The Altiplano Basin ( es, Cuenca del Altiplano) 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 subside ...

within the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

in Bolivia and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

. 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. The great thickness of the

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s accumulated in the basin is mostly the result of the

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

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. If ...

. 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 Oruro (Hispanicized spelling) or Uru Uru is a city in Bolivia with a population of 264,683 (2012 calculation), about halfway between La Paz and Sucre in the Altiplano, approximately above sea level. It is Bolivia's fifth-largest city by pop ...

and

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

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 geochron ...

. In the time from the middle

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

to the middle

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

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

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

and Oligocene, 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 Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...

.Jiménez et al., 2009 From bottom to top these are: *

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

–

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

– Oligocene age. * Sedimentary and volcanic rocks of Oligocene to Quaternary 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 Oligocene 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 The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

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 Puno Region