Parinacota (volcano)
Template:Short description Template:About Template:Good article Template:Infobox mountain Parinacota (in Hispanicized spelling), Parina Quta or Parinaquta is a dormant stratovolcano on the border of Bolivia and Chile. Together with Pomerape it forms the Nevados de Payachata volcanic chain. Part of the Central Volcanic Zone of the Andes, its summit reaches an elevation of Template:Convert above sea level. The symmetrical cone is capped by a summit crater with widths of Template:Convert or Template:Convert. Farther down on the southern slopes lie three parasitic centres known as the Ajata cones. These cones have generated lava flows. The volcano overlies a platform formed by lava domes and andesitic lava flows.
The volcano started growing during the Pleistocene and formed a large cone. At some point between the Pleistocene and the Holocene, the western flank of the volcano collapsed, generating a giant landslide that spread west and formed a large, hummocky landslide deposit. The avalanche crossed and dammed a previously existing drainage, impounding or enlarging Lake Chungará; numerous other lakes now forming the headwaters of the Rio Lauca sprang up within the deposit. Volcanic activity rebuilt the cone after the collapse, cancelling out the collapse scar.
Parinacota had numerous effusive and explosive eruptions during the Holocene, the latest about 200 years ago. While there are no recorded eruptions, legends of the local Aymara people imply that they may have witnessed one eruption. Renewed activity at Parinacota is possible in the future, although the relatively low population density in the region would limit potential damage. Some towns and a regional highway between Bolivia and Chile are potentially exposed to the effects of a new eruption.
Name
The name "Parinacota" is Aymara. Parina means flamingo<ref name="Name1" /> and quta lake.<ref name="Katari" /> Parinacota and its neighbour Pomerape are also known as the Nevados de Payachata,Template:Sfn "twins". This refers to the fact that the volcanoes resemble each other.<ref name="SchullRothhammer2012" />
Geomorphology and geology
Parinacota lies in the Altiplano, a high plateau in the Central Andes.Template:Sfn The border between Bolivia and Chile bisects the volcano and runs along the rim of the crater, which lies in Bolivia.Template:Sfn In Chile, where most of the edifice is located,Template:Sfn Parinacota lies in the commune of Putre, Arica y Parinacota Region, and in Bolivia in the Oruro Department of the Sajama Province.<ref name="SERNAGEOMIN" /> The towns of Ajata and Parinacota lie southwest and west of the volcano, respectively.Template:Sfn The region lies at high altitude and access is difficult, hampering research on the volcanoes of the Central Andes.Template:Sfn
Regional
The Nazca Plate and Antarctic Plate subduct beneath the South America Plate in the Peru-Chile Trench at a pace of Template:Convert and Template:Convert, respectively, resulting in volcanic activity in the Andes.<ref name="Stern2004" /> Present-day volcanism occurs within four discrete belts: The Northern Volcanic Zone (NVZ), the Central Volcanic Zone (CVZ), the Southern Volcanic Zone (SVZ) and the Austral Volcanic Zone (AVZ).Template:Sfn These extend between 2°N-5°S, 16°S-28°S, 33°S-46°STemplate:Sfn and 49°S-55°S, respectively.<ref name="Stern2004" /> Between them they contain about 60 active volcanoes and 118 volcanoes which appear to have been active during the Holocene, not including potentially active very large silicic volcanic systems or very small monogenetic ones.<ref name="Stern2004" /> These belts of active volcanism occur where the Nazca Plate subducts beneath the South America Plate at a steep angle, while in the volcanically inactive gaps between them the subduction is much shallower;Template:Sfn thus there is no asthenosphere between the slab of the subducting plate and the overriding plate in the gaps.<ref name="Stern2004" />
Parinacota is part of the CVZ, which contains about 44 active volcanoes.<ref name="Stern2004" /> Most volcanoes of the CVZ are relatively poorly researched and many exceed Template:Convert of elevation. Some of these edifices were active during historical time; these include El Misti, Lascar, San Pedro and Ubinas;Template:Sfn the largest historical eruption of the CVZ occurred in 1600 at Huaynaputina.<ref name="Stern2004" /> Other volcanoes in the CVZ that have been the subject of research are Galan and Purico complex.Template:Sfn The CVZ has a characteristically thick crust (Template:Convert) and the volcanic rocks have peculiar oxygen and strontium isotope ratios in comparison to the SVZ and NVZ.Template:Sfn Parinacota lies in a segment of the CVZ where the Peru-Chile Trench undergoes a 45° curvature,Template:Sfn and where the direction of subduction changes from diagonal to perpendicular. The crust is especially thick there,Template:Sfn the reasons for this are not agreed upon yet and may vary between the western and eastern sides of the CVZ.<ref name="Stern2004" />
Subduction-related volcanism in the region has been ongoing since 200 million years ago, burying most of the Precambrian basement. Various units of sedimentary and volcanic origin form most of the outcropping basement in the region.Template:Sfn A dramatic increment of volcanic activity occurred approximately 27 million years ago, when the Farallon Plate broke apart and subduction increased substantially.<ref name="Stern2004" /> On the Chilean side, the basement is formed by the Oligocene-Miocene Lupica formation, the Miocene Ajoya volcanics, the Lauca formationTemplate:Sfn and the Lauca Ignimbrite.Template:Sfn On the Bolivian side the oldest volcanites are the Oligocene Kollukollu formation 34 million years ago and the 23 million years old Rondal Lavas. Miocene volcanic activity generated the Berenguela, Carangas and Mauri formations,Template:Sfn followed by the Perez formation during the Pliocene and Pleistocene. These formations were all affected by terrain uplift and folding, probably linked to changes in the subduction regime. Volcanism continued into the late Pleistocene and Holocene (Condoriri 650,000±70,000Template:Sfn and Pomerape between 300,000-100,000 years agoTemplate:Sfn), and was accompanied by glacial activity during the Pleistocene.Template:Sfn During this whole time period, volcanic activity progressively migrated westward; presently, it is located on the Bolivia-Chile border.Template:Sfn
