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°WCoordinates: 4°54′40″N 74°27′50″W / 4.91111°N 74.46389°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 / 4.91111°N 74.46389°W |
| Approximate paleocoordinates | 3°00′S 52°00′W / 3.000°S 52.000°W |
| 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.
The formation was first described by Hubach in 1931 and elevated to formation in 1969 by Cáceres and Etayo. The formation is named after the quarry La Frontera near Albán, Cundinamarca.
The La Frontera Formation is characterised by a lower part consisting of limestones and an upper part comprising lydites.
The La Frontera Formation overlies the Simijaca Formation and is overlain by the Conejo Formation. The age has been estimated to be Turonian. Stratigraphically, the formation is time equivalent with the Chipaque Formation. The formation has been deposited in an open marine platform to submarine fan setting. The deposition is represented by a maximum flooding surface. The formation contains concretions and a high diversity of ammonites;, Vascoceras cf. constrictum, Vascoceras cf. venezolanum, Kamerunoceras sp., Kamerunoceras cf. turoniense, Hoplitoides cf. lagiraldae, Codazziceras ospinae, Coilopoceras cf. newelli,Hoplitoides wohltmanni, Neoptychites crassus, Hoplitoides ingens, Mammites sp., ?Fagesia sp., and Prionocycloceras sp. Also the bivalves Anomia colombiana and Inoceramus sp. have been found in the La Frontera Formation. Fossils of Yaguarasaurus columbianus have been uncovered from the La Frontera Formation, 78 kilometres (48 mi) south of Neiva, Huila.
...
Wikipedia