Rheology and the Fe3+–chlorine reaction in basaltic melts

Webb, Sharon L.; Murton, Bramley J.; Wheeler, Andrew J.

doi:10.1016/j.chemgeo.2013.12.006

Cited by 14 publications

(12 citation statements)

References 39 publications

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“…The large partial molar volume of CO 2 [Lange, 1994;Ni and Keppler, 2013], creating more "free volume" in the melt structure, may provide a possible explanation. Halogens generally have a negative influence on viscosity that is weaker than the influence of water [Baasner et al, 2013a], but in Fe-free peralkaline and metaluminous melts, Cl may lead to a viscosity increase [Baasner et al, 2013b;Webb et al, 2014]. Viscosity of Fe-bearing melts increases slightly with increasing oxygen fugacity because Fe 3+ can act as a network former [Liebske et al, 2003].…”

Section: Dependence On Melt Compositionmentioning

confidence: 99%

Transport properties of silicate melts

Hui

Steinle‐Neumann

2015

Reviews of Geophysics

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A quantitative description of the transport properties, diffusivity, viscosity, electrical, and thermal conductivity, of silicate melts is essential for understanding melting-related petrologic and geodynamic processes. We here provide a systematic overview on the current knowledge of these properties from experiments and molecular dynamics simulations, their dependence on pressure, temperature, and composition, atomistic processes underlying them, and physical models to describe their variations. We further establish phenomenological and physical links between diffusivity, viscosity, and electrical conductivity that are based on structural rearrangement in the melt. Neutral molecules and network-modifying cations with low electric field strength display intrinsic diffusivity, which is controlled by the intrinsic properties (size and valence) of the species. By contrast, oxygen and network formers with high field strength show extrinsic diffusivity, which is more sensitive to extrinsic parameters including temperature (T), pressure (P), and melt composition (X). Similar T-P-X dependence of diffusivity and electrical conductivity and their quantitative relation reveal the role of intrinsically diffusing species in electrical transport, while viscosity is tied to the extrinsically diffusing species in a similar way. However, the differences in the structural role and mobility of various atomic species diminish with increasing temperature and/or pressure: all transport processes are increasingly coupled, eventually converging to a uniform rate and mechanism. Accurate comprehension of interatomic interactions and melt structure is vital to fully accounting for the compositional dependence of transport properties, and simple polymerization parameters such as nonbridging oxygen per tetrahedrally coordinated cation are inadequate.

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Section: Dependence On Melt Compositionmentioning

confidence: 99%

Transport properties of silicate melts

Hui

Steinle‐Neumann

2015

Reviews of Geophysics

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“…The pioneering work of Webster and DeVivo (2002) established a quantitative link between the concentration of divalent cations such as Mg, Fe, and Ca and melt Cl-dissolution capacity. Several studies on the effects of Cl on the viscosity of silicate melts observed that the addition of Cl to some Fe-bearing melts results in an increase in the viscosity of these liquids, suggesting that dissolved Cl bonds with Fe 2+ in the melt and disrupts its networkmodifying structural role (Dingwell and Hess 1998;Zimova and Webb 2006;Webb et al 2014). Additionally, a recent X-ray absorption near edge structure (XANES) study conducted by Evans et al (2008) identified dissolved Cl bonded to divalent cations in the form of Mg-Cl and Ca-Cl species in haplobasaltic glasses.…”

Section: Introductionmentioning

confidence: 97%

“…After dissolved hydroxyl, chlorine is the second-most abundant anionic volatile component in evolved, subduction-related silicate magmas (Wallace 2005). Given the propensity for Cl to form ionic bonds with divalent cations in silicate melts (Carroll and Webster 1994;Webster and De Vivo 2002;Zimova and Webb 2006;Filiberto and Treiman 2009;Filiberto et al 2014;Webb et al 2014;Webster et al 2015), it is reasonable to hypothesize that dissolved chlorine may exert a significant influence on redox behavior of iron. Such an effect would have important implications for the stability fields of Febearing minerals in equilibrium with chlorinated melts, as well as understanding the relationship between the measured, formal valence of iron and magmatic f O2 .…”

Section: Introductionmentioning

confidence: 99%

Dissolved Cl, oxygen fugacity, and their effects on Fe behavior in a hydrous rhyodacitic melt

Bell

Webster

2015

American Mineralogist

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We have conducted a series of experiments to evaluate the intrinsic effects of dissolved chlorine on Fe 3+ /SFe and magnetite solubility in hydrous chloride-rich rhyodaciticliquids. The addition of Cl to the melt appears to have two prominent effects on iron in the melt: (1) dissolved Cl appears to perturb the magnetite-melt equilibrium, such that greater FeO total contents are required to support magnetite saturation in Cl-bearing melts than in Cl-free melts of equivalent bulk compositions; and (2) a systematic and progressive decrease of the measured Fe 3+ /SFe as f O2 is increased. These two intimately related effects each have important implications for redox processes occurring in Cl-enriched arc magmas.

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“…5 as a function of inverse temperature. The viscosity data of a MORB melt (Webb et al 2014) are plotted for comparison, showing that the MORB viscosity is lower than that of the foiditic PR and the tephri-phonolitic PN. At the fixed temperature of 700 °C, the most viscous melt from this study is the PN composition (12.89 log 10 Pa s) being nearly 1.2 orders of magnitude higher than that of PR (11.72 log 10 Pa s).…”

Section: Viscositymentioning

confidence: 99%

“…Fig.5Viscosities as a function of inverse temperature of the investigated melts with the original iron content in comparison with a MORB (dotted line)(Webb et al 2014) …”

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confidence: 99%

Rheology of melts from the colli albani volcanic district (Italy): a case study

Kleest

Webb

Fanara

2020

Contrib Mineral Petrol

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In this study the first viscosity measurements in the glass transition range of melts from highly explosive large-volume eruptions from the Colli Albani Volcanic District (CAVD) are presented. The magmas are ultrapotassic, rich in iron and CaO and characterised by a low silica content (< 45 wt%). Melt compositions range from tephri-phonolitic to foiditic. The Colli Albani eruptions appear anomalous since they produced a large volume of erupted material in spite of their silica undersaturated compositions. The viscosity of the Colli Albani melt changes as the melt composition evolves from the original melt to a country-rock contaminated melt to a crystal-bearing melt with a permanent decrease in liquid viscosity. Conventional estimations of viscosities assume these magmas to have a low viscosity. The presented data show that the melt viscosities are higher than expected. Taking into account further chemical or rheological features of a melt, the investigated CAVD melts are not that striking as assumed in comparison with other large-volume eruptions. Consequently, considering the alkaline-earth to alkaline ratio together with the SiO2 content could provide an alternative when comparing large volume eruptions.

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Rheology and the Fe3+–chlorine reaction in basaltic melts

Cited by 14 publications

References 39 publications

Transport properties of silicate melts

Transport properties of silicate melts

Dissolved Cl, oxygen fugacity, and their effects on Fe behavior in a hydrous rhyodacitic melt

Rheology of melts from the colli albani volcanic district (Italy): a case study

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