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= Laguna Miscanti =
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Introduction
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Laguna Miscanti is a brackish lake in the Altiplano of the Antofagasta
Region in Norte Grande, Chile. It has an area of about 13 km2 and the
shape of an arrowhead. The lake has no permanent surface inflows or
outflows apart from several springs, and is primarily fed and drained
by groundwater flows. Laguna Miscanti is located among the volcanoes
of the Central Andes. The smaller Laguna Miñiques lies immediately
south, separated from Miscanti by a lava flow.
The lake formed through tectonic processes about 22,000 years ago.
During the late Pleistocene, the wetter climate of the Central Andean
Pluvial Events caused Laguna Miscanti to grow, possibly until it
merged with Laguna Miñiques. During the Holocene, the climate became
drier again, and Laguna Miscanti shrank and may have dried out
completely, leaving wetlands behind. 3,400 years ago the lake reformed
and has persisted since.
Laguna Miscanti is an important breeding site for birds and a major
tourist destination within the Los Flamencos National Reserve.
Prehistoric peoples used the area as a hunting ground, and several
archaeological sites have been identified nearby.
Etymology
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The word 'Miscant', meaning 'toad' comes from the Kunza language, a
language formerly spoken in the Salar de Atacama and Loa River valley.
Alternate spellings are 'Miskanti' or 'Miscanter'. 'Miscanter' might
be the correct Kunza name and 'Miscanti' a Quechua-language form of
the name.
Overview
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Laguna Miscanti is in the Central Andes, southeast of the Salar de
Atacama salt flat within Chile's Antofagasta Region. The closest towns
are Socaire and San Pedro de Atacama, 20 km and 90 km away,
respectively. Miscanti is shaped like an arrowhead with a peninsula
jutting from the northern shore. A road departs from the Paso Sico
international road to Laguna Miscanti, where there are several
footpaths.
With a surface area between 12.27 and(-) depending on meteorological
conditions, Miscanti is one of the largest water bodies of the Atacama
Altiplano. The maximum depth is 10 m with the lake floor dropping
steeply in the west, more gently in the east and south, and a lava
flow dividing the otherwise flat bottom into two basins. There are no
streams feeding into Laguna Miscanti, but several dry valleys enter
from the north, east and south, and there are two springs in the bays
adjacent to the peninsula. The water is clear and brackish, with
little or no current. Most water comes from the Cordon de Puntas
Negras mountains and reaches Laguna Miscanti underground; this
groundwater supply explains why the lake persists year-round, although
the role of local climatic conditions is less certain.
The lake has no surface outflow and most water leaves Laguna Miscanti
through evaporation, making it a closed basin. Some water drains
underground into Laguna Miñiques (1.5 km to the south and 10 m lower
in elevation) and possibly to Salar de Atacama. The removal of salts
through this outflow prevents Miscanti from becoming a salt pan. The
lake produces banded muddy sediments consisting of fossil charophyte
and diatom remnants, salts and volcanic tephra.
A low ridge, probably of Pleistocene age, separates Miscanti from
Miñiques. West of the lake is the Chuculaqui or Miscanti Ridge. The
surrounding terrain is covered by lake sediments, including
calcarenite, diatomite, gravel and sand. Former shorelines occur at
distances approaching 1 km from the present-day lake shore.
Palaeolake
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In the past, Laguna Miscanti was more than twice as large as it is
today, covering an area of 38.2 km2. Its water levels were about 29 m
higher than today, reaching an altitude of 4179 m, and may have merged
with Laguna Miñiques or formed a lake chain with it. During former
episodes of maximum water level (highstands), Miscanti overflowed into
the Pampa Varela basin south-southwest of Miñiques, where former
shorelines are visible. The lake submerged alluvial fans and left
behind beach terraces, lake sediments and wave-cut platforms. The
sediments consist of stromatolithes, sand, pyroclastic rocks, gravel,
diatomites and calcarenites. The sediment sequence at Miscanti
resembles that at Miñiques, Lejia and Tuyajto, and was deposited at a
rate of about 1 mm/year, eventually reaching a thickness of 6 - in
sediment cores.
There was more life 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 of 'Ranunculus'
plants.
