Sajsi is the name of an ancient lake in the Andes
The existence of ancient lakes in the Altiplano was proposed as early as 1882. At first, a Lake Minchin was identified with ages of 30,000 years or older; later additional lake cycles were recognized. [1] The minor ones include Inca Huasi, Salinas and Coipasa. The major ones include Lake Tauca and Ouki. [2] Because of this, it was proposed that Lake Minchin was actually a combination of several different ancient lakes. [3]
This lake occupied the area of the current Salar de Uyuni; [4] it also covered the Salar de Coipasa but it is not clear whether and how it extended in the Lake Poopo. [5] Its waters reached altitudes of 3,670 metres (12,040 ft) and its depth did not exceed 17 metres (56 ft). [6] A sample dated 23,700 ± 2,600 years ago by uranium-thorium dating indicates that lake levels at that point were about 15 metres (49 ft) deep in the Uyuni basin. [7] Water levels subsequently decreased to less than 5 metres (16 ft) above the present day levels before Lake Tauca formed, [8] however both the timing and the history of water levels are uncertain. [9] The surface area of the lake may have been 21,000 square kilometres (8,100 sq mi) during the highstand. [10] By 19,900 ± 900 - 18,700 ± 200 years ago, the Lake Tauca was beginning to form. [7] The so-called "L2" unit in drill cores in Salar de Uyuni may correspond to both the Sajsi and the later Lake Tauca cycle. [11] Strontium isotope data indicate that about 41% of the water in Sajsi came from Lake Poopo and 4% from Lake Titicaca. [12]
Radiocarbon dates have been obtained for Sajsi-age ooids and tufa, uncalibrated they range from 17,080 ± 720 to 20,830 ± 140 years ago. [13] Later dates indicated that the lake existed between 25,000 and 19,000 years ago and reached its maximum depth 23,000 years ago. [7] The existence of this lake coincides with the Last Glacial Maximum. Earlier, lakes had formed in the Laguna Blanca, the Salar de Atacama, [4] as well as the Pozuelos Basin in northwest Argentina. [14] Given evidence from the Bolivian Eastern Cordillera [15] and the small size of the glacial Sajsi and Inca Huasi paleolakes, it is likely that the Last Glacial Maximum was accompanied by a dry climate on the Altiplano [8] and indeed climate modelling shows that only a small precipitation increase - or none at all - would be needed to create the Sajsi lake. [16] Glacier expansion is recorded at that time in Northwest Argentina. [17] The second Heinrich event seems to coincide with the Sajsi lake period. [18]
A maximum in local insolation about 21,000 years ago coincides with the existence of the Sajsi lake but was probably not responsible for the lake's existence. [19] Farther south, precipitation in the drainage area of the Rio Salado had increased by 10 millimetres per year (0.39 in/year) during the Sajsi time, [20] lakes formed within the Western Cordillera [21] and the Bolivian Chaco likewise shows evidence of increased precipitation. [22] Rising water levels during the Sajsi reduced dust deflation. [23] The Sajsi lake was apparently followed by Lake Tauca, but evidence is lacking. [24] Another theory postulates that Sajsi was simply a sub-phase of Lake Tauca, [25] an interpretation applied in particular to data taken from drill cores. [26]
Salar de Uyuni is the world's largest salt flat, or playa, at 10,582 square kilometres (4,086 sq mi) in area. It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of 3,656 m (11,995 ft) above sea level.
The Last Glacial Period (LGP), also known as the Last glacial cycle, occurred from the end of the Last Interglacial to the beginning of the Holocene, c. 115,000 – c. 11,700 years ago, and thus corresponds to most of the timespan of the Late Pleistocene.
The Altiplano, Collao or Andean Plateau, in west-central South America, is the most extensive high plateau on Earth outside Tibet. The plateau is located at the latitude of the widest part of the north–south-trending Andes. The bulk of the Altiplano lies in Bolivia, but its northern parts lie in Peru, and its southwestern fringes lie in Chile.
Pastos Grandes Lake is a lake in the Pastos Grandes caldera in the Potosí Department, Bolivia. At an elevation of 4,430 metres (14,530 ft), its surface area is 120 square kilometres (46 sq mi).
The geology of Bolivia comprises a variety of different lithologies as well as tectonic and sedimentary environments. On a synoptic scale, geological units coincide with topographical units. The country is divided into a mountainous western area affected by the subduction processes in the Pacific and an eastern lowlands of stable platforms and shields. The Bolivian Andes is divided into three main ranges; these are from west to east: the Cordillera Occidental that makes up the border to Chile and host several active volcanoes and geothermal areas, Cordillera Central once extensively mined for silver and tin and the relatively low Cordillera Oriental that rather than being a range by its own is the eastern continuation of the Central Cordillera as a fold and thrust belt. Between the Occidental and Central Cordillera the approximately 3,750-meter-high Altiplano high plateau extends. This basin hosts several freshwater lakes, including Lake Titicaca as well as salt-covered dry lakes that bring testimony of past climate changes and lake cycles. The eastern lowlands and sub-Andean zone in Santa Cruz, Chuquisaca, and Tarija Departments was once an old Paleozoic sedimentary basin that hosts valuable hydrocarbon reserves. Further east close to the border with Brazil lies the Guaporé Shield, made up of stable Precambrian crystalline rock.
