{"id":28434,"date":"2021-07-19T18:21:25","date_gmt":"2021-07-19T16:21:25","guid":{"rendered":"https:\/\/karmaka.de\/?p=28434"},"modified":"2021-07-19T18:21:27","modified_gmt":"2021-07-19T16:21:27","slug":"constraints-on-the-origins-of-iron-silicide-spherules-in-ultrahigh-temperature-distal-impact-ejecta","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=28434","title":{"rendered":"Constraints on the origins of iron silicide spherules in ultrahigh-temperature distal impact ejecta<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Sergei Batovrin, Boris Lipovsky, Yury Gulbin, Yury Pushkarev, Yury A. Shukolyukov<\/p>\n\n\n\n<p>Meteoritics &amp; Planetary Science<br>Version of Record online: 19 July 2021<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.13662\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.13662\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Terrestrially occurring iron silicide spherules, described in the geological literature for 160\u2009years as cosmogenic and approved as \u201cextraterrestrial\u201d minerals by IMA CNMMN in 1984, so far have escaped any serious examination by meteoriticists. Our isotopic and REE data, obtained for silicide spherules for the first time, disagree with the meteoritic origin of gupeiite (Fe3Si) and xifengite (Fe5Si3) spherules from two continents. Despite departures from terrestrial norms (87Rb\/86Sr\u20140.0174; 87Sr\/86Sr\u20140.700181; 3He\/4He\u20147.57\u2009\u00d7\u200910\u22126; 40Ar\/36Ar\u2014325.9), the compositions of 143Nd\/144Nd (0.512034) and 147Sm\/144Nd (0.06357), as well as REE abundances, clarify provenance from upper crust sediments for samples with U\/Pb age of 121\u2013314\u2009ka from the Ala-Tau range in the Urals. However, the morphology of flanged button shapes, ring waves, and eccentro-radiating ridges reliably constrains the origin of silicide spherules to distal meteoritic impact ejecta. Arc jet ablation experiments have previously demonstrated that similar morphologies, observed on australite tektites, reflect aerodynamic ablation rates corresponding to flight velocities well into orbital range. These features are generally accepted as conclusive evidence for hypervelocity atmospheric entry from space. Internal structure, consistent with accretion through the coalescence of 3\u20135\u2009\u00b5m droplets, and composition, closely corresponding to 1893\u20131154\u2009K span of C-type condensation sequences, indicate a high probability of processing through recondensation of ejecta vapor.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Sergei Batovrin, Boris Lipovsky, Yury Gulbin, Yury Pushkarev, Yury A. Shukolyukov Meteoritics &amp; Planetary ScienceVersion of Record online: 19 July 2021 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;Terrestrially occurring iron silicide spherules, described in the geological&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[90,3296],"tags":[2837,6041,2527],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28434"}],"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=28434"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28434\/revisions"}],"predecessor-version":[{"id":28435,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/28434\/revisions\/28435"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=28434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=28434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=28434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}