Ojos del Salado

Ojos del Salado
Ojos del Salado looming big on the horizon.jpg
The volcano looming on the horizon.
Highest point
Elevation6,893 m (22,615 ft) [1]
Prominence3,688 m (12,100 ft) [1]
Ranked 44th
Isolation631 kilometres (392 mi)
ListingVolcanic Seven Summits
Seven Second Summits
Country high point
Ultra
Coordinates27°06′35″S 68°32′29″W / 27°06′35″S 68°32′29″W / -27.10972; -68.54139
Geography
Ojos del Salado is located in Chile
Ojos del Salado
Ojos del Salado
Location on the Argentina–Chile border
LocationArgentinaChile
Parent rangeAndes
Topo mapHighest mountain: Highest Mountain in Chile
Geology
Mountain typestratovolcano
Last eruption700 AD ± 300 years[2]
Climbing
First ascentFebruary 26, 1937 by Jan Alfred Szczepański and Justyn Wojsznis
Easiest routeScramble
Volcanic Landscapes of the Central Andes. Shown are Nevado Ojos del Salado, Cerro El Cóndor, and Peinado, along the Argentina-Chile border. Astronaut photo from International Space Station, 2010

Nevado Ojos del Salado is an active stratovolcano in the Andes on the ArgentinaChile border and the highest active volcano in the world at 6,893 m (22,615 ft).[3] It is also the second highest mountain in both the Western Hemisphere and the Southern Hemisphere behind Aconcagua at approximately 7,000 meters (22,966 ft) and it is the highest in Chile. Nevado Ojos del Salado is translated to Snowy Salty Eyes describing it being very snowy in the winter and salty with many lakes.

Due to its location near the Atacama Desert, the mountain has very dry conditions, with snow usually only remaining on the peak during winter, though heavy storms can cover the surrounding area with a few feet of snow even in summer. Despite the generally dry conditions, there is a permanent crater lake about 100 m (330 ft) in diameter at an elevation of 6,390 m (20,960 ft) on the eastern side of the mountain.[4] This is most likely the highest lake of any kind in the world.

The ascent of Ojos del Salado is mostly a hike except for the final section to the summit which is a difficult scramble that may require ropes. The first ascent was made in 1937 by Jan Alfred Szczepański and Justyn Wojsznis, members of a Polish expedition in the Andes.

Its name, meaning roughly "Eyes of the Salty One" in Spanish, comes from the enormous deposits of salt that, in the form of lagoons or “eyes”, appear in its glaciers.[5] An international highway between Chile and Argentina runs north of the mountain.[6]

Geology and geomorphology

Regional

Ojos del Salado along with several other high volcanoes such as El Muerto, El Solo, Nevado Incahuasi and Nevado Tres Cruces lies at the southern end of the Central Volcanic Zone of the Andes.[7]

Volcanic activity in the region commenced 26 million years ago in the Cordillera Claudio Gay, at the same time as the neighbouring Maricunga Belt volcanoes were active. Starting 18 million years ago, local subduction of the Nazca Plate beneath the South America Plate became increasingly shallower and this caused volcanism to shift from the Maricunga Belt to the Ojos del Salado region.[7]

The Paleozoic basement crops out only northwest of Nevado Tres Cruces. Other geologic units in the region are Oligocene sedimentary units and volcanic rocks ranging from Oligocene age to less than 1.5 million years old.[8] The area is part of a tectonic boundary between a volcanically active region north of the boundary and a less volcanically active region south of the boundary, which is also characterized by geographical differences, e.g. the presence of transverse valleys.[9]

Local

Ojos del Salado like other major neighbouring mountains is a complex of lava domes and lava flows, with the main summit surrounded by peripheral domes such as El Solo and El Fraile[10] and many other lateral centres.[11] Fumaroles are encountered at the summit of Ojos del Salado within a depression.[12] Potassium-argon dating has yielded ages of 1.2 ± 0.3 million years ago and less than 1 million years ago from rocks north of Ojos del Salado.[13]

There are glaciers on the mountain, in the crater and in the form of penitentes[14] which reach heights of 8–5 metres (26–16 ft).[15] Other reports indicate the absence of glaciers on Ojos del Salado. Permafrost exists on the mountain and its melting nourishes several lakes; one lake fed by a creek lies at 6,500 metres (21,300 ft) altitude.[16]

Ojos del Salado is an active volcano, but the question of whether it should be considered currently (or "historically") active is arguable. According to the Smithsonian Institution's Global Volcanism Program,[2] the most recent known eruption was about 1,300 years ago, with a large margin of uncertainty. However, there is also some evidence for a minor ash emission in 1993, which would definitely qualify the volcano as historically active. The presence of fumaroles high on the mountain and recent-looking lava flows, albeit of uncertain age, also argues in favor of a categorization as "active." By these definitions, Ojos del Salado is the highest historically active volcano on Earth. If the older date is accepted, the title of "highest historically active volcano" might reside instead with the somewhat lower Llullaillaco volcano, which certainly has erupted in historic times (most recently in 1877) and is considered active.

Composition

Salado's rock is predominantly potassium-rich dacite and rhyodacite. Its lavas are high in biotite, hornblende, plagioclase, and opaques, with lower levels of augite, quartz, and hypersthene.[17]