LINK<\/a><\/p>\n“Jbilet Winselwan (JW) is a recently found CM2 chondrite breccia containing two lithologies. A study of 508 chondrules provides the first statistically reliable size distribution for CM chondrite chondrules, which is about log normal with a mean chondrule size of 149 \u03bcm (lithology I) and 141 \u03bcm (lithology II). Chondrules are surrounded by fine\u2010grained rims. Apparent chondrule diameters and their apparent rim thicknesses are positively correlated with slopes of 0.12 (lithology II) and 0.18 (lithology I), the latter typical of CM chondrites. The CM chondrites are generally primitive and parts of JW experienced only mild aqueous alteration. Bulk JW element ratios are solar (=CI chondritic), e.g., Si\/Mg (1.12), Fe\/Mg (1.80\u20131.83), Ti\/Al (0.053), and about solar for Ca\/Al. The 26 chemically studied chondrules have subchondritic Si\/Mg (0.88) and Fe\/Mg ratios (0.21). Matrix and the fine\u2010grained chondrule rims on the other hand have superchondritic Si\/Mg ratios with means of 1.34 and 1.41, respectively. The Fe\/Mg ratios are also superchondritic, with means of 2.41 (matrix) and 2.61 (fine\u2010grained rims). The refractory element ratios in chondrules are superchondritic (Ti\/Al: 0.106; Ca\/Al: 1.64), and subchondritic in the JW matrix (Ti\/Al: 0.031; Ca\/Al: 0.71) and in the fine\u2010grained rims (Ti\/Al: 0.023; Ca\/Al: 0.68). These complementary element ratios require formation of chondrules and matrix\/rims from the same reservoir in order to obtain a chondritic bulk composition. Most chondrules are mineralogically zoned, with olivine in the core and low\u2010Ca pyroxene in the rim; hence, CM chondrules were open systems, exchanging material with the surrounding gas.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Pia Friend, Dominik C. Hezel, Jean\u2010Alix Barrat, Jutta Zipfel, Herbert Palme, Knut Metzler Meteoritics & Planetary Science doi\/10.1111\/maps.13139 First published: 25 June 2018 LINK “Jbilet Winselwan (JW) is a recently found CM2 chondrite breccia containing…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,56,18,58],"tags":[3273,1839,450,4420,105,4588,752],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/15453"}],"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=15453"}],"version-history":[{"count":3,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/15453\/revisions"}],"predecessor-version":[{"id":17323,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/15453\/revisions\/17323"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}