LINK<\/strong><\/a><\/p>\n“The ungrouped carbonaceous chondrite Acfer 094 is among the least altered samples of the early solar system. We have studied concentric sulfide\u2013oxide aggregates from this meteorite by transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS). The main minerals present are magnetite, pentlandite, and pyrrhotite\/troilite. The outer parts of the aggregates include \u03bcm-sized olivine and pyroxenes with variable Mg\/Fe ratios. One aggregate contains taenite (56.7 wt% Ni) within its central part that is surrounded by pentlandite and magnetite. We conclude that both phases have formed by oxidation and sulfidization of metal and, based on the metal and sulfide Fe\/Ni ratio, a (sulfide)-formation temperature of 400\u2013550 \u00b0C can be constrained. This temperature is higher than any temperature that could be expected to have occurred on the Acfer 094 parent body, and also textural evidence indicates that the aggregates formed before parent-body accretion. We therefore conclude that the formation of the sulfide\u2013oxide aggregates occurred most likely in the solar nebular at highly variable H2O and H2S fugacities. Oxygen-isotopic compositions of magnetite within these assemblages show that they are indistinguishable from the meteorite’s matrix (\u03b417OSMOW \u2248 4 \u00b1 8\u2030, \u03b418OSMOW \u2248 10 \u00b1 6\u2030, and \u220617OSMOW \u2248 \u22121 \u00b1 5\u2030). An enrichment of 17,18O relative to chondrules of Acfer 094 suggests a link between the formation of the sulfide\u2013oxide aggregates and the preaccretionary processing of matrix grains in a volatile-enriched nebular environment.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Barth, M. I. F., Harries, D., Langenhorst, F. and Hoppe, P. Meteoritics & Planetary Science. doi: 10.1111\/maps.12992 LINK “The ungrouped carbonaceous chondrite Acfer 094 is among the least altered samples of the early solar system….<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,335],"tags":[568,3273,4233,1862],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13763"}],"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=13763"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13763\/revisions"}],"predecessor-version":[{"id":13764,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13763\/revisions\/13764"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13763"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13763"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13763"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}