LINK<\/strong><\/a><\/p>\nThis study is dedicated to our late colleague and friend Dr. Ian D. Hutcheon, who pioneered the use of 53Mn-53Cr systematics in secondary minerals as a means of dating aqueous alteration in chondritic meteorites.<\/p>\n
“High precision secondary ion mass-spectrometry (SIMS) analyses of kirschsteinite (CaFeSiO4) in the reduced CV3 chondrites Vigarano and Efremovka yield well resolved 53Cr excesses that correlate with 55Mn\/52Cr, demonstrating in situ decay of the extinct short-lived radionuclide 53Mn. To ensure proper correction for relative sensitivities between 55Mn+ and 52Cr+ ions, we synthesized kirschsteinite doped with Mn and Cr to measure the relative sensitivity factor. The inferred initial ratio (53Mn\/55Mn)0 in chondritic kirschsteinite is (3.71\u00b10.50)\u00d710\u20136. When anchored to 53Mn-53Cr relative and U-corrected 207Pb-206Pb absolute ages of the D\u2019Orbigny angrite, this ratio corresponds to kirschsteinite formation View the MathML source3.2-0.7+08 Ma after CV Ca-, Al-rich inclusions. The kirschsteinite data are consistent within error with the data for aqueously-formed fayalite from the Asuka 881317 CV3 chondrite as reported by Doyle et al. (2015), supporting the idea that Ca-Fe silicates in CV3 chondrites are cogenetic with fayalite (and magnetite) and formed during metasomatic alteration on the CV3 parent body. Concentrically-zoned crystals of kirschsteinite and hedenbergite indicate that they initially formed as near end-member compositions that became more Mg-rich with time, possibly as a result of an increase in temperature.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Glenn J. MacPherson, Kazuhide Nagashima, Alexander N. Krot, Patricia M. Doyle, Marina A. Ivanova Geochimica et Cosmochimica Acta In Press, Accepted Manuscript, Available online 1 October 2016 LINK This study is dedicated to our late…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,14,68],"tags":[981,671,1668,3289,687,3288,1519,482],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10094"}],"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=10094"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10094\/revisions"}],"predecessor-version":[{"id":10097,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10094\/revisions\/10097"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10094"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10094"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10094"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}