{"id":13968,"date":"2017-12-04T23:11:13","date_gmt":"2017-12-04T22:11:13","guid":{"rendered":"http:\/\/karmaka.de\/?p=13968"},"modified":"2017-12-05T18:08:36","modified_gmt":"2017-12-05T17:08:36","slug":"heterogeneous-delivery-of-silicate-and-metal-to-the-earth-by-large-planetesimals","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=13968","title":{"rendered":"Heterogeneous delivery of silicate and metal to the Earth by large planetesimals<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"<p>S. Marchi, R. M. Canup &#038; R. J. Walker<\/p>\n<p>Nature Geoscience (2017)<br \/>\ndoi:10.1038\/s41561-017-0022-3<br \/>\nPublished online: 04 December 2017<\/p>\n<p><a href=\"https:\/\/www.nature.com\/articles\/s41561-017-0022-3\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n<p>&#8220;After the Moon\u2019s formation, Earth experienced a protracted bombardment by leftover planetesimals. The mass delivered during this stage of late accretion has been estimated to be approximately 0.5% of Earth\u2019s present mass, based on highly siderophile element concentrations in the Earth\u2019s mantle and the assumption that all highly siderophile elements delivered by impacts were retained in the mantle. However, late accretion may have involved mostly large (\u2265\u20091,500\u2009km in diameter)\u2014and therefore differentiated\u2014projectiles in which highly siderophile elements were sequestered primarily in metallic cores. Here we present smoothed-particle hydrodynamics impact simulations that show that substantial portions of a large planetesimal\u2019s core may descend to the Earth\u2019s core or escape accretion entirely. Both outcomes reduce the delivery of highly siderophile elements to the Earth\u2019s mantle and imply a late accretion mass that may be two to five times greater than previously thought. Further, we demonstrate that projectile material can be concentrated within localized domains of Earth\u2019s mantle, producing both positive and negative 182W isotopic anomalies of the order of 10 to 100\u2009 ppm. In this scenario, some isotopic anomalies observed in terrestrial rocks can be explained as products of collisions after Moon formation.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>S. Marchi, R. M. Canup &#038; R. J. Walker Nature Geoscience (2017) doi:10.1038\/s41561-017-0022-3 Published online: 04 December 2017 LINK (OPEN ACCESS) &#8220;After the Moon\u2019s formation, Earth experienced a protracted bombardment by leftover planetesimals. The mass&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[131,72,112,73],"tags":[504,80,3234,404,257],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13968"}],"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=13968"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13968\/revisions"}],"predecessor-version":[{"id":13975,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13968\/revisions\/13975"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13968"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13968"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13968"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}