Monturaqui
Key facts
- Country
- Chile
- Diameter
- 370 m
- Age
- less than 1 million years
- Location
- 23.93° S, 68.26° W
A small, well-preserved bowl about 370 m across with a raised rim, set in the high, bare Atacama Desert south of the Salar de Atacama.
Monturaqui is a small meteorite crater in one of the driest places on Earth, the Atacama Desert of northern Chile. It lies at an altitude of about 3,000 m, south of the great salt flat called the Salar de Atacama, surrounded by barren hills and distant volcanoes.
The impact. An iron meteorite struck here, forming a crater about 370 m across and originally a few tens of metres deep. The rim still rises clearly above the surrounding land. The target rocks were granite and a layer of volcanic ash rock called ignimbrite, which lies on top of it. The impact broke up and threw out these rocks, and blocks of granite can be found on the rim and the surrounding slopes.
The crater's age is uncertain, but it is less than a million years old. In the extremely dry climate of the Atacama, erosion is very slow, which explains why such a small crater is so well preserved.
Iron shale and impact glass. Fragments of the meteorite itself are almost all weathered. What remains are pieces of iron shale, rusty lumps formed from the meteorite's metal, containing small amounts of nickel. Analyses show that the meteorite was an iron of group IAB, a common type of iron meteorite. The crater area also contains impact glass, dark glassy rock formed when the target rocks melted during the impact, sometimes mixed with tiny droplets of meteoritic metal.
Discovery. Monturaqui was identified from aerial photographs in the early 1960s, and expeditions soon afterwards confirmed it as a meteorite crater. It has since been studied by Chilean and international scientists, partly because it is a good example of a small, simple crater in hard granite.
The Atacama and meteorites. The Atacama is one of the best places in the world to find meteorites. Its dry climate preserves them for a very long time, and the bare ground makes them easier to spot. Large numbers of meteorites have been recovered from parts of the Atacama in recent decades, and they help scientists understand the rate at which meteorites fall over long periods. Chile has laws protecting meteorites and other geological heritage, so anyone searching there should check the current regulations.
Visiting. The crater is remote, reached by rough tracks from the town of San Pedro de Atacama and surrounding areas. The high altitude, strong sun and lack of water make visits demanding, and a guide or suitable vehicle is recommended. Removing material from the crater may be restricted.
Why it matters. Monturaqui is one of very few well-preserved meteorite craters in South America, and an excellent natural laboratory for studying small impacts into hard rock.
Did you know?
Monturaqui lies at about 3,000 m above sea level in one of the driest deserts on Earth.
Almost all of the iron meteorite has weathered into rusty iron shale.
Its impact glass sometimes contains tiny droplets of meteoritic metal.