Llanos Basin

The Llanos Basin (Spanish: Cuenca Llanos) or Eastern Llanos Basin (Spanish: Cuenca de los Llanos Orientales) is a major sedimentary basin of 96,000 square kilometres (37,000 sq mi) in northeastern Colombia. The onshore foreland on Mesozoic rift basin covers the departments of Arauca, Casanare and Meta and parts of eastern Boyacá and Cundinamarca, western Guainía, northern Guaviare and southeasternmost Norte de Santander. The northern boundary is formed by the border with Venezuela, where the basin grades into the Barinas-Apure Basin.

Llanos Basin
Cuenca Llanos
The Llanos Basin in Puerto López, Meta
Coordinates05°24′00″N 71°40′00″W
EtymologyLlanos Orientales
Spanish: "eastern plains"
RegionOrinoquía
Country Colombia
State(s)Arauca, Boyacá, Casanare, Cundinamarca, Guainía, Guaviare, Meta, Norte de Santander
CitiesVillavicencio, Yopal
Characteristics
On/OffshoreOnshore
BoundariesColombia-Venezuela border (N), Guiana Shield (E), Vaupés Arch (S), Serranía de la Macarena (SW), Eastern Ranges (W)
Part ofAndean foreland basins
Area96,000 km2 (37,000 sq mi)
Hydrology
River(s)Orinoco watershed
Main rivers: Arauca, Meta, Guaviare, Vichada
Geology
Basin typeForeland on rift basin[note 1]
PlateSouth American[note 2]
OrogenyBreak-up of Pangea (Mesozoic)
Andean (Cenozoic)
AgePaleozoic or Jurassic[note 3]
to Holocene
StratigraphyStratigraphy
FaultsEastern (W, bounding), Chichimene & Meta
Field(s)Rubiales, Caño Limón, many more

Description

The northeastern part of Colombia is characterized by its wavy plains, called Llanos Orientales, as part of the bigger Llanos that extend into Venezuela. The landscape is similar to a savanna and is poor in trees. It is located between the Eastern Ranges of the Colombian Andes in the west, the Vaupés Arch in the south and the Guiana Shield in the east.[1]

Geologically, the Llanos Basin underlies this typical landscape of the Llanos. An area where transport occurs mostly by small boats along the many rivers and the "buses of the Llanos", the Douglas DC-3 planes. The basin covers an area of 96,000 square kilometres (37,000 sq mi) and contains a stratigraphic column from the Paleozoic to recent.[2] Several of the formations in the basins are source rocks (Gachetá, Los Cuervos, Carbonera C8), reservoir rocks (Mirador, Barco, Guadalupe and the uneven numbered members of Carbonera). Seals are formed by the shaly intervals (even numbered) of the Carbonera Formation, Los Cuervos, and León.[3]

The basin is the main petroleum producing basin of Colombia, with four of the nations biggest oil fields located in the Llanos Basin. Major fields are Rubiales, Colombia's biggest and most recent giant discovery sealed by a complex of hydrodynamic processes, and Caño Limón, at the border with Venezuela.

Major concerns in the basin for the production of petroleum are biodegradation, hydrocarbon migration, fault seal capacity and water flow.

Hydrography
Rivers of the Llanos Basin
Ariarí River

The Llanos Basin is crossed by numerous rivers, all belonging to the Orinoco watershed. From north to south:

Flora and fauna

Fauna
Map of national parks in Orinoquía region
See also: List of flora and fauna of the Eastern Hills, Bogotá and List of flora and fauna named after the Muisca

Among other species, Lynch's swamp frog (Pseudopaludicola llanera) is endemic to the Llanos, with the species epithet referring to the plains.[4] Also the whip scorpion Mastigoproctus colombianus is reported from the Llanos Basin.[5]

Geodynamic situation
Plate tectonic situation of northwestern South America.
Nazca Plate has been subdivided into Coiba and Malpelo Plates
Coiba & Malpelo Plates
See also: Eastern Hills, Bogotá § Geology; Altiplano Cundiboyacense § Geology; Bogotá savanna § Geology; and Ocetá Páramo § Geology

The country of Colombia spreads out over six tectonic plates, clockwise from north:

  1. Caribbean Plate
  2. North Andes Plate
  3. South American Plate
  4. Malpelo Plate
  5. Coiba Plate
  6. Panama Plate

The Llanos Basin is situated entirely on the South American Plate, bordering the North Andean Block or North Andean microplate in the west. The basin is one of three Colombian basins on the South American Plate, to the south the Caguán-Putumayo Basin and to the southeast the Vaupés-Amazonas Basin. The northern boundary of the Llanos Basin is formed by the Colombia-Venezuela border where the basin grades into the Barinas-Apure Basin on the Venezuelan side. The Catatumbo Basin, representing the Colombian portion of the larger Maracaibo Basin borders the Llanos Basin in the northwest and the western boundary is formed by the foothills (Piedemonte) of the Eastern Cordillera Basin, the sedimentary basin covering the Eastern Ranges of the Colombian Andes.