Local
Parinacota is a highly symmetric volcanic cone,Template:Sfn having the classical "regular cone" shape of a stratovolcano.<ref name="KarátsonFavalli2010" /> The volcano is Template:ConvertTemplate:Sfn or Template:Convert highTemplate:Sfn and features both blocky lava flows and scoria flows.Template:Sfn Lava flows are fresh with levees, lobes and flow ridges, and reach lengths of Template:Convert on the slopes of the cone. The lava flows are between Template:Convert thick and can spread to widths of Template:Convert at the foot of the volcano. Pyroclastic flows are also found, reaching lengths of Template:Convert and are usually poorly consolidated, containing breadcrust bombs and breccia.<ref name="ClaveroSparks2004" />
The volcano is capped by a Template:Convert wideTemplate:Sfn and Template:Convert deep summit crater,Template:Sfn which has a pristine appearance.<ref name="GVP" /> Other data imply a width of Template:Convert and a depth of Template:Convert.<ref name="ClaveroSparks2004" /><ref name="SERNAGEOMIN" /> The crater is the source of pumice flows, which have well conserved surface features such as levees and lobes especially down on the eastern slope. These pumice flows extend as far as Template:Convert away from the crater.Template:Sfn An ashfall deposit spreads east from ParinacotaTemplate:Sfn to a distance of Template:Convert in Bolivia.<ref name="ClaveroSparks2004" /> Ash and lapilli deposits have been found at the shores of Lake Chungará as well.Template:Sfn
The cone sits atop a Template:Convert thick multilobed andesitic platform known as the "Chungará Andesites"Template:Sfn which crop out on the north shore of Lake Chungará in the form of a shelf.Template:Sfn Overlying this shelf is a system of lava domes,Template:Sfn which reach thicknesses of Template:Convert. The lava domes are accompanied by block and ash flow deposits that reach lengths of Template:Convert.<ref name="ClaveroSparks2004" /> A steep descent leads to Lake Chungará.Template:Sfn
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Parinacota volcano
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The white lava domes and a black lava flow are visible above the lake
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The domes at the foot of Parinacota are well visible. In the middle right of the image, one of the Ajata lava flows is recognizable
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The grey lava domes and a black Ajata lava flow are clearly visible
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A black lava flow almost reaches the lake
South of the main edifice lie the parasitic vents known as the Ajata cones,Template:Sfn which formed along a fissure that emanates from the main coneTemplate:Sfn and is aligned with the regional Condoriri-Parinacota lineament.<ref name="ClaveroSparks2004" /> The dimensions of the cones reach Template:Convert width and Template:Convert height.<ref name="ClaveroSparks2004" /> The High Ajata flow emanates from a single cone and spreads southwest as a lobated lava flow. The middle Ajata flow is much smaller and is sourced to three different cones below the source of the High Ajata, each cone having its own small flow field. The upper and lower Ajata flows are only slightly smaller than the High Ajata flow and form superposed lava flows lower on the edifice.Template:Sfn These lava flows are gray-blackTemplate:Sfn aa lava flows, commonly up to Template:Convert thick;<ref name="ClaveroSparks2004" /> the longest of these flows reaches a length of Template:Convert.Template:Sfn
Older are the large dacitic lava flows known as the "Border Dacites" on the southeastern side of Parinacota, which are Template:Convert over horizontal distance. A similar but smaller lava flow lies west of the Border Dacites, entirely within Chile. These three lava flows have a total volume of about Template:Convert.Template:Sfn Overall, Parinacota rises Template:Convert from a surface of Template:Convert; the resulting edifice has a volume of Template:ConvertTemplate:SfnTemplate:Sfn
On the northern side Parinacota partly overlaps with Pomerape,Template:Sfn which in turn overlies the rocks of Condoriri fartherTemplate:Sfn north; together the volcanoes form a north-northeast trending volcano chain.Template:Sfn Parinacota, Pomerape, and volcanoes farther south like Quisiquisini, Guallatiri and Poquentica constitute the eastern margin of the Lauca basin.Template:Sfn This is a relatively gentle plainTemplate:Sfn drained by the Rio Lauca. A chain of dormant or extinct volcanoes farther west like Taapaca forms the western margin of the basin and separates the Altiplano from the steep dropoff to the Atacama west of the Lauca basin.Template:Sfn
Glaciers
The old cone was subject to glaciation, and traces of glacial erosion are preserved on its lava flows.Template:Sfn A system of moraines can be seen at an elevation of Template:Convert<ref name="Paskoff1977" /> on the southeastern foot of the volcano, where they partly cross the shores of Lake Chungará.Template:Sfn Six such Template:Convert high moraines have been identified there, they were formed during the regional last glacial maximum (which did not coincide with the global last glacial maximum<ref name="ClaveroSparks2004" />)Template:Sfn although a pre-last glacial maximum origin has been proposed.<ref name="Heine2019" /> Other, unspecified glacial deposits have also been observed in this area.Template:Sfn
