Maracaibo Basin
Maracaibo Basin | |
---|---|
Depresión del lago de Maracaibo | |
Floor elevation | −12–200 m (−39–656 ft) |
Area | 36,803 km2 (14,210 sq mi) |
Geography | |
Country | Venezuela |
States | |
Coordinates | 9°N 71°W / 9°N 71°W |
The Maracaibo Basin, also known as Lake Maracaibo natural region, Lake Maracaibo depression or Lake Maracaibo Lowlands, is a foreland basin and one of the eight natural regions of Venezuela, found in the northwestern corner of Venezuela in South America. Covering over 36,657 square km, it is a hydrocarbon-rich region that has produced over 30 billion bbl of oil with an estimated 44 billion bbl yet to be recovered.[1][2] The basin is characterized by a large shallow tidal estuary, Lake Maracaibo, located near its center. The Maracaibo basin has a complex tectonic history that dates back to the Jurassic period with multiple evolution stages. Despite its complexity, these major tectonic stages are well preserved within its stratigraphy. This makes The Maracaibo basin one of the most valuable basins for reconstructing South America's early tectonic history.
Geologic setting
The Maracaibo basin is surrounded by two mountain ranges, the
Tectonic history
The formation of the Maracaibo basin began 160 Ma with the North American, South American, and Caribbean plates playing key roles in the evolution of the basin. It developed into the present-day foreland basin via multiple stages throughout time: Late Jurassic, Late Cretaceous, Paleocene-Eocene, and the Oligocene-Holocene stages.
Late Jurassic
During the break-up of
Late Cretaceous
After rifting, the northern edge of the South American plate developed into a passive margin with the Proto-Caribbean Seaway. This stable passive margin allowed for thermal subsidence to occur which began to increase due to the building up of the Cordillera Central range of Colombia.[1] This uplift was initiated by the eastward moving Caribbean plate interacting with the Nazca and northwestern South American plate.
Paleocene-Eocene
The Caribbean plate has been migrating eastward from the Pacific region and eventually collided with the South American plate in the middle Paleocene. This collision transformed the passive margin of northern South America into an
Oligocene-Holocene
The Caribbean plate continued its eastward migration and continued to deform the northwestern regions of South America while also producing deformation along the northeastern regions.[5] As plate migration proceeded, accretion along the South American plate increased. This accretion greatly influenced mountain building of the region. Uplift of the Sierra de Perijas occurred during the Oligocene whereas the Mérida Andes formed later in the middle Miocene.[3] This uplift and subsequent erosion deposited large amount of sediment into the basin. The Maracaibo syncline formed later in this stage due to "inversion of Eocene rift-related structures".[3]
Stratigraphy
The main events of sediment deposition follow the same pattern as the tectonic events, where major sedimentary formations coincide with the four tectonic stages mentioned above.
Depositional history
The break-up of Pangea resulted in the break-up of the Paleozoic
Icotea pull-apart basin
The Icotea pull-apart basin is a unique transtensional feature in the center of the Maracaibo Basin. This basin is fault bounded on all 4 sides and formed due to strike slip involved extension along the north to south striking left lateral Icotea strike slip fault. The Icotea fault originally formed as a normal fault during a Mesozoic rifting phase and was subsequently reactivated as a strike slip fault during the late Paleocene. There is a record of 7.5-18 km of fault offset. The basin records 3 km of Eocene sediment fill in a depocenter located in the northern part of the basin. Extension in the Icotea basin is estimated to be between 0.8-2.25 km. Since the Oligocene, basin extension, strike slip motion and basin fill has ceased and inversion has progressed in consequence to continued uplift of the Sierra de Perija and development of the convergent Maracaibo syncline.[7]
Hydrocarbon resources
Oil was discovered in producible quantities in Venezuela in 1914 at the town of Mene Grande in the east central part of the Maracaibo basin near a surface oil seep.
In December 1922,
Today the basin accounts for approximately 50% of Venezuela's crude export capacity and approximately 15% of proven
The Bolivar Coastal Field, BCF, on the eastern shore of Lake Maracaibo produces from Miocene sandstones and Eocene sandstones.[9] West of Maracaibo, the La Paz Field produces from Cretaceous limestones, and oil is found in the stratigraphic traps of Boscan, Los Claros and the Urdaneta fields.[9]
Venezuela produces a mix of conventional heavy crude and unconventional crude derived from bitumen. This latter source, previously too expensive to produce in quantity, now makes up an increasing large percent of Venezuela's oil exports – 600,000 of Venezuela's three million barrels per day in 2006. In the Maracaibo Basin, the balance of reserves is toward its conventional deposits. As the country continues shifting toward bitumen production due to its increasing profitability and decreases in conventional reserves, the level of Maracaibo Basin oil production will decrease, while that of the Orinoco Belt and its massive bitumen deposits will increase.
See also
References
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- ISSN 0264-8172.
- ISBN 9780671799328.
- ^ a b Martinez, A.R., Giant Fields of Venezuela, in Geology of Giant Petroleum Fields, AAPG Memoir 14, Halbouty, M.T., editor, Tulsa: American Association of Petroleum Geologists, p. 328.