{"id":21725,"date":"2020-03-16T19:01:35","date_gmt":"2020-03-16T18:01:35","guid":{"rendered":"http:\/\/karmaka.de\/?p=21725"},"modified":"2020-03-16T19:01:37","modified_gmt":"2020-03-16T18:01:37","slug":"early-silica-crust-formation-in-planetesimals-by-metastable-silica-rich-liquid-immiscibility-or-cristobalite-crystallisation-the-possible-origin-of-silica-rich-chondrules","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=21725","title":{"rendered":"Early silica crust formation in planetesimals by metastable silica-rich liquid immiscibility or cristobalite crystallisation: the possible origin of silica-rich chondrules<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Fran\u00e7ois Faure<\/p>\n\n\n\n<p>Scientific Reports 10, Article number: 4765 (2020) <\/p>\n\n\n\n<p><a href=\"https:\/\/www.nature.com\/articles\/s41598-020-61806-5\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br>\n<a href=\"https:\/\/www.nature.com\/articles\/s41598-020-61806-5.pdf\" 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 processes of planetesimals\u2014small bodies in the solar system\u2014remain actively debated. Planetesimal differentiation is known to have occurred early (&lt;1.5\u2009Myr after the formation of Ca-Al-rich inclusions), as attested by the ages of iron meteorites. Metal-silicate segregation implies global-scale melting, induced by heat released from short-lived radiogenic isotopes, and the consequent generation of a silicate magma ocean. Thermodynamic calculations show that silicate magma crystallisation would have induced silicate-silicate differentiation, leading to the formation of a thick olivine-dominated \u201cmantle\u201d and a thin basaltic \u201ccrust\u201d. However, thermodynamic modelling of magma ocean crystallisation does not produce any silica phases. Here I experimentally show that crystallisation of a chondritic liquid does not follow the thermodynamically predicted path. Silica phases are generated early (before 55% differentiation) as a function of initial magma ocean temperature. As cristobalite or liquid silica phases are less dense than residual liquids or olivine, silica phases could have formed proto-crusts that would have acted as buoyant lids at the surfaces of planetesimals, allowing the eventual accretion and preservation of debris (chondrites). Moreover, the destruction of such a crust by impacts could provide an explanation for the origin of the silica reservoir that condensed around some chondrules.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Fran\u00e7ois Faure Scientific Reports 10, Article number: 4765 (2020) LINK (OPEN ACCESS) PDF (OPEN ACCESS) &#8220;The formation and differentiation processes of planetesimals\u2014small bodies in the solar system\u2014remain actively debated. Planetesimal differentiation is known to have&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,56,148],"tags":[3740,257,1552,5492],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21725"}],"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=21725"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21725\/revisions"}],"predecessor-version":[{"id":21726,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21725\/revisions\/21726"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21725"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21725"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21725"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}