Keywords
volcanic activity
magmatic processes
igneous petrography
crystallization
Poás
actividad volcánica
procesos magmáticos
petrografía ígnea
cristalización
How to Cite
Abstract
Abstract: During the first semester of 2017, Poás Volcano, in the Central American Volcanic Arc (CAVA) initiated a period of volcanic unrest that included high energy phreatomagmatic and magmatic eruptions. The most notable eruptions occurred on April 14th and April 22nd of 2017, which produced abundant ashes and ballistic materials in the form of blocks and bombs. Here, we present results from the petrographic analyses conducted in the collected material from the largest eruptions of April 2017. Mineral textures observed on the petrographic analyses show evidence of reactivation and fragmentation of a crystal mush in the magma chamber, triggering re-melting episodes, volatile exsolution, and an increase in the pressure of the system, all of which are expected conditions during an eruption episode. Our analyses done on juvenile and non-juvenile material suggest that processes of magma mingling and injections of new batches of material of different compositions have played an important role throughout previous eruptions and likely in the current phase of volcanic activity in Poás.References
Barberi, F., Bertagnini, A., Landi, P. and Principe, C. (1992). A review on phreatic eruptions and their precursors. Journal of Volcanology and Geothermal Research, 52(1992), 231-246. doi:10.1016/0377-0273(92)90046-g
Browne, P. R. L. and Lawless, J. V. (2001). Characteristics of hydrothermal eruptions, with examples from New Zealand and elsewhere. Earth-Science Reviews, 52(4), 299–331. doi:10.1016/s0012-8252(00)00030-1
Casertano, L., Borgia, A. and Cigolini, C. (1983). El volcán Poás, Costa Rica: cronología y características de la actividad. Geofísica Internacional, 22(3), 215-233.
Couch, S., Sparks, R. and Carroll, M. (2001). Mineral disequilibrium in lavas explained by convective self-mixing in open magma chambers. Nature, 411(6841), 1037-1039.
Hogan, J. P. (1993). Monomineralic Glomerocrysts: Textural Evidence for Mineral Resorption during Crystallization of Igneous Rocks. The Journal of Geology, 101(4), 531-540. doi:10.1086/648245
Huber, C., Bachmann, O. and Dufek, J. (2011). Thermo-mechanical reactivation of locked crystal mushes: Melting-induced internal fracturing and assimilation processes in magmas. Earth and Planetary Science Letters, 304(3), 443-454. doi: dx.doi.org/10.1016/j.epsl.2011.02.022
Karlstrom, L., Rudolph, M. L. and Manga, M. (2012). Caldera size modulated by the yield stress within a crystal-rich magma reservoir. Nature Geoscience, 5(6), 402.
Lange, A. E., Nielsen, R. L., Tepley, F. J., & Kent, A. J. R. (2013). The petrogenesis of plagioclase-phyric basalts at mid-ocean ridges. Geochemistry, Geophysics, Geosystems, 14(8), 3282-3296. doi:10.1002/ggge.20207
Mora, M. (2017a). Resumen de la actividad sísmica y eruptiva del Volcán Poás 13 de abril de 2017. San José: Red Sismológica Nacional, Universidad de Costa Rica. Informe interno.
Mora, M. (2017b). Resumen de la actividad sísmica y eruptiva del Volcán Poás 12 al 14 de abril de 2017. San José: Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional. Informe interno.
OVSICORI. (2017). Desaparición de Lago y Otros Cambios Radicales en el Fondo del Volcán Poás (Reporte de campo: 07 de junio de 2017). San José: Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional. Informe interno.
Parmigiani, A., Huber, C. and Bachmann, O. (2014). Mushmicrophysics and the reactivation of crystal-rich magma reservoirs. Journal of Geophysical Research, 119, 6308–6322. doi:10.1002/2014JB011124
Pearce, T. and Kolisnik, A. (1990). Observations of plagioclase zoning using interference imaging. Earth-Science Reviews, 29(1-4), 9-26.
Rouwet, D., Sandri, L., Marzocchi, W., Gottsmann, J., Selva, J., Tonini, R. and Papale, P. (2014). Recognizing and tracking volcanic hazards related to non-magmatic unrest: a review. Journal of Applied Volcanology, 3(17), 1-17. doi:10.1186/s13617-014-0017-3
Streck, M. J. (2008). Mineral Textures and Zoning as Evidence for Open System Processes. Reviews in Mineralogy and Geochemistry, 69(1), 595-622. doi:10.2138/rmg.2008.69.15