Author : Pedro Antonio Valdivia-Munoz
Publisher :
ISBN 13 :
Total Pages : 52 pages
Book Rating : 4.:/5 (128 download)
Book Synopsis Mafic Explosive Volcanism at Llaima Volcano by : Pedro Antonio Valdivia-Munoz
Download or read book Mafic Explosive Volcanism at Llaima Volcano written by Pedro Antonio Valdivia-Munoz and published by . This book was released on 2021 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mafic eruptions, which are typically effusive to mildly explosive, can produce much stronger explosive eruptions. Eruption style is determined by the ability of gas to escape through the permeable network. If the permeability is sufficiently high to reduce vesicle overpressure during ascent, the volatiles may escape from the magma, inhibiting violent explosive activity. In contrast, if the permeability is sufficiently low to retain the gas phase within the magma during ascent, bubble overpressure may drive magma fragmentation. Rapid ascent rates may induce disequilibrium crystallization, increasing viscosity and explosivity, and have consequences for the geometry of the vesicle network. Quantitative vesicle texture analyses are commonly measured in 2D. However, 2D vesicle analyses do not provide sufficient information about the internal vesicle structures for permeability analysis. Here we use synchrotron X-ray computed microtomography of 10 pyroclasts from the 12.6 ka mafic Curacautín Ignimbrite (Llaima Volcano, Chile) to reconstruct and quantify pyroclast textures in three dimensions. Our goal is to obtain 3D measurements of porosity, bubble interconnectivity, bubble number density, and geometrical properties of the porous media to investigate the role of magma degassing processes at mafic explosive eruptions. We use an analytical technique to estimate permeability and tortuosity by combing empirical relationships and pyroclasts vesicle textures. We identified two populations of vesicles: (1) a convoluted connected vesicle network produced by extensive coalescence of smaller vesicles (> 99% of pore space), and (2) a population of very small and completely isolated vesicles (