The Llanos Basin () or Eastern Llanos Basin () is a major

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock They form when long-term subsidence ...

of in northeastern

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

. The onshore foreland on

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

rift basin In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

covers the

departments Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military * Department (administrative division), a geographical and administrative division within a country, ...

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 Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

, where the basin grades into the Barinas-Apure Basin.

Description

The northeastern part of Colombia is characterized by its wavy plains, called ''Llanos Orientales'', as part of the bigger

Llanos The Llanos ( Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, ...

that extend into Venezuela. The landscape is similar to a

savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

and is poor in trees. It is located between the Eastern Ranges of the Colombian

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

in the west, the Vaupés Arch in the south and the

Guiana Shield The Guiana Shield (; ; ; ) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on ...

in the east.Barrero et al., 2007, p.69 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 The Douglas DC-3 is a propeller-driven airliner manufactured by the Douglas Aircraft Company, which had a lasting effect on the airline industry in the 1930s to 1940s and World War II. It was developed as a larger, improved 14-bed sleeper ...

planes. The basin covers an area of and contains a

stratigraphic column A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest ...

from the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

to recent.ANH, 2010 Several of the formations in the basins are

source rock In petroleum geology, source rock is a sedimentary rock which has generated hydrocarbons or which has the potential to generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sedim ...

s ( Gachetá, Los Cuervos, Carbonera C8), reservoir rocks ( Mirador, Barco, Guadalupe and the uneven numbered members of Carbonera).

Seal Seal may refer to any of the following: Common uses * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, also called "true seal" ** Fur seal ** Eared seal * Seal ( ...

s are formed by the shaly intervals (even numbered) of the Carbonera Formation, Los Cuervos, and León.García González et al., 2009, p.58 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 Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...

, hydrocarbon migration, fault seal capacity and water flow.

Hydrography

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

Arauca River The Arauca River () rises in the Andes Mountains of north-central Colombia and ends at the Orinoco in Venezuela. For part of its run it is the boundary between Colombia and Venezuela. The major city on its banks is Arauca, Arauca, Arauca, Col ...

** Bojabá ** Margua *

Orinoco River The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

** Capanaparo ** Cinaruco ** Tomo *** Elvita ** Bita *

Meta River The Meta River is a major left tributary of the Orinoco River in eastern Colombia and southern Venezuela, South America. The Meta originates in the Cordillera Oriental (Colombia), Eastern Ranges of the Andes and flows through the Meta Department ...

** Casanare *** Cravo Norte *** Ele *** Tame ** Ariporo **

La Fortaleza La Fortaleza ( English: "the fortress"), also known as the ''Palacio de Santa Catalina'' (Saint Catherine's Palace), is the official residence and workplace of the governor of Puerto Rico. Located in the historic quarter of Old San Juan in the ...

** Guachiría ** Pauto ** Cravo Sur ** Cusiana ** Upía *** Guavio *** Lengupá ** Guatiquía ** Manacacías ** Metica *** Guayuriba *

Guaviare River The Guaviare is a tributary of the Orinoco in Colombia. It flows together with the upper Orinoco (until here also called Río Parágua), which it clearly surpasses in length (altogether about 1,760 km) and water flow. Thus, the Guaviare is hydrol ...

** Ariarí *** Güejar ** Guayabero ***

Duda The Hungary, Hungarian duda (also known as ''tömlősíp'' and ''bőrduda'') is the traditional bagpipe of Hungary. It is an example of a group of bagpipes called Medio-Carparthian bagpipes. Accounts are conflicting regarding the exact form of ...

*** Losada ** Uvá ** Siare *

Vichada River The Vichada River (, ) is a blackwater river in Colombia, South America. It flows into the Orinoco River. The eastward course of the Vichada is offset by an Impact crater, impact structure, called the Vichada Structure. The structure is most li ...