Geology and geomorphology
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The catchment of the lake consists mainly of volcanic and sedimentary
rocks ranging from Miocene to Holocene age and covers a surface area
of 320 km2. The catchment contains several Quaternary volcanoes rising
to 5000 -. Among these are Cerro Miscanti (5622 m) and Cerro Miñiques
(5910 m) northeast and south of the lake, respectively. The volcanoes
are part of the Andean Volcanic Belt, created by the subduction of the
Nazca Plate under the South American Plate.
The region is characterized by north-south-trending mountain chains,
which separate various basins occupied by salt flats or lakes. The
lakes Laguna Lejia, Laguna Miscanti and Laguna Miñiques occupy basins
formed by the Pliocene and Pleistocene reactivation of the 100 km
Quebrada Nacimiento fault west of Laguna Miscanti. The fault extends
from the Purico complex at Llano de Chajnantor to Cerro Miñiques, and
is one of the most important faults in the region. Groundwater flow
into and out of Laguna Miscanti occurs along the Quebrada Nacimiento
fault.
The Quebrada Nacimiento fault is part of a larger fault system,
variously described as a detachment or thrust fault system, separating
the Western Cordillera from the Cordillera Domeyko. The volcanoes
Lascar and the Cerros Saltar and Corona north and south of Lascar are
situated on the fault, they possibly formed under its influence. The
Miscanti Ridge also formed through activity on this fault.
Climate
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There are no long-running weather records from Laguna Miscanti. The
climate is cold, with average annual temperatures of 2 C, being
slightly higher at the lake than in the surrounding region.
Temperatures vary sharply between day and night, reaching lows of -10
to during the night; seasonal variations reach only 8-10 C-change.
Days are usually clear and sunny. Parts of the lake surface freeze
over during winter.
The region features a dry-winter cold semi-arid climate bordering on
tundra, according to the Köppen climate classification. The annual
evaporation rate of 2 m/year vastly exceeding the average
precipitation of .
The region's aridity results from the Andes rain shadow, the cold
Humboldt Current in the Pacific Ocean, and the subtropical
anticyclone. Most precipitation falls during austral 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 cut-off 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.
Geologic history
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Laguna Miscanti may have formed 22,000 years ago, when tectonic and
volcanic activity trapped water in the future lake basin. Soon after
forming, the lake reached its first highstand. At some point during
the Pleistocene, a lava flow from Cerro Miñiques formed the barrier
separating Miscanti and Miñiques. During the Last Glacial Maximum,
conditions became colder and drier than the present-day, leading to a
total disappearance of vegetation and a drying of the lake between
22,000 and 14,000 years ago.
In the Late Glacial/late Pleistocene and early Holocene the climate of
the Atacama and Central Andes was much wetter (Central Andean Pluvial
Event [CAPE] or "Tauca phase") and precipitation nearly doubled in the
southern Atacama. Vegetation extended into the Atacama and lakes
formed (Lake Tauca) or grew in size until the water-covered area in
the region had reached 5-10 times that of present-day water bodies.
Researchers divide this humid interval into two phases: 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. The second
highstand of Laguna Miscanti took place during CAPE II. 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 caused the lakes to shrink.
Miscanti became hypersaline as water levels dropped by about 10 m. It
may have dried up completely, forming a bog or a 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 might have been wetter during the
middle Holocene.
Occasional storms caused floods even during the dry period, and there
were short (yearly to centennial) wet periods that are not always
recorded in the lake. The late Holocene saw renewed wetness in the
region; 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 persisted since then. More
recent fluctuations include a dry period beginning 1650 AD and ending
either 1850 or 1920 AD, perhaps linked to the end of the Little Ice
Age. Between 1980 and 2000 water levels were approximately stable,
then decreased until about 2015 when another upward trend began. Such
variability is consistent with the behaviour of other high-altitude
lakes in northern Chile, which have largely escaped the effects of the
Chilean megadrought.
Biology
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Aquatic plants like 'Myriophyllum' and charophytes like 'Chara' grow
on the lake floor; 'Chara globularis' meadows cover most of the lake
floor. Aquatic fauna include amphipods, branchiopods ('Chydorus
sphaericus'), cladocerans ('Alona pulchella'), copepods ('Boeckella
poopoensis', the main crustacean in the lake and in other water bodies
of the region) and ostracods ('Hyalella fossamanchini' and 'Hyalella
kochi'). The existence of the cladoceran daphnids is uncertain.