Tectonics
See also: Eastern Frontal Fault System and List of earthquakes in Colombia

The basin is bound to the west by the Eastern Frontal Fault System, a 921.4 kilometres (572.5 mi) long fault system connecting the North Andes and South American Plates and thus the Eastern Cordillera Basin and the Llanos Basin. The fault system has an average strike of 042.1±19, but this orientation varies greatly along its course. The 1827, 1834, 1917, 1967, 1995, and 2008 earthquakes were all caused by fault movement as part of the system.[6]

Basin history
See also: Cesar-Ranchería Basin § Tectonic history, and Cocinetas Basin § Tectonic history

The tectonic history of the Llanos Basin, a foreland basin formed on top of Mesozoic rift basins, Paleozoic metasediments and Precambrian basement underlain by continental crust, goes back to the Early Jurassic.

The Andean orogeny, represented by the tectonic uplift of the Colombian Eastern Ranges and its northern extension, the Serranía del Perijá, caused tilting and uplift in the Llanos Basin. During the Andean orogenic phase, the paleotemperatures in the basin dropped considerably; in the Baja Guajira area from 115 °C (239 °F) in the Early Miocene to 70 °C (158 °F) in the Late Miocene.[7] In the Late Miocene to Pliocene, the major faults to the southwest of the Cocinetas Basin, the Oca and Bucaramanga-Santa Marta Faults were tectonically active.[8]

Basement
The Cerros de Mavecure in Guainía are a remnant of the Proterozoic basement underlying the Llanos Basin
The Serranía de Chiribiquete in Guaviare

The stratigraphy of the Llanos Basin ranges, depending on the definition from either Jurassic or Paleozoic to recent. The basement is formed by the westernmost extensions of the Guiana Shield. Remnants of these Precambrian formations are found as inselbergs in the far east of Colombia (Cerros de Mavecure), in the Serranía de la Macarena to the southwest of the basin and in the tepuis of the Serranía de Chiribiquete to the southeast.

The Proterozoic crystalline rocks are overlain by metamorphosed sedimentary and igneous rocks ranging in age from Cambrian to Devonian. Younger and contemporaneous Paleozoic deposits are only found in the subsurface and in regional correlative units as the Floresta and Cuche Formations of the Altiplano Cundiboyacense to the direct northwest and the Río Cachirí Group of the Cesar-Ranchería Basin farther northwest of the Llanos Basin.

The units found in the Llanos Basin pertain to the Farallones Group and comprise the Valle del Guatiquía Red Beds, Pipiral Shale and the Gutiérrez Sandstone.[9]

