Insight into monogenetic eruption processes at Pelagatos volcano, Sierra Chichinautzin, Mexico: a combined melt inclusion and physical volcanology study

Abstract

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.Supplementary material:new whole rock and matrix glass date are available at www.geolsoc.org.uk/SUP18782.

Spatial Visualization of Geochemical Data: Application to the Chichinautzin Volcanic Field, Mexico

“…At local scale, it perfectly marks the regional heterogeneity known in the CVF, but larger scale effects also occur (i.e. For example Pelagatos and the center of the monogenetic field is clearly less evolved and less alkaline; see [25,42,43]).…”

“…Mafic melt compositions (basalt, basaltic andesites) are found in olivine phenocrysts holding glass inclusions of ~49 to <54 wt.% SiO 2 (i.e. see Xitle, [24] and Pelagatos, [25]).…”

Revisiting the age of the Jumento volcano, Chichinautzin Volcanic Field (Central Mexico), using in situ-produced cosmogenic 10Be

“…Although the Sierra Chichinautzin is one of the most studied areas in the Trans-Mexican Volcanic Belt, the studies have focused mainly on the geology of the erupted magmas or the eruptive style and geometry of the volcanoes (Martín del Pozzo, 1982;Meriggi et al, 2008;Guilbaud et al, 2009;Agustín-Flores et al, 2011;Roberge et al, 2015). By contrast, detailed chronological information on the volcanic activity is available for only ~10 % of more than 220 volcanic cones; this is based on the use of radiocarbon (Siebe et al, 2004) and 40 Ar/ 39 Ar dating (Arce et al, 2013;Jaimes-Viera et al, 2018).…”