Multi-element ion-exchange chromatography and high-precision MC-ICP-MS isotope analysis of Mg and Ti from sub-mm-sized meteorite inclusions

Larsen, Kirsten; Wielandt, D.; Bizzarro, Martin

doi:10.1039/c7ja00392g

Cited by 22 publications

(15 citation statements)

References 42 publications

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“…The accuracy and external reproducibility of the 55 Mn/ 52 Cr ratio was tested using repeat measurements of PCC-1, which returned a value of 0.353±0.002 (2SD, N=6), which is consistent with a previously reported value of 0.370±0.019 (Qin et al 2010a). Compared the two values, the uncertainty of the Chromium was purified from 50% aliquots of dissolved samples, based on a procedure involving a three-step chromatographic ion-exchange purification protocol described in Zhu et al (2019b) and Larsen et al (2018) and using Cr pretreatment procedures to promote appropriate Cr-speciation described in detail in Larsen et al (2016). In detail, we used an anion chromatographic purification column to efficiently remove Fe from the remaining sample aliquot in 6M HCl, followed by elution of Cr through a cation exchange column in 0.5M HNO 3 (Bizzarro et al 2011), and subsequent elution of Mg, Ca, Mn, and Ni in 6M HCl.…”

Section: Samples and Analytical Methodssupporting

confidence: 77%

“…Prior to sample loading on the cation exchange column, we used a Cr pre-treatment procedure involving dissolution in 10M HCl at >120°C to efficiently promote the formation of Cr(III)-Cl species, which have a low affinity for the cation exchanger and thus elute early (Trinquier et al 2008a;Larsen et al 2016). The third ion-exchange column step aimed at Cr purification from the potential interfering element Fe (and other high-field-strength elements Ti and V) and Na (as well as potential organics) using a small cation exchange column and 0.5M HNO 3 , 1M HF, and 6M HCl as eluants (Larsen et al 2018). Prior to sample loading onto this last column, Cr was pre-treated by exposure to 0.5M HNO 3 + 0.6% H 2 O 2 at room temperature for two days to promote the formation of Cr 3+ (Larsen et al 2016).…”

Section: Samples and Analytical Methodsmentioning

confidence: 99%

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Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Zhu

Moynier

Schiller

et al. 2020

ApJ

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We report on the mass-independent Cr isotope compositions of 11 main group ureilites and an ureilitic trachyandesite (ALM-A). The 54 Cr/ 52 Cr ratios for main group ureilites vary from −1.06±0.04 to −0.78±0.05 and averaged at −0.91±0.15 (2SD, N=18) including the data from literature. We argue that this variation reflects primitive mantle heterogeneities within the ureilite parent body (UPB). As such, this body did not experience a global-scale magma ocean, which is consistent with heterogeneous O isotope in ureilites. Furthermore, the ε 54 Cr values, Mn/Cr ratios, C isotope ratios, Mg#values, and Fe/Mn ratios in the olivine cores of ureilites are correlated with each other, which suggests the mixing of ureilite precursors from at least two reservoirs, rather than a smelting process or the oxidation from ice melting. All the ureilite samples (including the ALM-A) fall on a well-defined 53 Mn-53 Cr isochron corresponding to a 53 Mn/ 55 Mn ratio of (6.02 ± 1.59)×10 −6 , which translates to an age of 4566.7±1.5 Ma (within 2 Ma after calcium-aluminum-rich inclusions; CAIs) when anchored to the U-corrected Pb-Pb age for the D'Orbigny angrite. This old age indicates early partial melting on the UPB, consistent with the early accretion of the UPB (within 1 Ma after CAIs) predicted by thermal modeling. Furthermore, there is a 4∼5 Ma age difference between the external isochron in this study and internal isochron ages for the feldspathic clasts in polymict ureilites, which likely reflects an impact history during the early evolution of the UPB.

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Section: Samples and Analytical Methodssupporting

confidence: 77%

Section: Samples and Analytical Methodsmentioning

confidence: 99%

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Zhu

Moynier

Schiller

et al. 2020

ApJ

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“…Possible locations of Venus, Mercury, and the Sun are indicated but have not been measured yet. CAIs = calcium, aluminium-rich inclusions have reported 54 Cr and 50 Ti anomalies that range from ∼5-8 and ∼9-15, respectively (Larsen et al 2018;Leya et al 2009;Trinquier et al 2009), and are thus represented, with the potential location of the Sun, off the chart. CC = carbonaceous chondrites and related groups, EC = enstatite chondrites (EH and EL groups), OC = ordinary chondrites (H, L and LL).…”

Section: Evidence From the Dichotomymentioning

confidence: 99%

Accretion of the Earth—Missing Components?

