Geology of Bolivia

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Map of the large-scale geology of Bolivia
Map showing the relief of Bolivia
Major geological units (left) in Bolivia coincide with topography (right)
Geological units:
  Quaternary deposits
  Quaternary volcanics
  Tertiary deposits
  Cretaceous-Tertiary volcanics
  Cretaceous age rocks
  Devonian age rocks
  Silurian age rocks
  Ordovician-Silurian age rocks
  Precambrian undifferentiated

The geology of Bolivia comprises a variety of different

hydrocarbon reserves. Further east close to the border with Brazil lies the Guaporé Shield, made up of stable Precambrian
crystalline rock.

Andes

6,542 meter high Nevado Sajama is one of several volcanoes along Cordillera Occidental

The Andes of Bolivia began to rise about 200 million years ago (mya) during the

Atacama Trench caused by arid climate induced high shear stresses in the subduction process that enhanced the Andean mountain building.[7]

Western Cordillera

The Western Cordillera is made up by a series of active and extinct volcanoes rising from the western edge of the Altiplano plateau. This range divides the Chilean watersheds of Salar de Atacama and the Pacific from the endorheic Altiplano basin. The western volcanoes of Bolivia are part of the Central Volcanic Zone of the Andes, a major upper Cenozoic volcanic province.[8] Volcanic eruptions in Bolivia are scarce, the latest one occurred in Irruputuncu in 1995. Volcanic hazards do not represent any threat to the major populated centres which are all in the eastern Altiplano or further east, far away from the volcanic centers. Although the Western Cordillera concentrates most active volcanoes (volcanoes active in the last 10000 years) many old large stratovolcanoes rises up to 100 km away from the main line of the Western Cordillera.

Altiplano plateau

Cordillera Occidental
's volcanoes (background mountain).

The Altiplano plateau or Meseta del Collasuyu to differentiate it from other Andean high

Cordillera Occidental and Cordillera Oriental. The origin of the Altiplano and its great height has long been major question among geologists. Today the Altiplano is believed to have been an early foreland basin of the "proto-Andes" that got uplifted by crustal shortening in the Late Miocene.[4][9]

The Bolivian Altiplano hosts the world's largest reserves of

table salt after being added iodine from Chile
.

Eastern Cordillera

Erosion landscapes are common in the Central Cordillera and the Sub-Andean Zone

Cordillera Oriental is made up of a bended arc of plutons. The bend occurs at the latitude of

igneous bodies have been interpreted as an effect of two temporary decreases in subduction angles of the ancient Farallon Plate.[11] This arc of magmatic material hosts Bolivia's widely known tin belt as well as the famous silver mine of Potosí. These mineralizations are of the porphyry mineralization type that are typical for convergent plate margins. The Cordillera Real
form the northern, highly uplifted and eroded, part of the Central Cordillera.

Lowlands and Sub-Andean zone

To reach the lowlands north of La Paz the Yungas-vegetated Cordillera Oriental has to be passed.

The Sub-Andean Zone and the Northern and Eastern Lowlands share a common ancient history but have since the Andean orogeny developed into two distinct zones. While both zones share essentially the same old

structural traps where hydrocarbon fluids have accumulated. The limit between the fold and thrust belt and the Eastern Lowlands is drawn by the Serranía del Aguaragüe, a north-south range representing the Andean thrust front
.

Fold and thrust belt

The relatively low

hydrographic network of Pilcomayo and other rivers. Currently one of Bolivia's most seismic zones is the Cochabamba Fault Zone, located just below the city of Cochabamba and its fertile valley. This fault zone is related to the Arica
elbow and the bend in the Andes at this latitude.

Eastern Lowlands

The geology of the eastern lowlands is dominated by the ancient

depositional environment for these channel systems has been likened to that on the floor of the present day Labrador Sea, which was influenced by repeated Pleistocene glaciations.[13] The late Cenozoic deformation associated with the Andean orogeny forced hydrocarbons sourced in Devonian shales to migrate to shallower stratigraphical levels.[14]

Northern Lowlands

The Northern Lowlands are and have long been a depositional milieu and are mostly covered by Tertiary and Quaternary deposits. The bulk of these deposits are now laterites. River erosion and sediment transport have created a large number of oxbow lakes and added copious meanders to the rivers.

Guaporé Shield

In the north and east of

Lost World of Conan Doyle.[19]

Proyecto Precámbrico,[20] an Anglo-Bolivian technical cooperation project, explored the area between 1976 and 1986. There are a series of published 1:250,000 scale maps of the area with accompanying bilingual reports, along with more detailed 1:100,000 maps of regions of economic interest. There is a published geochemical atlas. Most of this data is summarised in an "Overseas Memoir" of the British Geological Survey.[21]

See also

References

  1. ^ "The Use of Solar Energy for Improving the Living Conditions in Altiplano/Argentina" (PDF). Archived from the original (PDF) on 2011-07-19. Retrieved 2010-05-25.
  2. ^ Geology of the Altiplano, Oregon State University
  3. ^ Neogene climate change and uplift in the Atacama Desert, Chile
  4. ^ a b Garcia-Castellanos, D., 2007. The role of climate in high plateau formation. Insights from numerical experiments. Earth Planet. Sci. Lett. 257, 372–390, doi:10.1016/j.epsl.2007.02.039
  5. ^ Tectonics and Climate of the Southern Central Andes, Annual Review of Earth and Planetary Sciences, 2007.
    Cite: "precipitation and erosion may influence the kinematics and locus of tectonic activity in orogens."
  6. ^ David R. Montgomery, Greg Balco and Sean D. Willett. 2001 Climate, tectonics, and the morphology of the Andes
    Cite: "...like tectonics, nonuniform erosion due to large-scale climate patterns is a first-order control on the topographic evolution of the Andes."
  7. ^ Lamb and Davis. 2003. Cenozoic climate change as a possible cause for the rise of the Andes, Nature
  8. ^ Lamb, Hoke, Kennan, Dewey. 1996. Cenozoic evolution of the Central Andes in Bolivia and northern Chile.
  9. ^ Hydrothermal Processes and Mineral Systems. Pages 376–381.
  10. ^ Sandra L. McBride, Ronald C. R. Robertson, Alan H. Clark and Edward Farrar. 1983.Magmatie and Metallogenetie Episodes in the Northern Tin Belt, Cordillera Real, Bolivia. Geologische Rundschau. Vol. 72.
  11. ^ .
  12. .
  13. .
  14. ^ METALLIFEROUS ORE DEPOSITS OF BOLIVIA
  15. ^ "Serrania Mutun, Chiquitos Province, Santa Cruz Department, Bolivia". mindat.org. Retrieved 2006-10-20.
  16. ^ The geologic and geomorphic evolution of Serrania Huanchaca, eastern Bolivia: the legendary 'Lost World'. M Litherland and G Power: Journal of South American Earth Sciences, Vol 2, No 1, 1–17, 1989.
  17. ^ Mathers, S J, ed. (1991). "BGS Technical Cooperation in Latin America (1965–90)" (PDF). British Geological Survey Technical Report (WC191125): 19–28. Archived from the original (PDF) on August 4, 2008. Retrieved 8 April 2017.
  18. ^ The Geology and Mineral Resources of the Bolivian Precambrian Shield. M Litherland and others: Overseas Memoir 9, British Geological Survey, Her Majesty's Stationery Office, 1986.

External links