Degassing from magma reservoir to eruption in silicic systems: The Li elemental and isotopic record from rhyolitic melt inclusions and host quartz in a Yellowstone rhyolite

Neukampf, Julia; Laurent, Oscar; Tollan, Peter; Bouvier, Anne‐Sophie; Magna, Tomáš; Ulmer, Peter; France, Lydéric; Ellis, Ben

doi:10.1016/j.gca.2022.03.037

Cited by 13 publications

(6 citation statements)

References 104 publications

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“…During degassing of felsic melts, Li is partitioned into a vapor (fluid) phase (Webster et al., 1989). Fractionation of 6 Li and 7 Li via degassing also results in the depletion of 7 Li in a residual melt, and thus the [Li] and δ 7 Li values of co‐magmatic samples show a positive correlation (e.g., Neukampf et al., 2022). Such a positive correlation is not observed in IAB or ADK rocks from each volcanic field (Figure S1 in Supporting Information S1).…”

Section: Discussionmentioning

confidence: 99%

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Lithium Isotope Constraints on Slab and Mantle Contribution to Arc Magmas

2023

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Fluids lower the solidi of magma sources, thus inducing melting without the need for mantle with an anomalously high temperature. Fluids are considered to be expelled from oceanic lithospheric rocks during their subduction beneath an arc. Fluids also transport elements via dissolution of materials in subducted oceanic lithosphere (slab), resulting in elemental enrichments in arc magmas. The extents of the enrichments are related to the elemental solubility of a given element of group. For example, alkali metals and alkaline earth metals are highly soluble in fluids and thus are enriched in arc magmas (Kessel et al., 2005).Lithium represents an element with a high solubility in fluids (Kessel et al., 2005). It has two isotopes ( 7 Li and 6 Li) that fractionate during element partitioning between two substances; for example, fluid and rock or vapor and melt (Penniston-Dorland et al., 2017;Tomascak et al., 2016). In general, 7 Li is preferentially transferred into fluids (Caciagli et al., 2011;Wunder et al., 2006), and as a result, sub-arc mantle hydrated by fluids released by incipient dehydration of a slab would be enriched in 7 Li. Arc volcanic rocks, in particular those occurring in fore-arc region, are thus expected to record high δ 7 Li values from their hydrated sources. However, δ 7 Li values of most arc rocks fall within the range of unaltered mid-ocean ridge basalts (MORB with δ 7 Li = +1.6 to

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Section: Discussionmentioning

confidence: 99%

“…Fractionation of 6 Li and 7 Li could occur by degassing of magmas during their emplacements (Neukampf et al., 2022; Schiavi et al., 2010). During degassing of felsic melts, Li is partitioned into a vapor (fluid) phase (Webster et al., 1989).…”

Section: Discussionmentioning

confidence: 99%

Lithium Isotope Constraints on Slab and Mantle Contribution to Arc Magmas

2023

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“…In granitic pegmatites, interpreted as the final product of significant fractional crystallization of a peraluminous granitic melt, fluid exsolution during melt-fluid separation may be responsible for significant Li isotopic fractionation in a H 2 O-poor silica-rich melt (Zhang et al, 2021). During magma degassing, diffusional isotope fractionation may occur because 6 Li diffuses faster than 7 Li (e.g., Richter et al, 2003;Holycross et al, 2018) 2020), (S22): Spallanzani et al (2022).…”

Section: Isotope Fractionationmentioning

confidence: 99%

“…FIGURE 4 Compilation of the δ 7 Li data as a function of the Li content for rhyolitic bulk compositions. Data from (E18): Ellis et al (2018); (N19): Neukampf et al (2019); (N20): Neukampf et al (2021); (N22): Neukampf et al(2022). The legend refers to: bulk: the whole rock; gdm: the groundmass, which more (gdm*) or less (gdm) crystallized.…”

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confidence: 99%

Lithium in felsic magmas: a volcanological perspective

Dupont de Dinechin,

Balcone-Boissard,

Martel

et al. 2023

Front. Earth Sci.

