torres. 2005. Geología de la Sabana de Bogotá, 1–104. INGEOMINAS.
• Tchegliakova, Nadejda, and Vladimir Pérez. 1995. Registro de la Zona bioestratigrafica Dicarinella concavata (Foraminiferida) en el Extremo noroccidental de Suramerica (Colombia). 19. 131–143. Accessed 2017-04-06.
• Villamil, Tomas. 2012. Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia, 161–216. Society for Sedimentary Geology (SEPM).

Maps[]

• Ulloa, Carlos E, and Erasmo Rodríguez. 2009. Plancha 170 - Vélez - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Renzoni, Giancarlo, and Humberto Rosas. 2009. Plancha 171 - Duitama - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Fuquen M., Jaime A, and José F. Osorno M. 2009. Plancha 190 - Chiquinquirá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Renzoni, Giancarlo; Humberto Rosas, and Fernando Etayo Serna. 1998. Plancha 191 - Tunja - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Ulloa, Carlos, and Jorge Acosta. 1998. Plancha 208 - Villeta - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Montoya, Diana María, and Germán Reyes. 2009. Plancha 209 - Zipaquirá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Terraza, Roberto; Giovanni Moreno; José A. Buitrago; Adrián Pérez, and Diana María Montoya. 2010. Plancha 210 - Guateque - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Ulloa, Carlos E; Erasmo Rodríguez, and Jorge E. Acosta. 1998. Plancha 227 - La Mesa - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Acosta, Jorge E.; Rafael Guatame; Oscar Torres, and Frank Solano. 1999. Plancha 245 - Girardot - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Acosta, Jorge E., and Carlos E. Ulloa. 1998. Plancha 246 - Fusagasugá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Velandia, Francisco, and Héctor Cepeda. 2005. Planchas 171 & 191 - Geología sector del sur del municipio de Paipa (Boyacá) - 1:25,000. INGEOMINAS.

External links[]

• Gómez, J.; N.E. Montes; Á. Nivia, and H. Diederix. 2015. Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000, 1. Servicio Geológico Colombiano. Accessed 2017-03-16.