El Tatio

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File:Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 01-02 HDR.JPG

El Tatio geyser field

El Tatio is a geothermal field with many geysers located in the Andes Mountains of northern Chile at Template:Convert above mean sea level. It is the third-largest geyser field in the world and the largest in the Southern Hemisphere. Various meanings have been proposed for the name "El Tatio", including "oven" or "grandfather". The geothermal field has many geysers, hot springs, and associated sinter deposits.Template:Efn The water from these hot springs eventually forms the Rio Salado, a major tributary of the Rio Loa, significantly increasing the amount of arsenic in the river. The geothermal vents are sites of populations of extremophile microorganisms such as hyperthermophiles, and El Tatio has been studied as an analogue for the early Earth and possible past life on Mars.

El Tatio lies at the western foot of a series of stratovolcanoes which runs along the border between Chile and Bolivia. This series of volcanoes is part of the Central Volcanic Zone (one of several volcanic belts in the Andes), and of the Altiplano–Puna volcanic complex (APVC) – a system of large calderas and associated ignimbrites which were the sources of supereruptions between 10 million and 1 million years ago. Some of these calderas may be the source of heat for the El Tatio geothermal system. There are no recorded eruptions of the Tatio volcanoes in the historical period.

The field is a major tourism destination in northern Chile. It was prospected over the last century for geothermal power production, but development efforts were discontinued after a major incident in 2009 in which a geothermal well blew out, creating a steam column. The blowout caused a political controversy about geothermal power development in Chile.

Name and research historyEdit

The term "tatio" comes from the nearly-extinct Kunza language; known meanings of the word include 'to appear' and 'oven',Template:Sfn but it has also been translated as 'grandfather'Template:Sfn (whose tears form the geysersTemplate:Sfn) or 'burnt'. The geyser field is also known as the Copacoya geysers;Template:Sfn Copacoya is the name of a mountain in the area.Template:Sfn

The earliest mentions of geysers in the region are from the late 19th century,Template:Sfn and they were already well known by 1952.Template:Sfn The first geothermal prospecting of the field occurred in the 1920sTemplate:Sfn and the field was mentioned in academic literature in 1943.Template:Sfn More systematic research took place in 1967–1982;Template:Sfn most research on this geothermal field was done in the context of geothermal prospecting.Template:Sfn

Geography and geomorphologyEdit

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}</mapframe>El Tatio lies in the municipality of Calama,Template:Sfn Antofagasta Province of northern Chile close to the border between Chile and Bolivia.Template:Sfn Template:Efn The field is located Template:Convert north of the town San Pedro de Atacama and Template:Convert east of the town of Calama;Template:Sfn Template:Sfn Chile Route B-245 connects El Tatio to San Pedro de Atacama.Template:Sfn Towns close to El Tatio are Toconce to the north, Caspana to the west and Machuca to the south.Template:Sfn A workers' camp for a sulfur mine at Volcan Tatio was reported to exist in 1959.Template:Sfn The old Inca trail from San Pedro de Atacama to Siloli crossed the geyser field;Template:Sfn the Inca also operated a mountain sanctuary on Volcan Tatio.Template:Sfn There are several unpaved roads and all parts of the field are easily accessible by foot.Template:Sfn

File:El Tatio topography.png

Topography of the El Tatio region

El Tatio is part of the Central Volcanic Zone, a segment of the Andes between 14° and 28° southern latitude where the Andes are volcanically active. This volcanism manifests itself with about 10 silicic caldera complexes of the Altiplano–Puna volcanic complex and more than 50 recently active volcanoes; Lascar volcano erupted in 1993 and produced a tall eruption column.Template:Sfn

East of the field, andesitic stratovolcanoes reach elevations of about Template:Convert.Template:Sfn From north to south, the andesitic stratovolcanoes include the Template:Convert Template:Sfn Template:Sfn Template:Sfn or Template:Convert high Cerro Deslinde which is the highest in the area,Template:Sfn the Template:Convert high Cerro El Volcan, the Template:Convert high Cordillera del Tatio and the Template:Convert high Volcan Tatio, which collectively form the El Tatio volcanic group.Template:Sfn Template:Sfn Template:Sfn Template:Efn The Sierra de Tucle lies to the southwest of the field.Template:Sfn

Mountains southwest of El Tatio include the Template:Convert high Alto Ojo del Cablor range, while Template:Convert high Cerro Copacoya is situated northwest of the geothermal field.Template:Sfn Volcanism with dacitic composition, older than the easterly stratovolcanoes, has occurred west of El Tatio;Template:Sfn this volcanism was known as the "liparitic formation" and it covers large areas in the region.Template:Efn Template:Sfn

