{"id":6277,"date":"2015-11-22T12:20:25","date_gmt":"2015-11-22T11:20:25","guid":{"rendered":"http:\/\/karmaka.de\/?p=6277"},"modified":"2015-11-22T12:21:00","modified_gmt":"2015-11-22T11:21:00","slug":"the-pb-isotopic-evolution-of-the-martian-mantle-constrained-by-initial-pb-in-martian-meteorites","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=6277","title":{"rendered":"The Pb isotopic evolution of the Martian mantle constrained by initial Pb in Martian meteorites"},"content":{"rendered":"<p>Bellucci, J. J., Nemchin, A. A., Whitehouse, M. J., Snape, J. F., Bland, P., Benedix, G.K.<\/p>\n<p>Journal of Geophysical Research: Planets<br \/>\nAccepted manuscript online: 21 November 2015<br \/>\nDOI: 10.1002\/2015JE004809<\/p>\n<p><a href=\"http:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/2015JE004809\/abstract\" target=\"_blank\"><strong>LINK<\/strong><\/a><\/p>\n<p>&#8220;The Pb isotopic compositions of maskelynite and pyroxene grains were measured in ALH84001 and three enriched Shergottites (Zagami, RBT04262, and LAR12011) by Secondary Ion Mass Spectrometry (SIMS). A maskelynite-pyroxene isochron for ALH84001 defines a crystallization age of 4089\u00b173 Ma (2\u03c3). The initial Pb isotopic composition of each meteorite was measured in multiple maskelynite grains. ALH84001 has the least radiogenic initial Pb isotopic composition of any Martian meteorite measured to date (i.e., 206Pb\/204Pb=10.07\u00b10.17, 2\u03c3). Assuming an age of reservoir formation for ALH84001 and the enriched Shergottites of 4513 Ma (Borg et al., 2003, Lapen et al., 2010), a two stage Pb isotopic model has been constructed. This model links ALH84001 and the enriched Shergottites by their similar \u03bc-value (238U\/204Pb) of 4.1-4.6 from 4.51 Ga to 4.1 Ga and 0.17 Ga, respectively. The model employed here is dependent on a chondritic \u03bc-value (~1.2) from 4567\u20134513 Ma, which implies core segregation had little to no effect on the \u03bc-value(s) of the Martian mantle. The proposed Pb isotopic model here can be used to calculate ages that are in agreement with Rb-Sr, Lu-Hf and Sm-Nd ages previously determined in the meteorites and confirm the young (~170 Ma) ages of the enriched Shergottites and ancient, >4 Ga, age of ALH84001.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Bellucci, J. J., Nemchin, A. A., Whitehouse, M. J., Snape, J. F., Bland, P., Benedix, G.K. Journal of Geophysical Research: Planets Accepted manuscript online: 21 November 2015 DOI: 10.1002\/2015JE004809 LINK &#8220;The Pb isotopic compositions of&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[122,42,43],"tags":[2194,2196,1828,1920,789,2195,1829,1142],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/6277"}],"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=6277"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/6277\/revisions"}],"predecessor-version":[{"id":6278,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/6277\/revisions\/6278"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6277"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6277"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6277"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}