** Muco ** Tillava

Flora and fauna

Fauna

Among other species, Lynch's swamp frog ('' Pseudopaludicola llanera'') is endemic to the Llanos, with the species

epithet An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...

referring to the plains.''Pseudopaludicola llanera''
at

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

.org Also the whip scorpion '' Mastigoproctus colombianus'' is reported from the Llanos Basin.''Mastigoproctus colombianus''
at

GBIF The Global Biodiversity Information Facility (GBIF) is an international organisation that focuses on making scientific data on biodiversity available via the Internet using web services. The data are provided by many institutions from around the ...

.org

Geodynamic situation

The country of Colombia spreads out over six

tectonic plates Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

, clockwise from north: # Caribbean Plate # North Andes Plate #

South American Plate The South American plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African plate, with which it forms the southern part of the Mid ...

# Malpelo Plate # Coiba Plate # Panama Plate The Llanos Basin is situated entirely on the

, 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

n 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 Foothills or piedmont are geography, geographically defined as gradual increases in elevation at the base of a mountain range, higher hill range or an highland, upland area. They are a transition zone between plains and low terrain, relief hill ...

(''Piedemonte'') of the Eastern Cordillera Basin, the

covering the Eastern Ranges of the Colombian

Tectonics

The basin is bound to the west by the Eastern Frontal Fault System, a long fault system connecting the North Andes and

s and thus the Eastern Cordillera Basin and the Llanos Basin. The fault system has an average

strike Strike may refer to: People *Strike (surname) * Hobart Huson, author of several drug related books Physical confrontation or removal *Strike (attack), attack with an inanimate object or a part of the human body intended to cause harm * Airstrike, ...

of 042.1±19, but this orientation varies greatly along its course. The

1827 Events January–March * January 5 – The first regatta in Australia is held, taking place in Tasmania (called at the time ''Van Diemen's Land''), on the River Derwent at Hobart. * January 15 – Furman University, founded in 1826, b ...

1834 Events January–March * January 1 – Zollverein (Germany): Customs charges are abolished at borders within its member states. * January 3 – The government of Mexico imprisons Stephen F. Austin in Mexico City. * January – The W ...

1917 Events Below, the events of World War I have the "WWI" prefix. January * January 9 – WWI – Battle of Rafa: The last substantial Ottoman Army garrison on the Sinai Peninsula is captured by the Egyptian Expeditionary Force's ...

1967 Events January * January 1 – Canada begins a year-long celebration of the 100th anniversary of Canadian Confederation, Confederation, featuring the Expo 67 World's Fair. * January 6 – Vietnam War: United States Marine Corps and Army of ...

1995 1995 was designated as: * United Nations Year for Tolerance * World Year of Peoples' Commemoration of the Victims of the Second World War This was the first year that the Internet was entirely privatized, with the United States government ...

, and

2008 2008 was designated as: *International Year of Languages *International Year of Planet Earth *International Year of the Potato *International Year of Sanitation The Great Recession, a worldwide recession which began in 2007, continued throu ...

earthquakes An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they c ...

were all caused by fault movement as part of the system.Paris et al., 2000a, p.36 The faults formed because of the convergence of two plates, leading to compressional stresses that form thrust complexes. The thrust complexes and continued compression would cause uplift that developed the Andes and the associated basin. The foreland development of the basin is associated with the Eastern Cordillera caused by compressional forces forming inland subsidence. The uplift caused isostatic subsidence that would lead to the evolution of the Llanos Basin. Because of the desequilibrium caused by the uplift, the erosion and deposition rates are amplified within the near Andes and Llanos Basin. The watershed was also affected by tectonics because of different erosion rates and change in landscape.

Basin history

The tectonic history of the Llanos Basin, a

foreland basin A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithospher ...

formed on top of

metasediments and

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

underlain by

continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as '' continental shelves''. This layer is sometimes called '' si ...

, goes back to the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic� ...

. The

Andean orogeny The Andean orogeny () is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin o ...

, represented by the tectonic uplift of the Colombian Eastern Ranges and its northern extension, the

Serranía del Perijá The Serranía del Perijá, Cordillera de Perijá or Sierra de Perijá is a mountain range, an extension of the eastern Andean branch ( Cordillera Oriental), in northern South America, between Colombia and Venezuela, ending further north in the ...

