Middle Magdalena Valley | |
---|---|
Valle Medio del Magdalena (VMM) | |
Coordinates | 7°04′N73°51′W / 7.067°N 73.850°W |
Etymology | Magdalena River |
Region | Andean natural region |
Country | Colombia |
State(s) | Boyacá, Cundinamarca, Santander, Tolima |
Cities | Barrancabermeja |
Characteristics | |
On/Offshore | Onshore |
Boundaries | Lower Magdalena Valley, Eastern Ranges, Upper Magdalena Valley, Central Ranges |
Part of | Andean foreland basins |
Area | 34,000 km2 (13,000 sq mi) |
Hydrology | |
River(s) | Magdalena |
Geology | |
Basin type | Intermontane foreland basin |
Orogeny | Andean |
Age | Jurassic-Holocene |
Stratigraphy | Stratigraphy |
Faults | Cantagallo, Infantas, La Salina |
Field(s) | La Cira-Infantas, Casabe, Yariguí-Cantagallo, Velásquez |
[1] |
The Middle Magdalena Valley, Middle Magdalena Basin or Middle Magdalena Valley Basin (Spanish : Valle Medio del Magdalena, commonly abbreviated to VMM) is an intermontane basin, located in north-central Colombia between the Central and Eastern Ranges of the Andes. [2] The basin, covering an area of 34,000 square kilometres (13,000 sq mi), is situated in the departments of Santander, Boyacá, Cundinamarca and Tolima.
The basin is structurally bounded by the Palestina Fault to the west and the Bucaramanga Fault to the east. [2] The Middle Magdalena Valley hosts the middle course of the Magdalena River, the main river of Colombia, flowing from the Upper Magdalena Valley in the south to the Lower Magdalena Valley to the northwest. [3] The basin is elongated with an approximate width of 80 km (50 mi) and extends to the north for approximately 450 km (280 mi), where it terminates against the Santander Massif and Cesar Valley. [3] To the south, it terminates against the Upper Magdalena Valley, which consists of the Girardot and Neiva Sub-basins where the Central and Eastern Ranges converge. [4]
The basin is an important producer of oil in Colombia, with main fields Yariguí-Cantagallo, Moriche, Casabe, La Cira-Infantas, Velásquez, Santos, Palagua, Teca, Payoa and Lisama. The first three fields were among the twenty most producing fields of Colombia in 2016. [5] Until 2008, La Cira-Infantas and Casabe produced more than 730 million barrels (116×10 6 m3) and 289 million barrels (45.9×10 6 m3) respectively. [6] Main producing reservoirs are the Colorado, Mugrosa, Esmeraldas and La Paz Formations. Secondary reservoirs are Lisama and La Luna. [7]
The name of the basin is taken from the middle course of the Magdalena River.
During the Jurassic period, Pangea began to pull apart causing separation of North America from South America. [4] This rifting produced a subduction zone where the Nazca Plate was subducting to the east under the South American Plate. Part of this subducting plate was the Baudo-Island Arc separated from the South American continent by the marginal Colombian Sea. [3] The formation of the extensional back-arc basin associated with this subduction is the origin of the Middle Magdalena Basin in the late Jurassic. [3] Throughout the Cretaceous, the basin experienced thermal subsidence and five transgressive-regressive cycles as part of a marine megacycle. [3] [4]
In the Paleocene, the rate of subduction increased causing the marginal Colombian Sea to close and the Baudo-Island Arc to collide with the South American continent. [3] This caused accretion of the Western Ranges and uplift of the Central Ranges transforming the back-arc basin into the pre-Andean foreland basin. [2] [3] [4] Around the time of the Oligocene, the Nazca Plate increased its subduction to the east while the South American Plate experienced a westward pull. [8] This caused the Andean orogeny in the Miocene and uplift of the Eastern Ranges in the Pliocene. [2] Now the Middle Magdalena basin is an intermontane basin situated between the uplifted Central and Eastern Ranges. [2]
Faulting in the Middle Magdalena Basin is primarily reverse and thrust faulting. [4] Reverse faulting is high angle in the west and low angle in the eastern and central areas of the basin with normal faults also developing along the eastern margin. These thrust faults formed from thrusting from the eastern margin of the Central Ranges in the Eocene and the western margin of the Eastern Ranges in the Miocene. [4] The major thrust faults in the Middle Magdalena Basin include the Infantas Thrust, [4] La Salina Thrust, [9] and Cantagallo Thrust. [9] The basin is structurally bounded by the Palestina Fault, a dextral strike-slip fault system, in the west and the Bucaramanga-Santa Marta Fault, a sinistral strike-slip system, in the east. [2]
The major surface structures of the Middle Magdalena Basin are asymmetric synclines and basement cored anticlines, which formed as a result of thrusting from the Eastern and Central Ranges. The thrusting initiated faulting in the Pre-Mesozoic basement. The faults then pushed through the Jurassic layers to the Cretaceous ductile stratigraphy. The faults then form horizontally at the ductile-brittle transition for 10 to 20 kilometres (6.2 to 12.4 mi) before cutting through the upper brittle stratigraphy. The resulting structure is a syncline against the hanging wall of the fault next to an inclined anticline. [4] Key folds in the basin for hydrocarbon exploration include the Nuevo Mundo and Guaduas Synclines. [4] As suggested by the formation of the folds, both of these synclines are bounded by thrust faulting and anticlines. [4] [10]
The stratigraphy of the Middle Magdalena Basin can be divided into three sequences separated by angular unconformities. [2] The basement of these sequences is Pre-Mesozoic metaclastics and sediments which are now exposed on the surface of the Central Cordillera as a result of its deformation and uplift. [4] This geologic basement is at most 15 kilometres (9.3 mi) deep, with faulted sections shifted up to approximately 10 kilometres (6.2 mi) in depth. [11] The unconformity that separates the basement from the first sequences indicates the approximate time rifting began.
