French
DeutschConejo Formation
| Conejo Formation | |
|---|---|
| Stratigraphic range: Turonian-Santonian ~ | |
| 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 |
| 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 |
| 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
[edit]The formation was named in 1967 and published in 1981 by Renzoni, named after El Conejo Hill in Pontezuela, Toca, Boyacá, west of the Copa Reservoir.[1][2]
Description
[edit]Lithologies
[edit]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 Protopholoe colombiana, Archaeglobigerina blowi, Dicarinella concavata, Dicarinella primitiva, Sigalitruncana sigali, Marginotruncana sp. ct. M. renzi, Marginotruncana angusticarenata, Marginotruncana sp. cf. M.sinuosa, Rosita tornicata, Heterohelix globulosa, Heterohelix reussi, Whiteinella inornata, Hedbergella sp., and the ammonites Gloriaceras correai, Protexamites cucaitaense and Codazziceras scheibei have been found.[4][5][6]
Stratigraphy and depositional environment
[edit]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
[edit]
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
[edit]
See also
[edit]
References
[edit]- ^ Montoya & Reyes, 2005, p.29
- ^ a b c Acosta & Ulloa, 2001, p.43
- ^ Montoya & Reyes, 2005, p.30
- ^ a b Luque et al., 2015
- ^ a b Tchegliakova & Pérez, 1995
- ^ Acosta & Ulloa, 2002, p.48
- ^ a b Acosta & Ulloa, 2002, p.22
- ^ a b Montoya & Reyes, 2005, p.34
- ^ Plancha 191, 1998
- ^ Plancha 190, 2009
- ^ Planchas 171 & 191, 2005
- ^ Plancha 246, 1998
- ^ Plancha 227, 1998
Bibliography
[edit]- Acosta, Jorge E.; Ulloa, Carlos E. (2002), Mapa geológico del Departamento de Cundinamarca 1:250,000 - Memoria Explicativa, INGEOMINAS, pp. 1–108
- Acosta Garay, Jorge; Ulloa Melo, Carlos E. (2001), Geología de la Plancha 208 Villeta - 1:100,000 (PDF), INGEOMINAS, pp. 1–84, retrieved 2017-03-16 Archived 2017-03-24 at the Wayback Machine
- Luque, Javier; Hourdez, Stéphane; Vinn, Olev (2015), "A new fossil bristle worm (Annelida: Polychaeta: Aphroditiformia) from the late Cretaceous of tropical America", Journal of Paleontology, 89 (2): 257–261, Bibcode:2015JPal...89..257L, doi:10.1017/jpa.2014.22, retrieved 2017-04-04
- Montoya Arenas, Diana María; Reyes Torres, Germán Alfonso (2005), Geología de la Sabana de Bogotá, INGEOMINAS, pp. 1–104
- Tchegliakova, Nadejda; Pérez, Vladimir (1995), "Registro de la Zona bioestratigrafica Dicarinella concavata (Foraminiferida) en el Extremo noroccidental de Suramerica (Colombia)", Geología Colombiana, 19: 131–143, retrieved 2017-04-06
- 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
[edit]- Ulloa, Carlos E; Rodríguez, Erasmo (2009), Plancha 170 - Vélez - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Renzoni, Giancarlo; Rosas, Humberto (2009), Plancha 171 - Duitama - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Fuquen M., Jaime A; Osorno M, José F. (2009), Plancha 190 - Chiquinquirá - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Renzoni, Giancarlo; Rosas, Humberto; Etayo Serna, Fernando (1998), Plancha 191 - Tunja - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Ulloa, Carlos; Acosta, Jorge (1998), Plancha 208 - Villeta - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Montoya, Diana María; Reyes, Germán (2009), Plancha 209 - Zipaquirá - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
- Terraza, Roberto; Moreno, Giovanni; Buitrago, José A.; Pérez, Adrián; Montoya, Diana María (2010), Plancha 210 - Guateque - 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.; Guatame, Rafael; Torres, Oscar; Solano, Frank (1999), Plancha 245 - Girardot - 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
- Velandia, Francisco; Cepeda, Héctor (2005), Planchas 171 & 191 - Geología sector del sur del municipio de Paipa (Boyacá) - 1:25,000, INGEOMINAS
External links
[edit]- Gómez, J.; Montes, N.E.; Nivia, Á.; Diederix, H. (2015), Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000, Servicio Geológico Colombiano, p. 1, retrieved 2017-03-16