Presently, a Template:Convert<ref name="ClaveroSparks2004" /> or Template:Convert large ice cap covers the upper parts of the volcanoTemplate:Sfn and drops down to an elevation of about Template:Convert.Template:Sfn There is also a large glacier on its southern flank.Template:Sfn Some reports disagree with calling any part of Parinacota's ice cap a "glacier", however.<ref name="RiveraCasassa2000" /> Between 1987 and 2016, ice area at Parinacota and Pomerape declined by 1.94% every year.<ref name="Reinthaler2019" /> A retreat of Template:Convert was noted between 2002 and 2003,<ref name="BarcazaNussbaumer2017" /> and Template:As of most of the ice lies on the western slope of the mountain.Template:Sfn
Sector collapse
Parinacota shows evidence of a major sector collapse (a giant landslide),Template:Sfn whose deposit was originally interpreted to be a lava flow.Template:SfnTemplate:Sfn The collapse removed a volume of about Template:Convert from the cone, plunged over Template:Convert vertical distanceTemplate:Sfn and flowed Template:Convert west, covering a surface area of Template:ConvertTemplate:Sfn or Template:Convert with debris; the volume is not very well established.Template:Sfn Template:Sfn
As the volcano grew, it put more and more load on relatively weak sedimentary material that the volcano had developed on, deforming it, until these sedimentary rocks gave way.Template:SfnTemplate:Sfn The western slope might have been weakened by glacial action, further facilitating the onset of the collapse.Template:Sfn The collapse was probably sequential from the lower part of the edifice to the summit,Template:Sfn and it formed an avalanche of rocks that flowed down the volcano.Template:Sfn This flow was probably laminar and extremely fast (Template:Convert<ref name="ClaveroSparks2004" /> ), judging from the morphologies of the avalanche deposit,Template:Sfn and it incorporated substantial pre-collapse sediments from the Lauca basin.Template:Sfn As the avalanche descended the slopes of the volcano, it picked up enough speed to run up on some topographical obstacles.Template:Sfn Such collapses have occurred on other volcanoes in the CVZ such as Llullaillaco, Ollagüe, Socompa and Tata Sabaya; the most recent event occurred between 1787 and 1802 at Tutupaca in Peru and was much smaller than the Parinacota sector collapse.<ref name="SamaniegoValderrama2015" />
The collapse event resembled the one that occurred on Mount St. Helens during the latter's eruption in 1980,Template:Sfn although the Parinacota collapse was three times larger.<ref name="HoraSinger2005" /> A separate, minor sector collapse occurred on a lava dome on the southwestern foot of the volcano at an unknown time.Template:Sfn Such sector collapses are a common phenomenon on volcanoes.Template:Sfn
The avalanche eventually came to rest in a large "L" with the long side extending along the axis of the collapse and the short side closer to the edifice pointing northTemplate:Sfn where its advance was limited by tomography,Template:Sfn formed an exceptionally well preserved debris avalanche deposit.Template:Sfn This deposit has a "hummocky" appearance typical for sector collapse deposits; individual hummocks can reach sizes of Template:Convert and heights of Template:Convert,Template:Sfn with the size decreasing away from the volcano.Template:Sfn The formation of these hummocks was probably influenced by the pre-existing structure of the edifice; much of the original stratigraphy of the pre-collapse edifice was preserved within the final collapse deposit.Template:Sfn As the avalanche came to rest, compressional ridges formed with axes perpendicular to the movement of the avalanche.Template:Sfn A few large Toreva blocks lie in the avalanche deposit just at the foot of Parinacota,Template:Sfn they reach heights of Template:Convert and volumes of Template:Convert.Template:Sfn Large blocks with sizes of up to Template:Convert are part of the deposit, and some of these blocks preserve details of the pre-collapse structure;Template:Sfn the blocks reach sizes of Template:Convert even at large distances from Parinacota.Template:Sfn These large blocks dominate the avalanche deposit; fine material is not present in the Parinacota collapse deposit,Template:Sfn an unusual feature among debris avalanches.Template:Sfn Some blocks slid away from the main avalanche deposit.Template:Sfn The avalanche deposit displays a noticeable split into two units; the upper one is andesitic and originated from the actual cone, the lower one is derived from the lava domes beneath the present-day edifice.<ref name="ClaveroSparks2004" />
This collapse gave birth to Lake Chungará when the avalanche flowed across a westbound drainage between Choquelimpie and Parinacota,Template:Sfn forming a Template:Convert high volcanic dam that retained about Template:Convert of water. The formation of lakes during sector collapses has been observed at other volcanoes, including the 1988 Mount St. Helens collapse.Template:Sfn Prior to the collapse, alluvial and riverine deposits occupied the area.Template:Sfn In 2015 it was proposed that a much smaller lake occupied part of the Lake Chungará basin before the collapse.Template:Sfn