The first sequence was deposited in the Jurassic during the rifting which caused the initial formation of the basin. This Jurassic formation is called the Girón Formation which consists of siltstones and rhyolitic tuffs. [2] During this period, the basin also experienced granitic plutonism along its western margins. [3] [4] The Jurassic-Cretaceous angular unconformity, separating the first and second sequence, is representative of the post-rift boundary. [2]
The middle sequence represents the formations deposited throughout the Cretaceous and Early Paleocene. [2] The oldest formations in this sequence are the Tambor and Los Santos Formations. The conglomerates and sandstones indicate a continental to fluvial depositional environment. [2] In the Early Cretaceous, sea level began to rise and formed a shallow marine environment with siltstone and shale deposits of the Cumbre Formation. [2] [3] Sea level continued to rise throughout the Middle Cretaceous when the Tablazo and Salto limestones and Simití shales were deposited. [4] The La Luna Formation represents a maximum flooding surface with deep marine deposits of limestone, chert, and shale. [2] Sea level then began to fall, returning the environment to shallow marine with deposition of the Umir Formation of shales and sandstones. [2] Finally, the Paleocene saw the deposition of the Lisama Formation, consisting of deltaic mudstones and sandstones. [2] This entire middle sequence indicates a marine megacycle consisting of five transgressive-regressive cycles. [4] The angular unconformity between the second and third sequences is a result of erosion from the accretion of the Western Ranges. [2]
The final sequence represents deposition from the Early Tertiary to present day. [2] Within this sequence, there are three subsequences that are the result of deformation and uplift of the Central and Eastern Ranges. [4] The first subsequence consists of the Chorro Group with the La Paz and Esmeraldas Formations and the Chuspas Group with the Mugrosa and Colorado Formations, all deposited during the Eocene to Oligocene. [4] These groups consist of fluvial sandstones, mudstones, siltstones, and shales, and are a result of erosion in the Central Ranges. [2] [4] The second subsequence is the Miocene Real Group, consisting of fluvial sandstones and conglomerates. [2] Similar to the Real Group, the final subsequence is the Pliocene Mesa Formation, which is composed of sandstones and conglomerates deposited due to the Eastern Ranges uplift. [4] The uppermost sedimentary rocks of the basin are Pleistocene alluvial fan deposits, overlain by Holocene sediments of the Magdalena River. [4]
The primary reservoirs in the Middle Magdalena Basin are fluvial sandstones and conglomerates from the Churro and Chuspas Groups, which have 20 to 25% porosity and 0.5 to 1 D permeability. [4] The main source of hydrocarbons is the La Luna limestone, with a Total Organic Carbon (TOC) content of 3 to 4% and Type II marine kerogen, sealed by overlying Eocene shales. [4] There are three types of traps that house hydrocarbons in the Middle Magdalena Basin. The two structural traps are large anticlines in the center of the basin and smaller anticlines along the western margin. Both of these anticlinal traps produce from Tertiary sandstones within the Churro and Chuspas Groups. The third trap is stratigraphical with the La Luna limestone sealed by overlying shales. [4]
Field name | Producing formations | Lithologies | Structure |
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La Cira-Infantas | Colorado Fm., Mugrosa, La Paz | Sandstone, conglomerate, shale | Dome bounded by Infantas Thrust |
Casabe | Colorado Fm., Mugrosa Fm., La Paz Fm. | Claystone, sandstone | Fault bounded |
Yariguí-Cantagallo | La Paz Fm., Esmeraldas Fm. | Sandstone, claystone, shale | Fault bounded |
Velásquez | Tune, Avechucos | Claystone, siltstone, sandstone | Bounded by normal faults |
The table above shows some of the largest producing fields. Included is their producing formation, the lithologies of the formations, and the structure of the fields containing the hydrocarbons. The Tune and Avechucos Formations are equivalent to the Chorro and Chuspas Groups. Both the Casabe and Yariguí-Cantagallo Fields are located on the Magdalena River towards the western margin of the basin with the Yariguí-Cantagallo Field located approximately 40 kilometres (25 mi) north of the Casabe Field. Approximately 30 kilometres (19 mi) east of the Casabe Field is the oldest and largest La Cira-Infantas Field, situated towards the central to eastern margin of the basin. The Velásquez Field is located at the southern end of the basin near the Upper Magdalena Valley. [12]
