La Frontera Formation

La Frontera Formation
Stratigraphic range: Turonian
~93.9–89.8 Ma
↓
Type Geological formation
Unit of Villeta Group
Underlies Conejo Formation
Overlies Simijaca Formation
Thickness up to 206 metres (680 ft)
Lithology
Primary Lydite
Other Limestone
Location
Coordinates 4°54′40″N 74°27′50″W / 4.91111°N 74.46389°W / 4.91111; -74.46389Coordinates: 4°54′40″N 74°27′50″W / 4.91111°N 74.46389°W / 4.91111; -74.46389
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 / 4.91111°N 74.46389°W / 4.91111; -74.46389
Approximate paleocoordinates 3°00′S 52°00′W / 3.000°S 52.000°W / -3.000; -52.000
Region Cundinamarca, Boyacá, Huila
Country  Colombia

Paleogeography of Northern South America
90 Ma, by Ron Blakey

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). Fossils of Yaguarasaurus columbianus as well as a high diversity of ammonites have 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. The age has been estimated to be Turonian.[1] Stratigraphically, the formation is time equivalent with the Chipaque Formation.[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] Fossils of Yaguarasaurus columbianus have been uncovered from the La Frontera Formation, 78 kilometres (48 mi) south of Neiva, Huila.[9][10][11]

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,[12] south of Cachipay,[13] in a thin band east of Viotá,[14] and until 78 kilometres (48 mi) south of Neiva, Huila.[9][10]

See also

Geology of the Eastern Hills
Geology of the Ocetá Páramo
Geology of the Altiplano Cundiboyacense

References

  1. 1 2 3 4 Montoya & Reyes, 2005, p.24
  2. 1 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. 1 2 Yaguarasaurus columbianus in the Paleobiology Database
  10. 1 2 Yaguarasaurus columbianus at fossilworks.org
  11. ↑ Páramo Fonseca, 2000
  12. ↑ Plancha 190, 2009
  13. ↑ Plancha 227, 1998
  14. ↑ Plancha 246, 1998

Bibliography

Maps

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