, 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 in the Early Miocene to in the Late Miocene.Hernández Pardo et al., 2009, p.122 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.Hernández Pardo et al., 2009, p.28

Basement

The

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

of the Llanos Basin ranges, depending on the definition from either

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

to recent. The

is formed by the westernmost extensions of the

. Remnants of these

formations are found as

inselberg An inselberg or monadnock ( ) is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa, a similar formation of granite is known as a koppie, an ...

s in the far east of Colombia ( Cerros de Mavecure), in the Serranía de la Macarena to the southwest of the basin and in the

tepui A tepui , or tepuy (), is a member of a family of table-top mountains or mesas found in northern South America, especially in Venezuela, western Guyana, and northern Brazil. The word tepui means "house of the gods" in the native tongue of the ...

s of the Serranía de Chiribiquete to the southeast. The

Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...

crystalline rocks are overlain by

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

and

igneous rock Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...

s ranging in age from

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

. 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 The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. (Do not confuse with The Altiplano or the Altiplano Nariñense, both fur ...

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.Plancha 266, 1998

Stratigraphy

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 Buenavista may refer to: Colombia * Buenavista, Boyacá, a municipality in the department of Boyacá * Buenavista, Córdoba, a municipality in the department of Córdoba * Buenavista, Sucre, a municipality in the department of Sucre * Buenavista ...

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 .Producción de crudo bajó en 30.879 barriles por día en 2017
- El Tiempo In 2016, twenty oilfields produced 66% of all oil of Colombia, listed below in bold.En 20 campos se produce el 66 % del petróleo del país
- El Tiempo The total proven reserves of Colombia were in 2016.Oil reserves per department - 2016
- ANH Major oil fields in the Llanos Basin are:Mojica et al., 2009, p.30 * Other fields ** 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.Mapa de Territorios Indígenas y Minerales Preciosos
/ref> *

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

Producción de oro
– UPME *

halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

Producción de sal
– UPME *

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

Producción de carbón
– UPME In San José del Guaviare

platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...

is mined.Producción de platino
– UPME

Paleontology

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

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...

s surrounding and perforating the planar geography have provided fossils dating back to the

; the

and Ariarí Formations. Several fossiliferous formations of contemporaneous

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will b ...

s 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.Jaramillo & Dilcher, 2001 ;Other correlative units with surrounding basins * Guayabo - Sabana and Soatá,

Ware WARE (1250 AM) is a commercial radio station broadcasting a classic hits format. Licensed to Ware, Massachusetts, United States, the station serves the Springfield radio market. The station is currently owned by Success Signal Broadcasting ...

Honda commonly known as just Honda, is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate automotive manufacturer headquartered in Minato, Tokyo, Japan. Founded in October 1946 by Soichiro Honda, Honda has bee ...

* León -

* Carbonera - Barzalosa, Castilletes, Jimol * Mirador -

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish Imperial period and between 1991 and 2000, is the capital city, capital and largest city ...

- '' Etayoa'' * Los Cuervos -

Cerrejón Cerrejón is a large Coal mining, open-pit coal mine in Northern Colombia owned by Glencore. At Cerrejón, low-ash, low-sulphur bituminous coal from the Cerrejón Formation is excavated. At over the mine is one of the largest of its type, the la ...

- '' Titanoboa'', crocodylians, turtles, flora * Los Cuervos -

Guaduas Guaduas () is a municipality and town in Colombia, in the Lower Magdalena Province department of Cundinamarca Department, Cundinamarca, about 117 km from Bogotá. It is an agricultural and tourist center of some importance with a populati ...

- fossil flora * Gachetá - Chipaque - oysters * Gachetá - La Luna - many * Une - Hiló -

ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

Description

Hydrography

Flora and fauna

Fauna

Geodynamic situation

Tectonics

Basin history

Basement

Stratigraphy

Paleozoic

Jurassic

Petroleum geology

Fields

Mining

Paleontology

See also

Sources

Notes

References

Bibliography

General

Hydrodynamics

Tectonics

Petroleum

Paleontology

Reports

Maps

Further reading