Chile
Synonyms: None
Location: 23º01'S; 67º48'W
Type: Dome
Summit Elevation: 5018 m
Edifice Height: 418 m
Cerro Chascon de Purico (23° 01'S 67° 41'W) and Cerro Aspero (23° 05'S 67° 42'W) are both small silicic bodies that formed as late extrusives on the summit region of the Purico shield complex. Their preservation indicates their likely post-glacial age. The former is a 400m high flow/dome complex built up by a series of stubby, viscous lava flows and minor pyroclastic activity (4 km3), while the latter is a tent-shaped, perhaps Peléean-type dome, about 300 m in height (0.36 km3). Unlike the flat-topped tortas described above, Chascon de Purico and Aspero are both conical in shape and their lavas are typically glassy and relatively crystal poor. The difference in morphology reflects the difference in rheological properties of the two types of magmas which would result in different eruption characteristics (e.g. Blake, 1989). The two domes have 87Sr/86Sr ratios ranging form 0.707 and 0.709.
References
Blake, S., 1989. Viscoplastic models of lava domes. In Fink, J.H., ed. Lava flows and domes: Emplacement mechanisms and Hazard implications. Springer-Verlag. p88-126.
Schmidt, A.K., de Silva, S.L., Trumbull, R.B., Emmermann, R., 2001. Magma evolution in the Purico ignimbrite complex, northern Chile: evidence for zoning of a dacitic magma by injection of rhyolitic melts. Contr Mineral Petrol, 140: 680-700.