Barzalosa Formation

Barzalosa Formation
Stratigraphic range: ~Mid Eocene-Oligocene
or Oligocene-Early Miocene
~40–20 Ma
Type Geological formation
Underlies Honda Gp., Carmen de Apicalá Conglomerate
Overlies La Tabla Fm., Olini Gp., Seca Fm.
Thickness ~360 m (1,180 ft)
Lithology
Primary Conglomerates
Other Sandstones, siltstones, shale, gypsum
Location
Coordinates 4°21′50.2″N 74°47′29.8″W / 4.363944°N 74.791611°W / 4.363944; -74.791611Coordinates: 4°21′50.2″N 74°47′29.8″W / 4.363944°N 74.791611°W / 4.363944; -74.791611
Approximate paleocoordinates 2°42′N 71°12′W / 2.7°N 71.2°W / 2.7; -71.2
Region Upper Magdalena Valley
Central & Eastern Ranges
 Andes
Country  Colombia
Type section
Named for Barzalosa
Named by Scheibe
Location Girardot
Year defined 1934
Coordinates 4°21′50.2″N 74°47′29.8″W / 4.363944°N 74.791611°W / 4.363944; -74.791611
Region Cundinamarca
Country  Colombia

Paleogeography of Northern South America
35 Ma, by Ron Blakey

The Barzalosa Formation (Spanish: Formación Barzalosa, Pgb, Pgba) is a fossiliferous geological formation of the Upper Magdalena Valley and the bounding foothills of the Central Ranges and Eastern Ranges of the Colombian Andes. The formation consists of conglomerates, sandstones and siltstones. The Barzalosa Formation probably dates to the Late Paleogene to Early Neogene period; Oligocene to Early Miocene epochs, and has an approximate thickness of 360 metres (1,180 ft). Fossils of Balanerodus logimus, Lophiodolodus chaparralensis, Xenastrapotherium chaparralensis, Protheosodon sp. and Proadinotherium sp. have been uncovered from the formation in Chaparral, Tolima.

Etymology

The formation was defined by Scheibe in 1934 and named after Barzalosa, a vereda of Girardot, Cundinamarca. Cáceres and Etayo elevated the "Pisos de Barzalosa" to a formation in 1969.[1]

Description

Lithologies

The Barzalosa Formation consists of conglomerates, sandstones and siltstones.[2] In parts, the formation contains shale beds and gypsum.[3]

Stratigraphy and depositional environment

The approximately 360 metres (1,180 ft) thick Barzalosa Formation overlies the Olini Group and the Seca Formation in the west and is overlain by the Honda Group.[2] In the east towards Fusagasugá, the formation overlies the La Tabla Formation and is overlain by the Carmen de Apicalá Conglomerate.[4] As the formation does not contain foraminifera, the age is difficult to establish, but has been estimated to be Oligocene to Early Miocene,[2] or Middle Eocene to Oligocene.[5] The depositional environment has been interpreted as alluvial fans and braided rivers.[6]

Fossil content

Location Department Fossils Notes
Alto San José, Chaparral Tolima Balanerodus logimus
Lophiodolodus chaparralensis
Xenastrapotherium chaparralensis
Protheosodon sp.
Proadinotherium sp.
Megalonychoidae indet., Gavialidae indet.

Outcrops

Type locality of the Barzalosa Formation to the southwest of the Bogotá savanna

The Barzalosa Formation is apart from its type locality found in Tocaima and to the east of Agua de Dios,[1] and on the western side of the Magdalena River around Chaparral, Tolima.[12]

See also

Geology of the Eastern Hills
Middle Magdalena Valley
Geology of the Altiplano Cundiboyacense

References

  1. 1 2 Acosta et al., 2002, p.49
  2. 1 2 3 Acosta et al., 2002, p.50
  3. ↑ Acosta & Ulloa, 2001, p.56
  4. ↑ Acosta & Ulloa, 2001, p.52
  5. ↑ Acosta & Ulloa, 2001, p.57
  6. ↑ Acosta et al., 2002, p.51
  7. ↑ Balanerodus logimus in the Paleobiology Database
  8. ↑ Lophiodolodus chaparralensis in the Paleobiology Database
  9. ↑ Xenastrapotherium chaparralensis in the Paleobiology Database
  10. ↑ Protheosodon in the Paleobiology Database
  11. ↑ Proadinotherium in the Paleobiology Database
  12. 1 2 Chaparral Alto José in the Paleobiology Database

Bibliography

  • Acosta, Jorge E.; Rafael Guatame; Juan Carlos Caicedo A., and Jorge Ignacio Cárdenas. 2002. Mapa Geológico de Colombia - Plancha 245 - Girardot - 1:100,000 - Memoria Explicativa, 1–92. INGEOMINAS.
  • Acosta, Jorge E., and Carlos E. Ulloa. 2001. Mapa Geológico de Colombia - Plancha 246 - Fusagasugá - 1:100,000 - Memoria Explicativa, 1–77. INGEOMINAS.

Maps

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