Macanal Formation

Macanal Formation
Stratigraphic range: Berriasian-Valanginian
~140–132 Ma
Outcrop of the Macanal Formation along the road between Bogotá and Villavicencio
Type Geological formation
Unit of Cáqueza Group
Underlies Las Juntas Formation
Overlies Guavio Fm., Santa Rosa Fm., Ubalá Fm., Chivor Fm., Batá Fm.
Thickness up to 2,935 m (9,629 ft)
Lithology
Primary Organic shale
Other Limestone, gypsum, emeralds
Location
Coordinates 4°58′19″N 73°19′10″W / 4.97194°N 73.31944°W / 4.97194; -73.31944Coordinates: 4°58′19″N 73°19′10″W / 4.97194°N 73.31944°W / 4.97194; -73.31944
Region Altiplano Cundiboyacense & Tenza Valley
 Eastern Ranges
  Andes
Country  Colombia
Type section
Named for Macanal
Named by Rodríguez & Ulloa
Location Macanal
Year defined 1979
Coordinates 4°58′19″N 73°19′10″W / 4.97194°N 73.31944°W / 4.97194; -73.31944
Region Boyacá
Country  Colombia

The Macanal Formation or Macanal Shale (Spanish: (Formación) Lutitas de Macanal, Kilm, K1m) is a fossiliferous geological formation of the Altiplano Cundiboyacense and Tenza Valley in the Eastern Ranges of the Colombian Andes. The predominantly organic shale formation dates to the Early Cretaceous period; Berriasian to Valanginian epochs and has a maximum thickness of 2,935 metres (9,629 ft). The Macanal Formation contains numerous levels of fossiliferous abundances. Bivalves, ammonites and fossil flora have been found in the formation.

The formation is a source rock for oil and gas in the Eastern Cordillera Basin and adjacent Llanos Basin foothills and provides emeralds in the vicinity of Macanal, after which the formation is named.

Etymology

The formation was defined and named in 1979 by Rodríguez and Ulloa after Macanal, Cundinamarca.[1][2] The name Macanal is either derived from the Muysccubun word Macana, meaning garrote, or from the Macana palm tree.[3][4]

Description

Lithologies

Fractured sample of the Macanal Formation

The Macanal Formation has a maximum thickness of 2,935 metres (9,629 ft), and is characterised by a sequence of micaceous organic shales,[2] with calcite veins and gypsum occurrences intercalated in the formation. The Macanal Formation contains high values of TOC.[5] In the Eastern Cordillera Basin and the adjacent foothills of the Llanos Basin, the Macanal Formation is a source rock for oil and gas.[6] In the vicinity of Macanal, the formation provides emeralds.[7][8]

Stratigraphy and depositional environment

The Macanal Formation, a unit of the Cáqueza Group, concordantly overlies the Guavio, Santa Rosa, Ubalá, Chivor and Batá Formations,[9] and is concordantly overlain by the Las Juntas Formation. The age has been estimated to be Berriasian to Valanginian. Stratigraphically, the formation is time equivalent with the Mercedes, Tambor, Rosablanca, Murca and La Naveta Formations.[10] The formation has been deposited in a shallow marine environment in an enclosed basin,[5] with as provenance areas the Santander High and the Guiana Shield.[11] The Macanal Formation is part of the syn-rift sequence of eastern Colombia.[12]

Fossil content

The Macanal Formation contains numerous levels of fossiliferous abundances. Bivalves, ammonites and flora have been found in the formation.[13] Ammonites of Substeueroceras cf. mutabile, Sarasinella cf. hondana, Subalpinites sp., Berriasela sp., Neocomites cf. wichmanni, Olcostephanus sp., Olcostephanus cf. atherstoni, Favrella cf. colombiana, Acanthodiscus sp. have been registered in the formation, as well as bivalves of Corbis (Sphaera) cf. corrugata, Trigonia cf. hondana, Trigonia (Buchotrigonia) cf. abrupta, Trigonia (Notoscabrotrigonia) cf. tocaimaana, and Exogyra cf. boussingaulti.[14] Analysis of the deformation registered in ammonite fossils has helped in understanding the tectonic history of the Llanos foothills of the Eastern Ranges.[15]

Outcrops

The Macanal Formation is found bordering the Guavio Reservoir
Type locality of the Macanal Formation in the Tenza Valley to the east of the Altiplano Cundiboyacense

The Macanal Formation is apart from its type locality in the Batá River canyon,[16][17] found in the Cravo Sur anticline, east of the Ocetá Páramo,[18] in the Desespero Synclinal in the southern and northern parts of Labranzagrande,[19][20] around Páez and Campohermoso,[17] in the eastern part of Gama, bordering the Guavio Reservoir,[21] and in the Servitá Synclinal, west of Villavicencio.[22] The Macanal Formation crops out along the road between Bogotá and Villavicencio and is there heavily fractured and folded. The Macanal Formation is the most extensive formation around Cáqueza,[23] and Gachalá, Cundinamarca.[24]

