Abstract Details
(2020) A Combined Diffusion and Fractional Condensation Model for the Chemical and Isotopic Zoning in FeNi-Metal
Ralf D, Jutta Z & Stefan W
https://doi.org/10.46427/gold2020.2161
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01g: Room 1, Tuesday 23rd June 08:39 - 08:42
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Submitted by Noriko Kita on Monday 22nd June 16:33
The author list is somehow shown wrong (should be Dohmen, Zipfel, and Weyer). This is great presentation that I enjoyed very much. In your summary and conclusion II, pressure Po>1E4 Pa gives better match to delta-62Ni vs delta-56Fe, and delta-62Ni vs XNi. Do you infer CH/CB formed at such pressure?
The delta values can be fitted at low and high pressures by choosing respective cooling rates (relatively low and high cooling rates) but the XNi can be better approximated by choosing higher P > 1.e4 Pa. However, the model does not consider the condensation of other minerals like olivine, opx, etc., which could take up considerable amounts of Fe depending on the redox conditions. For canonical redox conditions (fO2 about IW-6) the Fe content in silicates would be negligible. So if the redox conditions would be significantly more oxidizing the Ni content in the metal could be raised also at lower P. Considering other indications from chondrules and the relatively young age of CH/CB chondrites an impact origin of chondrules and metal grains in CB/CH chondrites is most likely, which would be consistent with higher P at fast cooling rates and relatively oxidizing conditions compared to the canonical solar nebula.
The author list is somehow shown wrong (should be Dohmen, Zipfel, and Weyer). This is great presentation that I enjoyed very much. In your summary and conclusion II, pressure Po>1E4 Pa gives better match to delta-62Ni vs delta-56Fe, and delta-62Ni vs XNi. Do you infer CH/CB formed at such pressure?
The delta values can be fitted at low and high pressures by choosing respective cooling rates (relatively low and high cooling rates) but the XNi can be better approximated by choosing higher P > 1.e4 Pa. However, the model does not consider the condensation of other minerals like olivine, opx, etc., which could take up considerable amounts of Fe depending on the redox conditions. For canonical redox conditions (fO2 about IW-6) the Fe content in silicates would be negligible. So if the redox conditions would be significantly more oxidizing the Ni content in the metal could be raised also at lower P. Considering other indications from chondrules and the relatively young age of CH/CB chondrites an impact origin of chondrules and metal grains in CB/CH chondrites is most likely, which would be consistent with higher P at fast cooling rates and relatively oxidizing conditions compared to the canonical solar nebula.
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