The La Frontera Formation ( es, Formación La Frontera, K₂F, Ksf) is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

, part of the Villeta Group, of the

Altiplano Cundiboyacense The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. The altiplano corresponds to the ancient territory of the Muisca. The Alt ...

and neighbouring areas of the

Eastern Ranges The Eastern Ranges is an Australian rules football team in the NAB League, the Victorian statewide under-18s competition. The club is a founding member of the competition (1992) and has produced several players for the Australian Football Le ...

of the Colombian

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

. The sequence of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

s and lydites dates to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

period;

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded ...

epoch and has a maximum thickness of . 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 The Hondita Formation ( es, Formación Hondita, Ksh) is a List of fossiliferous stratigraphic units in Colombia, fossiliferous formation (geology), geological formation of the Upper Magdalena Valley (VSM) and surrounding Cordillera Central (Colomb ...

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

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

s 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.Montoya & Reyes, 2005, p.24 The formation is named after the quarry La Frontera near Albán, Cundinamarca.Acosta & Ulloa, 2001, p.41

Description

Lithologies

The La Frontera Formation is characterised by a lower part consisting of

s and an upper part comprising lydites.

Stratigraphy and depositional environment

The La Frontera Formation overlies the

Simijaca Formation The Simijaca Formation ( es, Formación Simijaca, K2S, Kss) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly mudstone formation dates to the Late Cretaceous period; Turonian and C ...

and is overlain by the Conejo Formation, all units belong to the Villeta Group. The age has been estimated to be

. Stratigraphically, the formation is time equivalent with the Chipaque, Hondita and

La Luna Formation LA most frequently refers to Los Angeles, the second largest city in the United States. La, LA, or L.A. may also refer to: Arts and entertainment Music * La (musical note), or A, the sixth note * "L.A.", a song by Elliott Smith on ''Figure ...

s.Montoya & Reyes, 2005, p.26 The formation has been deposited in an open marine platform to submarine fan setting.García González et al., 2009, p.218 The deposition is represented by a maximum flooding surface.Villamil, 2012, p.164 The formation contains

concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

s and a high diversity of

s;Villamil, 2012, p.181 '' Wrightoceras munieri'', '' Vascoceras cf. constrictum'', '' Vascoceras cf. venezolanum'', '' Kamerunoceras sp.'', '' Kamerunoceras cf. turoniense'', '' Hoplitoides cf. lagiraldae'', '' Codazziceras ospinae'', '' Coilopoceras cf. newelli'',Patarroyo, 2016, p.41 '' Hoplitoides wohltmanni'', '' Neoptychites crassus'', '' Hoplitoides ingens'', '' Mammites sp.'', '' ?Fagesia sp.'', and '' Prionocycloceras sp''.Blanco et al., 2004, p.26 Also the bivalves '' Anomia colombiana'' and '' Inoceramus sp.'' have been found in the La Frontera Formation.

''Yaguarasaurus''

Fossils of '' Yaguarasaurus columbianus'' were described as coming from the "La Frontera Member", part of the "Villeta Formation", in the Quebrada El Ocal, southwest of

Neiva Neiva () is the capital of the Department of Huila. It is located in the valley of the Magdalena River in south central Colombia with a population of about 357,392 inhabitants. It is one of the most important cities in southern Colombia, mainly ...

, Huila,''Yaguarasaurus columbianus''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org and in the Quebrada Itaibe southwest of Neiva,Páramo Fonseca, 2000, p.124 although in these areas the time-equivalent

is mapped.Plancha 344, 1999Plancha 345, 1999

Outcrops

The La Frontera Formation is apart from its

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

, found at surface in the north of the

Bogotá savanna The Bogotá savanna is a montane savanna, located in the southwestern part of the Altiplano Cundiboyacense in the center of Colombia. The Bogotá savanna has an extent of and an average altitude of . The savanna is situated in the Eastern Ra ...

, in the Tabio anticlinal, along the road Ubaté-

Carmen de Carupa Carmen de Carupa is a municipality and town of Colombia in the Ubaté Province, part of the department of Cundinamarca. The municipality, located in the Ubaté-Chiquinquirá Valley on the Altiplano Cundiboyacense borders San Cayetano in the w ...

, north and east of

Chiquinquirá Chiquinquirá is a town and municipality in the Colombian Department of Boyacá, part of the subregion of the Western Boyacá Province. Located some 115 km north of Bogotá, Chiquinquirá is above sea level and has a yearly average temp ...

,Plancha 190, 2009 south of

Cachipay Cachipay is a municipality and town of Colombia in the Tequendama Province, part of the department of Cundinamarca. Cachipay borders Quipile in the west, Zipacón in the east, Anolaima in the north and La Mesa in the south. The urban centre is ...

,Plancha 227, 1998 to a thin band east of

Viotá Viotá is a municipality and town of Colombia in the department Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative divisi ...

.Plancha 246, 1998

Regional correlations

References

Bibliography

* * * * * * *

Maps La Frontera Fm. proper

* * * * * *

Maps ''Yaguarasaurus'' locations

* *

External links

* {{DEFAULTSORT:Frontera Formation, La Geologic formations of Colombia Cretaceous Colombia Upper Cretaceous Series of South America Turonian Stage Limestone formations Deep marine deposits Open marine deposits Fossiliferous stratigraphic units of South America Paleontology in Colombia Formations Geography of Cundinamarca Department Geography of Boyacá Department