Compositionally zoned crystals and real-time degassing data reveal changes in magma transfer dynamics during the 2006 summit eruptive episodes of Mt. Etna

Kahl, Maren; Chakraborty, Sumit; Costa, Fidel; Pompilio, M.; Liuzzo, Marco; Viccaro, Marco

doi:10.1007/s00445-013-0692-7

Cited by 102 publications

(99 citation statements)

References 32 publications

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“…In this context, lavas are made up of a mixture of phenocrysts with different degree of disequilibrium: Some are in equilibrium with host magma, while other may have more primary or evolved features. This observation suggests that the erupted lava is a mixture of crystals from mushes equilibrated at different depth in the plumbing system, as also supported by Sr isotopes studies by Armienti et al (2007) and crystal-melt disequilibrium of olivine phenocrysts (Kahl et al 2011(Kahl et al , 2013. Phenocrysts indicating more evolved compositions reasonably resided in the uppermost portion of the feeding system where massive degassing promotes magma undercooling, crystallization, and fractionation (Crabtree and Lange 2011;Mollo et al 2015b).…”

Section: Magma Feeding Systemmentioning

confidence: 76%

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Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Giacomoni

Coltorti

Bryce

et al. 2016

Contrib Mineral Petrol

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International audienceCoupled textural and in situ geochemical studies of clinopyroxene (cpx) phenocrysts, from both historical and recent eruptions of Mt. Etna volcano, provide a means to investigate the processes occurring in the deepest portion of the feeding system (>10 km depth). Five distinct textures were recognized: (1) normal oscillatory zoning, (2) normal zoning with Fe-rich rim, (3) sieve-textured core, (4) reverse oscillatory zoning, and (5) dusty rim. Electron microprobe analyses indicate an almost constant diopside–augite composition, with a slight enrichment in the enstatite for more recent erupted cpx. Core-to-rim compositional profiles, performed along the cpx, reveal distinct compositional characteristics. Normal oscillatory zoning is often characterized by a sharp increase in FeO (Δ ~ 2 wt%) accompanied by a drop in Al2O3 on the outermost 30 μm. Reverse oscillatory zoning, by contrast, exhibits a drop in FeO, Al2O3 (Δ ~ 2 wt%), and a remarkable crystal rim increase in MgO (up to 5 wt%). Similar compositional changes are evident in dusty-textured rims, which are characterized by dissolution edges and overgrowth containing glass pockets and channels. No significant compositional variations have been observed across crystals with sieve-textured cores. Trace element concentrations show enrichments in Sr, La, Zr, and REE, together with a decreasing La/Yb ratio (from ~7 to ~4) in rims of normally zoned crystals. Cpx with reverse zoning and dusty rims has low Sr, La, Zr, and REE contents toward crystal rims. Thermometers and barometers, based on equilibrium cpx-melt pairs, suggest that cpx cores start nucleating at 720 MPa, with the majority of them forming between 600 and 400 MPa but continuing to crystallize until very shallow depths (<100 MPa). Normal oscillatory-zoned phenocrysts surrounded by rims form at pressures shallower than 400 MPa, while reverse zoning and dusty rims occur between 400 and 500 MPa. Coupled petrologic and thermobarometric studies on both clinopyroxenes and plagioclases, associated with detailed textural and in situ geochemical analyses, are promising tools to reconstruct the entire magma ascent path beneath open-system volcanoes. At Mt. Etna, two distinct processes could account for the observed textures: Fe-rich rims in normal oscillatory-zoned crystals can be related to decompression-induced crystallization, while reverse zoning and dusty rims can be produced by mixing with a more basic magma at 400–500 MPa (i.e., ~10 km). Textural features are not restricted to a particular evolutionary phase of the volcano, which suggest that the deep feeding system has not changed significantly since the first alkaline volcanic phase

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Section: Magma Feeding Systemmentioning

confidence: 76%

“…Comparatively, the few studies that have been dedicated to basaltic volcanic systems focused on Mauna Loa (Crisp et al 1994), Stromboli (Landi et al 2004), and Mt. Etna (Armienti et al 1994(Armienti et al , 2007Viccaro et al 2010;Kahl et al 2011Kahl et al , 2013Giacomoni et al 2014;Mollo et al 2015a).…”

Section: Introductionmentioning

confidence: 99%

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Giacomoni

Coltorti

Bryce

et al. 2016

Contrib Mineral Petrol

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“…Use of this approach on olivine crystals at Mt. Etna has led Kahl et al (2013) to detect at least two major recharging events before and during the 2006 eruptive episodes. Also, disequilibrium textures at the core and rim of plagioclase crystals at Mt.…”

Section: Petrological Modeling Of Magma Dynamicsmentioning

confidence: 98%

Continuous magma recharge at Mt. Etna during the 2011–2013 period controls the style of volcanic activity and compositions of erupted lavas

et al. 2014

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“…On the other hand, Kahl et al (2011Kahl et al ( , 2013 determined that the beginning of magma mixing recorded in olivine crystals from a recent eruption of Mt. Etna correlates to that of several signs of volcanic unrest.…”

Section: Magma-mixing Process Without Crustal Deformationmentioning

confidence: 99%

Short time scales of magma-mixing processes prior to the 2011 eruption of Shinmoedake volcano, Kirishima volcanic group, Japan

et al. 2013

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We estimated time scales of magma-mixing processes just prior to the 2011 sub-Plinian eruptions of Shinmoedake volcano to investigate the mechanisms of the triggering processes of these eruptions. The sequence of these eruptions serves as an ideal example to investigate eruption mechanisms because the available geophysical and petrological observations can be combined for interpretation of magmatic processes. The eruptive products were mainly phenocryst-rich (28 vol%) andesitic pumice (SiO 2 57 wt%) with a small amount of more silicic pumice (SiO 2 62-63 wt%) and banded pumice. These pumices were formed by mixing of low-temperature mushy silicic magma (dacite) and high-temperature mafic magma (basalt or basaltic andesite). We calculated the time scales on the basis of zoning analysis of magnetite phenocrysts and diffusion calculations, and we compared the derived time scales with those of volcanic inflation/deflation observations. The magnetite data revealed that a significant mixing process (mixing I) occurred 0.4 to 3 days before the eruptions (preeruptive mixing) and likely triggered the eruptions. This mixing process was not accompanied by significant crustal deformation, indicating that the process was not accompanied by a significant change in volume of the magma chamber. We propose magmatic overturn or melt accumulation within the magma chamber as a possible process. A subordinate mixing process (mixing II) also occurred only several hours before the eruptions, likely during magma ascent (syn-eruptive mixing). However, we interpret mafic injection to have begun more than several tens of days prior to mixing I, likely occurring with the beginning of the inflation (December 2009). The injection did not instantaneously cause an eruption but could have resulted in stable stratified magma layers to form a hybrid andesitic magma (mobile layer). This hybrid andesite then formed the main eruptive component of the 2011 eruptions of Shinmoedake.

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Compositionally zoned crystals and real-time degassing data reveal changes in magma transfer dynamics during the 2006 summit eruptive episodes of Mt. Etna

Cited by 102 publications

References 32 publications

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Mt. Etna plumbing system revealed by combined textural, compositional, and thermobarometric studies in clinopyroxenes

Continuous magma recharge at Mt. Etna during the 2011–2013 period controls the style of volcanic activity and compositions of erupted lavas

Short time scales of magma-mixing processes prior to the 2011 eruption of Shinmoedake volcano, Kirishima volcanic group, Japan

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