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Zinc isotopic composition of iron meteorites: Absence of isotopic anomalies and origin of the volatile element depletion
Author(s) -
Chen Heng,
Nguyen Bach Mai,
Moynier Frédéric
Publication year - 2013
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12229
Subject(s) - fractionation , meteorite , chondrite , parent body , chemistry , isotope , isotope fractionation , mass independent fractionation , evaporation , silicate , zinc , stable isotope ratio , volatiles , isotope analysis , isotopic shift , analytical chemistry (journal) , mineralogy , environmental chemistry , geology , astrobiology , chromatography , physics , oceanography , organic chemistry , quantum mechanics , thermodynamics
High‐precision Zn isotopic compositions measured by MC ‐ ICP ‐ MS are documented for 32 iron meteorites from various fractionally crystallized and silicate‐bearing groups. The δ 66 Zn values range from −0.59‰ up to +5.61‰ with most samples being slightly enriched in the heavier isotopes compared with carbonaceous chondrites (0 < δ 66 Zn < 0.5). The δ 66 Zn versus δ 68 Zn plot of all samples defines a common linear fractionation line, which supports the hypothesis that Zn was derived from a single reservoir or from multiple reservoirs linked by mass‐dependent fractionation processes. Our data for Redfields fall on a mass fractionation line and therefore refute a previous claim of it having an anomalous isotopic composition due to nonmixing of nucleosynthetic products. The negative correlation between δ 66 Zn and the Zn concentration of IAB and IIE is consistent with mass‐dependent isotopic fractionation due to evaporation with preferential loss of lighter isotopes in the vapor phase. Data for the Zn concentrations and isotopic compositions of two IVA samples demonstrate that volatile depletion in the IVA parent body is not likely the result of evaporation. This is important evidence that favors the incomplete condensation origin for the volatile depletion of the IVA parent body.