{"id":34590,"date":"2023-11-30T21:20:59","date_gmt":"2023-11-30T20:20:59","guid":{"rendered":"https:\/\/karmaka.de\/?p=34590"},"modified":"2023-11-30T21:21:30","modified_gmt":"2023-11-30T20:21:30","slug":"a-dunite-fragment-in-meteorite-northwest-africa-nwa-11421-a-piece-of-the-moons-mantle","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=34590","title":{"rendered":"A dunite fragment in meteorite Northwest Africa (NWA) 11421: A piece of the Moon\u2019s mantle<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Allan H. Treiman, Julia Semprich<\/p>\n\n\n\n<p>American Mineralogist (2023) 108 (12): 2182\u20132192<\/p>\n\n\n\n<p><a rel=\"noreferrer noopener\" href=\"https:\/\/pubs.geoscienceworld.org\/msa\/ammin\/article\/108\/12\/2182\/629849\/A-dunite-fragment-in-meteorite-Northwest-Africa\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;A centimeter-sized fragment of dunite, the first recognized fragment of Moon mantle material, has been discovered in the lunar highlands breccia meteorite Northwest Africa (NWA) 11421. The dunite consists of 95% olivine (Fo83), with low-Ca and high-Ca pyroxenes, plagioclase, and chrome spinel. Mineral compositions vary little across the clast and are consistent with chemical equilibration. Mineral thermobarometry implies that the dunite equilibrated at 980 \u00b1 20 \u00b0C and 0.4 \u00b1 0.1 gigapascal (GPa) pressure. The pressure at the base of the Moon\u2019s crust (density 2550 kg\/m3) is 0.14\u20130.18 GPa, so the dunite equilibrated well into the Moon\u2019s upper mantle. Assuming a mantle density of 3400 kg\/m3, the dunite equilibrated at a depth of 88 \u00b1 22 km. Its temperature and depth of equilibration are consistent with the calculated present-day selenotherm (i.e., lunar geotherm).<br>The dunite\u2019s composition, calculated from mineral analyses and proportions, contains less Al, Ti, etc., than chondritic material, implying that it is of a differentiated mantle (including cumulates from a lunar magma ocean). The absence of phases containing P, Zr, etc., suggests minimal involvement of a KREEP component, and the low proportion of Ti suggests minimal interaction with late melt fractionates from a lunar magma ocean. The Mg\/Fe ratio of the dunite (Fo83) is significantly lower than models of an overturned unmixed mantle would suggest, but is consistent with estimates of the bulk composition of the Moon\u2019s mantle.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Allan H. Treiman, Julia Semprich American Mineralogist (2023) 108 (12): 2182\u20132192 LINK (OPEN ACCESS) &#8220;A centimeter-sized fragment of dunite, the first recognized fragment of Moon mantle material, has been discovered in the lunar highlands breccia&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41,115],"tags":[1827,1857,6577],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/34590"}],"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=34590"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/34590\/revisions"}],"predecessor-version":[{"id":34594,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/34590\/revisions\/34594"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=34590"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=34590"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=34590"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}