{"id":20304,"date":"2019-08-20T22:33:28","date_gmt":"2019-08-20T20:33:28","guid":{"rendered":"http:\/\/karmaka.de\/?p=20304"},"modified":"2019-08-21T22:14:29","modified_gmt":"2019-08-21T20:14:29","slug":"modal-abundances-of-coarse-grained-5%e2%80%89%c2%b5m-components-within-ci-chondrites-and-their-individual-clasts-mixing-of-various-lithologies-on-the-ci-parent-bodyies","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=20304","title":{"rendered":"Modal abundances of coarse-grained (>5\u2009\u00b5m) components within CI-chondrites and their individual clasts \u2013 mixing of various lithologies on the CI parent body(ies)<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Julian Alfing, Markus Patzek, Addi Bischoff<\/p>\n\n\n\n<p>Geochemistry<br>\nAvailable online 20 August 2019<\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0009281919300248\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0009281919300248\/pdfft?md5=cbfdf529fdf266dc95297eafb0b68529&amp;pid=1-s2.0-S0009281919300248-main.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;For the bulk rocks of CI chondrites, various values are given for the modal abundance of matrix (95-100\u2009vol%) and the accompanying mineral constituents. Here, we have determined the modal abundance of phases &gt;5\u2009\u00b5m in the CI chondrites Orgueil, Ivuna, Alais, and Tonk. Considering this cut-off grain-size to distinguish between matrix and coarse-grained constituents, then, we find the modal abundance of the minor phases magnetite, pyrrhotite, carbonate, olivine, and pyroxene to be 6\u2009vol% in total, and these phases are embedded within the fine-grained, phyllosilicate-rich matrix, making up 94\u2009vol%. The values vary slightly from meteorite to meteorite. Considering all four chondrites, the most abundant phase is &#8211; by far &#8211; magnetite (4.3\u2009vol%) followed by pyrrhotite (\u02dc1.1\u2009vol%). All four CI chondrites are complex breccias, and their degree of brecciation decreases in the sequence: Orgueil\u2009&gt;\u2009Ivuna\u2009&gt;\u2009Alais \u02dc Tonk. Because these meteorites contain clasts with highly variable modal abundances, we therefore also studied individual clasts with high abundances of specific coarse-grained phases. In this respect, in Orgueil we found a fragment with a 21.5\u2009vol% of magnetite as well as a clast having 31.8\u2009vol% phosphate. In Ivuna, we detected an individual clast with a 21.5\u2009vol% of carbonates. Thus, since the CI composition is used as a geochemical standard for comparison, one also should keep in mind that sufficiently large sample masses are required to reveal a homogeneous CI composition. Small aliquots with one dominating lithology may significantly deviate from the suggested standard CI composition.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Julian Alfing, Markus Patzek, Addi Bischoff Geochemistry Available online 20 August 2019 LINK (OPEN ACCESS) PDF (OPEN ACCESS) &#8220;For the bulk rocks of CI chondrites, various values are given for the modal abundance of matrix&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,10],"tags":[733,3273,1809,5143,706,734,110,5144],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20304"}],"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=20304"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20304\/revisions"}],"predecessor-version":[{"id":20312,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20304\/revisions\/20312"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=20304"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=20304"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=20304"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}