Northern Chile
Synonyms: None
Location: 23º31'S; 67º40'W
Type: Discrete Maar
Summit Elevation: 4600 m
Edifice Height: 80 m (depth)
Cerro Overo (23° 31'S 68° 19'W) is a young 600 m diameter maar erupted along a regional fault through a basement of ignimbrites. It is the least silicic young volcanic rock so far found in the 21° to 24°S segment of the volcanic Central Andes (54.22% SiO2). Cerro Tucle, also a maar, is somewhat older but is also related to regional faulting. The siting of La Negrillar, a large compound flow (24° 17'S 68° 36'W) has been controlled by by faults on the southwestern flank of the Atacama basin. This compound basaltic andesite cone and lava complex is valley confined but of considerable extent with a maximum dimension of about 16 km.
References
O'Callaghan, L.J., and Francis, P.W. Volcanological and petrological evolution of San Pedro Volcano, Provincia El Loa, North Chile. Journal of the Geological Society of London, 143(2):275-286.