Geological Summary

Volcán Ollagüe, also known as Oyahué, is a massive andesitic stratovolcano with a summit dacitic lava dome. A large Pleistocene debris-avalanche deposit extending westward separates the Salar de San Martín from the Salar de Ollagüe. Three youthful-looking silicic lava flows mark late post-collapse eruptions, but show evidence of glaciation and are thought to pre-date the last glacial advance at about 11,000 years ago (Freeley et al., 1993). A youthful-looking scoria cone on the lower WSW flank, La Poruñita, was initially considered to be of Holocene age (González-Ferrán, 1995), however Wörner et al. (2000) later obtained Potassium-Argon dates of 420,000 to 680,000 years. Active sulfur mines on the upper western and southern flanks are reached by a road that climbs to about 5500 m elevation. No historical eruptions have been recorded; activity has been restricted to periods of intense fumarolic activity, and a persistent steam plume emanates from a fumarole on the south side of the summit dome.

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Casertano L, 1963. Chilean Continent. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 15: 1-55.

Clavero J, Polanco E, Godoy E, Aguilar G, Sparks R S J, van Wyk de Vries B, Perez de Arce C, Matthews S, 2004. Substrata influence in the transport and emplacement mechanism of the Ollague debris avalanche (northern Chile). Acta Vulcanologica, 16: 59-76.

de Silva S L, Francis P W, 1991. Volcanoes of the Central Andes. Berlin: Springer-Verlag, 216 p.

Feeley T C, Davidson J P, 1994. Petrology of calc-alkaline lavas at Volcan Ollague and the origin of compositional diversity at central Andeam stratovolcanoes. Journal of Petrology, 35: 1295-1340.

Feeley T C, Davidson J P, Armendia A, 1993. The volcanic and magmatic evolution of Volcan Ollague, a high-K, late Quaternary stratovolcano in the Andean Central Volcaniz Zone. Journal of Volcanology and Geothermal Research, 54: 221-245.

Francis P W, Wells G L, 1988. Landsat thematic mapper observations of debris avalanche deposits in the central Andes. Bulletin of Volcanology, 50: 258-278.

Gonzalez-Ferran O, 1972. Distribucion del volcanismo activo de Chile y la reciente erupcion del Volcan Villarrica. Instituto Geog Militar Chile, O/T 3491.

Gonzalez-Ferran O, 1995. Volcanes de Chile. Santiago: Instituto Geografico Militar, 635 p.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome, International Association of Volcanology and Chemistry of the Earth's Interior.

Vezzoli L, Tibaldi A, Renzullic A, Mennac M, Flude S, 2008. Faulting-assisted lateral collapses and influence on shallow magma feeding system at Ollagüe volcano (Central Volcanic Zone, Chile-Bolivia Andes). Journal of Volcanology and Geothermal Research, 171: 137-159.

Worner G, Hammerschmidt K, Henjes-Kunst F, Lezaun J, Wilke H, 2000. Geochronology (40Ar/39Ar, K-Ar and He-exposure ages) of Cenozoic magmatic rocks from Northern Chile (18-22° S): implications for magmatism and tectonic evolution of the central Andes. Rev Geol Chile, 27: 205-240.