{"id":36261,"date":"2024-05-31T15:38:29","date_gmt":"2024-05-31T13:38:29","guid":{"rendered":"https:\/\/karmaka.de\/?p=36261"},"modified":"2024-05-31T15:38:30","modified_gmt":"2024-05-31T13:38:30","slug":"identification-of-earths-late-accretion-by-large-impactors-through-mass-independent-cr-isotopes","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=36261","title":{"rendered":"Identification of Earth&#8217;s late accretion by large impactors through mass independent Cr isotopes"},"content":{"rendered":"\n<p>Yogita Kadlag, Aryavart Anand, Mario Fischer-G\u00f6dde, Klaus Mezger , Kristoffer Szilas , Steven Goderis, Ingo Leya<\/p>\n\n\n\n<p>Icarus<br>Available online 31 May 2024, 116143<\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0019103524002033\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK<\/strong><\/a><\/p>\n\n\n\n<p>&#8220;Highlights<\/p>\n\n\n\n<ul>\n<li>The average \u03b553Cr and \u03b554Cr of Earth&#8217;s mantle is 0.03\u202f\u00b1\u202f0.02 and 0.08\u202f\u00b1\u202f0.04, respectively.<\/li>\n\n\n\n<li>CC-like material added to the Earth&#8217;s mantle after Archean is limited to 0.01\u202fwt%.<\/li>\n\n\n\n<li>A carbonaceous chondrite-like impactors dominated the Meso- to Paleoarchean spherule layers (> 3.0\u202fGa), whereas a mixed impactor flux dominated after 3.0\u202fGa.&#8221;<\/li>\n<\/ul>\n\n\n\n<p class=\"justify-text\">&#8220;The late addition of extra-terrestrial material may represent an important source of Earth&#8217;s volatiles. The composition of impactors can be reconstructed using 54Cr abundances in impact related rocks preserved in the terrestrial record. The average \u03b553Cr and \u03b554Cr of Earth&#8217;s mantle determined from mantle rocks of 3.8\u202fGa to present are 0.03\u202f\u00b1\u202f0.02 and 0.08\u202f\u00b1\u202f0.04, respectively. Impact melt rocks and spherule beds linked to impact structures larger than 50\u202fkm that formed between 3.4\u202fGa and 66\u202fMa have \u03b553Cr ranging from \u22120.04 to 0.17, and \u03b554Cr ranging from \u22120.64 to 1.41. A carbonaceous chondrite-like impactor contribution dominated the Meso- to Paleoarchean spherule layers (&gt; 3.0\u202fGa), whereas a mixed chondrite flux composed of carbonaceous and non\u2011carbonaceous chondrites, with a possible contribution of differentiated meteorites is observed in the younger spherule layers (2.5\u202fGa to 66\u202fMa). This likely reflects the break-up of distinct asteroid families through time. Although available impact materials are limited, the Cr isotope signatures of materials related to large impacts suggest a change in the composition of crater-forming impactors on Earth, from predominantly carbonaceous chondrite-like more oxidized material during the Archean to predominantly non\u2011carbonaceous -like more reduced and volatile poor material in recent times. Chromium isotopes suggest that not &gt;0.01\u202fwt% of CC-like material added to the Earth&#8217;s mantle after Archean. Thus, it is inferred that the mass accreted after 3.0\u202fGa contributed insignificantly to the water and other volatile element budget of the Earth.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yogita Kadlag, Aryavart Anand, Mario Fischer-G\u00f6dde, Klaus Mezger , Kristoffer Szilas , Steven Goderis, Ingo Leya IcarusAvailable online 31 May 2024, 116143 LINK &#8220;Highlights &#8220;The late addition of extra-terrestrial material may represent an important source&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,112,81],"tags":[2270,121,3273,1564,2001,3218,3152,2888,2660,641,2527,1855,683],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36261"}],"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=36261"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36261\/revisions"}],"predecessor-version":[{"id":36262,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36261\/revisions\/36262"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36261"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36261"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36261"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}