Firn and snow fields were reported in the middle 20th century on the El Tatio volcanic group, at elevations of Template:Convert.Template:Sfn The region is too dry to support glaciers today,Template:Sfn but in the past higher moisture allowed their formation on mountains of this part of the Andes.Template:Sfn Template:Sfn Glacially eroded mountains and moraines testify to their existenceTemplate:Sfn in the form of large valley glaciers.Template:Sfn A large moraine complex, including both terminal structures and well-developed lateral moraines, can be found north of the geyser fieldTemplate:Sfn and reflects the past existence of a Template:Convert long glacier, the longest valley glacier in the region.Template:Sfn Two more moraine systems extend westward both northeast and southeast of El Tatio, and the terrain surrounding the geyser field is covered by sands that are interpreted as glacial outwash sands.Template:Sfn Surface exposure dating indicates that some moraines were emplaced at or before the Last Glacial Maximum and others in a time period 35,000 to 40,000 years before present.Template:Efn Template:Sfn Smaller moraines at higher altitude may date to the Antarctic Cold Reversal or the Younger Dryas climate periods;Template:Sfn moraines related to the Lake Tauca stage are either absent or restricted to high elevation sites.Template:Sfn

File:03-tocopilla-calama (El Tatio).jpg

1910 map of the region

Drainage in the area is generally from east to west down the Occidental Cordillera,Template:Sfn often in form of steeply incised valleys.Template:Sfn The Rio Salado drains most of the hot spring waterTemplate:Sfn Template:Sfn and has its headwaters in the fieldTemplate:Sfn where it is joined by the Rio Tucle Template:Sfn Template:Sfn and the Vicuna stream.Template:Sfn Temperature measurements of the water flowing to the Rio Salado have yielded values of Template:Convert,Template:Sfn while the discharge of the Rio Salado amounts to Template:Val.Template:Sfn The Rio Salado eventually joins the Rio Loa, a major source of freshwater for the region;Template:Sfn thus, El Tatio plays an important role in the regional water supply.Template:Sfn In the early 20th century there were several hydraulic engineering projects at El Tatio, aiming either to use its waters or to mitigate its impact on downstream water quality.Template:Sfn

Geothermal fieldEdit

El Tatio is well known as a geothermal field in Chile,Template:Sfn and is the largest geyser field in the Southern Hemisphere with about 8% of all geysers in the world. Only the fields at Yellowstone in the United States and Dolina Geizerov in Russia Template:Sfn are larger.Template:Sfn They also have taller geysers than at El Tatio,Template:Sfn where geyser fountains are on average only Template:Convert high.Template:Sfn Together with Sol de Mañana, which is just east of El Tatio in Bolivia,Template:Sfn it is also the highest-altitude geyser field in the world.Template:Sfn Template:Sfn

File:ElTatio-CerroSoquete-2004.jpg

The Andes rise behind El Tatio

The geothermal field covers an area of Template:Convert at elevations of Template:Convert, and is characterized by fumaroles, hot springs, steam vents and steaming soil. Stronger geothermal activity is located within three discrete areas covering a total of Template:Convert surface, and includes boiling water fountains, hot springs, geysers, mudpots, mud volcanoes and sinter terraces;Template:Sfn Template:Sfn further, chimneys of extinct geysers have been noted.Template:Sfn One of these three areas lies within a valley, the second on a flat surface and the third along the banks of the Rio Salado.Template:Sfn The first area offers a notable contrast between the snow-covered Andes, the coloured hills that surround the field and the white deposits left by the geothermal activity. Most geysers of El Tatio are found here and are particularly noticeable in cold weather. A similar landscape exists at the third (lower) area, with the presence of the Rio Salado river adding an additional element to the landscape.Template:Sfn Template:Sfn The second area is located between a creek and a hill and includes an artificial Template:Convert pool for tourists.Template:Sfn Its vents often have higher discharges than others in the field.Template:Sfn

About 110 documented geothermal manifestations have been documented at El Tatio, but the total has been estimated at 400.Template:Sfn The field once numbered 67 geysers and more than three hundred hot springs. Many vents are linked to fractures that run northwest–southeast or southwest–northeast across the field.Template:Sfn Some geyser fountains in the past reached heights greater than Template:Convert;Template:Sfn usually, however, they do not exceed Template:Convert Template:Sfn and their activity sometimes varies over time.Template:Sfn A few geysers have received names, such as Boiling Geyser, El Cobreloa, El Cobresal, El Jefe, Terrace Geyser, Tower Geyser and Vega Rinconada.Template:Sfn Template:Sfn Template:Sfn Minor eruptions of the geysers occur approximately every dozen minutes and major eruptions every few hours on average, and major eruptions take place after the conduit was "prepared" by multiple smaller ones.Template:Sfn The terrain surrounding a geyser tilts as it recharges and discharges.Template:Sfn An additional geothermal system lies southeast of and at elevations above El Tatio and is characterized by steam-heated ponds fed by precipitation water,Template:Sfn and solfataric activity has been reported on the stratovolcanoes farther east.Template:Sfn

File:Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 74-77 PAN.JPG

The sinter landscape formed at El Tatio

Deposition of sinter from the waters of the geothermal field has given rise to spectacular landforms, including, but not limited to mounds, terraced pools, geyser cones and the dams that form their rims.Template:Sfn Template:Sfn Small-scale features include cones, crusts, mollusc-shaped formations, waterfall-like surfacesTemplate:Sfn and very small terraces.Template:Sfn These sinter deposits cover an area of about Template:Convert and include both active and inactive deposits,Template:Sfn both of which were emplaced on glacial sediments.Template:Sfn High contents of silica give the waters a blueish colour, organic compounds such as carotenoids conversely often colour the sinter with orange-brown,Template:Sfn and greenish hues are owing to iron-oxidizing bacteria.Template:Sfn Sinter accumulation is so rapid that debris and microbes can become entrapped and preserved in the sinter.Template:Sfn

