Guaduas Formation

Guaduas Formation
Stratigraphic range: Maastrichtian-Paleocene
~68–60 Ma
Type Geological formation
Underlies Cacho Formation
Overlies Guadalupe Gp.
 Arenisca Labor-Tierna Fm.
Thickness up to 1,090 metres (3,580 ft)
Lithology
Primary Shale
Other Sandstone, coal
Location
Coordinates 5°05′N 74°36′W / 5.083°N 74.600°W / 5.083; -74.600Coordinates: 5°05′N 74°36′W / 5.083°N 74.600°W / 5.083; -74.600
Region Middle Magdalena Basin
Magdalena River Valley
Altiplano Cundiboyacense
Eastern Ranges, Andes
Country  Colombia
Type section
Named for Guaduas
Named by Hubach
Location Guaduas
Year defined 1931
Coordinates 5°05′N 74°36′W / 5.083°N 74.600°W / 5.083; -74.600
Approximate paleocoordinates 0°36′N 52°30′W / 0.6°N 52.5°W / 0.6; -52.5
Region Cundinamarca, Boyacá
Country  Colombia

Paleogeography of Northern South America
65 Ma, by Ron Blakey

The Guaduas Formation (Spanish: Formación Guaduas, K2P1G, K2E1G, KPgg, KTg, TKg, Ktg) is a geological formation of the Middle Magdalena Basin and the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale with coalbed formation dates to the Late Cretaceous and Paleogene periods; Maastrichtian-Paleocene epochs, and has a maximum thickness of 1,090 metres (3,580 ft). Fossils of Coussapoa camargoi, Ficus andrewsi, Berhamniphyllum sp. and Archaeopaliurus boyacensis have been found in coalbeds in Zipaquirá and Tasco, Boyacá.

Etymology

The formation was first described by Hettner in 1894 and named in 1931 by Hubach after Guaduas, Cundinamarca, former northern territory of the Panche.[1]

Description

Lithologies

The Guaduas Formation consists mainly of shales with intercalated sandstone beds. The formation contains coalbeds that are widely explored in the area.[2] Fossil remains of Coussapoa camargoi, Ficus andrewsi, Berhamniphyllum sp. and Archaeopaliurus boyacensis have been found in coalbeds in Zipaquirá and Tasco, Boyacá.[3][4][5]

Stratigraphy and depositional environment

The Guaduas Formation unconformably[6] overlies the Arenisca Labor-Tierna Formation of the Guadalupe Group and is overlain by the Cacho Formation. The age has been estimated to be Upper Maastrichtian-Lower Paleocene, spanning the K-T boundary.[7] The Guaduas Formation is thicker in Cundinamarca than in Boyacá. This has been explained by a decrease in subsidence and a higher amount of erosion in the northern area of original deposition.[8] The lateral thickness variations are thought to be the result of the movement of the Soapaga Fault.[9] The formation has been deposited in a coastal plain setting.[4]

Outcrops

Type locality of the Guaduas Formation to the west of the Altiplano Cundiboyacense

The Guaduas Formation is apart from its type locality, found in the Eastern Hills of Bogotá, the Ocetá Páramo and many other locations in the Eastern Ranges, such as Granada,[10] the Dintel Synclinal north of Facatativá,[11] the Suesca Synclinal,[12] east of Junín,[13] and surrounding Lake Tota.[14] The northeast-southwest Canocas Fault crosscuts the Guaduas Formation near San Cayetano.[15] The synclinals of the Río Frío, Neusa, Zipaquirá, Checua-Lenguazaque, Sesquilé, Sisga, Subachoque, Teusacá and Usme and Soacha are composed of the Guaduas Formation.[2] The Suba Hills are entirely composed of the Guaduas Formation.[16] The formation also has outcrops in the Sumapaz Páramo.[17]

See also

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

References

  1. ↑ Montoya & Reyes, 2005, p.51
  2. 1 2 Montoya & Reyes, 2005, p.52
  3. ↑ Coussapoa camargoi, Ficus andrewsi at fossilworks.org
  4. 1 2 Berhamniphyllum sp. & Archaeopaliurus boyacensis at fossilworks.org
  5. ↑ Archaeopaliurus boyacensis in the Paleobiology Database
  6. ↑ Villamil, 2012, p.208
  7. ↑ Montoya & Reyes, 2005, p.54
  8. ↑ Mariño & Amaya, 2016, p.B9
  9. ↑ Amaya et al., 2010
  10. ↑ Plancha 246, 1998
  11. ↑ Plancha 227, 1998
  12. ↑ Plancha 190, 2009
  13. ↑ Plancha 191, 1998
  14. ↑ Plancha 192, 1998
  15. ↑ Planchas 171 & 191
  16. ↑ Geological Map Bogotá, 1997
  17. ↑ (in Spanish) Geología y geomorfología - Salida de Campo: Región Llanos Orientales

Bibliography

Maps

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