Aracar
| Aracar | |
|---|---|
Aracar from the Space Shuttle, January 2003
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| Highest point | |
| Elevation | 6,095 m (19,997 ft) |
| Prominence | 1,791 m (5,876 ft) |
| Listing | Ultra |
| Coordinates | 24°17′24″S 67°47′00″W / 24.29000°S 67.78333°WCoordinates: 24°17′24″S 67°47′00″W / 24.29000°S 67.78333°W |
| Geography | |
 Aracar
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| Parent range | Andes |
| Geology | |
| Age of rock | Pliocene |
| Mountain type | Stratovolcano |
| Last eruption | 1993 |
Aracar is a large conical stratovolcano in northwestern Argentina, just east of the Chilean border. It has a main summit crater about 1–1.5 kilometres (0.6–0.9 mi) in diameter which sometimes contains crater lakes, and a secondary crater. The volcano has formed, starting during the Pliocene, on top of a lava platform and an older basement. Constructed on a base with an altitude of 4,100 metres (13,500 ft), it covers a surface area of 192.4 square kilometres (74.3 sq mi) and has a volume of 148 cubic kilometres (36 cu mi). The only observed volcanic activity was a possible steam or ash plume on March 28, 1993 seen from the village of Tolar Grande about 50 km (31 mi) southeast of the volcano, but with no evidence of deformation of the volcano from satellite observations. Inca archeological sites are found on the volcano.
Aracar is located in the Salta province, north of the Salar de Taca Taca and Arizaro and east of the Salar de Incahuasi and the Sierra de Taca Taca, close to the Chilean border. Volcanoes in the territory rise above the endorheic sinks and landscape. Cerro Arizaro (9.0 ± 1.3 mya) is another volcano southeast of Aracar.
The basement consists of Paleozoic granites. The Laguna de Aracar Formation north of Aracar was formed by Gondwana volcanism and has been dated by K-Ar methods to be 266±28 mya old, and it is associated with the Llullaillaco Unit.Tertiary sedimentary rocks in the east and arenites in the south form the rest of the basement. The height of the volcano over the surrounding terrain is between 1,900–2,800 m (6,200–9,200 ft) from north to south.
Aracar is a polygenetic volcanic cone with a diametre of 13.5 km (8.4 mi) and a rectangular basis 12–18 km (7.5–11.2 mi), covering a surface area of 192.4 km2 (74.3 sq mi). Four lava domes extend southeast from the volcano. Grey basaltic lava flows descend from its summit and form a gentle western flank and much steeper eastern, northern and southern flanks. West of the main summit a 1–1.5 km (0.62–0.93 mi) wide and several hundred meters deep crater forms Aracar's main crater. Snowmelt occasionally forms small ephemeral lakes in the main crater. A 100 m (330 ft) shallow 10 m (33 ft) deep secondary crater is surmounted by a flat semilunar 15–20 m (49–66 ft) wide surface. Small southbound andesitic lava flows are associated with the main crater. Some deep gorges cut into the volcano, and erosion has removed 1.8 km3 (0.43 cu mi) of rock.
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