Individual vent types and deposits found at El Tatio include:

Hot springs form pools with water temperatures of Template:Convert, which are often gently moving and surging and in the case of the warmer springs actively bubbling. These pools often contain ball-like rocks called oncoids and are surrounded by sinter rims, which have spicule-like textures.Template:Sfn These sinter rims often form dam-like structures around deeper vents which are filled with water.Template:Sfn Spherical grains develop in the hot springs as a consequence of hydrodynamic processes, and include biogenic material; during the growth of the sinter they often end up embedded in the material.Template:Sfn
Water draining from the springs deposits sinter, which can form fairly thick deposits and large aprons when sheet flow occurs, known as "discharge deposits"; sometimes terraces are developed instead. As in springs, oncoids and spicules are observed in channels. Much of the water evaporates and its temperature drops from Template:Convert to less than Template:Convert away from the springs;Template:Sfn the low air temperatures cause it to freeze occasionally, resulting in frost weathering.Template:Sfn
Geysers and also water fountains discharge from up to Template:Convert high conesTemplate:Sfn Template:Sfn with gently sloping surfaces, which sometimes support splash mounds.Template:Sfn The cones are made out of geyserite.Template:Sfn Other geysers and fountains instead discharge from within rim-bounded pools,Template:Sfn and some geysers are in the bed of the Rio Salado river.Template:Sfn The activity of geysers is not stable over time; changes in water supply or in the properties of the conduit that supplies them can cause changes in their eruptive activity. Such changes can be triggered by rainfall events or earthquakes and at El Tatio geyser behaviour changes have been linked to the 2014 Iquique earthquake and a 2013 precipitation event.Template:Sfn The water of geysers is Template:Convert hot.Template:Sfn
Mud pools are often bubbling, with the hot mud fountaining.Template:Sfn They are mainly found at the edges of the geothermal field and often produce highly acidic water; it converts rocks to clays.Template:Sfn Simmering pools of water have been recorded at El Tatio as well.Template:Sfn

Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 03-05 HDR.JPG

A vent surrounded by yellow rocks
Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 24-26 HDR.JPG

Geyser cone
Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 36-38 HDR.JPG

Geyser cone
Géiseres del Tatio, Atacama, Chile, 2016-02-01, DD 39-41 HDR.JPG

Geyser cone

GeologyEdit

Subduction of the Nazca Plate beneath the South American Plate is responsible for the formation of the Andes. Volcanism does not occur along the entire length of the Andes; there are three volcanic zones called the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone, all separated by areas with no Holocene-age volcanism.Template:Sfn Template:Sfn

El Tatio and a number of other geothermal fields such as Sol de Mañana are part of the Altiplano–Puna volcanic complex. The region was dominated by andesitic volcanism producing lava flows until the late Miocene, then large-scale ignimbrite activity took place between 10 and 1 million years ago. This ignimbrite volcanism is part of the APVC proper and produced about Template:Convert of ignimbrites, covering a surface area of Template:Convert. The APVC activity continued into the Holocene with the emission of voluminous lava domes and lava flows,Template:Sfn Template:Sfn and Tatio was one of the last volcanic centres in the APVC to erupt;Template:Sfn the present-day uplift of the Uturunku volcano in Bolivia may signal ongoing activity of the APVC.Template:Sfn The APVC is underpinned by a large magma chamber with the shape of a sill, the Altiplano-Puna Magma Body; a number of volcanoes and geothermal systems including El Tatio are geographically associated with the Altiplano-Puna Magma Body.Template:Sfn

The Laguna Colorada caldera lies east of El Tatio.Template:Sfn The terrain at El Tatio is formed by Jurassic–Cretaceous sediments of marine and volcanic origin, Tertiary–Holocene volcanic formations that were emplaced in various episodes, and recent sediments formed by glaciers, alluvium, colluvium and material formed by the geothermal field, such as sinter.Template:Sfn Template:Sfn Volcanic formations fill the Tatio graben, including the Miocene Rio Salado ignimbrite and related volcanics which reach thicknesses of Template:Convert in some places, the Sifon ignimbrite, the Pliocene Puripicar ignimbrite and the Pleistocene Tatio ignimbrite;Template:Sfn Template:Sfn the Puripicar ignimbrite crops out farther west.Template:Sfn Active volcanoes in the area include Putana and Tocorpuri.Template:Sfn

Hydrothermal alteration of country rock at El Tatio has yielded large deposits of alteration minerals such as illite, nobleite, smectite, teruggite and ulexite.Template:Sfn The summit parts of several volcanoes of the El Tatio volcanic group have been bleached and discoloured by hydrothermal activity.Template:Sfn

