Insight into monogenetic eruption processes at Pelagatos volcano, Sierra Chichinautzin, Mexico: a combined melt inclusion and physical volcanology study
Julie Roberge, Marie-Noëlle Guilbaud, Celestine N. Mercer, Paola C. Reyes-Luna, 2015. "Insight into monogenetic eruption processes at Pelagatos volcano, Sierra Chichinautzin, Mexico: a combined melt inclusion and physical volcanology study", The Role of Volatiles in the Genesis, Evolution and Eruption of Arc Magmas, G. F. Zellmer, M. Edmonds, S. M. Straub
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Eruptions and magma evolution of monogenetic volcanoes are thought to be controlled by rapid ascent of magmas over a short period of time. Volatiles degassing from magmas control the ascent velocity and therefore eruption intensity. Complex feedbacks exist between the rate and extent of volatile exsolution at shallow levels and groundmass crystallization, affecting the magma rheology, extent of fragmentation, resulting eruptive style and related hazards. Melt inclusions record the volatile contents and compositions of melts at various stages during their evolution, providing insights into degassing–crystallization processes at shallow crustal levels. Here we present new volatile and major element data from olivine-hosted melt inclusions from Pelagatos scoria cone, Mexico. These new data, combined with recent geochemical and textural data on Pelagatos eruptive products, allow us to propose a model for shallow magmatic processes at this volcano. Discharge of volatile-poor, low-viscosity magma drives early effusive activity along the fissure. Decreasing magma fluxes lead to the clogging of the fissure and the formation of a shallow magma reservoir where degassing and fractional crystallization take place. Subsequent explosive cone-forming activity is triggered by influx of deeper (c. 5 km), less evolved, more volatile-rich magma into this shallow (c. 1 km) reservoir.
new whole rock and matrix glass date are available at www.geolsoc.org.uk/SUP18782.
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The subduction zone volatile cycle is key to understanding the petrogenesis, transport, storage and eruption of arc magmas. Volatiles control the flux of slab components into the mantle wedge, are responsible for melt generation through lowering the solidi of mantle materials and influence the crystallizing phase assemblages in the overriding crust. Further, the rates and extents of degassing during magma storage and decompression affect magma rheology, ultimately control eruption style and have consequences for the environmental impact of explosive arc volcanism. This book highlights recent progress in constraining the role of volatiles in magmatic processes.
Individual book sections are devoted to tracing volatiles from the subducting slab to the overriding crust, their role in subvolcanic processes and eruption triggering, as well as magmatic-hydrothermal systems and volcanic degassing. For the first time, all aspects of the overarching theme of volatile cycling are covered in detail within a single volume.