{"id":30338,"date":"2022-03-15T21:24:36","date_gmt":"2022-03-15T20:24:36","guid":{"rendered":"https:\/\/karmaka.de\/?p=30338"},"modified":"2022-03-15T21:26:49","modified_gmt":"2022-03-15T20:26:49","slug":"half-life-and-initial-solar-system-abundance-of-146sm-determined-from-the-oldest-andesitic-meteorite","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=30338","title":{"rendered":"Half-life and initial Solar System abundance of 146Sm determined from the oldest andesitic meteorite<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Linru Fang, Paul Frossard, Maud Boyet, Audrey Bouvier, Jean-Alix Barrat, Marc Chaussidon, and Frederic Moynier<\/p>\n\n\n\n<p>PNAS<br>March 15, 2022 | 119 (12)<\/p>\n\n\n\n<p><a href=\"https:\/\/www.pnas.org\/doi\/10.1073\/pnas.2120933119\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/www.pnas.org\/doi\/epdf\/10.1073\/pnas.2120933119\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;The formation and differentiation of planetary bodies are dated using radioactive decay systems, including the short-lived 146Sm-142Nd (T\u00bd = 103 or 68 Ma) and long-lived 147Sm-143Nd (T\u00bd = 106 Ga) radiogenic pairs that provide relative and absolute ages, respectively. However, the initial abundance and half-life of the extinct radioactive isotope 146Sm are still debated, weakening the interpretation of 146Sm-142Nd systematics obtained for early planetary processes. Here, we apply the short-lived 26Al-26Mg, 146Sm-142Nd, and long-lived 147Sm-143Sm chronometers to the oldest known andesitic meteorite, Erg Chech 002 (EC 002), to constrain the Solar System initial abundance of 146Sm. The 26Al-26Mg mineral isochron of EC 002 provides a tightly constrained initial \u03b426Mg* of \u22120.009 \u00b1 0.005 \u2030 and (26Al\/27Al)0 of (8.89 \u00b1 0.09) \u00d7 10\u22126. This initial abundance of 26Al is the highest measured so far in an achondrite and corresponds to a crystallization age of 1.80 \u00b1 0.01 Myr after Solar System formation. The 146Sm-142Nd mineral isochron returns an initial 146Sm\/144Sm ratio of 0.00830 \u00b1 0.00032. By combining the Al-Mg crystallization age and initial 146Sm\/144Sm ratio of EC 002 with values for refractory inclusions, achondrites, and lunar samples, the best-fit half-life for 146Sm is 102 \u00b1 9 Ma, corresponding to the physically measured value of 103 \u00b1 5 Myr, rather than the latest and lower revised value of 68 \u00b1 7 Ma. Using a half-life of 103 Ma for 146Sm, the 146Sm\/144Sm abundance of EC 002 translates into an initial Solar System 146Sm\/144Sm ratio of 0.00840 \u00b1 0.00032, which represents the most reliable and precise estimate to date and makes EC 002 an ideal anchor for the 146Sm-142Nd clock.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linru Fang, Paul Frossard, Maud Boyet, Audrey Bouvier, Jean-Alix Barrat, Marc Chaussidon, and Frederic Moynier PNASMarch 15, 2022 | 119 (12) LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;The formation and differentiation of planetary bodies are dated&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28,75,72,112,122,115,73,71,507],"tags":[501,705,2109,6248,332,3701,5832,6247,1970,2285],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30338"}],"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=30338"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30338\/revisions"}],"predecessor-version":[{"id":30339,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/30338\/revisions\/30339"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=30338"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=30338"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=30338"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}