Within the hummock-like topography of the deposit, a number of other lakes and peat filled basins are found,Template:Sfn formed by water percolating through the avalanche deposit.Template:Sfn These lakes are known as the Lagunas Cotacotani lakes,<ref name="LautaroSantoro1988" /> and are an important bird refuge.Template:Sfn At least some of these lakes may be kettle holes, formed when blocks of ice transported within the avalanche melted.Template:Sfn With increasing distance from the main cone the size of the lakes decreases.Template:Sfn Some of these lakes are connected with each other and others are isolated, and during periods of low lake stands some of the lakes can become disconnected from each other. Springs at the foot of Parinacota form the Rio Benedicto Morales which flows through some of the lakes and ends in the main Lake Cotacotani.Template:Sfn Otherwise, these lakes receive water from Lake Chungará through seepage. The lakes ultimately form the headwaters of the Rio Lauca,Template:Sfn whose course previously extended across the area covered by the avalanche.Template:Sfn The river has not carved an outlet all the way to Lake Chungará, probably because the relatively coarse avalanche deposit allows large amounts of water to seep through without carving a new river channel.Template:Sfn The rate at which waters seep through the avalanche deposit has been estimated at Template:Convert;Template:Sfn it has progressively decreased over time, probably as a consequence of increased siltation within the avalanche deposit. Thus the depth and surface area of Lake Chungará have increased since the formation of the lake, and so has evaporation,Template:Sfn which currently removes almost 5/6 of the total inflow.Template:Sfn
A pumice fall deposit of dacitic composition is associated with the sector collapse event,Template:Sfn which together with lava bombs suggest that an eruption took place at the time of the collapse;Template:Sfn this has been contested however.Template:SfnTemplate:Sfn The sector collapse was probably not caused by an eruption,Template:Sfn although the intrusion of a cryptodome may have helped.<ref name="ClaveroSparks2004" /> There is no evidence on the edifice for the existence of a collapse scar,Template:Sfn indicating that post-collapse volcanic activity has completely filled up the space removed by the collapse.Template:Sfn The volcanic edifice has reached a volume similar to its volume before the failure.Template:Sfn
Surroundings
The terrain around Parinacota is mostly formed by Neogene volcanic rocks. These are for the most part over one million years old and include individual volcanic centres such as Caldera Ajoya, Caldera Lauca, Choquelimpie,Template:Sfn Condoriri,<ref name="ClaveroSparks2004" /> Guane Guane, Larancagua and Quisiquisini,Template:Sfn and the Miocene Lauca ignimbrite (2.7 ± 0.1 million years ago) that forms the basement.Template:Sfn The activity of many of these centres occurred over 6.6 million years ago.Template:Sfn At slightly larger distances lie the volcanoes Guallatiri, Nevados de Quimsachata and Taapaca.Template:Sfn Proterozoic and paleozoic basement rocks crop out as charnockite/granulite east and as amphibolite/gneiss west of the volcano, respectively.Template:Sfn Other formations include the volcaniclastic Lupica Formation of Oligocene-Miocene age and the lacustrine Lauca formation.<ref name="ClaveroSparks2004" />
A number of volcanoes have been active around Parinacota in the last one million years. Pomerape northeast of Parinacota is similar to Parinacota but the greater degrees of erosional decay suggest it is older than Parinacota; a subsidiary vent dated 205,000 years ago is found on its eastern slope.Template:Sfn Pomerape is a comparatively simple volcanic cone whose foot is covered by glacial debris. One age obtained on the cone is 106,000 ± 7,000 years ago.Template:Sfn The Caquena and Chucullo rhyolitic to andesitic lava domes are found northwest and southwest of Parinacota, respectively;Template:Sfn they are associated with the oldest stages of activity at Parinacota.Template:Sfn
Periglacial and erosional landforms
Periglacial landscapes are frequent in the area; they include rounded landforms, smooth surfaces, solifluction terrain and striated terrain.Template:Sfn This extensiveness is the result of the relatively dry climate in the region, which limits the development of glaciers.Template:Sfn On Parinacota, landforms of this type are found starting from Template:Convert elevation and become dominant above Template:Convert until the glacier line.Template:Sfn The extent of their development is a function of the age of the underlying rocks as well; Holocene volcanic rocks have little periglacial alteration while older rock formations at times are heavily altered.<ref name="Heine2019" /> Lahars also occurred during the history of Parinacota; Template:Convert thick layers of lahar deposits are found on the southern and eastern slopesTemplate:Sfn and form a fan on the northwestern slope of Parinacota. At this fan, lahar deposits reach distances of Template:Convert away from the volcano.<ref name="ClaveroSparks2004" />
Erosion has formed gullies on the upper sector of Parinacota.Template:Sfn Otherwise, the volcanic rocks of Parinacota are well preserved owing to the arid climate and the youth of the volcano.Template:Sfn
Petrology
Volcanic rocks erupted by Parinacota range in composition from basaltic andesite to rhyolite.Template:Sfn Andesites from the old cone are classified as hornblende and pyroxene andesites.Template:Sfn Minerals found within the rocks include amphibole, apatite, biotite, clinopyroxene, iron oxide and titanium oxide, feldspar, olivine, orthopyroxene, pyroxene, sanidine and zircon. Not all of these minerals are found in rocks from all stages of Parinacota.Template:Sfn Some of these minerals, such as quartz and sanidine, were at least in part formed by the inclusion of foreign rocks into the magma.Template:Sfn Gabbro and granite are found as xenoliths.<ref name="ClaveroSparks2004" />
Overall, volcanic rocks at Parinacota belong to a potassium-rich calc-alkaline suite. The volcanites have characteristically high contents of barium and strontium,Template:Sfn especially in the youngest Ajata rocks where their concentration is higher than in any other CVZ volcanic rock.Template:Sfn A trend to a more tholeiitic composition in younger eruptions may reflect an increased magma flux and a decreased interaction with the upper crust.Template:Sfn