HydrologyEdit

Most of the water that is discharged by the hot springs appears to originate as precipitation, which enters the ground east and southeast of El Tatio. The source of heat of the complex appears to be the Laguna Colorada caldera,Template:Sfn Template:Sfn Template:Sfn the El Tatio volcanic group,Template:Sfn Template:Sfn the Cerro Guacha and Pastos Grandes calderasTemplate:Sfn Template:Sfn or the Altiplano-Puna Magma Body.Template:Sfn The movement of the water in the ground is controlled by the permeability of the volcanic material and the Serrania de Tucle–Loma Lucero tectonic block west of El Tatio that acts as an obstacle.Template:Sfn Template:Sfn Template:Sfn As it moves through the ground, it acquires heat and mineralsTemplate:Sfn and loses steam through evaporation. Unlike geothermal fields in wetter parts of the world, given the dry climate of the area, local precipitation has little influence on the hot springs hydrology at El Tatio.Template:Sfn Neither magmatic water nor water from local precipitation are mixed into this water.Template:Sfn The time the water takes to traverse the whole path from precipitation to the springs is considered to be either 15 yearsTemplate:Sfn or more than 60,Template:Sfn and three-quarters of the heat is transported by steam.Template:Sfn

The water travels through a number of aquifers that correspond to permeable rock formations, such as the Salado and Puripicar ignimbrites,Template:Sfn Template:Sfn the Tucle dacitesTemplate:Sfn as well as through faults and fractures in the rock.Template:Sfn It steeply ascends under El TatioTemplate:Sfn and appears to be confined between northeast-trending fault systemsTemplate:Sfn such as the "Tatio fault".Template:Sfn Three separate geothermal reservoirs have been identified, which underlie the Cerros del Tatio and extend to the La Torta volcano; they are connected by, and partly formed in cavities formed by faults.Template:Sfn The Puripicar ignimbrite appears to be the main hydrothermal reservoir, with temperatures reaching Template:Convert.Template:Sfn The total heat output of El Tatio is about Template:Val.Template:Sfn The hydrothermal system beneath El Tatio appears to extend to the neighbouring La Torta system.Template:Sfn

Depending on the season, the hot springs yield Template:Val of water at temperatures reaching the local boiling point. The water is rich in minerals,Template:Sfn Template:Sfn especially sodium chloride Template:Sfn and silica.Template:Sfn Other compounds and elements in order of increasing concentration are antimony, rubidium, strontium, bromine, magnesium, caesium, lithium, arsenic, sulfate, boron, potassium and calcium.Template:Sfn Template:Sfn Template:Sfn Inorganic carbon (carbonate) occurs at a low concentration.Template:Sfn

Some of these minerals are toxic,Template:Sfn especially arsenic which pollutes a number of waters in the region.Template:Sfn Arsenic concentrations in waters at El Tatio can reach Template:Val – among the highest concentrations found in hot springs of the whole world –Template:Sfn Template:Sfn and Template:Val in sediments.Template:Sfn Producing about Template:Convert,Template:Sfn El Tatio is a principal source of arsenic in the Rio Loa system, and arsenic pollution in the region has been linked to health issues in the population.Template:Sfn

Composition of these hot springs is not uniform in El Tatio, with chloride content decreasing from the northern springs over the southwestern ones to the eastern springs, where sulfate is more frequent.Template:Sfn This sulfate enrichment appears to be driven by the steam-driven evaporation of the hot spring water,Template:Sfn with the sulfate forming when hydrogen sulfide is oxidized by atmospheric oxygen.Template:Sfn The decreasing chloride content on the other hand appears to be due to drainage coming from the east diluting the southern and western and especially eastern spring systems.Template:Sfn

FumarolesEdit

Steam vents are particularly noticeable in the morning hours when the steam columns emanating from them are visible,Template:Sfn Template:Sfn Template:Sfn and temperatures of Template:Convert have been found.Template:Sfn Carbon dioxide is the most important fumarole gas, followed by hydrogen sulfide.Template:Sfn Template:Sfn Template:Sfn The amount of water relative to these two gases is variable, probably due to condensation of water in the ground.Template:Sfn

Additional components include argon, helium, hydrogen, methane, neon, nitrogen and oxygen. Characteristically for fumarole gases on convergent plate boundaries, much of this nitrogen is non-atmospheric. However, atmospheric air is also involved in generating the chemistry of the El Tatio fumarole gases.Template:Sfn

Composition of spring depositsEdit

Opal is the most important component of sinter associated with hot springs; halite, sylvite and realgar are less common.Template:Sfn This dominance of opal is because usually conditions favour its precipitation from water but not of other minerals,Template:Sfn and it occurs both in subaqueous environments and on surfaces that are only occasionally wetted. During the precipitation, the opal forms tiny spheres which can aggregate as well as glassy deposits.Template:Sfn

Halite and other evaporites are more commonly encountered on the sinter surfaces outside of the hot springs,Template:Sfn and while opal dominates these environments too, sassolite and teruggite are found in addition to the aforementioned four minerals in the discharge deposits.Template:Sfn Cahnite has also been identified in sinter deposits.Template:Sfn Volcanic minerals such as plagioclase and quartz are found within cavities of the sinter.Template:Sfn Sandstone formed by debris flows and redeposited volcanic material is found embedded in sinter at some localities.Template:Sfn Finally, antimony, arsenic and calcium form sulfidic deposits in some springs.Template:Sfn

