{"id":28647,"date":"2021-08-24T17:49:56","date_gmt":"2021-08-24T15:49:56","guid":{"rendered":"https:\/\/karmaka.de\/?p=28647"},"modified":"2021-08-24T17:49:57","modified_gmt":"2021-08-24T15:49:57","slug":"formation-mechanisms-of-ringwoodite-clues-from-the-martian-meteorite-northwest-africa-8705","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=28647","title":{"rendered":"Formation mechanisms of ringwoodite: clues from the Martian meteorite Northwest Africa 8705<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Ting Zhang, Sen Hu, Nian Wang, Yangting Lin, Lixin Gu, Xu Tang, Xinyu Zou &amp; Mingming Zhang<\/p>\n\n\n\n<p>Earth, Planets and Space volume 73, Article number: 165 (2021)<\/p>\n\n\n\n<p><a href=\"https:\/\/link.springer.com\/article\/10.1186\/s40623-021-01494-1\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s40623-021-01494-1.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Ringwoodite and wadsleyite are the high-pressure polymorphs of olivine, which are common in shocked meteorites. They are the major constituent minerals in the terrestrial mantle. NWA 8705, an olivine-phyric shergottite, was heavily shocked, producing shock-induced melt veins and pockets associated with four occurrences of ringwoodite: (1) the lamellae intergrown with the host olivine adjacent to a shock-induced melt pocket; (2) polycrystalline assemblages preserving the shapes and compositions of the pre-existing olivine within a shock-induced melt vein (60 \u03bcm in width); (3) the rod-like grains coexisting with wadsleyite and clinopyroxene within a shock-induced melt vein; (4) the microlite clusters embedded in silicate glass within a very thin shock-induced melt vein (20 \u03bcm in width). The first two occurrences of ringwoodite likely formed via solid-state transformation from olivine, supported by their morphological features and homogeneous compositions (Mg# 64\u201362) similar to the host olivine (Mg# 66\u201364). The third occurrence of ringwoodite might fractionally crystallize from the shock-induced melt, based on its heterogeneous and more FeO-enriched compositions (Mg# 76\u201351) than those of the coexisting wadsleyite (Mg# 77\u201367) and the host olivine (Mg# 66\u201364) of this meteorite. The coexistence of ringwoodite, wadsleyite, and clinopyroxene suggests a post-shock pressure of 14\u201316 GPa and a temperature of 1650\u20131750 \u00b0C. The fourth occurrence of ringwoodite with compositional variation (Mg# 72\u201358) likely crystallized from melt at 16\u201318 GPa and 1750\u20131850 \u00b0C. The presence of the four occurrences of ringwoodite was probably due to their very fast cooling rates in and\/or adjacent to the thin shock-induced melt veins and small pockets. In addition, the higher Fa-contents of the host olivine (Fa35\u201339) in NWA 8705 than those in ordinary chondrites (Fa16\u201332) makes the olivine\u2013ringwoodite transformation prolong to a lower pressure.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ting Zhang, Sen Hu, Nian Wang, Yangting Lin, Lixin Gu, Xu Tang, Xinyu Zou &amp; Mingming Zhang Earth, Planets and Space volume 73, Article number: 165 (2021) LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;Ringwoodite and wadsleyite&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,43,63],"tags":[3262,6089,2794,1304,1829,1844],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28647"}],"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=28647"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28647\/revisions"}],"predecessor-version":[{"id":28648,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28647\/revisions\/28648"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28647"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28647"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28647"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}