Stratigraphy
Stratigraphy of the Llanos Basin and surrounding provinces
MaAgePaleomapRegional eventsCatatumboCordilleraproximal Llanosdistal LlanosPutumayoVSMEnvironmentsMaximum thicknessPetroleum geologyNotes
0.01Holocene
Holocene volcanism
Seismic activity		alluviumOverburden
1Pleistocene
Pleistocene volcanism
Andean orogeny 3
Glaciations		GuayaboSoatá
Sabana		NecesidadGuayaboGigante
Neiva
Alluvial to fluvial (Guayabo)550 m (1,800 ft)
(Guayabo)		[10][11][12][13]
2.6Pliocene
Pliocene volcanism
Andean orogeny 3
GABI		Subachoque
5.3MessinianAndean orogeny 3
Foreland		MarichuelaCaimánHonda[12][14]
13.5LanghianRegional floodingLeónhiatusCajaLeónLacustrine (León)400 m (1,300 ft)
(León)		Seal[13][15]
16.2BurdigalianMiocene inundations
Andean orogeny 2		C1Carbonera C1OspinaProximal fluvio-deltaic (C1)850 m (2,790 ft)
(Carbonera)		Reservoir[14][13]
17.3C2Carbonera C2Distal lacustrine-deltaic (C2)Seal
19C3Carbonera C3Proximal fluvio-deltaic (C3)Reservoir
21Early MiocenePebas wetlandsC4Carbonera C4BarzalosaDistal fluvio-deltaic (C4)Seal
23Late Oligocene
Andean orogeny 1
Foredeep		C5Carbonera C5OritoProximal fluvio-deltaic (C5)Reservoir[11][14]
25C6Carbonera C6Distal fluvio-lacustrine (C6)Seal
28Early OligoceneC7C7PepinoGualandayProximal deltaic-marine (C7)Reservoir[11][14][16]
32Oligo-EoceneC8UsmeC8onlapMarine-deltaic (C8)Seal
Source		[16]
35Late Eocene
MiradorMiradorCoastal (Mirador)240 m (790 ft)
(Mirador)		Reservoir[13][17]
40Middle EoceneRegaderahiatus
45
50Early Eocene
SochaLos CuervosDeltaic (Los Cuervos)260 m (850 ft)
(Los Cuervos)		Seal
Source		[13][17]
55Late PaleocenePETM
2000 ppm CO2		Los CuervosBogotáGualanday
60Early PaleoceneSALMABarcoGuaduasBarcoRumiyacoFluvial (Barco)225 m (738 ft)
(Barco)		Reservoir[10][11][14][13][18]
65Maastrichtian
KT extinctionCatatumboGuadalupeMonserrateDeltaic-fluvial (Guadalupe)750 m (2,460 ft)
(Guadalupe)		Reservoir[10][13]
72CampanianEnd of riftingColón-Mito Juan[13][19]
83SantonianVilleta/Güagüaquí
86Coniacian
89TuronianCenomanian-Turonian anoxic eventLa LunaChipaqueGachetáhiatusRestricted marine (all)500 m (1,600 ft)
(Gachetá)		Source[10][13][20]
93Cenomanian
Rift 2
100AlbianUneUneCaballosDeltaic (Une)500 m (1,600 ft)
(Une)		Reservoir[14][20]
113Aptian
CapachoFómequeMotemaYavíOpen marine (Fómeque)800 m (2,600 ft)
(Fómeque)		Source (Fóm)[11][13][21]
125BarremianHigh biodiversityAguardientePajaShallow to open marine (Paja)940 m (3,080 ft)
(Paja)		Reservoir[10]
129Hauterivian
Rift 1Tibú-
Mercedes		Las JuntashiatusDeltaic (Las Juntas)910 m (2,990 ft)
(Las Juntas)		Reservoir (LJun)[10]
133ValanginianRío NegroCáqueza
Macanal
Rosablanca		Restricted marine (Macanal)2,935 m (9,629 ft)
(Macanal)		Source (Mac)[11][22]
140BerriasianGirón
145TithonianBreak-up of PangeaJordánArcabucoBuenavista
Batá
SaldañaAlluvial, fluvial (Buenavista)110 m (360 ft)
(Buenavista)		"Jurassic"[14][23]
150Early-Mid Jurassic
Passive margin 2La Quinta
Montebel

