Morphochemistry of patterns produced by mixing of rhyolitic and basaltic melts

Morgavi, Daniele; Perugini, Diego; Campos, Cristina P. De; Ertel-Ingrisch, Werner; Dingwell, Donald B.

doi:10.1016/j.jvolgeores.2012.12.007

Cited by 21 publications

(26 citation statements)

References 49 publications

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“…10 0.4 Pa s −1 for the SRP basaltic melt and ca. 10 4 Pa s −1 for the SRP rhyolitic melt (Morgavi et al, 2013a). As such, the relatively lower viscosity of our experimental rhyolite melt compared to that of a natural, H 2 O-bearing rhyolite magma at depth, ensures reasonable experimental run times, while maintaining fluid mechanical scalability.…”

Section: Methodsmentioning

confidence: 82%

“…(iv) Forced intrusion implies a competent, felsic body of magma (mush), Table 1. Composition of end-member glasses from the Snake River Plain (data from Morgavi et al, 2013a almost solidified but still hot, which is being intruded by a mafic dyke (Pallister et al, 1992;Izbekov et al, 2004). Simultaneous reheating of the felsic magma may lead to collapse of the dyke, because the surrounding felsic magma melts and loses strength to contain the magma in a rigid conduit.…”

Section: Mechanisms Of Stirring or Mingling Magmamentioning

confidence: 99%

“…The rhyolite sample is from Unit V of the Cougar Point Tuff and the basalt sample from Mary's Creek (see Bonnichsen, 1982;Cathey and Nash, 2009). Samples of these units have been used in previous studies (see Morgavi et al, 2013a, b, c tholeiitic composition, and the rhyolite belongs to the subalkaline series (Table 1). Both materials were freed from weathered surfaces and crushed.…”

Section: Glass Preparationmentioning

confidence: 99%

“…Concentration variance σ 2 represents a statistical measure for the degree of homogenisation of a filament and has been applied successfully in previous experimental studies on magma mixing (Morgavi et al, 2012(Morgavi et al, , 2013aPerugini et al, 2013). The calculation of σ 2 is given by…”

Section: Calculation Of Concentration Variancementioning

confidence: 99%

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Magma mixing enhanced by bubble segregation

et al. 2015

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Abstract. In order to explore the materials' complexity induced by bubbles rising through mixing magmas, bubbleadvection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose via buoyancy forces into the rhyolitic melt, thereby entraining tails of basaltic liquid. In the experimental run products, these plume-like filaments of advected basalt within rhyolite were clearly visible and were characterised by microCT and high-resolution EMP analyses.The entrained filaments of mafic material have been hybridised. Their post-experimental compositions range from the originally basaltic composition through andesitic to rhyolitic composition. Rheological modelling of the compositions of these hybridised filaments yield viscosities up to 2 orders of magnitude lower than that of the host rhyolitic liquid. Importantly, such lowered viscosities inside the filaments implies that rising bubbles can ascend more efficiently through pre-existing filaments that have been generated by earlier ascending bubbles. MicroCT imaging of the run products provides textural confirmation of the phenomenon of bubbles trailing one another through filaments. This phenomenon enhances the relevance of bubble advection in magma mixing scenarios, implying as it does so, an acceleration of bubble ascent due to the decreased viscous resistance facing bubbles inside filaments and yielding enhanced mass flux of mafic melt into felsic melt via entrainment. In magma mixing events involving melts of high volatile content, bubbles may be an essential catalyst for magma mixing.Moreover, the reduced viscosity contrast within filaments implies repeated replenishment of filaments with fresh endmember melt. As a result, complex compositional gradients and therefore diffusion systematics can be expected at the filament-host melt interface, due to the repetitive nature of the process. However, previously magmatic filaments were tacitly assumed to be of single-pulse origin. Consequently, the potential for multi-pulse filaments has to be considered in outcrop analyses. As compositional profiles alone may remain ambiguous for constraining the origin of filaments, and as 3-D visual evidence demonstrates that filaments may have experienced multiple bubbles passages even when featuring standard diffusion gradients, therefore, the calculation of diffusive timescales may be inadequate for constraining timescales in cases where bubbles have played an essential role in magma mixing. Data analysis employing concentration variance relaxation in natural samples can distinguish conventional single-pulse filaments from advection via multiple bubble ascent advection in natural samples, raising the prospect of yet another powerful application of this novel petrological tool.

