LINK<\/strong><\/a><\/p>\n\n\n\n“I have done major element analyses by electron microprobe, in-situ trace element analyses by laser ablation inductively coupled plasma mass spectrometry, and instrumental neutron activation analyses on bulk samples of olivine grains separated from main-group and Eagle-Station pallasites. Most main-group pallasite olivines have homogeneous Fe\/Mg yet have varying Fe\/Mn. Those few with anomalously ferroan olivine have Fe\/Mn within the range of other main-group pallasites. High-temperature redox process coupled with diffusional exchange resulted in the homogeneous compositions of most main-group pallasites; simple diffusional exchange alone is insufficient. The Eagle-Station pallasites have Fe\/Mn twice that of main-group pallasites with similar Fe\/Mg, a result of having roughly half the Mn content. The Ni\/Co ratio of main-group pallasite olivines is relatively constant and was imposed by the same high-temperature redox\/diffusion process that established Fe\/Mg-Fe\/Mn relationships. Variability in trace lithophile element contents within individual pallasites and within individual olivine grains, coupled with very low contents for some that are inconsistent with formation from a magma, indicate that the current mm-sized olivine grains were recrystallized from a fragmental olivine breccia; grain fragments from different portions of an original dunitic mantle were juxtaposed in the breccia. Main-group pallasites are dimict breccias formed of fragmented and mixed monomict dunite breccia and metallic breccia that were formed in the walls and floor of a large basin that penetrated the mantle of their parent asteroid. Limited data indicate that Eagle-Station pallasites may have been formed by a similar process. Given that Eagle-Station and main-group pallasites were formed in distinct regions of the early Solar System, the pallasite forming process likely was common in early Solar System history.”<\/p>\n","protected":false},"excerpt":{"rendered":"
David W. Mittlefehldt Geochimica et Cosmochimica ActaAvailable online 13 August 2024 LINK “I have done major element analyses by electron microprobe, in-situ trace element analyses by laser ablation inductively coupled plasma mass spectrometry, and instrumental…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2583,810,2580],"tags":[5860,2585,2643,1894,4276,5189],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36492"}],"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=36492"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36492\/revisions"}],"predecessor-version":[{"id":36493,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36492\/revisions\/36493"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36492"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36492"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36492"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}