Towards an understanding of thallium isotope fractionation during adsorption to manganese oxides

Nielsen, Sune G.; Wasylenki, Laura E.; Rehkämper, Mark; Peacock, Caroline L.; Xue, Zhaohui; Moon, Ellen M.

doi:10.1016/j.gca.2013.05.004

Cited by 105 publications

(72 citation statements)

References 48 publications

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“…Such an approach was not employed here because leaching has the potential to generate significant stable isotope effects for Tl (e.g., Nielsen et al. ). Hence, Pb isotope measurements were carried out for all samples and these data in combination with Pb‐Tl elemental ratios were employed to assess and, using model calculations, semiquantitatively determine the extent of terrestrial Pb contamination.…”

Section: Introductionmentioning

confidence: 99%

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb

Palk

Andreasen

Rehkämper

et al. 2017

Meteorit & Planetary Scien

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Abstract-New Tl, Pb, and Cd concentration and Tl, Pb isotope data are presented for enstatite as well as L-and LL-type ordinary chondrites, with additional Cd stable isotope results for the former. All three chondrite suites have Tl and Cd contents that vary by more than 1-2 orders of magnitude but Pb concentrations are more uniform, as a result of terrestrial Pb contamination. Model calculations based on Pb isotope compositions indicate that for more than half of the samples, more than 50% of the measured Pb contents are due to addition of modern terrestrial Pb. In part, this is responsible for the relatively young and imprecise Pb-Pb ages determined for EH, L, and LL chondrites, which are hence only of limited chronological utility. In contrast, four particularly pristine EL chondrites define a precise Pb-Pb cooling age of 4559 AE 6 Ma.

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Section: Introductionmentioning

confidence: 99%

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb

Palk

Andreasen

Rehkämper

et al. 2017

Meteorit & Planetary Scien

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“…Trivalent thallium (Tl 3+ ) can also exist on Earth under highly oxidising conditions (Bately and Florence , Vink ), for example in the structure of the ferromanganese (Fe–Mn) mineral hexagonal birnessite (Peacock and Moon , Nielsen et al . ).…”

Section: The Literature Mc‐icp‐ms Tl Isotope Ratio Data For Igneous Rmentioning

confidence: 97%

Thallium Mass Fraction and Stable Isotope Ratios of Sixteen Geological Reference Materials

Brett

Prytulak

Hammond

et al. 2018

Geostandard Geoanalytic Res

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Thallium stable isotope ratio and mass fraction measurements were performed on sixteen geological reference materials spanning three orders of magnitude in thallium mass fraction, including both whole rock and partially separated mineral powders. For stable isotope ratio measurements, a minimum of three independent digestions of each reference material was obtained. High‐precision trace element measurements (including Tl) were also performed for the majority of these RMs. The range of Tl mass fractions represented is 10 ng g−1 to 16 μg g−1, and Tl stable isotope ratios (reported for historical reasons as ε205Tl relative to NIST SRM 997) span the range −4 to +2. With the exception – attributed to between‐bottle heterogeneity – of G‐2, the majority of data are in good agreement with published or certified values, where available. The precision of mean of independent measurement results between independent dissolutions suggests that, for the majority of materials analysed, a minimum digested mass of 100 mg is recommended to mitigate the impact of small‐scale powder heterogeneity. Of the sixteen materials analysed, we therefore recommend for use as Tl reference materials the USGS materials BCR‐2, COQ‐1, GSP‐2 and STM‐1; CRPG materials AL‐I, AN‐G, FK‐N, ISH‐G, MDO‐G, Mica‐Fe, Mica‐Mg and UB‐N; NIST SRM 607 and OREAS14P.

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“…It has been observed that coordination changes of Mo, U, Tl, Cu and Zn during adsorption onto Mnoxyhydroxides led to resolvable isotopic fractionation (Barling et al, 2004;Brennecka et al, 2011b;Nielsen et al, 2013;Little et al, 2014). Generally, metal complexes with smaller coordination number and shorter bond length have stronger chemical bonds, favoring incorporation of heavier isotopes (Schauble et al, 2004).…”

Section: Change In U Speciation During Incorporation Into Cacomentioning

confidence: 99%

“…Although no resolvable U isotopic fractionation has been observed between modern aragonite and calcite samples and seawater (Weyer et al, 2008;Romaniello et al, 2013) (Juillot et al, 2008;Brennecka et al, 2011b;Wasylenki et al, 2011;Nielsen et al, 2013;Little et al, 2014;Bryan et al, 2015). Previous studies found that the predominant U(VI) species in seawater, UO 2 (CO 3 ) 3 4-, was directly incorporated as a unit into aragonite without coordination change or reduction (Reeder et al, 2000).…”

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confidence: 99%

Uranium isotope fractionation during coprecipitation with aragonite and calcite

Chen

Romaniello

Herrmann

et al. 2016

Geochimica et Cosmochimica Acta

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Natural variations in 238 U/ 235 U of marine carbonates might provide a useful way of constraining redox conditions of ancient environments. In order to evaluate the reliability of this proxy, we conducted aragonite and calcite coprecipitation experiments at pH ~7.5 and ~ 8.5 to study possible U isotope fractionation during incorporation into these minerals.Small but significant U isotope fractionation was observed in aragonite experiments at pH ~ 8.5, with heavier U in the solid phase. 238 U/ 235 U of dissolved U in these experiments can be fit by Rayleigh fractionation curves with fractionation factors of 1.00007+0.00002/-0.00003, 1.00005 ± 0.00001, and 1.00003 ± 0.00001. In contrast, no resolvable U isotope fractionation was observed in an aragonite experiment at pH ~7.5 or in calcite experiments at either pH. Equilibrium isotope fractionation among different aqueous U species is the most likely explanation for these findings. Certain charged U species are preferentially incorporated into calcium carbonate relative to the uncharged U species Ca 2 UO 2 (CO 3 ) 3 (aq), which we hypothesize has a lighter equilibrium U isotope composition than most of the charged species. According to this hypothesis, the magnitude of U isotope fractionation should scale with the fraction of dissolved U that is present as Ca 2 UO 2 (CO 3 ) 3 (aq). This expectation is confirmed by equilibrium speciation modeling of our experiments. Theoretical calculation of the U isotope fractionation factors between different U species could further test this hypothesis and our proposed fractionation mechanism.ii These findings suggest that U isotope variations in ancient carbonates could be controlled by changes in the aqueous speciation of seawater U, particularly changes in seawater pH, P CO2 , [Ca], or [Mg] concentrations. In general, these effects are likely to be small (<0.13 ‰), but are nevertheless potentially significant because of the small natural range of variation of 238 U/ 235 U.

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Towards an understanding of thallium isotope fractionation during adsorption to manganese oxides

Abstract: Lett. 197,[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]

Cited by 105 publications

References 48 publications

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb

Thallium Mass Fraction and Stable Isotope Ratios of Sixteen Geological Reference Materials

Uranium isotope fractionation during coprecipitation with aragonite and calcite

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Towards an understanding of thallium isotope fractionation during adsorption to manganese oxides

Abstract: Lett. 197,[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]

Cited by 105 publications

References 48 publications

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct 205Pb

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct 205Pb

Thallium Mass Fraction and Stable Isotope Ratios of Sixteen Geological Reference Materials

Uranium isotope fractionation during coprecipitation with aragonite and calcite

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Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb

Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct ²⁰⁵Pb