The magmas that formed Parinacota and Pomerape are considered to be a group distinct from these that formed older volcanic centres in the region, but also distinct from the magmas that formed the subsidiary vent of Pomerape and the Ajata cones; these tend to be more mafic.Template:Sfn In turn, the younger and older Ajata cone lavas have different compositions,Template:Sfn one having a high quantity of strontium and the other a low one.Template:Sfn
Magmas in the Parinacota region formed through distinct processes. One of these is fractional crystallization within closed magma chambers.Template:Sfn Another is the mixing of different magmas, one of which in the case of Parinacota may be the Ajata magmas.Template:Sfn More specifically, two different magmas with compositions akin to the Ajata magmas contributed the mafic element to the Parinacota magmas.Template:Sfn Some differences in magma composition between various volcanoes and stages may reflect the occurrence of several different magma differentiation events.Template:Sfn
Processes within magma chambers play an important role in the formation of the magmas erupted by volcanoes.Template:Sfn The diversity of the petrographic patterns suggest that Parinacota did not have a single major magma chamber, but rather various magma reservoirs at various depths and with variable interconnection patterns. Some Ajata magmas bypassed the shallow reservoirs completely.Template:Sfn Starting about 28,000 years ago however several different magma systems consolidated into one, probably as a result of more frequent injections of new magma and/or the accumulation of cumulates that insulated the magmatic system.Template:Sfn The transit of the magmas through the conduit system probably takes several ten thousand years,Template:Sfn and the residence time within magma chambers could be on the order of 100,000 years.Template:Sfn
In the case of Parinacota, there is a noticeable difference between the pre-sector collapse and post-sector collapse magmas, indicating that a large turnover of the magmatic system was triggered by the landslide.Template:Sfn More specifically, after the collapse erupted rocks became more maficTemplate:Sfn and their composition more influenced by fractional crystallization, while the preceding magmas were more strongly affected by mixing processes.Template:Sfn Also, magma output increased significantly,Template:Sfn while the resting time in the magma chambers decreased.Template:Sfn Modelling indicates that over the short term, a collapse would cause activity to stop at a volcano of Parinacota's size, and over the long term the plumbing system would change and become shallower.Template:SfnTemplate:Sfn Also, the plumbing system of the volcano would become more permissive to denser mafic magmas after a sector collapse, perhaps explaining why the Ajata vents were active after the collapse but the magma erupted through them influenced petrogenesis of main cone magmas much earlier.Template:Sfn The magnitude of such changes is considerably larger than at neighbouring volcano Taapaca, where a sector collapse was not accompanied by changes in activity; presumably Parinacota's shallower magma supply system made it more susceptible to the effects of unloading.<ref name="WörnerHora2008" />
The source of the Parinacota magmas is ultimately the mantle wedge above the slab of the Nazca Plate. Fluids released from the slab flux the wedge and trigger the formation of melts, with the assistance of asthenospheric material that is hotter and gets transported into the wedge.Template:Sfn These ascending magmas then interact with the crust, resulting in extensive changes to their composition.Template:Sfn The area in the crust where such interaction takes place is known as "MASH" or "Melting Assimilation Storage Homogenization", and it is there that the base magmas are formed which then enter into shallow magmatic systems.Template:Sfn Further, the relative thickness of the crust and narrowness of the mantle wedge mean that garnet is stable within the wedge, causing the magmas to be influenced by garnet-linked petrogenic processes. Shallower crustal components such as the locally extensive Lauca-Perez ignimbrite may have been assimilated by Parinacota as well.Template:Sfn These crustal components contributed about 12% of the primitive magmas as erupted by the Ajata cones, while the mantle wedge contributed 83%. Fluids from the slab and sediments subducted in the Peru-Chile Trench added the remaining 3 and 2%.Template:Sfn
Climate
Average temperatures at Parinacota are about Template:Convert,Template:Sfn with the Template:Convert isotherm hovering between Template:Convert elevation.Template:Sfn On neighbouring Sajama, on the summit temperatures range Template:Convert.Template:Sfn The atmosphere becomes thinner and drier at higher altitudes, allowing both increased solar radiation to reach the surface during daytime and more thermal radiation from the ground to escape to the top of the atmosphere during night. This pattern determines a large diurnal temperature amplitude in the region, with variations on the scale of Template:Convert.Template:Sfn
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Average precipitation at Parinacota is about Template:Convert.<ref name="ClaveroSparks2004" /> Between about 12 and 26° degrees southern latitude, most of the moisture that arrives was absorbed by winds over the Amazon and transported to the Andes. Thus, humidity increases from west to east,Template:Sfn with the Pacific coastline being particularly dry.Template:Sfn Parinacota lies within the puna seca climate region,Template:Sfn where precipitation occurs over 7 or 8 months of wet season and results in a total amount of Template:Convert,Template:Sfn most of it falling during the summer months when the Altiplano warms up under the sun, generating a monsoon-like wind current.Template:Sfn The summer precipitation is also known as the "Bolivian winter" or "Altiplanic winter".Template:Sfn This is an unusual precipitation pattern for Chile; most of the country has a mediterranean climate where most precipitation occurs during the winter months.Template:Sfn
