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 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.
The lake is part of one of the seven sectors of Los Flamencos National Reserve. A number of birds and mammals live at the lake, which is a major tourist destination.
Laguna Miscanti lies in the Central Andes of Chile, east-southeast of the Salar de Atacama. Administratively, it is part of the Antofagasta Region. San Pedro de Atacama is north of Laguna Miscanti; the closest town is Socaire, away from the lake. A road departing from the Paso Sico international road goes to Miscanti, which is accessible by an unpaved road and numerous footpaths leading to Laguna Miñiques.
Laguna Miscanti has a surface area of , varying between depending on meteorological conditions, such as precipitation. The lake, one of the largest waterbodies of the Atacama Altiplano, has the shape of an arrowhead with a peninsula jutting from the northern shore. Maximum water depths reach . The western lakefloor is steep, while the eastern and southern shores have gentler slopes. A lava flow separates the otherwise flat lake floor into two basins. The surrounding terrain is covered by lake sediments, including calcarenite, diatomite, gravel and sand. Former shorelines occur at distances approaching from the present-day lake shore. A number of dry valleys - there are no no streams at Laguna Miscanti - enter into Laguna Miscanti from the north, east and south (Quebrada de Chaquisoqui), and there are two springs in the bays on either side of the peninsula.
The waters are clear and brackish, with only weak currents if at all. The lake has no surface outflow. Water seeps to the lower Miñiques through a lava flow along the path of the Quebrada Nacimiento fault, and possibly to Salar de Atacama; the removal of salts through this outflow prevents Miscanti from becoming a salt pan. Most water, however, leaves Laguna Miscanti through evaporation, making it a closed basin.
The Cordon de Puntas Negras is the main source of water. Water reaches Laguna Miscanti principally underground, which is directed there by the fault; this or the climatic traits of the area may explain why Laguna Miscanti is a permanent lake rather than a playa. The lake forms banded muddy sediments consisting of fossils, salts and volcanic tephra layers.
south of the lake is another waterbody, Laguna Miñiques. The low barrier separating the two probably formed during the Pleistocene, when a lava flow erupted from Cerro Miñiques split the lake basin in two. West of the lake is the Chuculaqui or Miscanti Ridge.
In the past, Laguna Miscanti more than twice as large as today, covering an area of . Its water levels were about higher than today, reaching an altitude of , and may have merged with Laguna Miñiques. The lake submerged alluvial fans and left beach terraces, lacustrine sediments and wavecut platforms. There was more biological activity in the lake during the highstand: Algal bioherms and stromatolithes grew in the water and along the shores. Fossils indicate the presence of the green algae Botryococcus patagonicum, Botryococcus pila and Pediastrum integrum, and Ranunculus plants. During former lake highstands Miscanti (either a lake chain or a combined lake) overflowed into the Pampa Varela basin south-southwest of Miñiques.
The catchment of the lake consists mainly of volcanic and sedimentary rocks ranging from Miocene to Holocene age and covers a surface area of . Quaternary volcanoes with summit elevations of dot the catchment. Among these are Cerro Miscanti () and Cerro Miñiques () northeast and south of the lake, respectively. The volcanoes are part of the Andean Volcanic Belt, which is formed by the subduction of the Nazca Plate under the South American Plate.
Laguna Lejia, Miscanti, Miñiques occupy basins formed by tectonic activity, specifically of the long Quebrada Nacimiento or Miscanti fault west of Laguna Miscanti, one of the most important faults in the region. It is the easternmost of a set of thrust faults associated with compression in the forearc of the Andes, and its reactivation during the Pliocene and Pleistocene formed the basins and the Miscanti Ridge.
The fault extends from the Purico complex at Llano de Chajnantor to Cerro Miñiques, and is part of a detachment fault system east of the Salar de Atacama separating the Western Cordillera from the Cordillera Domeyko. Volcanoes including Lascar and the Cerros Saltar and Corona north and south of Lascar formed on the fault, possibly under its influence.
There are no long-running weather records from Laguna Miscanti. Temperatures are cold, with average annual temperatures of , being slightly higher on the lake than the surrounding region. Temperature differences between day and night are stark, during night they can decrease to . Days are usually clear and sunny. Parts of the lake surface freeze over during winter.
The region features an arid climate, with the annual evaporation rate of vastly exceeding the average precipitation of . The aridity is due to the combined effects of the rain shadow of the Andes, the cold Humboldt Current off the coast in the Pacific Ocean and the subtropical anticyclone. Most precipitation falls during summer (December-February) during the so-called "Bolivian Winter", but winter precipitation is significant. Depending on the season, it is brought by the summer monsoon, weather fronts or cutoff lows but its ultimate origin is the Amazon. The El Niño-Southern Oscillation pattern of climatic variability influences precipitation in the Altiplano, being usually higher at Laguna Miscanti during La Nina events when more Amazon moisture reaches the area.
Laguna Miscanti may have formed 22,000 years ago, when tectonic and volcanic activity trapped water in the future lake basin. At this point, the lake reached its highstand for the first time. About 18,000 years ago, the Last Glacial Maximum turned drier and colder, leading to a total disappearance of vegetation and a drying of the lake between 22,000 and 14,000 years ago.
In the late Pleistocene and early Holocene the climate of the Atacama and Central Andes was much wetter (Central Andean Pluvial Event or "Tauca phase") and precipitation nearly doubled in the southern Atacama. As a consequence, lakes formed (Lake Tauca) or grew in size, including Laguna Miscanti where the second highstand occurred during the Late Glacial. This humid period has been subdivided into two stages, the wetter Tauca or CAPE I (17,50014,200 years before present) and Coipasa or CAPE II (13,8009,700 years before present), which are not entirely synchronous between the Atacama and the Altiplano. Pollen data indicate that a stronger easterly wind was responsible for the highstand at Miscanti.
