Caballos Formation

Caballos Formation
Stratigraphic range: Aptian-Albian
~120–100 Ma
Type Geological formation
Underlies Hondita Formation
Overlies Yaví Fm., Saldaña Fm.
Thickness up to 411 m (1,348 ft)
Lithology
Primary Sandstone, shale, siltstone
Other Limestone, coal
Location
Coordinates 3°49′18.9″N 75°21′22.4″W / 3.821917°N 75.356222°W / 3.821917; -75.356222Coordinates: 3°49′18.9″N 75°21′22.4″W / 3.821917°N 75.356222°W / 3.821917; -75.356222
Region VSM & Caguán-Putumayo Basin
Central & Eastern Ranges, Andes
Country  Colombia
Type section
Named for Cerro Caballos
Named by Corrigan
Location Olaya Herrera
Year defined 1967
Coordinates 3°49′18.9″N 75°21′22.4″W / 3.821917°N 75.356222°W / 3.821917; -75.356222
Approximate paleocoordinates 2°54′S 47°24′W / 2.9°S 47.4°W / -2.9; -47.4
Region Tolima
Country  Colombia
Thickness at type section 411 m (1,348 ft)

Paleogeography of Northern South America
105 Ma, by Ron Blakey

The Caballos Formation (Spanish: Formación Caballos, KI) is a geological formation of the Upper Magdalena Valley (VSM), Caguán-Putumayo Basin, Central and Eastern Ranges of the Colombian Andes. The sandstone and shale formation dates to the Middle Cretaceous period; Aptian to Albian epochs and has a maximum thickness of 411 metres (1,348 ft).

Etymology

The formation was defined and named in 1967 by Corrigan after Cerro Caballos, to the west of Olaya Herrera, Tolima.[1]

Description

Lithologies

The Caballos Formation has a maximum thickness of 411 metres (1,348 ft) in the Quebrada Bambucá and is characterized by a lower sequence of fine to coarse sandstones, of lithic arenite, quartz arenite and feldspar arenite composition, a middle section of fossiliferous black shales and siltstones, intercalated by micritic limestones and coals and very fine sandstones. The upper part of the formation contains conglomerates and glauconitic sandstones.[1]

Stratigraphy and depositional environment

The Caballos Formation in some parts concordantly overlies the Yaví Formation and in other parts rests unconformably on the Saldaña Formation and Ibagué Batholith.[2] The formation is overlain by the Hondita Formation. The age has been estimated to be Aptian to Albian. Stratigraphically, the formation is time equivalent with the Une, Aguardiente, Simijaca, El Peñón, Capotes, Tablazo, Tibú-Mercedes and Pacho Formations.[3] The formation has been deposited in a fluvial to estuarine and shallow marine environment.[4]

The Caballos Formation is a source, reservoir and seal rock in the Upper Magdalena Valley,[5][6] and a source and reservoir rock in the Caguán-Putumayo Basin.[7][8] The Orito and Moqueta Fields of the latter basin produce from Caballos reservoirs.

Fossil content

The formation has provided fossils of Heminautilus etheringtoni,[9] Araucarites sp., Brachyphyllum sp., Cladophlebis sp., and Weichselia sp.,[10] as well as many types of pollen.[11]

Outcrops

Type locality of the Caballos Formation in Tolima

The Caballos Formation is apart from its type locality, found in Huila, Tolima and Putumayo Departments.

See also

References

  1. 1 2 Velandia et al., 2001, p.53
  2. ↑ Velandia et al., 2001, p.34
  3. ↑ Velandia et al., 2001, p.54
  4. ↑ Villamil, 2012, p.166
  5. ↑ ANH, 2007, p.84
  6. ↑ García González et al., 2009, p.83
  7. ↑ ANH, 2007, p.57
  8. ↑ García González et al., 2009, p.16
  9. ↑ Badouin et al., 2016, p.87
  10. ↑ Monje et al., 2016, p.38
  11. ↑ Los Mangos at Fossilworks.org

Bibliography

Maps

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