{"id":14814,"date":"2018-05-18T20:47:42","date_gmt":"2018-05-18T18:47:42","guid":{"rendered":"http:\/\/karmaka.de\/?p=14814"},"modified":"2018-05-18T20:48:17","modified_gmt":"2018-05-18T18:48:17","slug":"nature-of-late-accretion-to-earth-inferred-from-mass-dependent-ru-isotopic-compositions-of-chondrites-and-mantle-peridotites","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=14814","title":{"rendered":"Nature of late accretion to Earth inferred from mass-dependent Ru isotopic compositions of chondrites and mantle peridotites<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"<p>Timo Hopp, Thorsten Kleine<\/p>\n<p>Earth and Planetary Science Letters,Volume 494,15 July 2018,Pages 50-59<\/p>\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0012821X18302693\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n<p>&#8220;Highlights<\/p>\n<p>\u2022    Uniform mass-dependent Ru isotopic compositions of chondrites.<br \/>\n\u2022    Chondritic mass-dependent Ru isotopic composition of Earth&#8217;s mantle.<br \/>\n\u2022    No fractionated metal component in late accretionary assemblage of Earth.<br \/>\n\u2022    Bulk addition of impactor cores to Earth&#8217;s mantle during late accretion.&#8221;<\/p>\n<p>&#8220;Elevated abundances of highly siderophile elements in Earth&#8217;s mantle are thought to reflect the late accretion of primitive material after the cessation of core formation, but the origin of this material, and whether or not it can be linked to specific types of meteorites remain debated. Here, mass-dependent Ru isotopic data for chondrites and terrestrial peridotites are reported to evaluate the chemical nature and type of the late-accreted material. After correction for nucleosynthetic Ru isotope anomalies, enstatite, ordinary and carbonaceous chondrites all have indistinguishable mass-dependent Ru isotopic compositions. Thus, neither distinct formation conditions in the solar nebula nor parent body processes resulted in significant mass-dependent Ru isotope fractionation. All five terrestrial peridotites analyzed have mass-dependent Ru isotopic compositions that are indistinguishable from each other and from the composition of chondrites. The chondritic mass-dependent Ru isotopic composition of Earth&#8217;s mantle is difficult to reconcile with prior suggestions that the late accretionary assemblage was a mixture of chondrites with a chemically evolved metal component. Although this mixture can reproduce the suprachondritic Ru\/Ir inferred for Earth&#8217;s mantle, it consistently predicts a heavy Ru isotopic composition of Earth&#8217;s mantle with respect to chondrites. This is because metal components with elevated Ru\/Ir are also enriched in heavy Ru isotopes, resulting from isotope fractionation during core crystallization. Thus, if late accretion involved impacts of differentiated protoplanetary bodies, then the projectile cores must have been either homogenized upon impact, or added to Earth&#8217;s mantle completely, because otherwise Earth&#8217;s mantle would have inherited a non-chondritic mass-dependent Ru isotopic composition from the unrepresentative sampling of core material.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Timo Hopp, Thorsten Kleine Earth and Planetary Science Letters,Volume 494,15 July 2018,Pages 50-59 LINK (OPEN ACCESS) &#8220;Highlights \u2022 Uniform mass-dependent Ru isotopic compositions of chondrites. \u2022 Chondritic mass-dependent Ru isotopic composition of Earth&#8217;s mantle. \u2022&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,17,7],"tags":[3273,3218,1813,641,1807,2714,3554],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14814"}],"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=14814"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14814\/revisions"}],"predecessor-version":[{"id":14816,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/14814\/revisions\/14816"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14814"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14814"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14814"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}