TITLE:
Pyroclasts of the First Phases of the Explosive-Effusive PCCVC Volcanic Eruption: Physicochemical Analysis
AUTHORS:
Lia Botto, Vicente Barone, María E. Canafoglia, Elizabeth Rovere, Roberto Violante, María J. González, Delia Gazzoli, Isidoro Schalamuk
KEYWORDS:
Pyroclastic Materials, Chemical Composition, Mineralogy, Sem Microscopy, Raman Spectroscopy
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.5 No.8,
August
10,
2015
ABSTRACT: The
morphology, texture, grain size and other physicochemical characteristics of
pyroclastic material from the first phases of the Puyehue-Cordon Caulle
volcanic complex (PCCVC) eruption, (Southern Andes, Chile), can be associated
to the model recently reported for the magma storage and its ascent conditions.
The eruption started June 4th 2011, and the studied volcanic
material corresponds to that collected in Argentine territory at different
distances from the source, between 4 and 12 June 2011. The explosive-effusive
volcanic process of the first days occurred with the simultaneous emplacement
of lava flows and the venting of pyroclastic material, ejecting two well
differentiated types of particles. The more abundant was constituted by
rhyolitic and light color pumice fragments, characterized by a typical vesicular
texture, easy fragmentation and absence of occluded crystalline phases.
Particles found in minor proportion were dark color, different in shape and
texture and rich in Fe and Ti. They seemed to be more effective for the
interaction with emitted gases in the upper part of the column, for this
reason, they appeared partially covered by condensation products. The ascent
conditions of the magma affected its rheological behavior through variations in
the degassing, viscosity and fragmentation. On the other hand, distance to the
source, depositional time, volcanic evolution and environmental conditions are
factors that affect the chemical composition of collected ash. So, the SiO2/FeO
ratio not only increases with the distance but also with the deposition time
and volcanic activity. The work was done with the aid of several techniques
such as a laser-sediment analyzer, X-ray diffraction (XRD), chemical analysis
(bulk and surface), SEM microscopy and Raman “microprobe” spectroscopy. On the
other hand, the physicochemical behavior of
the pyroclastic material allows us to suggest eventual applications.