The arid climate is a consequence of the activity of the South Pacific High just off the coast,Template:Sfn the rain shadow effect of the Andes and the cold Humboldt Current in the Pacific Ocean. The dry climate became apparent in the region 10–15 million years ago.Template:Sfn The generally arid climate of the region means that volcanoes can remain topographically recognizable for a long time, being subject to only minimal erosion.Template:Sfn Likewise, the groundwater pools in the region tend to be fairly old, going back to 13,000–12,000 years ago.Template:Sfn The climate was not always so dry in the past; around 28,000 years ago and between 13,000 and 8,200 years ago a wet period was accompanied by advances of glaciers.Template:Sfn The middle Holocene was dry, after 4,000 years before present climate became wetter again.Template:Sfn Because of the aridity, relatively little sediment is flushed into the Peru-Chile Trench from land, which has effects on the tectonics of the region and the chemistry of the magmas erupted in the volcanoes.<ref name="Stern2004" />
Winds at Parinacota come generally from the west, except during the wet season when easterly winds are common.Template:Sfn This wind pattern is controlled by the formation of a high-pressure area and a shift of the subtropical jet stream to the south.Template:Sfn
Flora and fauna
The Andes are a long mountain chain with different climates at various latitudes and elevations. Thus, vegetation differs from one location to the other.Template:Sfn In the region of Parinacota, between Template:Convert altitude the vegetation is formed by shrub steppe such as Baccharis incarum, Baccharis tola, Fabiana densa;Template:Sfn the dominant species are Deyuexia breviaristata, Festuca orthophylla, Parastrephia lucida and Parastrphia quadrangularis.Template:Sfn During the wet season, this vegetation is augmented by herbaceous plants. Above Template:Convert a grass vegetation dominates, which on rocky ground occasionally gives way to cushion vegetation such as Azorella compacta,Template:Sfn whose yellow colour is characteristic and can be seen from large distances.Template:Sfn This type of xeric vegetation is also known as "puna".Template:Sfn Herbs and shrubs reach elevations of Template:Convert.<ref name="Storz2024" /> Polylepis tarapacana is the only true tree found at high elevations (up to Template:ConvertTemplate:Sfn) and forms small woods.Template:Sfn Close to water, the bofedal marsh-like vegetation prevails,Template:Sfn with Oxychloe andina being the dominant species.Template:Sfn Some genera and species are endemic to the puna; they include Chilotrichiops, Lampaya, Parastrephia and Oreocerus.Template:Sfn
| Vegetation zone | Species |
|---|---|
| Wet sandy soils | Ephedra breana, Festuca, Pennisetum, Werneria glaberrima |
| Brackish and wet soils | Festuca orthophylla, Festuca scirpifolia, Poa |
| Wetlands and impermeable soils | Carex, Festuca scirphifolia, Oxychloe andina |
| Some species in the grass vegetation areaTemplate:Sfn | |
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Vegetation at Lake Chungará; the summit of Parinacota is enveloped in a cloud
Among the ecological factors that determine vegetation in the region are lack of water, saline soils, plentiful solar irradiation, herbivores, wind and cold nighttime temperatures.Template:Sfn These plant species which release airborne pollen can often be identified in samples taken from Parinacota's icecap, where winds deposit the pollen grains.Template:Sfn
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Animals in front of Lake Chungará
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Animals in front of Lake Chungará
Animal species that live around Parinacota include flamingo, guanaco, huemul, rhea, vicuña and viscacha.Template:Sfn Among predatory animals feature the Andean cat, the pampas cat and the puma. The most abundant animal species however are rodents, some of which can be found up to the highest treelinesTemplate:Sfn and which include the viscacha and the burrowing tuco-tuco. Also important are birds, such as the rhea, the tinamous, flamingos and various predatory and wetland birds, including the Andean condor.Template:Sfn
Many mammal species in the area were decimated in the past, although some have displayed a recent recovery in numbers.Template:Sfn Parinacota and surroundings in 1965 were made part of the Lauca National Park, which was further modified in 1970 and 1983 and is an UNESCO biosphere reserve. This natural preserve features a unique flora and fauna for Chile.Template:SfnTemplate:Sfn However, potential future water diversions from Lake Chungará, the hunting of indigenous animals, overharvesting of the vegetation, overgrazing and the existence of a major border-crossing highway close to Lake Chungará constitute ongoing threats to the environment around Parinacota.Template:Sfn
Lake Chungará adds to the local flora and fauna. These include charophytes,Template:Sfn diatoms and aquatic macrophyte plants. Animal taxa found in the lake include bivalves, gastropodsTemplate:Sfn and ostracods.Template:Sfn About 19 species of Orestias fish are found in the lake, some of which are endemic.Template:Sfn The speciation of Orestias chungarensis, Orestias laucaensis and Orestias piacotensis was aided by the volcanic activity of Parinacota and its collapse, which separated the watersheds inhabited by their ancestor species and caused allopatric speciation.<ref name="GuerreroPena2017" />
Eruptive history
Parinacota underwent five separate stages of volcanic activity.Template:Sfn A relatively young age of the last eruption is presumed considering the good preservation of volcanic landforms, such as lava flows and the summit crater;Template:Sfn SERNAGEOMIN considers it the most active volcano of the Central Andes by magma output.<ref name="SERNAGEOMIN" /> The high magma output may be facilitated by the presence of faults that facilitate the rising of magma; the Condoriri lineament in the area could be the fault that channels magma to Parinacota.Template:Sfn The injection of mafic magmas into magma chambers and the mixing between magmas of different composition has been held responsible for the onset of eruptions at many volcanoes including Parinacota.Template:Sfn
