Kinetic Fractionation of Non-Traditional Stable Isotopes by Diffusion and Crystal Growth Reactions

Watkins, James M.; DePaolo, Donald J.; Watson, E. Bruce

doi:10.2138/rmg.2017.82.4

Cited by 83 publications

(50 citation statements)

References 123 publications

(167 reference statements)

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“…The global dataset of experimentally-determined β values (β > 0) for fractionation in silicate liquids spans β Ca = 0.035 to our new value of β Li = 0.228 (compiled by Watkins et al, 2017). The β Li determined here for diffusion in hydrous obsidian melt at 790-875 °C is close to the value of Richter et al (2003), who found β = 0.215 for Li isotopes in dry silicate melt in a single experiment at 1350 ºC.…”

Section: Lithium Isotope Fractionation In Wet Rhyolitic Meltsupporting

confidence: 71%

“…In view of the widespread interest in the Li geochemistry of such systems, there is a compelling need for constraints on β in pertinent melt compositions and temperatures. Additionally, the work of Watkins et al (2009Watkins et al ( , 2011Watkins et al ( , 2017 showed significant compositional dependence of β for isotope diffusion in simple silicate liquids, providing further motivation for determining the kinetic isotope fractionation of Li in a common but not previously studied molten silicate system.…”

Section: Introduction and Experimental Approachmentioning

confidence: 91%

“…Watkins et al (2009Watkins et al ( , 2011Watkins et al ( , 2017 proposed that the β factor for isotopic fractionation of an element i in simple silicate melt may be a function of its Si-normalised diffusivity, (Fig. 3).…”

Section: Lithium Isotope Fractionation In Wet Rhyolitic Meltmentioning

confidence: 99%

“…This suggests diffusion of Li may be decoupled from the melt network and exhibit a greater mass discrimination. Figure after Watkins et al (2017).…”

Section: Figurementioning

confidence: 99%

See 3 more Smart Citations

Diffusive fractionation of Li isotopes in wet, silicic melts

Holycross¹,

Watson²,

Richter³

et al. 2018

Geochem. Persp. Let.

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The discovery of large lithium isotopic gradients in geologic media has motivated recent work examining the kinetic fractionation of Li isotopes in silicate materials. Here, piston-cylinder experiments were used to determine Li diffusivities in rhyolitic melts containing ~6 wt. % H 2 O at 1 GPa pressure and 790-875 ºC. Lithium transport in wet rhyolitic melt is almost an order of magnitude faster than diffusion in dry obsidian glass over the investigated temperature range. Li isotope profiles collected by ion microprobe show that the kinetic exponent β = 0.228 for diffusive fractionation of Li isotopes in wet rhyolite. This value is very close to β = 0.215 determined by Richter et al. (2003) for Li isotope diffusion in a dry basalt-rhyolite couple at 1350 °C. The similarity of the two values indicates little or no dependence of β Li in silicate melts on either temperature or melt composition. The new data confirm a very high potential for diffusive fractionation of 6 Li from 7 Li and can be confidently used to model deviations in δ 7 Li to determine the time-temperature histories of natural rhyolite samples.

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Section: Lithium Isotope Fractionation In Wet Rhyolitic Meltsupporting

confidence: 71%

Section: Introduction and Experimental Approachmentioning

confidence: 91%

Section: Lithium Isotope Fractionation In Wet Rhyolitic Meltmentioning

confidence: 99%

“…This suggests diffusion of Li may be decoupled from the melt network and exhibit a greater mass discrimination. Figure after Watkins et al (2017).…”

Section: Figurementioning

confidence: 99%

See 2 more Smart Citations

Diffusive fractionation of Li isotopes in wet, silicic melts

Holycross¹,

Watson²,

Richter³

et al. 2018

Geochem. Persp. Let.

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show abstract

“…This can only be achieved through use of the double-spike technique. Equilibrium or kinetic fractionation effects (e.g., Blanchard et al, 2017;Watkins et al, 2017) in the data presented here can be related to two different realms of processes. First, the fractionation that occurred during the development of the components that were assembled to produce the meteorites (regardless of their degree of differentiation).…”

Section: Resultsmentioning

confidence: 91%

Stable strontium isotopic heterogeneity in the solar system from double-spike data

Charlier¹,

Parkinson²,

Burton³

et al. 2017

Geochem. Persp. Let.

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Strontium isotopic anomalies in meteorites are important in assessing nucleosynthetic sources to, and measuring the timing of, early solar system processes. However, conventional use of a constant 88 Sr/ 86 Sr value in correcting for instrumental mass fractionation during analysis renders measurements ambiguous and removes information on mass-dependent fractionation variations. From doublespike techniques we obtain data for the four stable strontium isotopes free of this ambiguity, and report measurements from a range of meteoritic, lunar and terrestrial materials. The Earth, Moon, basaltic eucrites and feldspars from angrites (differentiated samples) follow a single mass-dependent fractionation line and have a common nucleosynthetic origin in terms of their strontium isotopes. In contrast, bulk rock CI, CV3, CM and CO chondrite samples serve to define another mass-dependent fractionation line, displaced by 94 ± 28 ppm to heavier 84 Sr/ 86 Sr and/or 88 Sr/ 86 Sr ratios than that for the differentiated samples. Our Sr-isotopic data are consistent with a primary contrast in early solar system composition between an outer zone of primitive, mostly undifferentiated, materials and an inner zone of (almost entirely) differentiated materials that accumulated to form the terrestrial planets.

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High‐Temperature Kinetic Isotope Fractionation of Silicate Materials

Richter¹

2022

Isotopic Constraints on Earth System Processes

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Kinetic Fractionation of Non-Traditional Stable Isotopes by Diffusion and Crystal Growth Reactions

Cited by 83 publications

References 123 publications

Diffusive fractionation of Li isotopes in wet, silicic melts

Diffusive fractionation of Li isotopes in wet, silicic melts

Stable strontium isotopic heterogeneity in the solar system from double-spike data

High‐Temperature Kinetic Isotope Fractionation of Silicate Materials

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