Various facies have been identified in drill cores through the sinter, including arborescent, columnar, fenestral palisade, laminated (both inclined and planar), particulate, spicular and tufted structures. These structures contain varying amounts of microfossils and formed at diverse temperatures and locations of individual sinter mounds.Template:Sfn Microorganisms and material like pollen is found integrated within the sinter deposits.Template:Sfn The rate at which sinter is deposited has been estimated at Template:Convert.Template:Sfn

Climate and biologyEdit

The climate is dry with about Template:Convert precipitation per year.Template:Sfn Most of it falls between December and March,Template:Sfn a precipitation pattern mediated by the South American monsoon Template:Sfn and by the South Pacific High which is responsible for the dry climate.Template:Sfn The whole Central Andes were wetter in the past, resulting in the formation of lakes such as Lake Tauca in the Altiplano.Template:Sfn This, and a colder climate, resulted in the development of glaciers at El Tatio, which have left moraines.Template:Sfn

The region is additionally rather windyTemplate:Sfn with mean windspeeds of Template:Convert,Template:Sfn which influence the hot springs by enhancing evaporationTemplate:Sfn and imparting a directional growth to certain finger-like sinter deposits.Template:Sfn The evaporation rates per month reach Template:Convert Template:Sfn and they facilitate the deposition of sinters.Template:Sfn There is a diurnal cycle in wind and atmospheric humidity, with no wind and high humidity during the night and wind with low humidity during the day.Template:Sfn The atmospheric pressure at this elevation drops to about 0.58 atmospheres, lowering the boiling point of water to about Template:Convert.Template:Sfn Template:Sfn

Apart from precipitation, the area is characterized by extreme temperature variations between day and nightTemplate:Sfn which can reach Template:Convert Template:Sfn and induce freeze-thaw cycles.Template:Sfn The Chilean Dirección General del Agua operates a weather station at El Tatio; according to data from this station air temperatures average Template:Convert and precipitation Template:Convert.Template:Sfn Template:Sfn El Tatio further features high ultraviolet (UV) insolation,Template:Sfn which can reach Template:Val UV-A and Template:Val UV-B. The low atmospheric pressure and high UV irradiation has led scientists to treat El Tatio as an analogue for environments on Mars.Template:Sfn

The dry grassland vegetation of the region is classified as Central Andean dry puna Template:Sfn and lies above the treeline.Template:Sfn About 90 plant species have been identified at El Tatio and surroundings,Template:Sfn such as the endemic Adesmia atacamensis, Calceolaria stellariifolia, Junellia tridactyla and Opuntia conoidea.Template:Sfn Tussock grasses like Anatherostipa, Festuca and Stipa occur at Template:Convert elevation, while rosette and cushion plants reach elevations of Template:Convert; these include Azorella, Chaetanthera, Mulinum, Senecio, Lenzia, Pycnophyllum and Valeriana.Template:Sfn Bushland species include Lenzia chamaepitys, Senecio puchii and Perezia atacamensis,Template:Sfn while Arenaria rivularis, Oxychloe andina and Zameioscirpus atacamensis grow in wetlands.Template:Sfn Riparian vegetation occurs along the Rio Salado.Template:Sfn Among the animals in the region are chinchillas and viscachas and llamas, mainly the vicuña.Template:Sfn

Vicuñas near el Tatio geysers - panoramio.jpg

Vicuñas at El Tatio
Yareta near el Tatio geysers - panoramio.jpg

A yareta growing between rocks
Bienes Nacionales entrega a comunidades atacameñas concesión de uso gratuito de Geysers del Tatio (15205193918).jpg

Landscape of the El Tatio region

Spring biologyEdit

The geothermal field El Tatio is populated by various plants, microbes and animals.Template:Sfn The vents are an extreme environment, given the presence of arsenic, the large amount of UV radiation that El Tatio receivesTemplate:Sfn and its high elevation.Template:Sfn

Hot springs have characteristic microbial communities associated with them that leave characteristic fossil traces in the spring deposits; environmental conditions on the early Earth resembled these of hot springsTemplate:Sfn with potentially high UV radiation exposure, as the ozone layer did not yet existTemplate:Sfn and life probably developed within such conditions.Template:Sfn In addition, microbial metabolism of arsenic influences its toxicity and the effects of arsenic pollution.Template:Sfn

MicroorganismsEdit

Biofilms and microbial mats are omnipresent at El Tatio,Template:Sfn including Arthrospira,Template:Sfn Calothrix,Template:Sfn Template:Sfn Fischerella,Template:Sfn Leptolyngbya,Template:Sfn Lyngbya and PhormidiumTemplate:Efn cyanobacteria, which form mats within the hot springs covering the solid surfaces, including oncoids and the sinter.Template:Sfn Template:Sfn In other places, the aforementioned three genera form stromatolithic structuresTemplate:Sfn or floating rafts of bubbly mats. The mats have tufted, layered and conical textures and their colours include orange and olive green;Template:Sfn they give the channels and pools their colour.Template:Sfn Additional cyanobacteria genera reported from El Tatio are Chroococcidiopsis,Template:Sfn Chlorogloeocystis, Chroogloeopsis, Fischerella, Synechococcus and Thermosynechococcus.Template:Sfn Non-cyanobacteria bacteria have also been found in the mats and sinter;Template:Sfn they include heterotrophic bacteria such as Isosphaera pallida.Template:Sfn

