LINK<\/strong><\/a><\/p>\n\n\n\n“Highlights<\/p>\n\n\n\n
\u2022 Aqueous alteration was a key event during the history of carbonaceous chondrites.
\u2022 We explored this process by examining the morphology of magnetite among chondrites.
\u2022 CO & CM chondrites exhibit different magnetite morphologies to CI & C2 chondrites.
\u2022 This is seemingly due to different fluid compositions between these pairs of groups.
\u2022 This is most feasibly explained by the accretion of ammonia into CI & C2 chondrites.”<\/p>\n\n\n\n
“Carbonaceous chondrites experienced varying degrees of aqueous alteration on their parent asteroids, which influenced their mineralogies, textures, and bulk chemical and isotopic compositions. Although this alteration was a crucial event in the history of these meteorites, their various alteration pathways are not well understood. One phase that formed during this alteration was magnetite, and its morphology and abundance vary between and within chondrite groups, providing a means of investigating chondrite aqueous alteration. We measured bulk magnetic properties and first-order reversal curve (FORC) diagrams of CM, CI, CO, and ungrouped C2 chondrites to identify the morphology and size range of magnetite present in these meteorites. We identify two predominant pathways of aqueous alteration among these meteorites that can be distinguished by the resultant morphology of magnetite. In WIS 91600, Tagish Lake, and CI chondrites, magnetite forms predominantly from Fe-sulfides as framboids and stacked plaquettes. In CM and CO chondrites, <0.1 \u03bcm single-domain (SD) magnetite and 0.1\u20135 \u03bcm vortex (V) state magnetite formed predominantly via the direct replacement of metal and Fe-sulfides. After ruling out differences in temperature, water: rock ratios, terrestrial weathering effects, and starting mineralogy, we hypothesise that the primary factor controlling the pathway of aqueous alteration was the composition of the ice accreted into each chondrite group’s parent body. Nebula condensation sequences predict that the most feasible method of appreciably evolving ice concentrations was the condensation of ammonia, which will have formed a more alkaline hydrous fluid upon melting, leading to fundamentally different conditions that may have caused the formation of different magnetite morphologies. As such, we suggest that WIS 91600, Tagish Lake, and the CI chondrites accreted past the ammonia ice line, supporting a more distal or younger accretion of their parent asteroids.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Sanjana Sridhar, James F.J. Bryson, Ashley J. King, Richard J. Harrison Earth and Planetary Science LettersVolume 576, 15 December 2021, 117243 LINK “Highlights \u2022 Aqueous alteration was a key event during the history of carbonaceous…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61,9,10,18,19,72,335],"tags":[2242,1842,3273,3275,105,3646,1814,994,463,1581],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29312"}],"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=29312"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29312\/revisions"}],"predecessor-version":[{"id":29313,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29312\/revisions\/29313"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}