Noreán		hiatusCoastal tuff (La Quinta)100 m (330 ft)
(La Quinta)		[24]
201Late Triassic
MucuchachiPayandé[14]
235Early Triassic
Pangeahiatus"Paleozoic"
250Permian
300Late Carboniferous
Famatinian orogenyCerro Neiva
()		[25]
340Early CarboniferousFossil fish
Romer's gap		Cuche
(355-385)		Farallones
()		Deltaic, estuarine (Cuche)900 m (3,000 ft)
(Cuche)
360Late Devonian
Passive margin 1Río Cachirí
(360-419)		Ambicá
()		Alluvial-fluvial-reef (Farallones)2,400 m (7,900 ft)
(Farallones)		[22][26][27][28][29]
390Early Devonian
High biodiversityFloresta
(387-400)
El Tíbet
Shallow marine (Floresta)600 m (2,000 ft)
(Floresta)
410Late SilurianSilurian mystery
425Early Silurianhiatus
440Late Ordovician
Rich fauna in BoliviaSan Pedro
(450-490)		Duda
()
470Early OrdovicianFirst fossilsBusbanzá
(>470±22)
Chuscales
Otengá
Guape
()		Río Nevado
()
Hígado
()
Agua Blanca
Venado
(470-475)
[30][31][32]
488Late Cambrian
Regional intrusionsChicamocha
(490-515)		Quetame
()		Ariarí
()		SJ del Guaviare
(490-590)		San Isidro
()		[33][34]
515Early CambrianCambrian explosion[32][35]
542Ediacaran
Break-up of Rodiniapre-Quetamepost-ParguazaEl Barro
()		Yellow: allochthonous basement
(Chibcha Terrane)
Green: autochthonous basement
(Río Negro-Juruena Province)		Basement[36][37]
600Neoproterozoic
Cariri Velhos orogenyBucaramanga
(600-1400)		pre-Guaviare[33]
800
Snowball Earth[38]
1000Mesoproterozoic
Sunsás orogenyAriarí
(1000)		La Urraca
(1030-1100)		[39][40][41][42]
1300Rondônia-Juruá orogenypre-AriaríParguaza
(1300-1400)		Garzón
(1180-1550)		[43]
1400
pre-Bucaramanga[44]
1600PaleoproterozoicMaimachi
(1500-1700)		pre-Garzón[45]
1800
Tapajós orogenyMitú
(1800)		[43][45]
1950Transamazonic orogenypre-Mitú[43]
2200Columbia
2530Archean
Carajas-Imataca orogeny[43]
3100Kenorland
Sources
Legend
  • group
  • important formation
  • fossiliferous formation
  • minor formation
  • (age in Ma)
  • proximal Llanos (Medina)[note 4]
  • distal Llanos (Saltarin 1A well)[note 5]

Paleozoic
Cambro-Ordovician
  • Guape Formation
  • Duda Formation
  • Ariarí Formation
  • Ariarí Metagabbro
Pre-Devonian
  • Quetame Group
    • Río Guamal Metasiltstones
    • Guayabetal Phyllites and Quartzites
    • San Cristóbal Quartzites and Phyllites
    • Susumuco Metaconglomerates and Phyllites
Devonian
  • Farallones Group
    • Valle del Guatiquía Red Beds
    • Pipiral Shale
    • Gutiérrez Sandstone

Jurassic
  • Buenavista Breccia

Petroleum geology

The Llanos Basin is the most prolific hydrocarbon basin of Colombia, hosting well-known petroleum deposits as Caño Limón, Rubiales and other fields. Nine of the twenty most producing oil fields of Colombia are situated in the Llanos Basin.

Fields

Based on data released in March 2018, Colombia is the 21st oil producer in the world. Daily production dropped in 2017 to 854.121 thousand barrels per day (135.7944×10^3 m3/d).[50] In 2016, twenty oilfields produced 66% of all oil of Colombia, listed below in bold.[51] The total proven reserves of Colombia were 1,665.489 million barrels (264.7916×10^6 m3) in 2016.[52]

Major oil fields in the Llanos Basin are:[53]

Major oil and gas fields of the Llanos Basin
NameMapLocationOperatorReservoirsReserves
Production (2016)		Notes
Rubiales
Puerto Gaitán
Meta		EcopetrolCarbonera 74,380 million bbl (696 million m3)
132.000 kbbl/d (20.9863×10^3 m3/d)
Castilla
Castilla la Nueva
Meta		EcopetrolMirador
Gachetá
Une		452 million bbl (71.9 million m3)
121.363 kbbl/d (19.2952×10^3 m3/d)		[54][55]
Chichimene
Acacias
Meta		EcopetrolMirador
Guadalupe
Gachetá
Une		74.052 kbbl/d (11.7733×10^3 m3/d)[56][57]
Quifa
Puerto Gaitán
Meta		Meta PetroleumCarbonera613 million bbl (97.5 million m3)
46.557 kbbl/d (7.4020×10^3 m3/d)		[58][59]
Caño Limón
Puerto Rondón
Arauca		Ecopetrol20.930 kbbl/d (3.3276×10^3 m3/d)[60]
Avispa
Cabuyaro
Meta		Pacific Rubiales11.625 kbbl/d (1.8482×10^3 m3/d)
Ocelote
Puerto Gaitán
Meta		Hocol11.228 kbbl/d (1.7851×10^3 m3/d)
Chipirón
Puerto Rondón
Arauca		OXY10.459 kbbl/d (1.6628×10^3 m3/d)[59]
Jacana
Villanueva
Casanare		Geopark7.477 kbbl/d (1.1887×10^3 m3/d)
Cupiagua
Aguazul
Casanare		Ecopetrol5.358 kbbl/d (851.9 m3/d)
Apiay
Villavicencio
Meta		EcopetrolGachetá
Une
Arauca
Arauca
Arauca		Ecopetrol
Cusiana
Tauramena
Casanare		EcopetrolMirador
Barco
Guadalupe
  • Other fields[53]
    • Caño Verde
    • Chaparrito
    • Concesión
    • Corcel
    • Cravo Sur
    • La Gloria
    • Santiago
    • Trinidad
    • Valdivia

