{"id":23368,"date":"2020-08-25T18:11:16","date_gmt":"2020-08-25T16:11:16","guid":{"rendered":"http:\/\/karmaka.de\/?p=23368"},"modified":"2020-08-25T18:19:37","modified_gmt":"2020-08-25T16:19:37","slug":"signatures-of-the-post-hydration-heating-of-highly-aqueously-altered-cm-carbonaceous-chondrites-and-implications-for-interpreting-asteroid-sample-returns","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=23368","title":{"rendered":"Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Paula Lindgren, Martin R. Lee, Robert Sparkes, Richard C. Greenwood, Romy D. Hanna, Ian A. Franchi, Ashley J. King, Cameron Floyd, Pierre-Etienne Martin, Victoria E. Hamilton, Chris Haberle<\/p>\n\n\n\n<p>Geochimica et Cosmochimica Acta<br>In Press, Journal Pre-proof, Available online 25 August 2020<\/p>\n\n\n\n<p><a rel=\"noreferrer noopener\" href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0016703720305287\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;The CM carbonaceous chondrites have all been aqueously altered, and some of them were subsequently heated in a parent body environment. Here we have sought to understand the impact of short duration heating on a highly aqueously altered CM through laboratory experiments on Allan Hills (ALH) 83100. Unheated ALH 83100 contains 83 volume per cent serpentine within the fine-grained matrix and altered chondrules. The matrix also hosts grains of calcite and dolomite, which are often intergrown with tochilinite, Fe(Ni) sulphides (pyrrhotite, pentlandite), magnetite and organic matter. Some of the magnetite formed by replacement of Fe(Ni) sulphides that were accreted from the nebula. Laboratory heating to 400 \u00b0C has caused partial dehydroxylation of serpentine and loss of isotopically light oxygen leading to an increase in bulk \u03b418O and fall in \u039417O. Tochilinite has decomposed to magnetite, whereas carbonates have remained unaltered. With regards to infrared spectroscopy (4000\u2013400 cm-1; 2.5 \u2013 25 \u00b5m), heating to 400 \u00b0C has resulted in decreased emissivity (increased reflectance), a sharper and more symmetric OH band at 3684 cm-1 (2.71 \u00b5m), a broadening of the Si-O stretching band together with movement of its minimum to longer wavenumbers, and a decreasing depth of the Mg-OH band (625 cm-1; 16 \u00b5m). The Si-O bending band is unmodified by mild heating. With heating to 800 \u00b0C the serpentine has fully dehydroxylated and recrystallized to \u223cFo60\/70 olivine. Bulk \u03b418O has further increased and \u039417O decreased. Troilite and pyrrhotite have formed, and recrystallization of pentlandite has produced Fe,Ni metal. Calcite and dolomite were calcined at \u223c700 \u00b0C and in their place is an un-named Ca-Fe oxysulphide. Heating changes the structural order of organic matter so that Raman spectroscopy of carbon in the 800 \u00b0C sample shows an increased (D1 + D4) proportional area parameter. The infrared spectrum of the 800 \u00b0C sample confirms the abundance of Fe-bearing olivine and is very similar to the spectrum of naturally heated stage IV CM Pecora Escarpment 02010. The temperature-related mineralogical, chemical, isotopic and spectroscopic signatures defined in ALH 83100 will help to track the post-hydration thermal histories of carbonaceous chondrite meteorites, and samples returned from the primitive asteroids Ryugu and Bennu.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Paula Lindgren, Martin R. Lee, Robert Sparkes, Richard C. Greenwood, Romy D. Hanna, Ian A. Franchi, Ashley J. King, Cameron Floyd, Pierre-Etienne Martin, Victoria E. Hamilton, Chris Haberle Geochimica et Cosmochimica ActaIn Press, Journal Pre-proof,&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61,77,9,18,62],"tags":[2984,2935,1842,1854,3273,105,5667,5668,4899,1843],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23368"}],"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=23368"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23368\/revisions"}],"predecessor-version":[{"id":23372,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/23368\/revisions\/23372"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=23368"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=23368"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=23368"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}