The Pajarito Fault thrusts the Macanal Formation on top of the Fómeque Formation to the east of Lake Tota,[25] and the Chámeza Fault thrusts the Macanal Formation on top of the overlying Las Juntas Formation around Chámeza, Casanare.[26] The Ubaque Fault forms the contact between the Fómeque Formation and the Macanal Formation,[27] while the Las Mercedes Fault puts the Quetame Group in contact with the Macanal Formation near Quetame,[28] as does the San Juanito Fault.[29] The Servitá Fault forms the contact between the Guatiquía Redbeds and the Macanal Formation,[30] and the Upín Fault, part of the same system puts the Macanal Formation in contact with the Tertiary Palmichal Group.[31] At this contact, brines are extracted from the formation.[32]

Regional correlations

Cretaceous stratigraphy of the central Colombian Eastern Ranges
AgePaleomapVMMGuaduas-VélezW Emerald BeltVilleta anticlinalChiquinquirá-
Arcabuco		Tunja-
Duitama		Altiplano CundiboyacenseEl Cocuy
MaastrichtianUmir Fm.Córdoba Fm.Seca Fm.erodedGuadalupe Gp.Colón-Mito Juan Fm.
Umir Fm.
CampanianCórdoba Fm.
Oliní Gp.
SantonianLa Luna Fm.Cimarrona Fm. - La Tabla Fm.La Luna Fm.
ConiacianOliní Gp.Conejo Fm.Chipaque Fm.
Güagüaquí Gp
Loma Gorda Fm.undefinedLa Frontera Fm.
TuronianHondita Fm.La Frontera Fm.Otanche Fm.
CenomanianSimití Fm.hiatusLa Corona Gb.Simijaca Fm.Capacho Fm.
Pacho Fm.Hiló Fm. - Pacho Fm.Churuvita Fm.Une Fm.Aguardiente Fm.
AlbianHiló Fm.Chiquinquirá Sst.Tibasosa Fm.Une Fm.
Tablazo Fm.Tablazo Fm.Capotes Fm. - La Palma Fm. - Simití Fm.Simití Fm.Tibú-Mercedes Fm.
AptianCapotes Fm.Socotá Fm. - El Peñón Fm.Paja Fm.Fómeque Fm.
Paja Fm.Paja Fm.El Peñón Fm.Trincheras Fm.Río Negro Fm.
La Naveta Fm.
Barremian
HauterivianMuzo Fm.
Cáqueza Gp
Las Juntas Fm.
Rosablanca Fm.Ritoque Fm.
ValanginianRitoque Fm.Furatena Fm.Útica Fm. - Murca Fm.Rosablanca Fm.Girón Fm.Macanal Fm.
Rosablanca Fm.
BerriasianCumbre Fm.Cumbre Fm.Los Medios Fm.Guavio Fm.
Tambor Fm.Arcabuco Fm.Cumbre Fm.
Sources

See also

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

References

  1. ↑ Acosta & Ulloa, 2002, p.51
  2. 1 2 Rodríguez & Solano, 2000, p.47
  3. ↑ (in Spanish) Official website Macanal
  4. ↑ (in Spanish) Etymology Municipalities Boyacá
  5. 1 2 Acosta & Ulloa, 2002, p.52
  6. ↑ García González et al., 2009, p.49
  7. ↑ Uribe, 1960, p.5
  8. ↑ ANM, 2015, p.1
  9. ↑ Terraza et al., 2013, p.110
  10. ↑ Villamil, 2012, p.168
  11. ↑ Villamil, 2012, p.165
  12. ↑ Schütz, 2012, p.26
  13. ↑ Patiño et al., 2011, p.45
  14. ↑ Piraquive et al., 2011, p.204
  15. ↑ Montaña Cárdenas, 2015, p.52
  16. ↑ Rodríguez & Solano, 2000, p.46
  17. 1 2 Plancha 210, 2010
  18. ↑ Plancha 172, 1998
  19. ↑ Plancha 193, 1992
  20. ↑ Pinto Valderrama et al., 2010, p.44
  21. ↑ Plancha 228, 1998
  22. ↑ Plancha 266, 1998
  23. ↑ Patiño et al., 2011, p.44
  24. ↑ Terraza et al., 2013, p.101
  25. ↑ Plancha 192, 1998
  26. ↑ Plancha 211, 2009
  27. ↑ Patiño et al., 2011, p.102
  28. ↑ Patiño et al., 2011, p.110
  29. ↑ Patiño et al., 2011, p.114
  30. ↑ Patiño et al., 2011, p.122
  31. ↑ Patiño et al., 2011, p.123
  32. ↑ Patiño et al., 2011, p.125

Bibliography

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