page_title: Purico complex
section_title: Local
hierarchical_section_title: Purico complex / Geography and structure / Local
caption_attribution_description: English: A view from Cerro Chico (5124 m a.s.l.) to the north across the plains of Chajnantor with a part of the ALMA construction site at the centre. Deutsch: Ausblick vom Cerro Chico (5124 m ü.M.) nach Norden über die Chajnantor-Ebene mit einem Teil des ALMA-Baugeländes im Zentrum. Español: Vista dede el Cerro Chico (5124 m s.n.m.) hacia el norte a través del Llano de Chajnantor con una parte del sitio de construcción de ALMA en el centro.
context_page_description: The Purico complex is a Pleistocene volcanic complex in Chile close to Bolivia, formed by an ignimbrite, several lava domes and stratovolcanoes and one maar. It is one of the Chilean volcanoes of the Andes, and more specifically the Chilean segment of the Central Volcanic Zone, one of the four volcanic belts which make up the Andean Volcanic Belt. The Central Volcanic Zone spans Peru, Bolivia, Chile and Argentina and includes 44 active volcanoes as well as the Altiplano-Puna volcanic complex, a system of large calderas and ignimbrites of which Purico is a member of. Licancabur to the north, La Pacana southeast and Guayaques to the east are separate volcanic systems.
  The Purico complex consists of a shield shaped volcanic structure consisting of the Purico ignimbrite and a number of secondary volcanoes that are emplaced on this volcanic shield. During the ice ages, the shield was in part covered by glaciers which have left moraines. Purico is the source of the Purico ignimbrite, a moderately large ignimbrite with a volume of about 80–100 cubic kilometres. After the emplacement of the Purico ignimbrite, a number of lava domes and stratovolcanoes developed on the ignimbrite shield.
context_section_description: Purico is a circular shield with a diameter of 15–25 kilometres (9.3–15.5 mi), whose slopes descend away from a centre at an elevation of 5,000 metres (16,000 ft). This shield forms a plateau, which is known as the Chajnantor Plateau, and which contains further flat areas such as Llano de Chajnantor, Pampa El Vallecito and Pampa La Bola. There is no evidence that a caldera exists there, unlike in many other volcanoes of this type. To the west, close to the margin of the Salar de Atacama, the shield drops down to a bajada. A north-south trending system of fractures and conspicuous normal faults cuts across the western margin of the Purico complex.
  On top of this shield, a complex of lava domes and lavas reaches elevations of over 5,800 metres (19,000 ft) above sea level; the vent of the ignimbrite may be buried beneath this complex. This complex forms approximately a 10 by 20 kilometres (6.2 mi × 12.4 mi) wide semicircle open to the southwest around the centre of the shield, which may reflect the existence of a ring fault on which the individual centres were emplaced.
  Clockwise starting from the west this semicircle includes 5,016 metres (16,457 ft) high Cerro Negro (23°1′0″S 67°51′0″W), Cerro Purico, "dacite dome D" and 5,639 metres (18,501 ft) high El Cerillo which is also known as Cerro Chajnantor (22°59′0″S 67°44′0″W), 5,703 metres (18,711 ft) high Cerro El Chascon (23°1′0″S 67°41′0″W), the 5,262 metres (17,264 ft) high Cerro Aspero (23°5′0″S 67°42′0″W and the 5,462 metres (17,920 ft) high Cerro Putas (23°6′0″S 67°43′0″W) to the south. All these domes (with the exception of the pancake-like "dacite dome D") have conical shapes, and Aspero, El Cerillo and El Chascon appear to be post-glacial in age.
  The Chascon dome is constructed by lava flows and has a well preserved summit crater, while Cerro Purico is a stratovolcano and also known as Cerro Toco (22°57′0″S 67°47′0″W). Additional more subdued structures in the principal complex are 5,058 metres (16,594 ft) high Cerro Agua Amarga (23°1′0″S 67°43′0″W) just southwest of El Chascon and the Cordon Honor with Cerro Purico Sur in the "opening" of the semicircle. Lahars and debris flows from the volcanoes have covered parts of the ignimbrite shield with gravels. A meltwater-fed spring on Cerro Toco is known as Aguada Pajaritos, and a small lake Laguna de Agua Amarga is found south of Chascon. Presently, the Purico complex forms the drainage divide between the Salar de Atacama and the Salar de Pujsa. The 5,130 metres (16,830 ft) high Macon stratovolcano (23°2′0″S 67°49′0″W) and the Alitar maar (23°9′0″S 67°38′0″W) lie to the south of the main complex.
caption: A view across the Purico complex
exif: {"Image ImageDescription": "A view across the plains of Chajnantor with the ALMA construction site at the centre.", "Image Copyright": "ESO"}