La Frontera Formation

The La Frontera Formation (Spanish: Formación La Frontera, K₂F, Ksf) is a geological formation, part of the Villeta Group, of the Altiplano Cundiboyacense and neighbouring areas of the Eastern Ranges of the Colombian Andes. The sequence of limestones and lydites dates to the Late Cretaceous period; Turonian epoch and has a maximum thickness of 206 metres (676 ft).

La Frontera Formation Stratigraphic range: Turonian ~93.9–89.8 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Villeta Group
Underlies	Conejo Formation
Overlies	Simijaca Fm., La Corona Gb.
Thickness	up to 206 metres (680 ft)
Lithology
Primary	Lydite
Other	Limestone
Location
Coordinates	4°54′40″N 74°27′50″W
Region	Altiplano Cundiboyacense Eastern Ranges, Andes
Country	Colombia
Type section
Named for	La Frontera quarry
Named by	Cáceres & Etayo
Location	Albán
Year defined	1969
Coordinates	4°54′40″N 74°27′50″W
Region	Cundinamarca, Boyacá
Country	Colombia
Paleogeography of Northern South America 90 Ma, by Ron Blakey

Fossils of Yaguarasaurus columbianus were said to be found in this formation (listed as "La Frontera Member"), although the geological mapping of the area state the time-equivalent Hondita Formation as the stratigraphic unit present in the Quebradas El Ocal and Itaibe in Huila. The La Frontera Formation does not outcrop south of Cundinamarca. A high diversity of ammonites has been found in the La Frontera Formation.

Etymology

The formation was first described by Hubach in 1931 and elevated to formation in 1969 by Cáceres and Etayo.[1] The formation is named after the quarry La Frontera near Albán, Cundinamarca.[2]

Description

Lithologies

The La Frontera Formation is characterised by a lower part consisting of limestones and an upper part comprising lydites.[1]

Stratigraphy and depositional environment

The La Frontera Formation overlies the Simijaca Formation and is overlain by the Conejo Formation, all units belong to the Villeta Group. The age has been estimated to be Turonian.[1] Stratigraphically, the formation is time equivalent with the Chipaque, Hondita and La Luna Formations.[3] The formation has been deposited in an open marine platform to submarine fan setting.[4] The deposition is represented by a maximum flooding surface.[5] The formation contains concretions and a high diversity of ammonites;[6] Wrightoceras munieri, Vascoceras cf. constrictum, Vascoceras cf. venezolanum, Kamerunoceras sp., Kamerunoceras cf. turoniense, Hoplitoides cf. lagiraldae, Codazziceras ospinae, Coilopoceras cf. newelli,[7] Hoplitoides wohltmanni, Neoptychites crassus, Hoplitoides ingens, Mammites sp., ?Fagesia sp., and Prionocycloceras sp.[8] Also the bivalves Anomia colombiana and Inoceramus sp. have been found in the La Frontera Formation.[2]

Yaguarasaurus

Fossils of Yaguarasaurus columbianus were described as coming from the "La Frontera Member", part of the "Villeta Formation", in the Quebrada El Ocal, 26 kilometres (16 mi) southwest of Neiva, Huila,[9][10] and in the Quebrada Itaibe 78 kilometres (48 mi) southwest of Neiva,[11] although in these areas the time-equivalent Hondita Formation is mapped.[12][13]

Outcrops

Type locality of the La Frontera Formation to the west of the Bogotá savanna

The La Frontera Formation is apart from its type locality, found at surface in the north of the Bogotá savanna, in the Tabio anticlinal, along the road Ubaté-Carmen de Carupa,[1] north and east of Chiquinquirá,[14] south of Cachipay,[15] to a thin band east of Viotá.[16]

