Lithium-isotope fractionation during continental weathering processes

Pistiner, Janna S; Henderson, Gideon M.

doi:10.1016/s0012-821x(03)00348-0

Cited by 379 publications

(315 citation statements)

References 25 publications

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“…The importance of Li isotopic fractionation during formation of Libearing secondary minerals has already been addressed in previous works (Chan and Edmond, 1988;Chan et al, 1992;1993;1994;James et al, 1999), which have shown that fractionation occurs when 6 Li is removed from the solution when clay minerals precipitate. In contrast, according to such work, the heavy Li isotope ( 7 Li) is not preferentially released into solution since there are no reason to expect Li isotope fractionation during dissolution of a fresh basalt (Pistiner and Henderson, 2003).…”

Section: Lithium Isotope Exchange Experimentsmentioning

confidence: 99%

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach

Millot

Scaillet

Sanjuan

2010

Geochimica et Cosmochimica Acta

119

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. Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach. Geochimica et Cosmochimica Acta, Elsevier, 2010, 74 (6) AbstractWe report Li isotopic measurements in seawater derived waters discharged from geothermal wells, thermal and submarine springs located in volcanic island arc areas in Guadeloupe (the Bouillante geothermal field) and Martinique (Lamentin plain and the Diamant areas). The lithium isotopic signatures of the geothermal fluids collected from deep reservoirs are homogeneous for a given site.However, the δ 7 Li signatures of each of these reservoirs are significantly different. We provide the first low temperature (25-250°C) experiments of Li isotope exchange during seawater/basalt interaction), which confirm that Li isotopic exchange is strongly temperature dependent, as previously inferred from natural studies. Li isotopic fractionation ranges from +19.4‰ (Δ solution -solid ) at 25°C to +6.7‰ at 250°C.The experiments also evidence the importance of Li isotopic fractionation during formation of Libearing secondary minerals by the uptake of lithium into the alteration minerals. Application of experimental results to the Bouillante area suggests that the geothermal water is in equilibrium at 250-260°C with a deep and large reservoir located in the transition zone possibly at the contact between volcanic flows and basaltic dikes. For the Lamentin and Diamant areas, the geothermal fluid appear to be partially in equilibrium at 90-120°C and 180°C, respectively, with reservoir sedimentary rocks. Our study highlights that lithium isotopic systematics is a powerful tool for the characterization of the origin of geothermal waters as well as the nature of their reservoir rocks.

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Section: Lithium Isotope Exchange Experimentsmentioning

confidence: 99%

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach

Millot

Scaillet

Sanjuan

2010

Geochimica et Cosmochimica Acta

119

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“…Because the mass difference between these two isotopes is relatively large (approximately 16%), they show significant mass dependent fractionation in nature (>50‰) (12), expressed in δ 7 Li notation: δ 7 Lið‰Þ ¼ ð½ 7 Li∕ 6 Li sample ∕½ 7 Li∕ 6 Li standard − 1Þ × 1000, where the standard used is a synthetic Li carbonate, L-SVEC (13). During chemical weathering, secondary minerals, such as clays, take 6 Li preferentially into their structure, resulting in heavier Li isotopic composition in rivers and lighter isotopic composition in the regolith (14)(15)(16)(17)(18)(19)(20)(21)(22). The lithium concentration and isotopic composition of the continental crust, as well as river waters, are well documented by various authors (17,(19)(20)(21)(22)(23)(24)(25)(26).…”

Section: Lithium Isotopesmentioning

confidence: 99%

Constraints on continental crustal mass loss via chemical weathering using lithium and its isotopes

Liu

Rudnick

2011

Proc. Natl. Acad. Sci. U.S.A.

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Chemical weathering, as well as physical erosion, changes the composition and shapes the surface of the continental crust. However, the amount of continental material that has been lost over Earth’s history due to chemical weathering is poorly constrained. Using a mass balance model for lithium inputs and outputs from the continental crust, we find that the mass of continental crust that has been lost due to chemical weathering is at least 15% of the original mass of the juvenile continental crust, and may be as high as 60%, with a best estimate of approximately 45%. Our results suggest that chemical weathering and subsequent subduction of soluble elements have major impacts on both the mass and the compositional evolution of the continental crust.

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“…On one hand, Li isotopes can be a powerful tracer of chemical weathering (Chan et al, 1992;Pistiner and Henderson, 2003;Rudnick et al, 2004;Liu et al, 2013;Dellinger et al, 2017). On the other hand, the rapid diffusivity of Li and the associated large kinetic isotopic fractionations make Li a promising geospeedometer for determining rates of rapid geologic processes that can be difficult to determine using other perimental studies (Cherniak and Watson, 2010), which showed that Li can diffuse rapidly in zircon under crustal P-T-X conditions.…”

Section: Introductionmentioning

confidence: 99%

Multi-mode Li diffusion in natural zircons: Evidence for diffusion in the presence of step-function concentration boundaries

Tang

Rudnick

McDonough

et al. 2017

Earth and Planetary Science Letters

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Available online xxxx Editor: A. Yin Keywords:Li diffusion zircon charge coupling geospeedometer ToF-SIMS NanoSIMS Micron-to submicron-scale observations of Li distribution and Li isotope composition profiles can be used to infer the mechanisms of Li diffusion in natural zircon. Extreme fractionation (20-30❤) within each single crystal studied here confirms that Li diffusion commonly occurs in zircon. Sharp Li concentration gradients frequently seen in zircons suggest that the effective diffusivity of Li is significantly slower than experimentally determined (Cherniak and Watson, 2010;Trail et al., 2016), otherwise the crystallization/metamorphic heating of these zircons would have to be unrealistically fast (years to tens of years). Charge coupling with REE and Y has been suggested as a mechanism that may considerably reduce Li diffusivity in zircon (Ushikubo et al., 2008;Bouvier et al., 2012). We show that Li diffused in the direction of decreasing Li/Y ratio and increasing Li concentration (uphill diffusion) in one of the zircons, demonstrating charge coupling with REE and Y. Quantitative modeling reveals that Li may diffuse in at least two modes in natural zircons: one being slow and possibly coupled with REE+Y, and the other one being fast and not coupled with REE+Y. The partitioning of Li between these two modes during its diffusion may depend on the pre-diffusion substitution mechanism of REE and Y in the zircon lattice. Based on our results, sharp Li concentration gradients are not indicative of limited diffusion, and can be preserved at temperatures >700 • C on geologic timescales. Finally, large δ 7 Li variations observed in the Hadean Jack Hills zircons may record kinetic fractionation, rather than a record of ancient intense weathering in the granite source materials.

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Lithium-isotope fractionation during continental weathering processes

Cited by 379 publications

References 25 publications

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach

Lithium isotopes in island arc geothermal systems: Guadeloupe, Martinique (French West Indies) and experimental approach

Constraints on continental crustal mass loss via chemical weathering using lithium and its isotopes

Multi-mode Li diffusion in natural zircons: Evidence for diffusion in the presence of step-function concentration boundaries

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