Tunupa is a dormant volcano in the Potosí Department of southwestern Bolivia.
Tuyajto Lake is a salt lake located in the Antofagasta Region, northern Chile. Located at an elevation of about 4,010 metres (13,160 ft), its surface area presently fluctuates between 1.7–2.7 square kilometres (0.66–1.04 sq mi) but in the past it was considerably larger; this led to humans going to the lake and creating archeological sites there. Presently, the lake is groundwater-fed and has no surface outlet but water might seep out underground. It is part of the Los Flamencos Natural Reserve.
Lake Tauca is a former lake in the Altiplano of Bolivia. It is also known as Lake Pocoyu for its constituent lakes: Lake Poopó, Salar de Coipasa and Salar de Uyuni. The lake covered large parts of the southern Altiplano between the Eastern Cordillera and the Western Cordillera, covering an estimated 48,000 to 80,000 square kilometres of the basins of present-day Lake Poopó and the Salars of Uyuni, Coipasa and adjacent basins. Water levels varied, possibly reaching 3,800 metres (12,500 ft) in altitude. The lake was saline. The lake received water from Lake Titicaca, but whether this contributed most of Tauca's water or only a small amount is controversial; the quantity was sufficient to influence the local climate and depress the underlying terrain with its weight. Diatoms, plants and animals developed in the lake, sometimes forming reef knolls.
Inca Huasi was a paleolake in the Andes. It was named by a research team in 2006.
Salinas is a lake event in the Salar de Uyuni, Bolivia.
Ouki was an ancient lake in the Bolivian Altiplano. Its existence was postulated in 2006 by a group of scientists who had subdivided the Lake Minchin lake cycle into several lake phases. The Lake Minchin cycle had been previously identified in 1904 as a now disappeared lake in the central Altiplano. Sediments attributed to Lake Minchin may rather be part of Ouki. The dating is uncertain, with radiocarbon and uranium-thorium dating yielding different dates spanning the time between 28,200 and 125,990 ± 9,580 years ago.
Lake Mataro is an ancient lake in the Andes. It formed over the northern Altiplano at an altitude of 3,950 metres (12,960 ft) and extended over the central Altiplano. It is one of the ancient lakes of the Altiplano like Lake Minchin, Lake Ballivian and Lake Cabana. It existed between 2.8 and 1.8 million years ago.
Lake Cabana is an ancient lake in the Altiplano.
Lake Ballivián is an ancient lake in the Altiplano of South America and is named after the Bolivian scholar Don Manuel Vicente Ballivian. It is part of a series of lakes which developed in the Titicaca basin along with Lake Mataro and Lake Cabana, reaching an altitude of 3,860 metres (12,660 ft). Lake Ballivián itself is of late Quaternary age and may have influenced the spread and development of animals in the Altiplano. In the southern Altiplano, Lake Escara may be coeval with Lake Ballivián.
Pastos Grandes is the name of a caldera and its crater lake in Bolivia. The caldera is part of the Altiplano-Puna volcanic complex, a large ignimbrite province that is part of the Central Volcanic Zone of the Andes. Pastos Grandes has erupted a number of ignimbrites through its history, some of which exceeded a volume of 1,000 cubic kilometres (240 cu mi). After the ignimbrite phase, the lava domes of the Cerro Chascon-Runtu Jarita complex were erupted close to the caldera and along faults.
Tata Sabaya is a 5,430-metre (17,810 ft) high volcano in Bolivia. It is part of the Central Volcanic Zone, one of several volcanic belts in the Andes which are separated by gaps without volcanic activity. This section of the Andes was volcanically active since the Jurassic, with an episode of strong ignimbritic volcanism occurring during the Miocene. Tata Sabaya lies in a thinly populated region north of the Salar de Coipasa salt pan.
Laguna Miscanti is a brackish water lake located in the altiplano of the Antofagasta Region in northern Chile. Cerro Miñiques volcano and Cerro Miscanti tower over this lake. This 13.5 square kilometres (5.2 sq mi) large heart-shaped lake has a deep blue colour and developed in a basin formed by a fault. South of Miscanti lies Laguna Miñiques, another lake which is separated from Miscanti by a lava flow that was emplaced there during the Pleistocene.
Salar de Punta Negra is a saltpan in the Antofagasta Region of Chile with a surface area of about 230 square kilometres (89 sq mi). It is surrounded by deposits left by dry valleys that descend the Western Cordillera. These dry valleys, from mountains such as the Llullaillaco volcano, carry water only occasionally. More permanent sources of water, in the form of springs, also exist at Salar de Punta Negra.
Uturuncu is a dormant volcano in the Sur Lípez Province of Bolivia. It is 6,008 metres (19,711 ft) high, has two summit peaks, and consists of a complex of lava domes and lava flows with a total volume estimated to be 50–85 km3. It bears traces of a former glaciation, even though it does not currently carry glaciers. Volcanic activity took place during the Pleistocene epoch and the last eruption was 250,000 years ago; since then Uturuncu has not erupted but active fumaroles occur in the summit region, between the two summits.
Salar de Pajonales is a playa in the southern Atacama Region of Chile and the third-largest in that country, behind Salar de Punta Negra and Salar de Atacama. It consists mostly of a gypsum crust; only a small portion of its area is covered with water. During the late Pleistocene, Salar de Pajonales formed an actual lake that has left shoreline features.