2020

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Primitive meteorites preserve the chemical and isotopic composition of the first aggregates that formed from dust and gas in the solar nebula during the earliest stages of solar system evolution. Gradual increase in the size of solid bodies from dust to aggregates and then to planetesimals finally led to the formation of planets within a few to tens of million years after the start of condensation. Thus the rocky planets of the inner solar system are likely the result of the accumulation of numerous smaller primitive as well as differentiated bodies. The chemically most primitive known meteorites are chondrites and they consist mostly of metal and silicates. Chondritic meteorites are derived from distinct primitive planetary bodies that experienced only limited element fractionation during formation and subsequent differentiation. Different chondrite classes show distinct chemical and isotopic characteristics, which may reflect heterogeneities in the solar nebula and the slightly different pathways of their formation. To a first approximation the chemical composition of the bulk Earth bears great similarities to primitive meteorites. However, for some elements there are striking and significant differences. The Earth shows a much stronger depletion of the moderate to highly volatile elements compared to chondrites. In addition, mixing trends of specific isotopes reveal that the Earth is most enriched in s-process isotopes compared to all other analysed bulk solar system materials. It is currently not possible to fully define and quantify the different chemical and isotopic materials that formed the Earth, because a major component seems missing in the extant collections of extraterrestrial samples. Variations in nucleosynthetic isotope compositions as well as the strong depletion of moderately and strongly volatile elements points towards a source in the inner solar system for this missing material. It is conceivable that Venus and Mercury contain a much larger fraction of this

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“…Yet, the sequential chemical separation scheme developed here allows us to extract Cr and Ti with fewer steps than in Larsen et al . () and other previous studies (i.e., three steps for both Cr and Ti elution compared with two to five steps for each individual element extraction; e.g., Trinquier et al . , Wombacher et al .…”

Section: Resultsmentioning

confidence: 89%

“…Recently, Larsen et al . () reported an ion‐exchange chromatography for combined isotope analysis of Mg and Ti, which is applicable to Cr isotope analysis as well. Yet, the sequential chemical separation scheme developed here allows us to extract Cr and Ti with fewer steps than in Larsen et al .…”

Section: Resultsmentioning

confidence: 99%

Sequential Chemical Separation of Cr and Ti from a Single Digest for High‐Precision Isotope Measurements of Planetary Materials

Hibiya

Iizuka

Yamashita

et al. 2018

Geostandard Geoanalytic Res

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Combined determination of Cr and Ti isotopes of planetary materials offers a means with which to investigate their genetic relationship and the evolution of the protoplanetary disk. Here, we report the new sequential chemical separation procedure for combined Cr and Ti isotope ratio measurements. It comprises three steps: (a) Fe removal using AG1-X8 anion exchange resin, (b) Ti separation using TODGA resin and (c) Cr separation using AG50W-X8 cation exchange resin (with one additional step of Ti purification using AG1-X8 anion exchange resin for samples having high Cr/Ti and Ca/Ti ratios). We applied the proposed procedure to terrestrial and meteorite samples with various compositions. Typical recovery rates of 90-100% were achieved with total procedural Cr and Ti blanks of 3-5 and 2-3 ng, respectively. We measured the Cr and Ti isotope compositions of the separated samples using thermal ionisation mass spectrometry and multiple collector-inductively coupled plasma-mass spectrometry, respectively. Our Cr and Ti isotope data were found to be consistent with those of previous studies of individual Cr and Ti isotopic compositions of the meteorites. These results demonstrate the capability of our separation method when applied to combined high-precision Cr and Ti isotope analyses for single digests of planetary materials.

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Multi-element ion-exchange chromatography and high-precision MC-ICP-MS isotope analysis of Mg and Ti from sub-mm-sized meteorite inclusions

Cited by 22 publications

References 42 publications

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Accretion of the Earth—Missing Components?

Sequential Chemical Separation of Cr and Ti from a Single Digest for High‐Precision Isotope Measurements of Planetary Materials

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