Cerro Panizos

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Cerro Panizos (Spanish: [ˈse.ro paˈni.sos], "Maize Hill") is a late Miocene-age shield-shaped volcano spanning the Potosi Department of Bolivia and the Jujuy Province of Argentina. It features two calderas (depressions formed by the collapse of a volcano) and a group of lava domes. It is part of the Altiplano–Puna volcanic complex (APVC), a group of calderas and associated ignimbrites (a form of volcanic rock) that erupted during the past ten million years. Cerro Panizos is part of the Central Volcanic Zone (CVZ), a volcanic arc that extends from Peru to Chile that was formed mostly by subduction of the Nazca Plate beneath South America. Volcanic activity commenced in the APVC about ten million years ago, producing the volcano Uturuncu and the large volcanic calderas Panizos, Vilama, and Cerro Guacha. The formation of the APVC has been linked to the existence of a giant magmatic body in the crust of the Central Andes. The Cienago Ignimbrite erupted over 350 cubic kilometres (84 mi3) from Panizos about 7.9 million years ago, and 6.7 million years ago the Panizos Ignimbrite erupted over 650 cubic kilometres (160 mi3). The Panizos Ignimbrite has been noted for volcanic rocks containing orbs. Several volcanic cones such as Limitayoc were active between the ignimbrite eruptions, and a plateau of lava flows and lava domes formed in the central area of the Panizos Ignimbrite after the last eruptions.

Cerro Panizos lies in the Cordillera de Lipez mountain range of the Andean Altiplano-Puna high plateau. The volcano is a 40-kilometre-wide (25-mile), gently-sloping ignimbrite shield surrounding a 10–15-kilometre-wide (6.2–9.3-mile) lava dome semicircle. The mountain named "Cerro Panizos" is a c. 5,300-metre-high (17,400-foot) lava dome in the southeastern semicircle. The other domes are Cerro Cuevas, Cerro Crucesnioc, Cerro Vicunahuasi west, and the 5,540-metre-high (18,180-foot) Cerro La Ramada north of Cerro Panizos mountain. Two calderas have been identified at Cerro Panizos. The larger one, which is centred south of the lava dome semicircle, may have been formed by downward sagging of the ground. Within this lies a smaller collapse caldera, outlined by the lava domes. Cerro Anta Cuevas, Cerro Chinchijaran, Cerro Limitayoc/Limitayo, and Cerro Tucunquis are lava plateaus that rise from the ignimbrite shield. The 5,158-metre-high (16,923-foot) Limitayoc formed along a north-south trending fault and has an elongated shape, with traces of hydrothermal alteration at its northern end. Owing to the arid climate, little erosion has taken place. Parts of the ignimbrite are covered with windblown sand. Landforms have conical, dome-like, or table-like shapes. Erosion of the ignimbrite has formed cliffs and rows of pinnacles, the latter of which draw photographers owing to their exotic appearance. The ignimbrite shield of Panizos has been compared to paterae on Mars.

Several (often ephemeral) streams cut into the rocks of the shield to form a radial drainage system. The streams run mostly to the east; from north to south they are Rio Khuchu Mayu and the Quebradas Buenos Aires, Cienago, Paicone, Potrero, Guanapata, Pupusayo, Cusi Cusi, Cueva, Garcia, and Quenoal. Most of them eventually join the San Juan de Oro River, which flows into the Atlantic Ocean. Panizos can be accessed through the valleys of these streams. Small lakes dot the southwestern sector of the shield, and there are ephemeral lakes on its southeastern side. The mountain Cerro San Matias borders Panizos to the north, Cerro Lipez northwest, and Corutu southwest of Panizos, while the San Juan de Oro depression is east of the volcano. The region is remote and inhospitable. Most of the volcano is in Bolivia's Potosi Department (Sud Lipez Province), except for the southeastern quadrant which lies in Argentina's Jujuy Province (Rinconada and Santa Catalina Departments). The border between Argentina and Bolivia runs along the domes. The towns of Cusi Cusi and San Antonio de Esmoruca are southeast and north of the volcano, respectively. There are several archeological sites on Panizos, and a branch of the Inca road system passed over the volcano. Most of the central domes were first climbed in November 1939, but the volcano itself was only identified as such in 1977, thanks to images from the Landsat satellite.

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.