High precision measurement of iron isotopes by plasma source mass spectrometry

Belshaw, N.S.; Zhu, Xuwei; Guo, Y.; O’Nions, R.K.

doi:10.1016/s1387-3806(99)00245-6

Cited by 175 publications

(140 citation statements)

References 12 publications

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“…On Earth, it is a major element in the core, the mantle and the crust (Allègre et al, 1995;Rudnick and Gao, 2003). In the past decade, the development of high-resolution Multi-Collector InductivelyCoupled-Plasma Mass-Spectrometers (MC-ICP-MS) has allowed measurements of iron isotope composition at high precision (Belshaw et al, 2000;Zhu et al, 2001;Weyer and Schwieters, 2003;Dauphas et al, 2009b;Millet et al, 2012). Following this improvement, small yet resolvable iron isotopic variations in igneous rocks have been discovered (Poitrasson et al, 2004;Weyer et al, 2005;Schoenberg and von Blanckenburg, 2006;Weyer and Ionov, 2007;Heimann et al, 2008;Teng et al, 2008Teng et al, , 2011Dauphas et al, 2009a;Weyer and Seitz, 2012).…”

Section: Introductionmentioning

confidence: 99%

Iron isotope fractionation in planetary crusts

Wang

Moynier

Dauphas

et al. 2012

Geochimica et Cosmochimica Acta

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We present new high precision iron isotope data (d 56 Fe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite-eucrite-diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe compared to chondrites (by an average of +0.12& in d 56 Fe). While the reason for such fractionation is not completely understood, it might be related to isotopic fractionation by volatilization during accretion or more likely magmatic differentiation in the angrite parent-body. We also report precise data on martian and HED meteorites, yielding an average d 56 Fe of 0.00 ± 0.01&. Stannern-trend eucrites are isotopically heavier by +0.05& in d 56 Fe than other eucrites. We show that this difference can be ascribed to the enrichment of heavy iron isotopes in ilmenite during igneous differentiation. Preferential dissolution of isotopically heavy ilmenite during remelting of eucritic crust could have generated the heavy iron isotope composition of Stannern-trend eucrites. This supports the view that Stannern-trend eucrites are derived from main-group eucrite source magma by assimilation of previously formed asteroidal crust.These new results show that iron isotopes are not only fractionated in terrestrial and lunar basalts, but also in two other differentiated planetary crusts. We suggest that igneous processes might be responsible for the iron isotope variations documented in planetary crusts.

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Section: Introductionmentioning

confidence: 99%

Iron isotope fractionation in planetary crusts

Wang

Moynier

Dauphas

et al. 2012

Geochimica et Cosmochimica Acta

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“…The effect is more dramatic for [Fe] sample <[Fe] Std , as suggested by other authors. 22,36 We suspect that in this region, Fe concentration is small relative to the interferences and therefore the peaks are committed to variations in interference production from the plasma. The deviation from linear response is thus due to plasma behaviour and not detector non-linearity over that range.…”

Section: Matrix Effects and Sample Uptakementioning

confidence: 98%

A procedural development for the analysis of 56/54Fe and 57/54Fe isotope ratios with new generation IsoProbe MC-ICP-MS

Guilbaud

Ellam

Butler

et al. 2010

J. Anal. At. Spectrom.

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We have developed a procedure for iron isotope analysis using a hexapole collision cell MC-ICP-MS which is capable of Fe isotope ratio analysis using two different extraction modes.Matrix effects were minimised and the signal-to-background ratio was maximised using highconcentration samples (~ 5μg Fe) and introducing 1.8 mL/min Ar and 2 mL/min H 2 into the collision cell to decrease polyatomic interferences. The use of large intensity on the faraday cups considerably decreases the internal error of the ratios and ultimately, improves the external precision of a run. Standard bracketing correction for mass bias was possible when using hard extraction. Mass bias in soft extraction mode seems to show temporal instability that makes the standard bracketing inappropriate. The hexapole rf amplitude was decreased to 50 % to further decrease polyatomic interferences and promote the transmission of iron range masses. We routinely measure Fe isotopes with a precision of ± 0.05 ‰ and ± 0.12 ‰ (2σ) for δ 56 Fe and δ 57 Fe respectively.

