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
↓
TypeGeological formation
Unit ofVilleta Group
UnderliesConejo Formation
OverliesSimijaca Fm., La Corona Gb.
Thicknessup to 206 metres (680 ft)
Lithology
PrimaryLydite
OtherLimestone
Location
Coordinates4°54′40″N 74°27′50″W
RegionAltiplano Cundiboyacense
Eastern Ranges, Andes
Country Colombia
Type section
Named forLa Frontera quarry
Named byCáceres & Etayo
LocationAlbán
Year defined1969
Coordinates4°54′40″N 74°27′50″W
RegionCundinamarca, 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
AgePaleomapVMMGuaduas-VélezW Emerald BeltVilleta anticlinalChiquinquirá-
Arcabuco		Tunja-
Duitama		Altiplano CundiboyacenseEl Cocuy
MaastrichtianUmirCórdobaSecaerodedGuaduasColón-Mito Juan
UmirGuadalupe
CampanianCórdoba
Oliní
SantonianLa LunaCimarrona - La TablaLa Luna
ConiacianOliníConejoChipaque
Güagüaquí
Loma GordaundefinedLa Frontera
TuronianHonditaLa FronteraOtanche
CenomanianSimitíhiatusLa CoronaSimijacaCapacho
Pacho Fm.Hiló - PachoChuruvitaUneAguardiente
AlbianHilóChiquinquiráTibasosaUne
TablazoTablazoCapotes - La Palma - SimitíSimitíTibú-Mercedes
AptianCapotesSocotá - El PeñónPajaFómeque
PajaPajaEl PeñónTrincherasRío Negro
La Naveta
Barremian
HauterivianMuzo
Cáqueza
Las Juntas
RosablancaRitoque
ValanginianRitoqueFuratenaÚtica - MurcaRosablancaGirónMacanal
Rosablanca
BerriasianCumbreCumbreLos MediosGuavio
TamborArcabucoCumbre
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

Maps La Frontera Fm. proper

Maps Yaguarasaurus locations
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