LINK<\/strong><\/a><\/p>\n\n\n\n“IIE irons were derived from chondritic precursors that were the most reduced ordinary chondrites. The bulk chemical (e.g., Ir\/Ni, Ir\/Au, Au\/Ni, Co\/Ni) and bulk isotopic (i.e., \u039417O and \u03b474\/70Ge) compositions of IIE irons lie along extensions of LL-L-H trends. Chondrule-bearing silicate clasts in IIE irons have mineralogical and petrological characteristics that extend LL-L-H trends; these clasts have higher modal metallic Fe-Ni and lower values for olivine Fa, low-Ca-pyroxene Fs, kamacite Co, and mean chondrule diameter. IIE irons are modeled as agglomerating before H-L-LL chondrites; they acquired more 26Al and reached the Fe,Ni-FeS eutectic temperature (\u02dc940 \u00b0C). An FeS-rich metallic melt separated from unmelted silicate and drained to the core, eventually generating a dynamo. Most IIE metal remained within the crust\/mantle region alongside recrystallized chondritic clasts. Alkali-rich IIE silicate inclusions formed from late-stage impacts via preferential melting of plagioclase. Some separation of K from Na occurred during vapor transport. Because most type I chondrules formed before most type II chondrules, the (type I)\/(type II) modal ratio decreased from IIE to H to L to LL during agglomeration. Earlier-formed chondrules acquired higher abundances of refractory metal nuggets within CAI-fragment precursors, accounting for systematic changes in bulk OC of refractory\/common siderophile and refractory\/volatile siderophile ratios (IIE>H>L>LL). Because more Au and Co than Ni were retained in silicates, loss of metal globules from spinning partly molten type I chondrules caused systematic whole-rock decreases in Au\/Ni and Co\/Ni from IIE through LL. Expelled globules had different nebular aerodynamic properties than chondrules and drifted away (accounting, in part, for the metal\/silicate fractionation).”<\/p>\n","protected":false},"excerpt":{"rendered":"
Alan E. Rubin Meteoritics & Planetary ScienceVersion of Record online: 19 July 2021 LINK “IIE irons were derived from chondritic precursors that were the most reduced ordinary chondrites. The bulk chemical (e.g., Ir\/Ni, Ir\/Au, Au\/Ni,…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[148,419,214,7],"tags":[1864,1670,5207,1807,1592],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28436"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=28436"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28436\/revisions"}],"predecessor-version":[{"id":28438,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28436\/revisions\/28438"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28436"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}