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“…(in press); hydrothermal plume particle and plume derived sediment data from Severmann et aL. (in press); Pacific, Atlantic, Arctic, and freshwater nodule data from and ; Shelf porewater data from natural spring ferrhydrite data from ; sedimentar mineral data from Belshaw et aL. (2000); paleosol data from and Arnold et aL.…”

Section: Iron Isotopesmentioning

confidence: 99%

“…Both techniques have been explored for Fe, and several studies have found no significant improvement in precision of Fe isotope measurements using Cu internal spiking compared with SSB (BELSHAW et al, 2000;. However, recent studies have highlighted potential pitfalls in relying solely on SSB or solely on internal spiking (CARLSON et al, 2001;ALBAREDE and BEARD, 2004;ARNOLD et al, 2004).…”

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confidence: 99%

“…Albarede and Beard (2004) inferred from their observations that the matrix-induced variations in mass bias resulted from changing the space-charge effects or ionization properties of the plasma. Despite the potential complications with SSB, it is the most common technique employed in Fe isotopic analysis by MC-ICPMS with reported precisions of 0.05 to 0.15 %0 (2a, 56Fe/54Fe ratio) (BELSHAW et al, 2000;. It is believed that rigorous sample purification can avoid many matrix problems, although one must be aware of potential problems when only using SSB to define instrument mass bias.…”

Section: ------R------j-----------j---------------i 1----1---~~mentioning

confidence: 99%

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The marine geochemistry of iron and iron isotopes

Bergquist¹

2004

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Fractionation of iron isotopes could be an effective tool to investigate the geochemistr of iron. Trace metal clean plankton tows, river samples, aerosolleachates, and porewater samples were measured for their iron isotopic composition using a GV Instruments IsoProbe Multi-collector ICPMS. The Fe isotopic composition of plankton tow samples vared by over 4%0 (in 56Fe/54Fe). North Pacific plankton tow samples had isotopically lighter Fe isotopic compositions than samples from the Atlantic. The overall isotopic range observed in the Amazon River system was 1.5%0, with variability observed for different types of tributaries. The main channel river dissolved Fe samples and suspended loads were isotopically similar (= -0.2 to -0.45%0 relative to igneous rocks). The isotopically heaviest sample collected was dissolved Fe from an organic rich trbutar, the Negro River (+0.16%0). In contrast, the suspended load from the Negro River was isotopically light (-1 %0). The isotopically lightest sample from the Amazon region was shelf pore water (-1.4%0). In river water-seawater mixing experiments, the Fe isotopic signal of dissolved Fe of river water was modified by flocculation of isotopically heavy Fe. The observed range in the Fe isotopic composition of the natural samples including biological and aqueous samples demonstrates that significant and useful fractionation is associated with Fe biogeochemistry in the environment. 3 THESIS SUMMARYThis study addressed questions about the Fe cycle by measuring detailed profiles and transects of Fe in the ocean and also by exploring the use of a new tracer of Fe, stable Fe isotopic fractionation. Iron distribution, speciation, and dissolution were investigated on three cruises in the sub-tropical and tropical Atlantic Ocean in regions where dust deposition varies by three orders of magnitude. Detailed profiles and transects were collected and analyzed for "dissolved" Fe (DFe, 0.4 i.m filtered) and "soluble" Fe (SFe, 0.02 i.m filtered). The difference between DFe and SFe is inferred to be the "colloidal" fraction of Fe (CFe). Iron concentrations were measured by a new isotope dilution multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) method, which allows manganese and chromium concentrations to be measured simultaneously. Iron and manganese comparsons are useful because the source for manganese is aeolian deposition and it is removed by scavenging like iron, but the DMn profile (0.4 i.m filtered) is not indicative of a nutrient-type element. In the subtropical and tropical Atlantic Ocean, surface DFe and DMn concentrations reflect dust deposition trends. CFe followed dust deposition trends more strongly than the SFe, and observed maxima in DFe profiles were always due to maxima in the CFe fraction. Where dust deposition was low (e.g., the South Atlantic), CFe concentrations were also low and sometimes negligible in surface waters.SFe and CFe profiles had distinct profiles both in the upper water column and in deeper waters. SFe profiles were always depleted in sur...

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High precision measurement of iron isotopes by plasma source mass spectrometry

Cited by 175 publications

References 12 publications

Iron isotope fractionation in planetary crusts

Iron isotope fractionation in planetary crusts

A procedural development for the analysis of 56/54Fe and 57/54Fe isotope ratios with new generation IsoProbe MC-ICP-MS

The marine geochemistry of iron and iron isotopes

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