Lithium diffusion in olivine records magmatic priming of explosive basaltic eruptions

Lynn, Kendra J.; Shea, Thomas; Garcia, Michael O.; Costa, Fidel; Norman, Marc D.

doi:10.1016/j.epsl.2018.08.002

Cited by 25 publications

(34 citation statements)

References 54 publications

(99 reference statements)

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“…The time scales of the second diffusion event determined by Li diffusion modeling are 20-80 days for Banne D'Ordanche and 30-200 days for Roche Sauterre which is longer than the time scales obtained by Lynn et al (2018) for the Keanakâko'i Tephra (Kîlauea Volcano, Hawai'i), also using Li diffusion modeling (only Li concentrations). The authors conclude a similar process of syn-eruptive degassing in their study with time scales of only hours to days which is 1-2 orders of magnitude faster than that estimated with the fitted D Li values of this study.…”

Section: The Second Diffusion Eventmentioning

confidence: 66%

“…In principle, chemically zoned crystals can be the result of crystal growth in an evolving melt (growth zoning) or of chemical diffusion, as the result of disequilibrium, between minerals and the surrounding melt (diffusion zoning) (Costa et al, 2008). In the case of Li, this can be caused either by an increase in Li concentration in the magma, typically either due to magma mixing or crystal fractionation, or, due to a decrease in Li concentration in the melt, e.g., during degassing (Vlastélic et al, 2011;Lynn et al, 2018). The resulting zoning can be used to reconstruct the migration of crystals through dynamic plumbing systems with several reservoirs of compositionally different melts (Kahl et al, 2013(Kahl et al, , 2015.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, Li behaves incompatibly during magma differentiation, with typical concentration levels of 3 to 8 µg/g in basalts and of ∼20 µg/g in rhyolites (Ryan and Langmuir, 1987;Ryan and Kyle, 2004) and with olivine/melt distribution coefficients of 0.2-0.35 (Ryan and Langmuir, 1987;Brenan et al, 1998). As olivine is a very abundant mineral in primitive basalts and chemical diffusion in olivine is well characterized, e.g., for Fe-Mg exchange or for Li (Dohmen et al, 2010;Richter et al, 2017), it frequently serves for diffusion studies (e.g., Lynn et al, 2018;Oeser et al, 2018). However, growth and diffusive origins of zoning cannot easily be distinguished by the investigation of chemical zoning alone and, notably, only the latter bears timescale information.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Stage Magma Evolution in Intra-Plate Volcanoes: Insights From Combined in situ Li and Mg–Fe Chemical and Isotopic Diffusion Profiles in Olivine

et al. 2020

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Understanding the timescales of magma evolution and ascent is essential for interpreting geophysical monitoring signals from active volcanoes. In this study, we explore the potential of diffusion-driven Li concentration and isotope zoning profiles recorded by magmatic olivine crystals to unravel time scales of magma evolution processes. Lithium is a fast-diffusing element and may provide the opportunity to investigate changes in magma composition during magma ascent, shortly before eruption. Lithium chemical and isotopic profiles were determined in olivines from two localities in the Massif Central volcanic region (France) that have previously been investigated for their Fe-Mg isotope systematics. The combined investigation of isotopic and chemical profiles makes it possible to distinguish between crystal growth and diffusion events. Extremely low δ 7 Livalues down to −30.7 (relative to the commonly used Li isotope standard IRMM-16) in the crystal core regions and elevated values at crystal rims (δ 7 Li ∼8 to 10 ), along with increasing concentrations from cores (∼3 to 1 µg/g) toward rims (12 to 6 µg/g) were found. The shape and orientation of both the chemical and isotopic profiles indicate that they were dominantly generated by Li diffusion into and within the olivine grains during magmatic differentiation. While Mg-Fe isotope and major element profiles have been modeled by a single diffusion event (Oeser et al., 2015), concentration and isotope profiles of Li indicate that a second diffusion event took place, that was not recorded by the Mg-Fe exchange diffusion couple. The first diffusion event was interpreted as reflecting the residence of the olivine crystals in a magma chamber. As diffusion coefficients for Fe-Mg exchange diffusion are very well determined, the time scales of this event are likely best quantified by Mg-Fe isotopic exchange diffusion modeling (Oeser et al., 2015). This event probably also generated the low δ 7 Li observed in olivine cores. Comparing the length of the Mg-Fe and Li profiles could thus be used to determine the less well-known diffusion coefficients of Li in the studied olivine crystals. The findings of this study indicate that Li diffusion at low Li concentration levels, as typically observed in natural olivine, may be not as fast as previously thought. The second diffusion event might represent a short-lived event, such as degassing, related to the ascent of the magma and/or magma cooling after emplacement of the lava. Such

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Section: The Second Diffusion Eventmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-Stage Magma Evolution in Intra-Plate Volcanoes: Insights From Combined in situ Li and Mg–Fe Chemical and Isotopic Diffusion Profiles in Olivine

et al. 2020

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“…If homogenization remains incomplete, the compositional gradient between crystal core and rim (in equilibrium with the new melt) can be modeled to constrain the timescales of diffusion and to track the relative periods of time between distinct magmatic events such as magma mixing and eruption (e.g. Costa and Dungan 2005;Cooper and Kent 2014;Lynn et al 2018). Compositional gradients also allow to reconstruct the temperature history of crystals with known residence time (Rubin et al 2017;Rout and Wörner 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies show that mixing and eruption in basaltic magma systems can occur within days to months (e.g. Viccaro et al 2016;Brenna et al 2018;Lynn et al 2018;Albert et al 2019;Sundermeyer et al 2020). Even large and compositionally evolved, silicic systems may also yield timescales of only a few years between recharge events and eruption, which is an exceedingly short time for reactivation of these long-lived systems (Cooper and Kent 2014;Cooper et al 2016;Druitt et al 2012Druitt et al , 2016.…”