Mining

Mining activities in the Llanos Basin are restricted to certain areas, resulting in less conflicts, more common with indigenous peoples in the Amazonian part of Colombia.[61]

In San José del Guaviare platinum is mined.[65]

Mining in the Llanos Basin and surrounding areas
ResourcesMapDepartmentMunicipalityMineNotes
halite
MetaRestrepoUpín[63][66]
gold
Puerto Rico[62]
AraucaArauca
gold
GuaviareSan José del Guaviare
platinum, iron, albite, andradite (var: melanite), 'apatite', arfvedsonite, 'biotite', calcite, cancrinite, epidote, fluorite, 'garnet', microcline, 'monazite', nepheline, siderite, titanite, zircon[65][67]
coal
CasanareRecetor[64]

Paleontology
Llanos Basin is located in Colombia
B
B
C
C
F
F
L
L
J
J
M
M
P
P
H
H
Co
Co
Major fossiliferous formations
Neogene
 H = Honda Group
 Co = Cocinetas Basin
Paleogene
 B = Bogotá
 C = Cerrejón
Cretaceous
 L = La Frontera
 P = Paja
Jurassic
 J = Valle Alto
Devonian
 F = Cuche and Floresta
Cambro-Ordovician
 M = Duda, La Macarena
See also: List of fossiliferous stratigraphic units in Colombia

Compared to many fossiliferous formations in Colombia, the Llanos Basin has been lean in fossil content. Most of the basin stratigraphy is only known from wells.

Paleozoic outcrops surrounding and perforating the planar geography have provided fossils dating back to the Cambrian; the Duda and Ariarí Formations.

Several fossiliferous formations of contemporaneous depositional environments have provided many unique fossils indicative of paleoclimatic conditions; turtle fossils were described from Los Cuervos in the Cesar-Ranchería Basin, and the Mirador Formation in the Catatumbo Basin direct northwest of the Llanos Basin has provided many fossil flora.[68]

Other correlative units with surrounding basins

See also

Sources

Notes
  1. More detailed: continental margin (Protero- and Paleozoic), rift basin (Mesozoic), foredeep (Paleogene and early Neogene), foreland (late Neogene to recent)
  2. The northernmost of three Colombian basins on this plate, to the south the Caguán-Putumayo and Vaupés-Amazonas Basins
  3. Depending on the definition of basement, the stratigraphic succession starts either in the Paleozoic on Proterozoic crystalline basement or Jurassic on top of both
  4. based on Duarte et al. (2019)[46], García González et al. (2009),[47] and geological report of Villavicencio[48]
  5. based on Duarte et al. (2019)[46] and the hydrocarbon potential evaluation performed by the UIS and ANH in 2009[49]

