{"id":41792,"date":"2026-06-05T18:13:10","date_gmt":"2026-06-05T16:13:10","guid":{"rendered":"https:\/\/karmaka.de\/?p=41792"},"modified":"2026-06-05T18:13:11","modified_gmt":"2026-06-05T16:13:11","slug":"ftir-constraints-on-martian-mantle-water-from-clinopyroxene-in-nakhlite-and-shergottite-meteorites","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=41792","title":{"rendered":"FTIR constraints on Martian mantle water from clinopyroxene in nakhlite and shergottite meteorites<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Ioana-Bogdana Radu, C\u00e9cile Deligny, Henrik Skogby, Roland Stalder, Jeremy J. Bellucci, Martin J. Whitehouse<\/p>\n\n\n\n<p>Geochimica et Cosmochimica Acta<br>In Press, Journal Pre-proof, Available online 5 June 2026<\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0016703726003546\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK + PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Water on Mars has traditionally been estimated from hydrogen contents in melt inclusions and apatite, yet these may not account for magma degassing or post-crystallization dehydration. Pyroxenes offer an alternative approach, as they incorporate trace amounts of water during crystallisation via charge-balancing structural defects, that are retained after dehydration enabling experimentally reversing water loss and constraining magmatic water contents. Here we report the first hydrothermal rehydration experiments on pyroxene from both nakhlites and shergottites. The treated nakhlite augites contain 140\u2012185\u202fppm H2O, consistent with previous values for Nakhla (130\u202f\u00b1\u202f26\u202fppm) and within the range of terrestrial basaltic pyroxene. Using clinopyroxene-melt partition coefficients, this corresponds to 1.59\u202f\u00b1\u202f0.03\u20121.83\u202f\u00b1\u202f0.10\u202fwt% average H2O in the nakhlite magma, slightly higher than previous estimates (0.69\u20121.42\u202fwt% H2O). The complex hydrothermal history of nakhlites, including evidence for magmatic degassing and interaction with H2O-poor, Cl-rich fluids, suggests these estimates may represent minimum values of the nakhlite magmatic water content. Assuming a low degree of partial melting, the nakhlite mantle source is expected to contain 80\u201291\u202fppm H2O, overlapping previous estimates (59\u2012184\u202fppm), and comparable to Earth\u2019s MORB mantle (54\u2012330\u202fppm). This is consistent with a common magmatic source for all nakhlites, and broadly consistent with water estimates for the chassignite mantle source (39\u2012252\u202fppm), suggesting that any exogenous fluid assimilation had a negligible effect on the net water budget. In contrast, shergottite pigeonites show no detectable water by Fourier Transform Infrared Spectroscopy, consistent with expected water contents of\u202f\u223c\u202f2\u201211\u202fppm H2O derived from published source compositions for depleted and enriched shergottites. Together, these results refine our understanding of Martian magmatic water content, consistent with a common, more water-rich mantle source for nakhlites, distinct from the more heterogeneous and generally drier shergottite mantle reservoirs&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ioana-Bogdana Radu, C\u00e9cile Deligny, Henrik Skogby, Roland Stalder, Jeremy J. Bellucci, Martin J. Whitehouse Geochimica et Cosmochimica ActaIn Press, Journal Pre-proof, Available online 5 June 2026 LINK + PDF (OPEN ACCESS) &#8220;Water on Mars has&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,44,43],"tags":[1332,3421,3346,1858,1920,383,1830,6116,4174,6859,640,3566,639,633,4889,1829,697,1855],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41792"}],"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=41792"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41792\/revisions"}],"predecessor-version":[{"id":41793,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41792\/revisions\/41793"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41792"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41792"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41792"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}