Microorganisms living in the lake waters include bacteria and
ciliates; fossils of diatoms and the ostracod 'Limnocythere
sappaensis' occur in the sediments of Laguna Miscanti.
The beaches and alluvial cones of Laguna Miscanti feature meadows
consisting of 'Fabiana', 'Festuca', 'Ruppia' and 'Stipa chrysophylla'.
Sparser vegetation known as "tolar" grows on the surrounding terrain.
It is dominated by grasses, along with bushes and perennial herbs;
species include 'Baccharis', ichu and yareta. Above 4250 m 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 (Chilean
flamingo 'Phoenicopterus chilensis', Andean flamingo 'Phoenicoparrus
andinus' and the James flamingo 'Phoenicoparrus jamesi') and horned
coot ('Fulica cornuta'). Other birds found in the region include
'Anarhynchus alticola' (Puna plover), 'Chloephaga melanoptera' (Andean
goose; aquatic), 'Fulica ardesiaca' (Andean coot), 'Fulica gigantea'
(Giant coot), 'Larus serranus' (Andean gull; aquatic), 'Lophonetta
speculiarioides' (Crested duck), 'Eligmodontia puerulus' (Andean
gerbil mouse), '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.
Other fauna include butterflies, including some threatened species.
Human activities
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Tourism is an important economic activity in the region; regional
tourism is of national importance. The spectacular landscape of Laguna
Miscanti and Miñiques, with its surrounding mountains and birds, is a
tourist attraction and the lakes are among the best-known of Chile.
Political and infrastructural undertakings in the San Pedro de Atacama
area during the 1980s created the necessary conditions, with new
infrastructure (including housing for staff close to Miscanti)
inaugurated in 2004. Laguna Miscanti and Laguna Miñiques are in the
Los Flamencos National Reserve, and are among the best-known
destinations in the national park. In 2002, there were 5,000 tourists
at Miscanti and nearby lake Miñiques, increasing to 75,000 in 2015;
that year, one in three tourists who went to the National Reserve
visited the two lakes. Access requires payment and it is forbidden to
leave the footpaths around the lake.
Since about 1997, the town of Peine draws its water supply from the
Chakizoke spring in the Miscanti basin; it is of higher quality than
the town's earlier water sources. Disputes over water rights and
concerns about the use of water sources are commonplace in the region.
Water consumption by mining companies is particularly contentious; the
"Pampa Colorada" dispute erupted in 2007 about a project to draw water
from the Miscanti watershed, including local protests and an
intervention by the environmental authorities; the project was
eventually halted.
Residents of Socaire traditionally used the area for grazing, and it
is important to them for spiritual and religious reasons as well.
Laguna Miscanti is of scientific importance, as it has a record of
vegetation (including vegetation far away from Miscanti) and
palaeoclimatic changes going back to the last glacial maximum.
Archaeology
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An archaeological site ("Miscanti-1") has been discovered on a beach
terrace at the southeastern end of the lake. The site contains animal
remains, hearths and lithic artefacts buried beneath volcanic ash. The
site was used during the dry middle Holocene. It was presumably a
campsite used by prehistoric hunter-gatherer populations, which
produced hunting tools and consumed game (mostly guanacos and vicuñas,
as well as birds and rodents) there. Another site is Tulan-99, a camp
situated between the Miscanti and Miñiques lakes. Other archaeological
findings in the area include petroglyphs and other archaeological
sites. Some of these sites are interpreted as stops along frequently
used prehistoric paths, which reflect a seasonal or periodic use of
the Laguna Miscanti area. Humans arrived in lower altitude areas
first, reaching Miscanti only later, and there might have been
seasonal migration to the Miscanti area during summer via the Tulan
valley.
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, retreating to 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 habitation.
External links
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*
*
*
[https://bibliotecadigital.ciren.cl/server/api/core/bitstreams/5bc1fa42-4e6f-40c7-9ff1-bbb56d04c2ef/content
Los Flamencos National Park report]
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Original Article: http://en.wikipedia.org/wiki/Laguna_Miscanti
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