There is a thermal gradation of microorganisms, with the hottest waters supporting Chloroflexus green bacteria and hyperthermophiles, cyanobacteria at less than Template:Convert water temperature and diatoms at even lower temperatures.Template:Sfn Microbial mats have been found at other hot springs in the world such as Yellowstone and Steamboat Springs, both in the United States, and New Zealand, but they are thinner at El Tatio.Template:Sfn

These mats often have their organic material replaced with opal and thus end up forming much of the sinter, which has thus characteristic biogenic textures, such as filaments and laminae.Template:Sfn Such biogenic textures have been observed on sinter deposits around the world and are usually microbial in origin,Template:Sfn at El Tatio they sometimes feature still living bacteriaTemplate:Sfn which can get entombed and preserved within the sinter deposits.Template:Sfn In the case of El Tatio, these biogenic textures are particularly well preserved in the sinter deposited by water flowing away from springs.Template:Sfn Chloroflexus is a thermophilic filamentous green bacterium found in hot waters at Yellowstone; filamentous structures within geyser cones at El Tatio may have been formed by this bacterium.Template:Sfn In splash cones Synechococcus-like microbes are instead responsible for the structures, which resemble those of hot springs.Template:Sfn Sinter absorbs much of UV radiation, protecting microorganisms that dwell within the sinter against this harmful radiationTemplate:Sfn although it also absorbs light required for photosynthesis.Template:Sfn

Diatoms are also found in El Tatio waters, including Synedra species, which are often found attached to filamentous substrates,Template:Sfn and algae are found in the waters.Template:Sfn Among bacteria identified in the somewhat colder flowing waters are Bacteroidota and Pseudomonadota, with Thermus species in the hot waters.Template:Sfn Various archaeans have been cultured from El Tatio waters, with hot springs producing Thermoproteota (formerly crenarchaea), desulfurococcales, and methanobacteriales.Template:Sfn One species, Methanogenium tatii, has been discovered at El Tatio, and is a methanogen recovered from a warm pool. The species name is derived from the geothermal fieldTemplate:Sfn and other methanogens may be active in El Tatio.Template:Sfn

MacroorganismsEdit

In the upper geyser basin, vegetation has been observed to grow within thermal areas, like a thermal marsh.Template:Sfn A wetland, known as Vega Rinconada, with hydrothermal vents lies west of the upper geyser basin.Template:Sfn Animal species found at El Tatio include the snail Heleobia,Template:Sfn the frog Rhinella spinulosa,Template:Sfn and water mites.Template:Sfn The larvae of this frog at El Tatio live in water with approximately constant temperatures of Template:Convert and show atypical development patterns compared to frogs of the same species that developed in places with more variable water temperatures.Template:Sfn Liolaemus lizard species have been recovered from the geyser area.Template:Sfn

Analogies to MarsEdit

The climate, environmentTemplate:Sfn and hydrothermal activity at El Tatio has been used as analogues for processes that took place on early Mars.Template:Sfn Some microstructures found in the Columbia Hills Template:Sfn at the Home Plate landformTemplate:Sfn are similar to these biogenic structures at El Tatio, but do not necessarily imply that the microstructures on Mars are biogenic.Template:Sfn Template:Sfn

Geological historyEdit

During the Pliocene–Quaternary the Cordillera Occidental was subject to extensional tectonics. A related fault system was active; it is linked to Sol de Mañana in BoliviaTemplate:Sfn and controls the position of several vents in El Tatio.Template:Sfn The intersection between northwest–southeast trending, north-northwest-south-southeast-trending lineaments at El Tatio has been correlated with the occurrence of geothermal activity.Template:Sfn The tectonics of the El Tatio area were originally interpreted as reflecting the existence of a graben before a compressive tectonic regime was identified.Template:Sfn

A series of ignimbrites was emplaced.Template:Sfn The first was the 10.5–9.3 million year oldTemplate:Efn Rio Salado ignimbrite, which forms a Template:Convert thick layer; this might imply that the source of this ignimbrite was close to El Tatio. The Rio Salado ignimbrite elsewhere crops out as two flow units, with varying colours, and close to El Tatio it is crystalline and densely welded.Template:Sfn It was followed by the 8.3 million year old voluminous Sifon ignimbrite, which reaches a thickness of about Template:Convert in the area.Template:Sfn The Pliocene Puripicar ignimbrite reaches a similar thickness,Template:Sfn and it was later downwarped by faulting.Template:Sfn

This strong ignimbrite volcanism is associated with activity of the Altiplano–Puna volcanic complex, which has produced large volume dacite ignimbrites and sizable calderas, starting from the middle Miocene. Among these, Cerro Guacha, La Pacana, Pastos Grandes and Vilama produced supereruptions.Template:Sfn