The Holocene brought a more stable, warmer and drier climate to the central and south-central Andes which causes the lakes to dry up. Miscanti became hypersaline as water levels dropped by about . It may have dried up completely, forming a bog or mudflat surrounded by wetlands that attracted camelids like guanacos and vicuñas. The dry period was caused by decreased insolation caused by the Milankovich cycles weakening the monsoon. A widespread abandonment of archaeological sites, the "archaeological silence", coincides with the drought although Miscanti itself remained inhabited during that time. The exact chronology of the dry period depends on the site, in the case of Laguna Miscanti, there are uncertainties caused by issues with radiocarbon dating, and some places (not Laguna Miscanti) might have been wetter during the middle Holocene.
Occasional storms caused floods even during the dry period. There were wet pulses on century or decade time scales, and a brief moist epoch between 6,500 and 5,000 years ago. At Miscanti, the dry period definitively ended after about 4,000 years ago through several pulses of moisture, and human resettlement at Laguna Miscanti took place about 3,400 years ago. The lake reformed 3,600 years ago and has remained since. More recent fluctuations include a dry period between 16501850 AD, perhaps linked to the ending Little Ice Age. Between 1980 and 2000 water levels were approximately stable, then decreased until about 2015 when another upward trend began. Such variabiliy is consistent with the behaviour of high-altitude lakes of northern Chile, which have not been impacted by the Chilean megadrought.
The lakefloor is populated by aquatic plants, including water plant Myriophyllum and charophytes like Chara; charophytes like Chara globularis form meadows covering the entire lake floor. Animals living in the water of Laguna Miscanti include amphipods, branchiopods (Chydorus sphaericus), cladocerans (Alona pulchella and Daphnia), copepods (Boeckella poopoensis) and ostracods (Hyalella fossamanchini and Hyalella kochi). Bacteria in the lake waters have been classified, and fossils of diatoms and the ostracod Limnocythere sappaensis occur in the sediments of Laguna Miscanti.
There are meadows consisting of Fabiana, Festuca, Ruppia, Stipa chrysophylla on the alluvial cones and beaches of Laguna Miscanti. Sparser vegetation consisting of Baccharis species also known as "tolar", ichu and yareta grow on the surrounding terrain. Above elevation, vegetation disappears and the landscape transitions to high-altitude desert. Vegetation composition has been stable during the Holocene.
The two lakes are important breeding sites for flamingos and horned coot. Other birds found in the region include Anarhynchus alticola (Puna plover), Chloephaga melanoptera (Andean goose; aquatic), Fulica ardesiaca (Andean coot), Fulica cornuta (Horned coot), Fulica gigantea (Giant coot), Larus serranus (Andean gull; aquatic), Lophonetta speculiarioides (Crested duck), Metriopelia melanoptera (Black-winged ground dove), Nycticorax nycticorax (Black-crowned night heron; aquatic), Podiceps occipitalis (Silvery grebe), Rhea tarapacensis (Darwin's rhea) and Tinamotis pentlandii (Puna tinamou). Mammals like Chinchilla chinchilla (Short-tailed chinchilla), Ctenomys opimus (Highland tuco-tuco), Lagidium viscacia (Southern viscacha), Lama guanaco (Guanaco), Oreailurus jacobita (Andean mountain cat), Phyllotis darwini (Darwin's leaf-eared mouse), Pseudalopex culpaeus (culpeo) and Vicugna vicugna (vicuña) inhabit the area.
The landscape of Laguna Miscanti and Miñiques, with its surrounding mountains and birds, is a tourist attraction. Tourist activity began in the 1980s, when political and infrastructural efforts in the San Pedro de Atacama area created the necessary conditions, and in 2004 new infrastructure (including housing for staff close to Miscanti) became active. In 2002, there were 5,000 tourists at Miscanti and the nearby lake Miñiques, and in 2015, one in three tourists who went to the Los Flamencos National Reserve visited the two lakes. Laguna Miscanti and Laguna Miñiques are part of the third sector of the Los Flamencos National Reserve, and it is forbidden to leave the footpaths around the lake. The inhabitants of Socaire used the area for grazing, and it bears spiritual and religious importance for them. Since about 1997, the town of Peine draws its water supply from the Miscanti basin; it is of higher quality than the town's earlier water sources. The use of water sources in the area by mining companies has caused controversy, including the "Pampa Colorada" dispute in 2007 about a project to draw water from the Miscanti watershed that triggered local protests and an intervention by the environmental authorities. Disputes over water rights and concerns about the use of water sources are commonplace in the region. Laguna Miscanti is of scientific importance, as it has a record of vegetation (including remote vegetation) and palaeoclimatic changes going back to the last glacial maximum.
An archeological site ("Miscanti-1") has been discovered on a beach terrace at the southeastern end of the lake. It contains remnants of animals, hearths and lithic artifacts buried in volcanic ash. It was presumably a campsite used by prehistoric hunter-gatherer populations, which produced hunting tools and consumed game there. Other archaeological findings in the area include petroglyphs and sites interpreted as stops along frequently used prehistoric paths, which reflect a seasonal or periodic use of the Laguna Miscanti area.
Climate variability influenced human settlement in the region during the Holocene, which took place mainly during wetter periods when the environment became much more favourable, becoming concentrated in several environmentally favourable spaces during dry periods. At Miscanti, wetlands and areas suitable for grazing formed during the middle Holocene drought, thus the area remained hospitable for human inhabitation.