Section: Introductionmentioning

confidence: 99%

Timescales from magma mixing to eruption in alkaline volcanism in the Eifel volcanic fields, western Germany

Sundermeyer

Gätjen

Weimann

2020

Contrib Mineral Petrol

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Diffusion profiles in olivine crystals from the final mafic eruption products of the compositionally zoned Laacher See tephra deposit were measured to identify recharge and eruption-triggering events prior to the eruption of the Laacher See volcano (12.9 kyr). These products represent the hybrids of mixing between phonolite and intruding basanite at the bottom of the reservoir, which is likely related to the eruption-triggering event. Additionally, olivine crystals from ten basanitic scoria cones and maar deposits (East Eifel) and two nephelinites (West Eifel) were analyzed to constrain histories of olivine in Quaternary basanite magmas. Olivine crystals from the Laacher See hybrids vary in core composition (Fo 83-89) and show reversely zoned mantles with high Fo 87.8-89 compared to olivine in East Eifel basanites erupted in nearby, older scoria cones. Towards the crystal margin, olivine in the hybrids develop a normally zoned overgrowth (Fo 86.5-87.5). Olivine from East Eifel basanites show similar zonation and core compositions (Fo 80-88) but have less forsteritic mantles (Fo 83-88) indicating that these basanites are less primitive than those recharging the Laacher See reservoir (> Fo 89). Olivine in the West Eifel nephelinites show mantles similar to those from Laacher See (Fo 87.5-90), but have normal zoning and high-Fo cores (Fo 88-92). This indicates that olivine in the Laacher See hybrids were entrained by a near-primary basanite from older cumulates just before hybridization of the basanite with the phonolite. Diffusion modeling indicates maximum timescales between entrainment and eruption of Laacher See of 30-400 days that are comparable to those calculated for olivine from basanitic scoria cones (10-400 days).

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Phosphorus and aluminum zoning in olivine: contrasting behavior of two nominally incompatible trace elements

Shea

Hammer

Hellebrand

et al. 2019

Contrib Mineral Petrol

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Phosphorus zoning in olivine is receiving considerable attention for its capacity to preserve key information about rates and mechanisms of crystal growth. Its concentration can vary significantly over sub-micron spatial scales and form intricate, snowflake-like patterns that are generally attributed to fast crystal growth. Ostensibly similar aluminum enrichment patterns have also been observed, suggesting comparable incorporation and partitioning behavior for both elements. We perform 1-atm crystallization experiments on a primitive Kīlauea basalt to examine the formation of P and Al zoning as a function of undercooling − ΔT (− ΔT = Tliquidus − Tcrystallization) during olivine growth. After 24 h spent at Tinitial = 1290 °C (10 °C above olivine stability), charges are rapidly cooled to final temperatures Tfinal = 1220-1270 °C, corresponding to undercoolings −ΔT= 10-60 °C (with Tliquidus = 1280 °C). Compositional X-ray maps of experimental olivine reveal that only a small undercool-ing (≤ 25 °C) is required to produce the fine-scale enrichments in P and Al associated with skeletal growth. Concentration profiles indicate that despite qualitatively similar enrichment patterns in olivine, P and Al have contrasting apparent crystal/ melt mass distribution coefficients of = 0.01-1 and = 0.002-0.006. Phosphorus can be enriched by a factor > 40-fold in the same crystal, whereas Al enrichment never exceed factors of 2. Glass in the vicinity of synthetic and natural olivine is usually enriched in Al, but, within analytical uncertainty, not in P. Thus, we find no direct evidence for a compositional boundary layer enriched in P that would suffice to produce P enrichments in natural and synthetic olivine. Numerical models combining growth and diffusion resolve the conditions at which Al-rich boundary layers produce the observed enrichment patterns in olivine. In contrast, the same models fail to reproduce the observed P enrichments, consistent with our observation that P-rich boundary layers are insignificant. If instead, P olivine/melt partitioning is made to depend on growth rate, models adequately reproduce our observations of 40-fold enrichment without boundary layer formation. We surmise that near-partitionless behavior ( close to 1) of P is related to the olivine lattice being perhaps less stiff in accommodating P during rapid crystallization, and/or to enhanced formation of vacancy defects during fast growth. Our results confirm that P is a robust marker of initial rapid growth, but reveal that the undercooling necessary to induce these enrichments is not particularly large. The near-ubiquitous process of magma mixing under volcanoes, for instance, is likely sufficient to induce low-tomoderate degrees of undercooling required for skeletal growth.

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Lithium diffusion in olivine records magmatic priming of explosive basaltic eruptions

Cited by 25 publications

References 54 publications

Multi-Stage Magma Evolution in Intra-Plate Volcanoes: Insights From Combined in situ Li and Mg–Fe Chemical and Isotopic Diffusion Profiles in Olivine

Multi-Stage Magma Evolution in Intra-Plate Volcanoes: Insights From Combined in situ Li and Mg–Fe Chemical and Isotopic Diffusion Profiles in Olivine

Timescales from magma mixing to eruption in alkaline volcanism in the Eifel volcanic fields, western Germany

Phosphorus and aluminum zoning in olivine: contrasting behavior of two nominally incompatible trace elements

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