{"id":23945,"date":"2020-09-30T14:06:11","date_gmt":"2020-09-30T12:06:11","guid":{"rendered":"http:\/\/karmaka.de\/?p=23945"},"modified":"2026-04-07T10:55:47","modified_gmt":"2026-04-07T08:55:47","slug":"hf%e2%80%90w-chronology-of-a-macrochondrule-from-the-l5-6-chondrite-northwest-africa-8192","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=23945","title":{"rendered":"Hf\u2010W chronology of a macrochondrule from the L5\/6 chondrite Northwest Africa 8192<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Jan L. Hellmann, Thomas S. Kruijer, Knut Metzler, Markus Patzek, Andreas Pack, Jasper Berndt, Thorsten Kleine<\/p>\n\n\n\n<p>Meteoritics &amp; Planetary Science<br>Version of Record online: 30 September 2020<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.13571\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.13571\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>UPDATE: 7 April 2026<br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.70147\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>Correction to \u201cHf-W chronology of a macrochondrule from the L5\/6 chondrite Northwest Africa 8192\u201d<\/strong><\/a><br>MAPS, Version of Record online: 07 April 2026<\/p>\n\n\n\n<p>&#8220;In Table 2, the reported \u03b5<sup>182<\/sup>W (6\/4) values for Bulk (\u201311.86), Metal (\u201312.58), and BHVO-2 (\u201310.07), as well as the \u03b5<sup>183<\/sup>W (6\/4) values for Metal (\u201310.12), BHVO-2 (\u201310.02), and NIST 129c (\u201310.11), are incorrect. The correct values are as follows: \u03b5<sup>182<\/sup>W (6\/4) = \u20131.86 (Bulk), \u20132.58 (Metal), and \u20130.07 (BHVO-2); and \u03b5<sup>183<\/sup>W (6\/4) = \u20130.12 (Metal), \u20130.02 (BHVO-2), and \u20130.11 (NIST 129c).<\/p>\n\n\n\n<p>We apologize for this error.&#8221;<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"justify-text\">&#8220;A large, igneous\u2010textured, and 2 cm\u2010sized spherical object from the L5\/6 chondrite NWA 8192 was investigated for its chemical composition, petrography, O isotopic composition, and Hf\u2010W chronology. The petrography and chemical data indicate that this object closely resembles commonly found chondrules in ordinary chondrites and is therefore classified as a \u201cmacrochondrule.* As a result of metal loss during its formation, the macrochondrule exhibits elevated Hf\/W, which makes it possible to date this object using the short\u2010lived 182Hf\u2010182W system. The Hf\u2010W data provide a two\u2010stage model age for metal\u2013silicate fractionation of 1.4 \u00b1 0.6 Ma after Ca\u2010Al\u2010rich inclusion (CAI) formation, indicating that the macrochondrule formed coevally to normal\u2010sized chondrules from ordinary chondrites. By contrast, Hf\u2010W data for metal from the host chondrite yield a younger model age of ~11 Ma after CAIs. This younger age agrees with Hf\u2010W ages of other type 5\u20136 ordinary chondrites, and corresponds to the time of cooling below the Hf\u2010W closure temperature during thermal metamorphism on the parent body. The Hf\u2010W model age difference between the macrochondrule and the host metal demonstrates that the Hf\u2010W systematics of the bulk macrochondrule were not disturbed during thermal metamorphism, and therefore, that the formation age of such objects can still be determined even in strongly metamorphosed samples. Collectively, this study illustrates that chondrule formation was not limited to mm\u2010size objects, implying that the rarity of macrochondrules reflects either that this process was very inefficient, that subsequent nebular size\u2010sorting decimated large chondrules, or that large precursors were rare.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Jan L. Hellmann, Thomas S. Kruijer, Knut Metzler, Markus Patzek, Andreas Pack, Jasper Berndt, Thorsten Kleine Meteoritics &amp; Planetary ScienceVersion of Record online: 30 September 2020 LINK (OPEN ACCESS)PDF (OPEN ACCESS) UPDATE: 7 April 2026Correction&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[56,148,1607,23,7],"tags":[1839,1864,1611,5016,5580,5017,5733,1807,1843],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23945"}],"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=23945"}],"version-history":[{"count":3,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23945\/revisions"}],"predecessor-version":[{"id":41282,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23945\/revisions\/41282"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=23945"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=23945"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=23945"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}