LINK<\/strong><\/a><\/p>\n\n\n\n“Tochilinite\/cronstedtite intergrowths are commonly observed as alteration products in CM chondrite matrices, but the conditions under which they formed are still largely underconstrained due to their scarcity in terrestrial environments. Here, we report low temperature (80 \u00b0C) anoxic hydrothermal experiments using starting assemblages similar to the constituents of the matrices of the most pristine CM chondrite and S\u2010rich and S\u2010free fluids. Cronstedtite crystals formed only in S\u2010free experiments under circumneutral conditions with the highest Fe\/Si ratios. Fe\u2010rich tochilinite with chemical and structural characteristics similar to chondritic tochilinite was observed in S\u2010bearing experiments. We observed a positive correlation between the Mg content in the hydroxide layer of synthetic tochilinite and temperature, suggesting that the composition of tochilinite is a proxy for the alteration temperature in CM chondrites. Using this relation, we estimate the mean precipitation temperatures of tochilinite to be 120\u2013160 \u00b0C for CM chondrites. Given the different temperature ranges of tochilinite and cronstedtite in our experiments, we propose that Fe\u2010rich tochilinite crystals resulted from the alteration of metal beads under S\u2010bearing alkaline conditions at T = 120\u2013160 \u00b0C followed by cronstedtite crystals formed by the reaction of matrix amorphous silicates, metal beads, and water at a low temperature (50\u2013120 \u00b0C).”<\/p>\n","protected":false},"excerpt":{"rendered":"
Lionel G. Vacher, Laurent Truche, Fran\u00e7ois Faure, Laurent Tissandier, R\u00e9gine Mosser\u2010Ruck, Yves Marrocchi Meteoritics & Planetary Science First Published: 23 June 2019 LINK “Tochilinite\/cronstedtite intergrowths are commonly observed as alteration products in CM chondrite matrices,…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,18,58],"tags":[3273,105,5061,5060],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/19871"}],"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=19871"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/19871\/revisions"}],"predecessor-version":[{"id":19872,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/19871\/revisions\/19872"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=19871"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=19871"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=19871"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}