The Altiplano Cundiboyacense, in the Eastern Ranges of the Colombian Andes, was formed late in the regional uplift of the
Andean orogeny. It is estimated that the main stage of uplift happened during the
Plio-
Pleistocene. The
Western and
Central Ranges were submerged much earlier, leaving a corridor to the Caribbean in the
Neogene.
The compression in the Andean orogenic belt caused the formation of
fold and thrust belts in the Eastern Ranges, where Cretaceous and Jurassic
normal faults were inverted as
thrust faults lifting up the Paleozoic (
Floresta and
Cuche Formations), Mesozoic and Paleogene strata. A hiatus existed on the Altiplano between the
Late Eocene and
Late Miocene, in several parts of the Altiplano continuing until the Pleistocene.
During the
glacials and
interglacials of the Pleistocene ("ice ages"), several paleolakes formed on the Altiplano Cundiboyacense, of which Lake Humboldt on the Bogotá savanna was the most extensive (approximately 4,500 square kilometres (1,700 sq mi)).
Rivers were restricted during the drier glacial periods and the vegetation changed from
páramo to
Andean forest between the glacials and
stadials and interglacials and interstadials.[2]
The middle, younger unit is composed of basal greyish claystones with non-uniform
matrix-supportedconglomerates at the upper section. The uppermost layer contains siltstones, probably of volcaniclastic origin.[3]
The youngest sediments are found deepest in the basin and consist of claystones and greenish matrix-supported conglomerates. Rootlets and mammal fossils are more abundant in this layer.[3]
Stratigraphy
The Soatá Formation unconformably overlies the
CretaceousCapacho Formation, and is overlain by the
Holocene infill sediments of the
Chicamocha River, the course of which severely eroded and fragmented the Soatá formation.[4] The formation is subdivided into three units of different lithological character and sedimentary dip in a terrace setting. The Soatá Formation is time-equivalent with the upper part of the
Sabana Formation on the
Bogotá savanna and the Chinauta deposits near
Fusagasugá in the southwest of the Altiplano.[5][6] Two samples were analysed for radiometric dating and provided ages of 45,900 ± 1,600 and 39,600 ± 800 years
BP.[7] This corresponds to the
Chicagota interstadial and the
Tagua stadial, when the glaciations were at their maximum extent.[8][9]
Depositional environment
The
depositional environment has been interpreted as
lacustrine (
Lake Soatá) and fluvio-deltaic. Contrasting with the wide and shallow
Lake Humboldt on the
Bogotá savanna, Lake Soatá was probably close to 400 metres (1,300 ft) deep.[10] The paleolake was approximately 30 kilometres (19 mi) long and widest between Soatá and
Boavita at 7 kilometres (4.3 mi).[11]
Type locality of the Soatá Formation to the northeast of the Altiplano Cundiboyacense. The Chicamocha River valley is clearly visible.
The Soatá Formation is apart from its
type locality Portugalete found around Soatá (Jútua), and stretches to the north near the border of Boyacá and
Santander, northeast of
Tipacoque. To the south, the formation may have reached until
Socotá.[10]
Regional correlations
Stratigraphy of the
Llanos Basin and surrounding provinces
Van der Hammen, Thomas. 1986. Cambios medioambientales y la extinción del mastodonte en el norte de los Andes. Revista de Antropología,
Universidad de los Andes II. 27-34. .
Hoyos, Natalia; O. Monsalve; G.W. Berger; J.L. Antinao; H. Giraldo; C. Silva; G. Ojeda; G. Bayona, and J. Escobar and C. Montes. 2015. A climatic trigger for catastrophic Pleistocene–Holocene debris flows in the Eastern Andean Cordillera of Colombia. Journal of Quaternary Science 30(3). 258-270. .
Rutter, N.; A. Coronato; K. Helmens; J. Rabassa, and M. Zárate. 2012. Glaciations in North and South America from the Miocene to the Last Glacial Maximum, 1–67.
Springer.
Urrego, Dunia H.; Henry Hooghiemstra; Oscar Rama Corredor; Belén Martrat; Joan O. Grimalt; Lonnie Thompson; Mark B. Bush; Zaire González Carranza, and Jennifer Hanselman, Bryan Valencia and César Velásquez Ruiz. 2016. Millennial-scale vegetation changes in the tropical Andes using ecological grouping and ordination methods. Climate of the Past 12. 697-711. .
Villarroel, Carlos; Ana Elena Concha, and Carlos Macía. 2001. El Lago Pleistoceno de Soatá (Boyacá, Colombia): Consideraciones estratigráficas, paleontológicas y paleoecológicas. Geología Colombiana 26. 79-93. .
Villarroel, Carlos; Jorge
Brieva B., and Alberto Cadena. 1996. La Fauna de Mamíferos Fósiles del Pleistoceno de Jútua, Municipio de Soatá (Boyacá, Colombia). Geología Colombiana 21. 81-87. .
Various, Authors. 2005. Estudio General de Suelos y Zonificación de Tierras del Departamento de Boyacá, 1-256.
IGAC.