The Tatio ignimbrite was emplaced 710,000 ± 10,000 years ago,Template:Sfn while the Tucle volcanics are dated to 800,000 ± 100,000 years ago.Template:Sfn The ignimbrite reaches a volume of Template:Convert and crops out over a surface area of Template:Convert.Template:Sfn The Tatio ignimbrite contains rhyolitic pumice and crystals, while the Tucle volcanics are andesitic and include both lava and tuffs.Template:Sfn The El Tatio ignimbrite ponded in the El Tatio area and may have originated at the Tocorpuri rhyolite dome, which is less than one million years old,Template:Sfn in a vent now buried beneath the El Tatio volcanic group,Template:Sfn or at the Laguna Colorada caldera.Template:Sfn

The El Tatio volcanic group has likewise been dated to be less than one million years old,Template:Sfn and its lavas overlie the older formations.Template:Sfn Volcan Tatio erupted mafic Template:Efn lavas probably during the Holocene;Template:Sfn later this volcano was reinterpreted to be of Pleistocene age.Template:Sfn Petrological data suggest that over time the erupted lavas of the El Tatio volcanic group have become more mafic, with older products being andesitic and later ones basaltic-andesitic.Template:Sfn

There is no recorded historical volcanism in the El Tatio areaTemplate:Sfn and volcanism has not directly affected it for about 27,000 years.Template:Sfn Based on the rates of sinter precipitation and the thickness of the sinter deposits, it has been estimated that the sinters at El Tatio started to form between 4,000 and 1,500 years ago; these age estimates were not based on direct dating of the deposits, however,Template:Sfn and older sinter deposits extend past the present-day geothermal field.Template:Sfn Later, radiocarbon dating of the sinter deposits found that their deposition began after the end of the last ice age,Template:Sfn an observation endorsed by the presence of glacial deposits beneath the sinterTemplate:Sfn and radiocarbon dating evidence that sinter deposition began after glaciers retreated.Template:Sfn Research published in 2020 suggests that the geothermal activity commenced in the southern part of the field about 27,000–20,000 years ago and spread northwards, reaching the western part of the field less than 4,900 years ago.Template:Sfn Secular variations in the deposition rate have been found, with an increase noted in the last 2,000 years.Template:Sfn

Geothermal exploitationEdit

File:Geyser of El-Tatio, technical use of the hot water.jpg

Technical equipment at El Tatio

Geothermal energy comes from the internal heat of the Earth, where the heat flow is sufficiently high that it can be used for heating and for the generation of electrical power.Template:Sfn In Chile, various legal and economic hurdles have so far prevented substantial development of geothermal energy.Template:Sfn Template:Sfn

The earliest references to geothermal power at El Tatio go back to the beginning of the 20th century, when a private society "Comunidad de El Tatio" was founded by Italians in AntofagastaTemplate:Sfn and employed Italian engineers from Larderello, who probed the field in 1921 and 1922.Template:Sfn Technical and economic problems prevented further progress at that time.Template:Sfn Later feasibility studies in northern Chile identified El Tatio as a potential site for geothermal power generation, and large-scale prospecting took place in the 1960s and 1970s. Wells were drilled in 1973 and 1974, and it was estimated that if the geothermal resources were fully exploited, about Template:Val of electric power could be produced,Template:Sfn but the 1973 Chilean coup d'etat derailed further exploration efforts.Template:Sfn Also in 1974 a desalination facility was built at El Tatio and could still be seen there in 2003;Template:Sfn a thermal desalination process was developed at El Tatio that produced fresh water while also saving the remaining brine to extract valuable minerals.Template:Sfn The drilling substantially altered the behaviour of the hot springs; already in November 1995, reports indicated that a number of geysers had disappeared or become hot springs and fumaroles.Template:Sfn

El Tatio is remote, and this along with economic difficulties eventually led to the abandonment of the efforts at power generation;Template:Sfn a bidding process for exploration rights in 1978 to attract private companies to El Tatio was interrupted by government changesTemplate:Sfn and until 2000 geothermal development programs were paralyzed.Template:Sfn

More recently in the 2000s several companies expressed interest in restarting geothermal power projects at El Tatio.Template:Sfn A dispute over the gas supply from Argentina to Northern Chile in 2005 helped push the project forward,Template:Sfn and after an environmental impact review in 2007Template:Sfn the Chilean government in 2008 granted a concession to develop geothermal resources in the field, with the expected yield being about 100Template:Sfn Template:Sfn-40 megawatt.Template:Efn The first drilling permits were issued for the Quebrada de Zoquete area Template:Convert away from the main field.Template:Sfn

ControversyEdit

File:60m artificial fumarole at el tatio geothermal field.jpg

Steam venting created by the geothermal well blowout

On 8 September 2009,Template:Sfn an older well in El Tatio that was being reused blew out,Template:Sfn generating a Template:Convert high steam fountainTemplate:Sfn that was not plugged until 4 October.Template:Sfn The operator of the geothermal project restricted access to the blow-out vent and stated through the technical manager of the El Tatio geothermal project that the blowout was neither a threat to the springs nor to tourists visiting El Tatio, and the Empresa Nacional de Geotermia company that operates it denied any responsibility for the incident.Template:Sfn