References
  1. Barrero et al., 2007, p.69
  2. ANH, 2010
  3. García González et al., 2009, p.58
  4. Pseudopaludicola llanera at IUCN.org
  5. Mastigoproctus colombianus at GBIF.org
  6. Paris et al., 2000a, p.36
  7. Hernández Pardo et al., 2009, p.122
  8. Hernández Pardo et al., 2009, p.28
  9. Plancha 266, 1998
  10. García González et al., 2009, p.27
  11. García González et al., 2009, p.50
  12. García González et al., 2009, p.85
  13. Barrero et al., 2007, p.60
  14. Barrero et al., 2007, p.58
  15. Plancha 111, 2001, p.29
  16. Plancha 177, 2015, p.39
  17. Plancha 111, 2001, p.26
  18. Plancha 111, 2001, p.24
  19. Plancha 111, 2001, p.23
  20. Pulido & Gómez, 2001, p.32
  21. Pulido & Gómez, 2001, p.30
  22. Pulido & Gómez, 2001, pp.21-26
  23. Pulido & Gómez, 2001, p.28
  24. Correa Martínez et al., 2019, p.49
  25. Plancha 303, 2002, p.27
  26. Terraza et al., 2008, p.22
  27. Plancha 229, 2015, pp.46-55
  28. Plancha 303, 2002, p.26
  29. Moreno Sánchez et al., 2009, p.53
  30. Mantilla Figueroa et al., 2015, p.43
  31. Manosalva Sánchez et al., 2017, p.84
  32. Plancha 303, 2002, p.24
  33. Mantilla Figueroa et al., 2015, p.42
  34. Arango Mejía et al., 2012, p.25
  35. Plancha 350, 2011, p.49
  36. Pulido & Gómez, 2001, pp.17-21
  37. Plancha 111, 2001, p.13
  38. Plancha 303, 2002, p.23
  39. Plancha 348, 2015, p.38
  40. Planchas 367-414, 2003, p.35
  41. Toro Toro et al., 2014, p.22
  42. Plancha 303, 2002, p.21
  43. Bonilla et al., 2016, p.19
  44. Gómez Tapias et al., 2015, p.209
  45. Bonilla et al., 2016, p.22
  46. Duarte et al., 2019
  47. García González et al., 2009
  48. Pulido & Gómez, 2001
  49. García González et al., 2009, p.60
  50. Producción de crudo bajó en 30.879 barriles por día en 2017 - El Tiempo
  51. En 20 campos se produce el 66 % del petróleo del país - El Tiempo
  52. Oil reserves per department - 2016 - ANH
  53. Mojica et al., 2009, p.30
  54. ANH & Halliburton, s.a., p.2
  55. Castilla, área petrolera especial - El Tiempo
  56. ANH & Halliburton, s.a., p.3
  57. Chichimene
  58. Las reservas de campo Quifa se reducen en 5,9 millones de barriles
  59. Mapa de Tierras, ANH, 2017
  60. Caño Limón
  61. (in Spanish) Mapa de Territorios Indígenas y Minerales Preciosos
  62. (in Spanish) Producción de oro – UPME
  63. (in Spanish) Producción de sal – UPME
  64. (in Spanish) Producción de carbón – UPME
  65. (in Spanish) Producción de platino – UPME
  66. Upin at Mindat.org
  67. San José del Guaviare at Mindat.org
  68. Jaramillo & Dilcher, 2001

General
  • Barrero, Dario; Andrés Pardo; Carlos A. Vargas, and Juan F. Martínez. 2007. Colombian Sedimentary Basins: Nomenclature, Boundaries and Petroleum Geology, a New Proposal, 1–92. ANH.
  • García González, Mario; Ricardo Mier Umaña; Luis Enrique Cruz Guevara, and Mauricio Vásquez. 2009. Informe Ejecutivo - evaluación del potencial hidrocarburífero de las cuencas colombianas, 1-219. Universidad Industrial de Santander.

Hydrodynamics

Tectonics

Petroleum
  • Martínez Sánchez, Dilan, and Giovanny Jiménez. 2019. Hydraulic fracturing considerations: Insights from analogue models, and its viability in Colombia. Earth Sciences Research Journal 23. 5-15. Accessed 2019-10-26. ISSN 1794-6190
  • Vargas Jiménez, Carlos A. 2012. Evaluating total Yet-to-Find hydrocarbon volume in Colombia. Earth Sciences Research Journal 16. 1–290. Accessed 2017-06-14.
  • Mojica, Jairo; Oscar J. Arévalo, and Hardany Castillo. 2009. Cuencas Catatumbo, Cesar – Ranchería, Cordillera Oriental, Llanos Orientales, Valle Medio y Superior del Magdalena, 1–65. ANH. Accessed 2017-06-14.
  • Piedrahita, Carlos, and Clara L. Montaña. 2007. Methodology implemented for the 3D-Seismic modelling using GoCad and NORSAR 3D Software applied to complex areas in the Llanos foothills. Earth Sciences Research Journal 11. 35-43. Accessed 2019-10-26.
  • Hernández Pardo, Orlando; Ralph R.B. von Frese, and Jeong Woo Kim. 2007. Crustal thickness variations and seismicity of northwestern South America. Earth Sciences Research Journal 11. 81-94. Accessed 2019-10-26.
  • N., N. 2006. Cuenca Llanos Orientales - Estudio Integrado - Crudos Pesados, 1-10. ANH. Accessed 2017-06-07.

Paleontology

Reports

Maps
Departmental
Local

Further reading
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