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		Umir	Córdoba		Seca		eroded		Guaduas				Colón-Mito Juan
					Umir				Guadalupe
Campanian					Córdoba
					Oliní
Santonian		La Luna	Cimarrona - La Tabla										La Luna
Coniacian			Oliní				Villeta	Conejo		Chipaque
			Güagüaquí	Loma Gorda	undefined			La Frontera
Turonian				Hondita	La Frontera	Otanche
Cenomanian		Simití	hiatus		La Corona			Simijaca					Capacho
					Pacho Fm.			Hiló - Pacho	Churuvita	Une			Aguardiente
Albian					Hiló				Chiquinquirá	Tibasosa	Une
		Tablazo			Tablazo			Capotes - La Palma - Simití	Simití				Tibú-Mercedes
Aptian					Capotes			Socotá - El Peñón	Paja		Fómeque
		Paja			Paja	El Peñón		Trincheras					Río Negro
							La Naveta
Barremian
Hauterivian						Muzo					Cáqueza	Las Juntas
		Rosablanca							Ritoque
Valanginian					Ritoque	Furatena	Útica - Murca		Rosablanca	hiatus		Macanal
					Rosablanca
Berriasian		Cumbre			Cumbre				Los Medios			Guavio
		Tambor			Arcabuco				Cumbre
Sources

See also

Geology of the Eastern Hills

Geology of the Ocetá Páramo

Geology of the Altiplano Cundiboyacense

References

1. Montoya & Reyes, 2005, p.24
2. Acosta & Ulloa, 2001, p.41
3. Montoya & Reyes, 2005, p.26
4. García González et al., 2009, p.218
5. Villamil, 2012, p.164
6. Villamil, 2012, p.181
7. Patarroyo, 2016, p.41
8. Blanco et al., 2004, p.26
9. 'Yaguarasaurus columbianus' in the Paleobiology Database
10. Yaguarasaurus columbianus at Fossilworks.org
11. Páramo Fonseca, 2000, p.124
12. Plancha 344, 1999
13. Plancha 345, 1999
14. Plancha 190, 2009
15. Plancha 227, 1998
16. Plancha 246, 1998

Bibliography

• Acosta Garay, Jorge, and Carlos E. Ulloa Melo. 2001. Geología de la Plancha 208 Villeta - 1:100,000, 1-84. INGEOMINAS. Accessed 2017-04-04.
• Blanco, Johana Paola; Paula Andrea Medina, and Pedro Patarroyo. 2004. La Formación La Frontera, Sección Vereda Tóriba: Una propuesta para la designación del Lectoestratotipo. Geología Colombiana 29. 23-40. Accessed 2017-04-04.
• García González, Mario; Ricardo Mier Umaña; Luis Enrique Cruz Guevara, and Mauricio Vásquez. 2009. Informe Ejecutivo - evaluación del potencial hidrocarburífero de las cuencas colombianas, 1-219. Universidad Industrial de Santander.
• Montoya Arenas, Diana María, and Germán Alfonso Reyes Torres. 2005. Geología de la Sabana de Bogotá, 1–104. INGEOMINAS.
• Páramo Fonseca, María Euridice. 2000. Yaguarasaurus columbianus (Reptilia, Mosasauridae), a primitive mosasaur from the Turonian (Upper Cretaceous) of Colombia. Historical Biology 14. 121-131. Accessed 2018-05-30.
• Patarroyo, Pedro. 2016. Amonoideos y otros macrofósiles del lectoestratotipo de la Formación la Frontera, Turoniano inferior - medio (Cretácico Superior) en San Francisco, Cundinamarca (Colombia). Boletín de Geología, Universidad Industrial de Santander 38. 41-54. Accessed 2017-04-04.
• 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 La Frontera Fm. proper

• Ulloa, Carlos E, and Erasmo Rodríguez. 2009. Plancha 170 - Vélez - 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.
• 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.
• 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., and Carlos E. Ulloa. 1998. Plancha 246 - Fusagasugá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.

Maps Yaguarasaurus locations

• Marquínez, Germán; C. Morales, and Alberto Núñez. 1999. Plancha 344 - Tesalia - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
• Velandia, F.; C.J. Morales; J.C. Caicedo, and Alberto Núñez. 1999. Plancha 345 - Campoalegre - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.

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 2017-04-04.