The project had earlier been opposed by the local Atacameño population, owing to concerns about environmental damageTemplate:Sfn and the religious importance of waterTemplate:Sfn and El Tatio in the region.Template:Sfn Before the incident, an issue of the English-language newspaper The Economist had called attention to the adverse consequences of geothermal power extraction;Template:Sfn the incident triggered a major controversy over geothermal power, with ramifications beyond Chile.Template:Sfn The controversy gained widespread nationalTemplate:Sfn and international attention,Template:Sfn leading to the Chilean government shutting down geothermal exploration at El TatioTemplate:Sfn and drawing attention to the drawbacksTemplate:Sfn of geothermal power generation.Template:Sfn There were public demonstrations against the project, such as the march of two women to the capital Santiago to defend the geothermal field.Template:Sfn The environmental authorities of Antofagasta subsequently suspended the El Tatio geothermal project, and the Geotérmica del NorteTemplate:Efn company responsible for the project received strong criticism and was targeted by legal action. Both the Ministers of Mining and Energy cautioned against stigmatizing geothermal energy, however,Template:Sfn and some local authorities disagreed with the rejection.Template:Sfn The director of the National Geology and Mining Service (SERNAGEOMIN) stated that the company had no plans to handle such a situation.Template:Sfn The Geotérmica del Norte company was fined 100 Template:Ill Template:Efn (a Chilean unit of account for fines and sanctions) for violating mitigation plans, a fine upheld in 2011 by the Court of Appeals in Santiago.Template:Sfn Legal cases related to the Tatio field went as far as the Inter-American Court of Human Rights.Template:Sfn

Industry-community disputes have occurred before in northern Chile, typically tied to conflicts about the use of water,Template:Efn which was in large part privatized during the Pinochet era; during the Tatio controversy, power generationTemplate:Sfn and relations between the Chilean government and native communities also gained prominence among the disputed issues.Template:Sfn An important factor in the Tatio controversy is the role of the tourism industry, which viewed the geothermal project as a threat; this kind of industry-industry conflict was unusual.Template:Sfn Geothermal projects in New Zealand and the United States have resulted in the extinction of geysers.Template:Sfn While the incident ultimately did not result in lasting changes to the El Tatio geysers, the widespread media attention did create adverse publicity and social opposition - in particular among indigenous leaders in the region - against geothermal energy in Chile.Template:Sfn Template:Sfn

TourismEdit

El Tatio is a tourism destination, with substantial numbers of travelers both from Chile and other countries. This tourism is an important economic resource for the region,Template:Sfn Template:Sfn and the site is administered by the local Atacameño populationTemplate:Sfn as part of a wider trend of cooperations between native communities and heritage sites in the region.Template:Sfn About 100,000 tourists visit El Tatio every year.Template:Sfn In 2009, there were more than 400 daily visitors of the geysers, about 90 percent of all tourism of San Pedro de AtacamaTemplate:Sfn from where El Tatio can be reached.Template:Sfn Aside from viewing the geysers, bathing in the hot water, watching the natural sceneryTemplate:Sfn and visiting surrounding Atacameño villages with their adobe buildings are other activities possible at El Tatio.Template:Sfn Environmental impacts such as pollution and vandalism of geothermal landforms have been documented.Template:Sfn

File:Medidads de seguridad en los Geisers del Tatio 03.JPG

Safety warning sign

El Tatio displays some typical hazards of geothermal areas.Template:Sfn Exposure to the hot gases and water can result in burn injuries, and both sudden eruptions of geysers and fountains and fragile ground above vents and above boiling water, concealed beneath thin covers of solid ground, increase the risk to unwary travelers.Template:Sfn The site lies at high altitude, frequently leading to altitude sickness, and the cold dry climate creates further danger.Template:Sfn The Chilean government recommends that tourists take warm clothing, sunscreen and mineral water.Template:Sfn

The indigenous communities of Toconce and Caspana administer the geysers.Template:Sfn Template:Sfn In 2002, El Tatio was declared part of a "zone of touristic interest"; a classification which implies that local institutions ought to develop an action plan to induce the development of tourism.Template:Sfn In 2009, José Antonio Gómez Urrutia, then-senator of Chile for the Antofagasta region proposed that El Tatio be declared a natural sanctuary (a type of protected area); the corresponding parliamentary motion was approved in the same year.Template:Sfn In 2010, the El Tatio area was declared to be a protected area, with a surface area of Template:Convert. It was not clear at that time what the exact status would be, with the regional Secretary of Agriculture proposing that it should become a national park.Template:Sfn In 2022, the International Union of Geological Sciences listed it among its 100 heritage sites.Template:Sfn

NotesEdit

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ReferencesEdit

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SourcesEdit

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El Tatio

Contents

Name and research historyEdit

Geography and geomorphologyEdit

Geothermal fieldEdit

GeologyEdit

HydrologyEdit

FumarolesEdit

Composition of spring depositsEdit

Climate and biologyEdit

Spring biologyEdit

MicroorganismsEdit

MacroorganismsEdit

Analogies to MarsEdit

Geological historyEdit

Geothermal exploitationEdit

ControversyEdit

TourismEdit

See alsoEdit

NotesEdit

ReferencesEdit

SourcesEdit

External linksEdit