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 in 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. 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, which has a volume of about . After the emplacement of the Purico ignimbrite, a number of lava domes and stratovolcanoes developed on the ignimbrite shield. The maar of Alitar is still fumarolically active. In historical times, sulfur was mined on Purico. Today, the Llano de Chajnantor Observatory lies on the ignimbrite shield. Geography and structure The Purico complex lies in Chile close to the border between Bolivia and Chile, east of the town of San Pedro de Atacama and northeast of Toconao. The volcanic complex can be seen from San Pedro de Atacama. A road runs along the northern and eastern margin of the Purico complex, and a gas pipeline crosses the complex as well. The existence of the Purico complex was established on the basis of Landsat images. Regional Licancabur volcano was constructed on ignimbrites from Purico just north of the complex. Guayaques lies east of Purico, the La Pacana caldera is located southeast of the complex, and La Pacana's Filo Delgado ignimbrite has buried part of the Purico ignimbrite. The known volcanoes Lascár and El Tatio are found at larger distances from Purico. Purico is part of the Central Volcanic Zone (CVZ), a belt of volcanoes that runs along the western margin of South America between 14° and 28° southern latitude. This long belt is one of four separate volcanic belts that make up the Andean Volcanic Belt. They are separated from each other by gaps where no recent volcanism occurs. The CVZ segment includes