{"id":36917,"date":"2024-11-14T14:37:37","date_gmt":"2024-11-14T12:37:37","guid":{"rendered":"https:\/\/karmaka.de\/?p=36917"},"modified":"2024-11-14T14:37:38","modified_gmt":"2024-11-14T12:37:38","slug":"a-reappraisal-of-the-petrogenesis-of-apollo-17-lunar-dunites-72415-72417-relics-of-the-deep-lunar-mantle","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=36917","title":{"rendered":"A reappraisal of the petrogenesis of Apollo 17 lunar dunites 72415-72417: Relics of the deep lunar mantle?<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>K. K. Bhanot, H. Downes, B. G. Rider-Stokes, E. S. Jennings, M. Anand, J. F. Snape, M. J. Whitehouse<\/p>\n\n\n\n<p>MAPS, Version of Record online: 13 November 2024<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.14269\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.14269\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Lunar dunite samples 72415\u201372417, collected by Apollo 17 astronauts from a South Massif boulder in the Taurus\u2013Littrow valley, are crushed breccias composed of several types of olivine- and clinopyroxene-rich clasts, some of which are (or contain) intergrowths of Cr-spinel and pyroxenes or plagioclase. Among the clasts are ellipsoidal symplectites of Cr-spinel and pyroxene, up to 300\u2009\u03bcm in diameter, which have bulk compositions consistent with those of olivine\u2009+\u2009garnet. These symplectites are inferred to originally have been olivine + Mg-Cr-rich garnet (pyrope\u2013uvarovite) that formed deep in the lunar mantle and were subsequently transported closer to the lunar surface (spinel- or plagioclase-peridotite stability fields), perhaps during gravitationally driven overturn. Abundant microsymplectite (30\u2009\u03bcm diameter) intergrowths of Cr-spinel and pyroxene inside olivine grains, many associated with inclusions of plagioclase and augite, formed during a later decompression event (perhaps excavation to the lunar surface). These inclusions have not previously been recorded in these samples and could be responsible for earlier reports of igneous zoning in olivine. Electron backscatter diffraction data show evidence of high shock pressures (&gt;50\u2009GPa), which are inferred to have occurred during the impact which excavated the dunites from the shallow anorthite-bearing lunar mantle. Apatite veinlets post-date the shock metamorphism and have been dated to 3983\u2009\u00b1\u200972\u2009Ma and 3913\u2009\u00b1\u2009118\u2009Ma by the U\u2013Pb method. This age is consistent with that inferred for the Imbrium impact basin, suggesting that the dunite was finally excavated from the mantle during formation of the Imbrium basin.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>K. K. Bhanot, H. Downes, B. G. Rider-Stokes, E. S. Jennings, M. Anand, J. F. Snape, M. J. Whitehouse MAPS, Version of Record online: 13 November 2024 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;Lunar dunite samples&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41,115,63],"tags":[2121,2210,1827,1340,1857,1844],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36917"}],"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=36917"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36917\/revisions"}],"predecessor-version":[{"id":36918,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36917\/revisions\/36918"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36917"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36917"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36917"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}