LINK<\/strong><\/a><\/p>\n\n\n\n“Silicate-bearing iron meteorites record metal\u2013silicate separation and mixing processes of planetesimals. Of particular interest is the IIE group as its silicate inclusions show great petrological diversity, probably resulting from the complex petrogenesis involving early differentiation and impact-induced dynamic mixing, re-melting, and reduction. These geologic records may have been documented by individual minerals to various extents, which blurs the chronological records on the formation of IIEs. Here, by combining X-ray elemental mapping with ion microprobe dating technique, we show that two groups of phosphates are present in the Weekeroo Station IIE iron meteorite. They have distinct petrography, mineralogy, Th\/U ratios, and Pb isotopic compositions, which reflects their different formation mechanisms. One group (Group 1) has a fine-grained, euhedral or acicular habit, suggesting rapid crystallization from a melt during the metal\u2013silicate mixing. By contrast, the other group (Group 2) is intimately associated with the decomposition and reduction of pyroxene under subsolidus conditions. The Group 1 phosphates yield a precise Pb\u2013Pb age of 4528 \u00b1 11 Ma and they provide the first robust constraint on the timing of impact-induced metal\u2013silicate mixing on the IIE iron meteorite parent body. The Group 2 phosphates, on the other hand, probably record a Pb\u2013Pb age at least 50 Myr younger, and they give insight into the role of subsequent impacts on the alteration of IIE irons. Combining our results with published chronological data suggests that the formation of IIEs irons is consistent with early partial differentiation followed by multiple impact-driven metal\u2013silicate mixing and that most of them were not shielded from subsequent impacts.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Shaolin Li, Weibiao Hsu (\u5f90\u4f1f\u5f6a), Alexander Nemchin, Xiaochao Che, Dunyi Liu, Tao Long, Yexing Luo, Sky Beard, Chipui Tang Geochimica et Cosmochimica ActaIn Press, Journal Pre-proof, Available online 20 June 2021 LINK “Silicate-bearing iron meteorites…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[419,214],"tags":[1670,3443,2326,664,5982],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28113"}],"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=28113"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28113\/revisions"}],"predecessor-version":[{"id":28114,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28113\/revisions\/28114"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28113"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28113"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28113"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}