Structure and Evolution
Chiliques is a simple volcano located directly south of Laguna Lejia (Figure 28.1). The most recent activity in its vicinity may have been the eruption which formed the Cerro Overo maar (q.v.), 8 km to the north (CO). Chiliques has a 500 m diameter circular summit crater (SC) and several young flank lava flows (possible Holocene); the largest of these (L), is found on the northwest flank of the volcano extending for about 5 km from the summit. Lava flows belonging to two older phases of activity from the ancestral Chiliques are also present. These older flows are more extensive than those from the present volcano and extend for up to 10 km from the present summit. The most extensive of these is found to the north of the volcano and is a flat, tabular, blocky flow (Figure 28.2). Chiliques occupies an interesting position at the intersection of two of the major volcano-tectonic lineaments in this region; the major N-S trending Upper Miocene to Recent 'Miscanti Lineament' which forms the western margin of the uplifted puna block, and the NW-SE trending Cordon Puntas Negras lineament which is manifested by the eponymous volcanic complex (Cordon de Puntas Negras - CPNq.v.). Although it is likely that Chiliques is part of the CPN system, unlike most of the centers of the CPN, it is a major center with a history as long as the CPN itself.
Until 2002, Chliiques was believed to be dormant, however infrared images collect by NASA's ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) reveal new thermal hot spots caused by shallow magma in the summit crater and upper flanks of the volcano. These were not seen in a comparable image taken in 2000 (Pieri and Abrams, 2004; see image). The summit lakes also appear to be warming. There has been no deformation associated this this thernal activity seen with InSAR (Pritchard and Simons, 2004).
The lavas of Chiliques are porphyritic pyroxene andesites with dominant plagioclase (An34-48), augite, hypersthene, and rare hornblende and biotite. Olivine and quartz are also rarely found coexisting Ramirez and Gardeweg, 1982).
ASTER Science Team, 2002. Visible Earth: Chiliques Volcano, Chile. http://visibleearth.nasa.gov/view_rec.php?id=2632.
Pieri, D., Abrams, M., 2004. ASTER watches the world's volcanoes: a new paradigm for volcanological observations from orbit. Journal of Volcanology and Geothermal Research, 135(1-2):13-28.
Pritchard, M. E., and Simons, M., 2004. An InSAR-based survey of volcanic deformation in the central Andes, Geochem. Geophys. Geosyst., 5, Q02002, doi:10.1029/2003GC000610.
Ramierez-C.F. and Gardeweg-M. (1982) Hoja Toconao. Carta Geologica de Chile, 58. SNGM, Santiago.