Trincheras Formation

The Trincheras Formation (Spanish: Formación Trincheras, Kitr) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cretaceous period; Early Aptian epoch and has a maximum thickness of 1,260 metres (4,130 ft). The formation, deposited in a marine platform environment, part of a transgressive cycle, hosts ammonite, bryozoan, mollusc and echinoid fossils.

Trincheras Formation
Stratigraphic range: Early Aptian
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TypeGeological formation
Unit ofVilleta Group
Sub-unitsAnapoima Mb., El Tigre Mb.
UnderliesSocotá Fm., El Peñón Fm.
OverliesMurca Fm., La Naveta Fm., Útica Fm.
Thicknessup to 1,260 m (4,130 ft)
Lithology
PrimaryShale
OtherSandstone, limestone
Location
Coordinates4°30′13″N 74°36′22″W
RegionAltiplano Cundiboyacense
Eastern Ranges, Andes
Country Colombia
Type section
Named forQuebrada Trincheras
Named byCáceres & Etayo
LocationApulo
Year defined1969
Coordinates4°30′13″N 74°36′22″W
RegionCundinamarca
Country Colombia

Paleogeography of Northern South America
120 Ma, by Ron Blakey

Etymology

The formation was defined and named in 1969 by Cáceres and Etayo after Quebrada Trincheras, Apulo, Cundinamarca.[1]

Description

Lithologies

The Trincheras Formation has a maximum thickness of 1,260 metres (4,130 ft),[2] and is characterised by a sequence of claystones with intercalated limestones and sandstones. Fossils of the ammonites Heinzia sp., Pseudohaploceras sp., Heminautilus etheringtoni, Cheloniceras sp. and bryozoans, molluscs and echinoids have been found in the Trincheras Formation.[3]

Stratigraphy and depositional environment

The Trincheras Formation is the lowermost unit of the Villeta Group,[4] and conformably overlies the Murca, La Naveta and Útica Formations. The formation is overlain in a transitional pattern by the Socotá and El Peñón Formations.[2] The Trincheras Formation is subdivided into the El Tigre and Anapoima Members. The age has been estimated to be Early Aptian. Stratigraphically, the formation is time equivalent with the fossiliferous Paja Formation of Boyacá and the Las Juntas Formation.[5] The formation has been deposited in a marine well oxygenated platform environment.[3] In terms of sequence stratigraphy, this phase was transgressional.[5]

Outcrops

Trincheras Formation is located in the Bogotá savanna
Trincheras Formation
Type locality of the Trincheras Formation to the southwest of the Bogotá savanna

The Trincheras Formation is apart from its type locality in Apulo, found near La Mesa and Anapoima,[3] in the Villeta Anticlinal, the Murca-Guayabal-Nimaima Anticlinal and along the roads between Pacho and La Palma and Útica-La Peña.[2] The formation also crops out around San Joaquín east of La Mesa,[6] and on the right bank of the Bogotá River near Apulo.[7]

The reverse Bituima Fault thrusts the Trincheras Formation on top of the Güagüaquí Group,[6] while the Bogotá River Fault laterally displaces the formation near Anapoima.[7]

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
ConiacianOliníVilletaConejoChipaque
GüagüaquíLoma 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
HauterivianMuzoCáquezaLas Juntas
RosablancaRitoque
ValanginianRitoqueFuratenaÚtica - MurcaRosablancahiatusMacanal
Rosablanca
BerriasianCumbreCumbreLos MediosGuavio
TamborArcabucoCumbre
Sources

See also

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

References

  1. Acosta & Ulloa, 2002, p.39
  2. Acosta & Ulloa, 2001, p.23
  3. Acosta & Ulloa, 2002, p.40
  4. Acosta & Ulloa, 2001, p.22
  5. Villamil, 2012, p.168
  6. Plancha 227, 1998
  7. Plancha 246, 1998

Bibliography

Maps

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