Structure and Evolution
Known by several names, Putana (Figure 21.1), is one of the few volcanoes in the Central Andes which exhibits conspicuous fumarolic activity, visible from a distance of many kilometres (Figure 21.2). Putana is but one component of a much larger complex extending southwards as far south as Volcan Sairecabur (q.v.) and which includes Apogado and Curiquinca volcanoes and several other un-named large centers. The main edifice consists of a tangled accumulation of several post-glacial lava flows mantling the older pre-Holocene edifice. While the older lavas are relatively long, the young lava flows (i.e L) are typically short and stubby, rarely more than 3 km in length, suggesting a relatively evolved composition (dacite?). Several satellite vents on the flanks of Putana are undoubtedly parts of the same magmatic system. One of these, on the western side of Putana, is the source of a fan shaped lava (L1), which from its appearance appears to be less viscous and therefore probably more basic than those on Putana itself. It is noteworthy that there is no evidence for significant pyroclastic eruptions during the construction of the Putana complex.
Sulphur has been mined in the the summit region, which contains a well preserved summit crater (SC). Active fumarolic steam plumes vent from several distinct sources near the summit (Figure 21.2). There are no records of historic eruptions. Young lava flows were probably the most recent eruptive events from Putuna.
Extensive fumarolic activity persists to the present day.
Marinovic and Lahsen (1984) report that the lavas of Putana range from hornblende and biotite dacites to pyroxene andesites.
Marinovic-N, and Lahsen-A. (1984) Hoja Calama. Carta Geologica de Chile, 58. SNGM, Santiago.