The Altiplano Basin () is a

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 ...

within the

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 ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

and

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

. The basin is located on the Altiplano plateau between the Cordillera Occidental and the Cordillera Oriental. Over-all the basin has evolved through time in a context of horizontal shortening of

Earth's crust Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper ...

. The great thickness of the

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

s accumulated in the basin is mostly the result of the

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

of Cordillera Oriental.

Description

The Altiplano Basin has an approximate area of .Ficha técnica Cuenca del Altiplano
/ref> The northern part of the basin is overridden by the Cordillera Occidental along the Pasani Fault, a

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...

. To the east, the northern part of the basin was overridden by the Cordillera Oriental along the Ayaviri Fault, another thrust fault albeit the fault is now buried under more recent sediments. Further south near Oruro and

Sica Sica Sica Sica (Aymara language, Aymara: ''Sika Sika'') is a small town and capital of Aroma Province in the La Paz Department, Bolivia, La Paz Department of western Bolivia. It is located some 115 kilometres from La Paz, on the southwestern edge of th ...

the boundary of the basin with the Cordillera Oriental block is made up by the largely buried Coniri Fault. The fault contact is not reflected in surface topography since Cordillera Oriental rises more than 10 kilometers to the east of Coniri Fault. The sedimentation rate in the basin has varied strongly over

geological time The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronolo ...

. In the time from the middle

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

to the middle

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

on average less than of sediments accumulated in the basin every million years. In the

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

and

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, sediments accumulated in the basin at a rate of up to every million years. Similarly in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

and Oligocene (15 to 30 million years ago) the Ayaviri Sub-basin in the north accumulated of sediments every million years.

Stratigraphy

The basin contains three large successions of sediments. The sedimentary sequence in the basin started in the Early Paleozoic.Jiménez et al., 2009 From bottom to top these are: *

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

–

aged marine and non-marine sediments of the Santa Lucía and El Molino Formations. Their thickness is about . * The thick non-marine Potoco Formation. Most of the formation is of

–

age. * Sedimentary and volcanic rocks of

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

age making of a thick pile. It has been suggested that the northern part of the Altiplano Basin experienced a significant reverse fault movement in the

and

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

(c. 28 to 16

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

References

Bibliography

* {{Sedimentary basins of Peru Altiplano Sedimentary basins of Bolivia Sedimentary basins of Peru Geology of La Paz Department (Bolivia) Geology of Oruro Department Geology of Potosí Department Geography of the Department of Puno