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Volcanic eruptions are unpredictable phenomena that pose a challenge to crisis management, owing to the fact that contrasted eruptive styles (explosive versus effusive) exhibited at the surface depend on unobservable deep processes occurring in the reservoir and the volcanic conduit. Constricting the behaviour of magma during ascent, and the degassing in particular, allows for a clearer understanding of the relationships between petrological and volcano monitoring signals, and hence a better description of the volcanic hazard. To this aim, lithium (Li) has been used to track magmatic and post-eruptive processes, as a geospeedometer for processes operating on short time scales due to its high mobility in silicate melts and crystals. Yet, the accurate use of Li to assess syn- and post-eruptive processes still lack complete dataset. We propose a review of our current knowledge on Li behavior, with an emphasis on felsic (andesitic to rhyolitic) magmas whose explosive behavior during volcanic eruptions is still poorly understood. We present current knowledge regarding the Li concentration and isotopic compositions, intracrystalline diffusion, and crystal-melt-fluid partition coefficients discovered in felsic magmas and primary crystals. We describe difficulties in interpreting Li data to investigate the differentiation, degassing, ascent rate, volatile fluxing, and cooling of magmas. Finally, we suggest future directions for expanding our understanding of Li behavior.

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“…In their vertical parts, the trends of equilibrium decompression degassing and disequilibrium CO2 flushing are quite similar, which, at least requires not to ignore the possibility of the later process. Additional information, such as the isotopic composition ( 7 Li,  11 B,  34 S) [Gurenko et al, 2021;Neukampf et al, 2022;Zelenski et al, 2022] which is affected by isotope fractionation during degassing, could potentially help in choosing between these alternative mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental modeling of local scale CO2 flushing of hydrous rhyolitic magma

Simakin¹,

Devyatova²,

Shiryaev³

2023

Preprint

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Flushing of hydrous silicic magmas with crustal carbonic fluid may be an important factor controlling the explosiveness of rhyolitic eruptions. We present combined theoretical and experimental study of the interaction of carbonic fluid with a hydrous silicic melt. The process of diffusional equilibration of a CO2 bubble with a silicic melt was simulated numerically in the spherical approximation. The rapid water transfer from the melt to the bubble is followed by a slower diffusion of CO2 into the melt. The water distribution becomes almost uniform over a period proportional to the diffusional unit of time 0.14W, determined by the initial inter-bubble distance W and the water diffusion coefficient Dw (W =W2/Dw), while the CO2 distribution remains strongly contrasting. This process was modelled experimentally with a hydrous albite melt at P=200 MPa and T=950-1000oC. In the first series of experiments at T=950oC, a glass powder was filled with pure CO2 at the beginning of the experiment, forming numerous bubbles at the run temperature. Micro-FTIR measurements showed that after 40 minutes the water content decreased from 4.9 down to 1.8 wt.% with the maximum CO2 content 500 ppm. After 4 hours, the crystallinity increases to 85%, and the fluid bubbles almost disappear. The second series of experiments CO2 interacted with a 2 mm high column of hydrous albite melt. Diffusion profiles in the quenched glass were measured using EMPA (H2O) and micro-FTIR (CO2 and H2O). The estimated diffusion coefficients for H2O (1.1×10-6 cm2/s) and CO2 (1.5e×10-7 cm2/s) are consistent with published data. Scaling analysis predicts that in natural environment the homogenization of water in rhyolitic magma after an influx of CO2 bubbles few millimeters in size lasts for 1-30 days, i.e. a period compatible with pre-eruptive processes in a magma chamber.

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Degassing from magma reservoir to eruption in silicic systems: The Li elemental and isotopic record from rhyolitic melt inclusions and host quartz in a Yellowstone rhyolite

Cited by 13 publications

References 104 publications

Lithium Isotope Constraints on Slab and Mantle Contribution to Arc Magmas

Lithium Isotope Constraints on Slab and Mantle Contribution to Arc Magmas

Lithium in felsic magmas: a volcanological perspective

Theoretical and experimental modeling of local scale CO2 flushing of hydrous rhyolitic magma

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