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Section: Methodsmentioning

confidence: 82%

Section: Mechanisms Of Stirring or Mingling Magmamentioning

confidence: 99%

Section: Glass Preparationmentioning

confidence: 99%

Section: Calculation Of Concentration Variancementioning

confidence: 99%

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Magma mixing enhanced by bubble segregation

et al. 2015

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“…Examples include Vesuvius 79 AD (Cioni et al 1995), Krakatau 1883 (Self 1992), Pinatubo 1991 (Kress 1997), the Campanian Ignimbrite (Arienzo et al 2009) and Eyjafjallajökull 2010 (Sigmundsson et al 2010). Injection of the more mafic magma into the felsic experimental setup, from Morgavi et al (2013b); right: simulations of magma chamber replenishment magma triggers convection dynamics and widespread mixing (Sparks et al 1977). Vesiculation induced by convection increases magma pressure and may fracture the volcanic edifice triggering an explosive eruption.…”

Section: Magma Mixing Time Scale and Eruption Triggermentioning

confidence: 99%

Magma Mixing: History and Dynamics of an Eruption Trigger

Morgavi

Arienzo

Montagna

et al. 2017

Advances in Volcanology

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The most violent and catastrophic volcanic eruptions on Earth have been triggered by the refilling of a felsic volcanic magma chamber by a hotter more mafic magma. Examples include Vesuvius 79 AD, Krakatau 1883, Pinatubo 1991, and Eyjafjallajökull 2010. Since the first hypothesis, plenty of evidence of magma mixing processes, in all tectonic environments, has accumulated in the literature allowing this natural process to be defined as fundamental petrological processes playing a role in triggering volcanic eruptions, and in the generation of the compositional variability of igneous rocks. Combined with petrographic, mineral chemistry and geochemical investigations, isotopic analyses on volcanic rocks have revealed compositional variations at different length scales pointing to a complex interplay of fractional crystallization, mixing/mingling and crustal contamination during the evolution of several magmatic feeding systems. But to fully understand the dynamics of mixing and mingling

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Approximate chemical analysis of volcanic glasses using Raman spectroscopy

Genova

Morgavi

Hess

et al. 2015

J Raman Spectroscopy

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The effect of chemical composition on the Raman spectra of a series of natural calcalkaline silicate glasses has been quantified by performing electron microprobe analyses and obtaining Raman spectra on glassy filaments (~450 µm) derived from a magma mingling experiment. The results provide a robust compositionally‐dependent database for the Raman spectra of natural silicate glasses along the calcalkaline series. An empirical model based on both the acquired Raman spectra and an ideal mixing equation between calcalkaline basaltic and rhyolitic end‐members is constructed enabling the estimation of the chemical composition and degree of polymerization of silicate glasses using Raman spectra. The model is relatively insensitive to acquisition conditions and has been validated using the MPI‐DING geochemical standard glasses1 as well as further samples. The methods and model developed here offer several advantages compared with other analytical and spectroscopic methods such as infrared spectroscopy, X‐ray fluorescence spectroscopy, electron and ion microprobe analyses, inasmuch as Raman spectroscopy can be performed with a high spatial resolution (1 µm2) without the need for any sample preparation as a nondestructive technique. This study represents an advance in efforts to provide the first database of Raman spectra for natural silicate glasses and yields a new approach for the treatment of Raman spectra, which allows us to extract approximate information about the chemical composition of natural silicate glasses using Raman spectroscopy. We anticipate its application in handheld in situ terrestrial field studies of silicate glasses under extreme conditions (e.g. extraterrestrial and submarine environments). © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd

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Morphochemistry of patterns produced by mixing of rhyolitic and basaltic melts

Cited by 21 publications

References 49 publications

Magma mixing enhanced by bubble segregation

Magma mixing enhanced by bubble segregation

Magma Mixing: History and Dynamics of an Eruption Trigger

Approximate chemical analysis of volcanic glasses using Raman spectroscopy

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