کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4678451 1634847 2010 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A nebula setting as the origin for bulk chondrule Fe isotope variations in CV chondrites
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
A nebula setting as the origin for bulk chondrule Fe isotope variations in CV chondrites
چکیده انگلیسی

We combined micro computer tomography with Fe and Si isotope measurements of Mokoia, Allende and Grosnaja chondrules. Ten Mokoia chondrules contain 0.9 to 11.8 vol.% opaque phases (metal + sulfide), and 6 Allende chondrules contain 0.0 to 6.6 vol.% opaque phases. Hence, the Fe isotope composition of many chondrules is dominated by the Fe isotope composition of their opaque phases. We studied Fe isotopes of 35 bulk chondrules. The range is different for each of the three meteorites studied and largest for Allende with δ56Fe ranging from − 0.82 to + 0.37‰. Six out of seven chondrules analysed for their Si isotope composition in Mokoia and Grosnaja have similar δ29Si of around − 0.12‰. One anomalous chondrule in Mokoia has a δ29Si of + 0.58‰. We exclude isotopically heterogeneous chondrule precursors and different isotopic chondrule reservoirs as the source of the observed Fe isotope variation among bulk chondrules. We conclude that the observed bulk chondrule Fe isotope variation is the result of evaporation and re-condensation processes in a nebula setting with high dust densities, required to explain the comparatively low isotope fractionations. Subsequent parent body alteration slightly overprinted this pre-accretionary Fe isotope variation.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 296, Issues 3–4, 1 August 2010, Pages 423–433
نویسندگان
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