Walker, James Allen, 1952-
M.S. (Master of Science)
Department of Geology and Environmental Geosciences
Petrology; Geology; Geochemistry
Cerro Quemado and Volcan de Almolonga are two Quaternary volcanoes located in southwestern Guatemala, approximately 5 km from the large city of Quetzaltenango. Both volcanoes neighbor Santa Maria which produced an explosive and catastrophic eruption in 1902 and subsequently created the Santiaguito dome. Cerro Quemado's most recent eruption in 1818 produced a dacite lava flow that contains abundant mafic inclusions. An undated Volcan de Almolonga eruption produced an andesitic lava. Pre-eruptive intensive variables using various geothermometers and geohygrometers were calculated to determine magmatic temperatures and water contents for each lava flow. Two liquids were involved in the 1818 lava flow. The first is a rhyolite liquid with a temperature of 793--915°C and a water content of 4.3--5.1 wt.%, and the second is a mafic liquid with a temperature of 1009--1057°C. Plagioclase equilibrium from a Volcan de Almolonga lava flow also suggests two liquids existed prior to eruption, a rhyolite liquid with a temperature of 872--918°C and a water content of 4.3--5.0 wt.%, and an andesite liquid with a temperature of 941--1015°C and a water content of 2.9--5.1 wt.%. Models of magmatic evolution are proposed for each lava flow. The 1818 Cerro Quemado flow is thought to have erupted because of an influx of mafic magma that injected into a static rhyolite magma. At Volcan de Almolonga, two eruptive models are proposed. The first model is a single reservoir model, where the andesite magma exists within a crystal mush zone that is overlaid by a rhyolite magma. An unidentified mechanism triggered the eruption of both magmas to create the lava flow seen at the surface. The second model is a two reservoir model, where each liquid exists as a magma in its own reservoir. An unidentified mechanism triggers the eruption that incorporates magma from the oval reservoir.
Schwoerer, Andrew, "Pre-eruptive constraints for two neighboring volcanic systems in Southwestern Guatemala" (2017). Graduate Research Theses & Dissertations. 4479.
Northern Illinois University
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