Document Type

Student Presentation

Presentation Date

4-17-2017

Faculty Sponsor

Dorsey Wanless

Abstract

In March of 2015, twelve samples of vesicular basalt were collected from Villarrica volcano in Southern Chile. The samples were collected along a northeast-southwest trending fissure and cinder cone system on the east side of the stratovolcano, at nine locations. Samples were crushed, sieved, cleaned, and picked in preparation for ICP-MS (inductively coupled plasma mass spectrometry). ICP-MS data is used to determine the major and trace elements composition of the rock. We will use this geochemical data , so we can determine if these lava flows were sourced by a single eruptive event, or multiple eruptive events. Since these are mafic rocks, we are primarily going to be looking for significant differences in iron and magnesium content. Compositional analysis will also give us insight regarding magma source, and magmatic evolution. Hickey-Vargas et al., (1989), found that small satellite cones have higher olivine/plagioclase ratios compared to the lava from the main Villarrica volcano, so we expect to see something similar.

References

Hickey-Vargas, R., Moreno-Roa, H., Lopez-Escobar, L., Frey, F.,1989. Geochemical variations in Andean basaltic and silicic lavas from the Villarrica-Lanín volcanic chain (39.5 °S): an evaluation of source heterogeneity, fractional crystallization and crustal assimilation. Contributions to Mineralogy and Petrology, 103, 361-386.

Leach, R. A. (2012). A textural and chemical study of lavas from Villarrica and Llaima volcanoes, Chile: Evidence for magma recharge and mixing (Masters thesis). Retrieved from GeoRef database.

Wehrmann, H., Hoernle, K., Jacques, G., Garbe-Schönberg, D., Schumann, K., Mahlke, J., & Lara, L. E. (2014). Volatile (sulphur and chlorine), major, and trace element geochemistry of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33-43S). International Journal of Earth Sciences, 103(7), 1945–1962.

Witter, J. 2003. Convection of Magma in Volcanic Conduits as a Degassing Mechanism at Active Volcanoes (Doctoral dissertation). Retrieved from GeoRef database.

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