Macusani (volcano)

Macusani is a volcanic field in the Carabaya Province of Peru. It is formed by ignimbrites filling basins in the mountain range, with a total remnant volume of 430 cubic kilometres (100 cu mi). Some granitic stocks are also found there. A notable mineral found in the field is macusanite; indeed the field is notable for the unusual rock composition.

Macusani is not part of the principal volcanic arc, it belongs to the so-called "inner volcanic arc" of the eastern Cordillera. It is not clear why volcanism occurred in the Macusani region.

The Macusani volcanics are located in the Carabaya Province,Puno Department of Peru. The towns of Macusani, Crucero and Ananea lie in the region. The Macusani River flows east of the field, and the 5,000–6,000 metres (16,000–20,000 ft) high mountain range surrounds the area, forming a quadratic depression.

The Macusani volcanics lie in the Cordillera de Carabaya. There, on the western foot of the Oriental Cordillera north of Lake Titicaca, ignimbrites fill out basins like Cojata-Ulla Ulla, Crucero, Macusani and Picotani, of which the Macusani basin is the largest. These are separated by topographic ridges. The Macusani basin is covered by 860 square kilometres (330 sq mi) of pyroclastic flows at an altitude of 4,400 metres (14,400 ft). Part of the ignimbrites are hidden beneath glaciers on the western end of the Macusani basin. In addition, several granitic stocks are found there. The Crucero and Picotani field may have been one single volcanic field once, covering a surface area of 1,500 square kilometres (580 sq mi). The total volume of ignimbrites in the field is about 430 cubic kilometres (100 cu mi), not counting eroded material. Some calderas and fissures that may be the source of the Macusani rocks lie south of the Macusani basin, in the Nevado La Huana area; no caldera has been directly imaged though. The Macusani volcanics belong to the so-called "inner volcanic arc" in the Cordillera Oriental.

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