{"id":13991,"date":"2017-12-13T07:04:45","date_gmt":"2017-12-13T06:04:45","guid":{"rendered":"http:\/\/karmaka.de\/?p=13991"},"modified":"2017-12-13T07:04:45","modified_gmt":"2017-12-13T06:04:45","slug":"the-chelyabinsk-meteorite-thermal-history-and-variable-shock-effects-recorded-by-the-40ar-39ar-system","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=13991","title":{"rendered":"The Chelyabinsk meteorite: Thermal history and variable shock effects recorded by the 40Ar-39Ar system"},"content":{"rendered":"<p>Trieloff, M., Korochantseva, E. V., Buikin, A. I., Hopp, J., Ivanova, M. A. and Korochantsev, A. V.<\/p>\n<p>Meteoritics &#038; Planetary Science. doi: 10.1111\/maps.13012<\/p>\n<p><a href=\"http:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.13012\/abstract\" target=\"_blank\"><strong>LINK<\/strong><\/a><\/p>\n<p>&#8220;We studied three lithologies (light and dark chondritic and impact melt rock) differing in shock stage from the LL5 chondrite Chelyabinsk. Using the 40Ar-39Ar dating technique, we identified low- and high-temperature reservoirs within all samples, ascribed to K-bearing oligoclase feldspar and shock-induced jadeite\u2013feldspar glass assemblages in melt veins, respectively. Trapped argon components had variable 40Ar\/36Ar ratios even within low- and high-temperature reservoirs of individual samples. Correcting for trapped argon revealed a lithology-specific response of the K-Ar system to shock metamorphism, thereby defining two distinct impact events affecting the Chelyabinsk parent asteroid (1) an intense impact event ~1.7 \u00b1 0.1 Ga ago formed the light\u2013dark-structured and impact-veined Chelyabinsk breccia. Such a one-stage breccia formation is consistent with petrological observations and was recorded by the strongly shocked lithologies (dark and impact melt) where a significant fraction of oligoclase feldspar was transformed into jadeite and feldspathic glass; and (2) a young reset event ~30 Ma ago particularly affected the light lithology due to its low argon retentivity, while the more retentive shock-induced phases were more resistant against thermal reset. Trapped argon with 40Ar\/36Ar ratios up to 1900 was likely incorporated during impact-induced events on the parent body, and mixed with terrestrial atmospheric argon contamination. Had it not been identified via isochrons based on high-resolution argon extraction, several geochronologically meaningless ages would have been deduced.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Trieloff, M., Korochantseva, E. V., Buikin, A. I., Hopp, J., Ivanova, M. A. and Korochantsev, A. V. Meteoritics &#038; Planetary Science. doi: 10.1111\/maps.13012 LINK &#8220;We studied three lithologies (light and dark chondritic and impact melt&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48,24,7,63,47],"tags":[3259,1833],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13991"}],"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=13991"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13991\/revisions"}],"predecessor-version":[{"id":13992,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13991\/revisions\/13992"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13991"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13991"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}