Chungará Andesites and lava domes
The oldest volcanic structure of Parinacota are the "Chungará Andesites" and the overlying lava dome, which form the platform that crops out on the southern side of the Parinacota volcano, facing Lake Chungará.Template:Sfn Erosion and glacial action has smoothed the surfaces of these rocks, leaving no primary textures.<ref name="ClaveroSparks2004" />
This platform was erupted between 300,000 and 100,000 years ago.Template:Sfn The finer subdivision defines the "Chungará Andesites" as having erupted 163,000–117,000 years ago and the "Rhyolite domes" being 52,000–42,000 years old.Template:Sfn Other dates obtained on these stages are 110,000 ± 4,000 and 264,000 ± 30,000 years ago for the Chungará Andesites and over 112,000 ± 5,000 for the "rhyolite domes".Template:Sfn These two units are also called "Parinacota 1".<ref name="ClaveroSparks2004" /> A hiatus of over 60,000 years occurred between the eruption of the "Chungará Andesites" and the formation of the lava dome plateau. Traces of explosive activity during the lava dome stage have been found.Template:Sfn
The "Chungará Andesites" have a volume of over Template:Convert;Template:Sfn material from these stages was incorporated in the collapse deposit.Template:Sfn Pomerape volcano developed during this time as well.Template:Sfn This and the long delay between the eruption of the Chungará Andesites and the rest of the volcano's history may imply that the magmatic systems involved were different.Template:Sfn Magma output during the early stage was low, with a magma output of Template:Convert with the dome growth contributing Template:Convert.Template:Sfn
Old Cone and sector collapse
At the same time as the lava domes were emplaced, the Old Cone started growing a short distance northwest of the domes.Template:Sfn The temporal gap between this stage of Parinacota's activity and the previous one may be because the deposits from this time interval are only poorly preserved.<ref name="ConwayLeonard2016" /> The Old Cone developed over 85,000 years until the sector collapse,Template:Sfn and is also known as Parinacota 2.<ref name="ClaveroSparks2004" /> Outcrops of this stage are found mostly low on the southeastern and north-northwestern slopes;Template:Sfn individual dates obtained on rocks from this stage are 20,000 ± 4,000, 46,700 ± 1,600,Template:Sfn and 53,000 ± 11,000 years ago.Template:Sfn The "Border Dacites" also belong to this stage, being dated at 28,000 ± 1,000 years ago.Template:Sfn Likewise, ash fall deposits found in the Cotacotani lakes have been dated to this period of volcanic history, indicating that the Old Cone occasionally featured explosive eruptions.<ref name="ClaveroSparks2004" /> This stage erupted andesite and daciteTemplate:Sfn in the form of three distinct suites.Template:Sfn Magma output during this time was about Template:Convert.Template:Sfn This also was a time of glacier growth and development in the region, and consequently a glacier cap developed on the Old Cone during this time. By the time of the sector collapse, the glaciers were already retreating.Template:Sfn
The date of the collapse is not known with certainty, because dates have been obtained on various materials with different stratigraphic interpretations.Template:Sfn Template:As of 18,000 years ago was considered the most likely estimate, but ages as young as 8,000 years ago were also proposed.Template:Sfn Radiocarbon dates from peat within the collapse deposit indicated an age of 13,500 years ago,Template:Sfn or 11,500–13,500 years ago.Template:Sfn Many dates were obtained on material predating the collapse that was embedded within the collapse deposit, and thus the most likely time for the collapse was considered to be 8,000 years ago.Template:Sfn Later research indicated an age between 13,000 and 20,000 years ago,Template:Sfn the most recent proposal is 8,800 ± 500 years before present.Template:Sfn
The postulated period coincides with a global clustering of volcano collapse events; perhaps global warming occurring during this time when the last glacial maximum approached its end predisposed volcanoes to collapse.Template:Sfn<ref name="CapraLucia2006" /> On the other hand, the younger dates of around 8,000 years ago significantly post-date the end of glaciation, thus if the collapse occurred at that time it was probably unrelated to glacial fluctuations.Template:Sfn This collapse and the collapse of Socompa farther south may have affected humans in the region.<ref name="LautaroSantoro1988" />
Young cone and Ajata
After the collapse, the cone was relatively rapidly rebuilt during the Young Cone stageTemplate:Sfn reaching a total volume of approximately Template:Convert.Template:Sfn The units erupted during this time are also known as the "healing flows"Template:Sfn or Parinacota 3.<ref name="ClaveroSparks2004" /> During this stage, volcanic activity was focused on the summit crater.Template:Sfn This stage was relatively short and accompanied by an increase in the magma output of ParinacotaTemplate:Sfn to Template:Convert depending on how the duration of this stage is measured.Template:Sfn The higher magma flux is comparable to peak output by other large stratovolcanoes.<ref name="HoraSinger2005" /> The maximum possible magma flux at Parinacota during this period is about Template:Convert.Template:Sfn