Current exploration is focused in the southern area of the basin, where heavy amounts of faulting could house potential hydrocarbons. Aside from the La Luna limestone, other potential source rocks include Early Cretaceous sediments such as the Paja and Simití Formations, or the Late Cretaceous shales of the Umir Formation. [10]
The Paja Formation is an Early Cretaceous geologic formation of central Colombia. The formation extends across the northern part of the Altiplano Cundiboyacense, the Western Colombian emerald belt and surrounding areas of the Eastern Ranges of the Colombian Andes. In the subsurface, the formation is found in the Middle Magdalena Valley to the west. The Paja Formation stretches across four departments, from north to south the southernmost Bolívar Department, in Santander, Boyacá and the northern part of Cundinamarca. Well known fossiliferous outcrops of the formation occur near Villa de Leyva, also written as Villa de Leiva, and neighboring Sáchica.
The Chipaque Formation (Spanish: Formación Chipaque, K2cp, Kc) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation is also described as Gachetá Formation, named after Gachetá, in the area of the Llanos foothills of the Eastern Ranges. The predominantly organic shale formation dates to the Late Cretaceous period; Cenomanian-Turonian epochs and has a maximum thickness of 1,700 metres (5,600 ft). The formation, rich in TOC, is an important oil and gas generating unit for the giant oilfields Cupiagua and Cusiana of the Eastern Ranges as well as in the Llanos Orientales.
The Guadalupe Group (Spanish: Grupo Guadalupe, K2G, Ksg) is a geological group of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The group, a sequence of shales and sandstones, is subdivided into three formations; Arenisca Dura, Plaeners and Arenisca Labor-Tierna, and dates to the Late Cretaceous period; Campanian-Maastrichtian epochs and at its type section has a thickness of 750 metres (2,460 ft).
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.
The Conejo Formation (Spanish: Formación Conejo, K2C, Kscn) is a fossiliferous geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The uppermost unit of the Villeta Group, a sequence of shales and sandstones dates to the Late Cretaceous period; Turonian, Coniacian and Santonian epochs, and has a maximum thickness of 1,022 metres (3,353 ft).
The Arcabuco Formation is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of thick beds of light-coloured quartzitic sandstones and conglomerates with occasional shales and dates to the Late Jurassic and Early Cretaceous periods; Tithonian to Berriasian epochs. Dinosaur footprints have been found in the Arcabuco Formation near the Iguaque anticlinal outside Chíquiza, Boyacá.
The Honda Group is a geological group of the Upper and Middle Magdalena Basins and the adjacent Central and Eastern Ranges of the Colombian Andes. The group, in older literature also defined as formation, is in its present-day type section in the Tatacoa Desert in the department of Huila subdivided into two main formations; La Victoria and Villavieja.
The Trincheras Formation is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cretaceous period; Early Aptian epoch and has a maximum thickness of 1,260 metres (4,130 ft). The formation, deposited in a marine platform environment, part of a transgressive cycle, hosts ammonite, bryozoan, mollusc and echinoid fossils.
The Cesar-Ranchería Basin is a sedimentary basin in northeastern Colombia. It is located in the southern part of the department of La Guajira and northeastern portion of Cesar. The basin is bound by the Oca Fault in the northeast and the Bucaramanga-Santa Marta Fault in the west. The mountain ranges Sierra Nevada de Santa Marta and the Serranía del Perijá enclose the narrow triangular intermontane basin, that covers an area of 11,668 square kilometres (4,505 sq mi). The Cesar and Ranchería Rivers flow through the basin, bearing their names.
