Fractionation of highly siderophile and chalcogen elements in components of EH3 chondrites

Kadlag, Yogita; Becker, Harry

doi:10.1016/j.gca.2015.04.022

Cited by 17 publications

(33 citation statements)

References 68 publications

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“…Isotopic similarities of refractory elements between Earth's building materials and enstatite chondrites probably indicate a common reservoir for their refractory components, perhaps in the terrestrial planet formation region (Dauphas et al, 2014). However, the chemical fractionation history of refractory elements in these materials may be decoupled from the volatile elements as is the case in chondrites (e.g., Albarède, 2009;Kadlag and Becker, 2015). The differences in volatile element abundances and ratios in different groups of chondrites (Fig.…”

Section: Volatile Element Composition Of Bulk Earth and Accreted Matementioning

confidence: 97%

Earth's moderately volatile element composition may not be chondritic: Evidence from In, Cd and Zn

Wang

Laurenz

Petitgirard

et al. 2016

Earth and Planetary Science Letters

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Section: Volatile Element Composition Of Bulk Earth and Accreted Matementioning

confidence: 97%

Earth's moderately volatile element composition may not be chondritic: Evidence from In, Cd and Zn

Wang

Laurenz

Petitgirard

et al. 2016

Earth and Planetary Science Letters

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“…Since their oxygen isotope composition plots on the terrestrial fractionation line, enstatite chondrites probably formed in the innermost part of the solar system (Clayton et al, 1984). Element fractionation patterns are complex in bulk enstatite chondrites, which could result from volatility-controlled partial condensation or evaporation, incorporation of different precursor material in chondrules, different elemental volatilities due to different redox conditions, and/or later partitioning between sulphides, silicates, and metal during chondrule formation and/or impacts on the parent bodies (Kadlag and Becker (2015) and references therein). The relative importance of these processes remains, however, unclear.…”

Section: Enstatite Chondritesmentioning

confidence: 99%

“…Bulk meteorites are therefore considered to represent a mixture of undepleted matrix and volatile-depleted chondrules, which are thought to be residues from partial vaporization of CI-like material (Alexander, 2005). Also impacts on the chondrite parent bodies have been considered to result in a redistribution and depletion of volatile elements (Kadlag and Becker (2015) and references therein). However, heating experiments on fragments of the Allende CV and Murchison CM chondrites showed depletions of volatile elements in the residues that are inconsistent with the origin by thermal processing of CI-like material (Wulf et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

The isotope composition of selenium in chondrites constrains the depletion mechanism of volatile elements in solar system materials

Vollstaedt

Mezger

Leya

2016

Earth and Planetary Science Letters

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Solar nebula processes led to a depletion of volatile elements in different chondrite groups when 26 compared to the bulk chemical composition of the solar system deduced from the Sun's 27 photosphere. For moderately-volatile elements, this depletion primarily correlates with the 28 element condensation temperature and is possibly caused by incomplete condensation from a hot 29 solar nebula, evaporative loss from the precursor dust, and/or inherited from the interstellar 30 medium. Element concentrations and interelement ratios of volatile elements do not provide a 31 clear picture about responsible mechanisms. Here, the abundance and stable isotope composition 32 of the moderately-to highly-volatile element Se are investigated in carbonaceous, ordinary, and 33 enstatite chondrites to constrain the mechanism responsible for the depletion of volatile elements 34 in planetary bodies of the inner solar system and to define a δ 82/78 Se value for the bulk solar system. The δ 82/78 Se of the studied chondrite falls are identical within their measurement uncertainties with a mean of-0.20±0.26 ‰ (2 s.d., n = 14, relative to NIST SRM 3149) despite Se abundance depletions of up to a factor of 2.5 with respect to the CI group. The absence of resolvable Se isotope fractionation rules out a kinetic Rayleigh-type incomplete condensation of Se from the hot solar nebula or partial kinetic evaporative loss on the precursor material and/or the parent bodies. The Se depletion, if acquired during partial condensation or evaporative loss, therefore must have occurred under near equilibrium conditions to prevent measurable isotope fractionation. Alternatively, the depletion and cooling of the nebula could have occurred simultaneously due to the continuous removal of gas and fine particles by the solar wind accompanied by the quantitative condensation of elements from the pre-depleted gas. In this scenario the condensation of elements does not require equilibrium conditions to avoid isotope 3 fractionation. The results further suggest that the processes causing the high variability of Se concentrations and depletions in ordinary and enstatite chondrites did not involve any measureable isotope fractionation. Different degrees of element depletions and isotope fractionations of the moderately-volatile elements Zn, S, and Se in ordinary and enstatite chondrites indicate that their volatility is controlled by the thermal stabilities of their host phases and not by the condensation temperature under canonical nebular conditions. 52