Apart from lava flows, sub-Plinian eruptions generated pumice and scoria flows,Template:Sfn with some individual explosive eruptions dated to 4,800 ± 800, 4,300 ± 2,600 and 3,600 ± 1,100 years ago.Template:Sfn Based on the patterns of tephra deposition in Lake Chungará, it is inferred that the rate of explosive activity increased after the early Holocene until recent times;Template:SfnTemplate:Sfn in addition, tephra falls contributed calcium to the lake watersTemplate:Sfn and impacted its biological productivity.Template:Sfn It has been proposed that dust particles found in ice cores at Nevado Sajama may actually be tephra from Parinacota.<ref name="GiraltMoreno2008" />
Various Holocene dates have been obtained from rocks on the southern flank of the Young Cone;Template:Sfn the youngest date for this stage was obtained by argon-argon dating: 500 ± 300 years ago.Template:Sfn Further, an age of less than 200 BP has been determined by radiocarbon dating for a pyroclastic flow.<ref name="ClaveroSparks2004" />
Other recent activity, originally considered to be the youngest, formed the Ajata cones.<ref name="ClaveroSparks2004" /> These cones are constructed by basaltic andesiteTemplate:Sfn with a volume of about Template:Convert.Template:Sfn The Ajata cones form four groups of different ages:Template:Sfn The lower Ajata flows were erupted 5,985 ± 640 and 6,560 ± 1,220 years ago,<ref name="WörnerHammerschmidt2000" /> the upper Ajata flows 4,800 ± 4,000 years ago, the middle Ajata flows 9,900 ± 2,100 years ago,Template:Sfn and the High Ajata flows 2,000 – 1,300 years ago. These groups also form compositionally distinct units.Template:Sfn The youngest surface exposure date obtained is 1,385 ± 350 years ago.<ref name="WörnerHammerschmidt2000" />
According to SERNAGEOMIN, Aymara legends referencing volcanic activity imply a latest eruption date of 1800 AD.<ref name="SERNAGEOMIN" /> One history narrating of a bearded man, son of the Sun, that was mistreated by a local town head with the exception of a woman and her son. They were warned that a great disaster would happen, and as they fled from the town it was destroyed by fire. Details of the story imply that the story might reference a small explosive eruption that sent a pyroclastic flow into Lake Chungará after the time of the Spanish conquest; the theory that it references the sector collapse conversely appears to be unlikely.<ref name="ClaveroSparks2004" />
Present-day activity and hazards
Presently, Parinacota is dormant,<ref name="WörnerHammerschmidt2000" /> but future volcanic activity is possible.<ref name="WörnerHammerschmidt2000" /> Explicit fumarolic activity has not been observed,Template:SfnTemplate:Sfn but satellite imaging has shown the evidence of thermal anomalies on the scale of Template:Convert,Template:Sfn and reports of sulfurous smells at the summit imply that a fumarole may exist in the summit area.<ref name="OregonState" /> The volcano is seismically active including one potential seismic swarm,Template:Sfn but earthquake activity is less than at Guallatiri farther south.Template:Sfn Based on Landsat Thematic Mapper images, it was considered a potentially active volcano in 1991.Template:Sfn A small explosion was reported in 2016.<ref name="Clavero2018" />
The volcano is one among ten volcanoes in northern Chile monitored by SERNAGEOMIN and has a volcano hazard level published.<ref name="SERNAGEOMINNew" /> The relatively low population density on the Bolivian side of the volcano means that renewed activity would not constitute a major threat there,<ref name="LatrubesseBaker2009" /> although the town of Sajama may be affected.<ref name="ClaveroSparks2004" /> The Arica-La Paz highway runs close to the volcano and might be threatened by mud and debris flows, along with small communities in the area.<ref name="LatrubesseBaker2009" /> Communities close to the volcano include Caquena, Chucullo and Parinacota. Potential hazards from future activity include the development of lahars from interactions between magma and the ice cap,<ref name="SERNAGEOMIN" /> pyroclastic flows especially on the southern flank,Template:Sfn and eruptions from the flank vents; ash fall from prolonged flank vent eruptions could disturb pastures in the region. The important natural preserve that is the Lauca National Park could suffer significant disruption from renewed eruptions of Parinacota.<ref name="ClaveroSparks2004" />
Human history and cultural value
The region around Parinacota has been inhabited for about 7,000–10,000 years. Politically, since 1,000 years ago first Tiwanaku and then the Inka ruled over the region.Template:Sfn Sources disagree on whether there are archaeological sites on the summit of Parinacota.<ref name="Reinhard2002" /><ref name="Bello2025" />
Several legends concern Parinacota and its sister mountain Pomerape, which are often portrayed as unmarried sisters. Some involve a dispute with or between the mountains Tacora and Sajama, often resulting in Tacora being driven off.<ref name="Reinhard2002" /> Parinacota is one among several volcanoes that figure on the Chilean passport.<ref name="AcuñaClunes2024" />
Gallery
- Parinacota and Pomerape, the Nevados de Payachata
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Parinacota on the right and Pomerape on the left
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Parinacota and Pomerape
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Parinacota on the right and Pomerape just right of the centre
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Parinacota, on the left Pomerape
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Parinacota, on the left Pomerape
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See also
References
Sources
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External links
- Pages with broken file links
- Volcanoes of Arica y Parinacota Region
- Volcanoes of Oruro Department
- Andean Volcanic Belt
- Stratovolcanoes of Chile
- Subduction volcanoes
- Mountains of Chile
- Polygenetic volcanoes
- Potentially active volcanoes
- Bolivia–Chile border
- International mountains of South America
- Six-thousanders of the Andes
- Pleistocene stratovolcanoes
- Holocene stratovolcanoes