The Las Juntas Formation or Las Juntas Sandstone is a geological formation of the Altiplano Cundiboyacense and Tenza Valley, Eastern Ranges of the Colombian Andes. The Las Juntas Formation is found in the departments Cundinamarca, Boyacá and Casanare. The predominantly sandstone formation dates to the Early Cretaceous period; Hauterivian epoch, and has a maximum thickness of 910 metres (2,990 ft).
The Macanal Formation or Macanal Shale 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 Fómeque Formation is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly organic shale formation dates to the Early Cretaceous period; Barremian to Late Aptian epochs and has a maximum thickness of 1,200 metres (3,900 ft).
The Rosablanca Formation is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes and the Middle Magdalena Basin. The formation consists of grey limestones, dolomites and shales with at the upper part sandstones. The formation dates to the Early Cretaceous period; Valanginian epoch and has a thickness of 425 metres (1,394 ft) in the valley of the Sogamoso River.
The Mulato-Getudo or Mulato-Jetudo Fault is a sinistral oblique thrust fault in the departments of Tolima, Caldas and Antioquia in central Colombia. The fault has a total length of 187.3 kilometres (116.4 mi) and runs along an average north-northeast to south-southwest strike of 016.7 ± 9 in the Middle Magdalena Valley and along the western foothills of the Central Ranges of the Colombian Andes.
The Villeta Group is a geological group of the Eastern Ranges of the Colombian Andes, to the west of the Altiplano Cundiboyacense. The group, a sequence of shales, limestones and sandstones, is subdivided into various formations; Conejo, La Frontera, Simijaca, Hiló, Pacho, Chiquinquirá, Capotes, Socotá, El Peñón, and Trincheras, and dates to the Cretaceous period; Aptian-Coniacian epochs. The group stretches out across four departments, from Huila in the south, through Cundinamarca and Boyacá to southern Santander in the north. The upper part of the Villeta Group is time-equivalent with the La Luna Formation of the Middle Magdalena Valley (VMM) and Sierra Nevada del Cocuy, the Oliní and Güagüaquí Groups of the Guaduas-Vélez synclinal and the Chipaque Formation of the Altiplano Cundiboyacense. The lower part has been correlated with the Simití, Tablazo and Paja Formations of the VMM, the upper Tibasosa, Une and Fómeque Formations of the Altiplano Cundiboyacense and the Capacho, Aguardiente, Tibú-Mercedes and upper Río Negro Formations of the Sierra Nevada del Cocuy.
The Loma Gorda Formation is a fossiliferous geological formation of the Upper Magdalena Valley (VSM) and surrounding Central and Eastern Ranges of the Colombian Andes, extending from Cundinamarca in the north to Huila and easternmost Tolima in the south. The uppermost unit of the Güagüaquí Group, a sequence of laminated siltstones and shales, dates to the Late Cretaceous period; Turonian to Coniacian epochs, and has a maximum thickness of 167 metres (548 ft).
The Hondita Formation is a fossiliferous geological formation of the Upper Magdalena Valley (VSM) and surrounding Central and Eastern Ranges of the Colombian Andes, extending from Cundinamarca in the north to Huila and easternmost Tolima in the south. The lowermost unit of the Güagüaquí Group, a sequence of sandy limestones and shales, dates to the Late Cretaceous period; Turonian epoch, and has a maximum thickness of 90 metres (300 ft).
The Oliní Group (Spanish: Grupo Oliní, K3k5o, K2ol, Kso) is a fossiliferous geological group of the VMM, VSM and the eastern flanks of the Central and western flanks of the Eastern Ranges of the Colombian Andes. The regional group stretches from north to south across approximately 700 kilometres (430 mi) and dates to the Late Cretaceous period; Coniacian, Santonian and Campanian epochs, and has a maximum thickness of 287 metres (942 ft). Fossils of Eonatator coellensis have been found in the unit, near Coello, Tolima.
The Caballos Formation is a geological formation of the Upper Magdalena Valley (VSM), Caguán-Putumayo Basin, Central and Eastern Ranges of the Colombian Andes. The sandstone and shale formation dates to the Middle Cretaceous period; Aptian to Albian epochs and has a maximum thickness of 411 metres (1,348 ft).
The Santa Teresa Formation is a geological formation of the western Eastern Ranges of the Colombian Andes, west of the Bituima Fault, and the southern Middle Magdalena Valley. The formation spreads across the western part of Cundinamarca and the northern portion of Tolima. The formation consists of grey claystones intercalated by orange quartz siltstones and sandstones of small to conglomeratic grain size. The thickness at its type section has been measured to be 118 metres (387 ft) and a maximum thickness of 150 metres (490 ft) suggested.