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“…For instance, Horan et al . () and Kadlag and Becker (, ) determined the Re/Os and 187 Os/ 188 Os ratios in separated magnetic and nonmagnetic components from ordinary and enstatite chondrites. The smaller the target sample is, the more challenging the Os isotopic analysis becomes, especially when the quantity of Os available for a single measurement is at a level of a few pg.…”

mentioning

confidence: 99%

“…In addition, Re and Os are strongly fractionated from each other during melting events because they have different compatibility between liquid metal and solid metal (Walker et al 2008). For these reasons, 187 Re- 187 Os systematics have been extensively investigated in geochemical and cosmochemical applications (e.g., Walker et al 1994, Smoliar et al 1996, Levasseur et al 1998, Peucker-Ehrenbrink and Ravizza 2000, Hattori et al 2003, Cook et al 2004, Day et al 2007, Gannoun et al 2007, Dale et al 2008, Horan et al 2009, Day 2013, Gannoun and Burton 2014, Kadlag and Becker 2015.…”

mentioning

confidence: 99%

Refinement of the Micro‐Distillation Technique for Isotopic Analysis of Geological Samples with pg‐Level Osmium Contents

Nakanishi

Yokoyama

Ishikawa

2019

Geostandard Geoanalytic Res

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In recent years, the 187Re–187Os isotope system has been increasingly used to study samples containing very small quantities of Os. For such samples, optimisation of measurement procedures is essential to minimise the loss of Os before mass spectrometric measurements. Micro‐distillation is a necessary purification step that is applied after the main Os chemical separation procedure, prior to Os isotope ratio measurements by negative‐thermal ionisation mass spectrometry (N‐TIMS). However, unlike the other separation steps, this procedure has not yet been optimised for small samples. In this study, we present a refined micro‐distillation method that achieved higher yields and allowed high‐precision R(187Os/188Os) expressed as 187Os/188Os measurements for small‐sized geological samples that contain only a few pg Os. The Os recovery in the micro‐distillation step was tested by changing the operating conditions including heating time and temperature, and amounts of oxidant and reductant. Recoveries were measured by the isotope dilution ICP‐MS method after the addition of 190Os‐enriched spike solution. We found that the most critical factor controlling the chemical yield of Os during micro‐distillation is the extent of dilution of the reductant (HBr) by H2O evaporated from the oxidant. A refined micro‐distillation method, in which the amount of oxidant solution is reduced from the conventional method, achieved an improved chemical yield of Os (~ 90%). This refined method was applied to the measurement of 187Os/188Os by N‐TIMS of varying test portions of the geological reference material BIR‐1a. The resulting 187Os/188Os ratios of BIR‐1a matched the literature data, with propagated uncertainties of 0.2, 1.1 and 11% digested sample quantities containing 150, 10 and 1 pg of Os, respectively.

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Fractionation of highly siderophile and chalcogen elements in components of EH3 chondrites

Cited by 17 publications

References 68 publications

Earth's moderately volatile element composition may not be chondritic: Evidence from In, Cd and Zn

Earth's moderately volatile element composition may not be chondritic: Evidence from In, Cd and Zn

The isotope composition of selenium in chondrites constrains the depletion mechanism of volatile elements in solar system materials

Refinement of the Micro‐Distillation Technique for Isotopic Analysis of Geological Samples with pg‐Level Osmium Contents

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