LINK<\/strong><\/a><\/p>\n\n\n\n“Assessing the water abundance and hydrogen isotopic signature (\u03b4D) of the Martian interior dictates our understanding of the formation of inner solar-system planets, the origin of their volatiles, Martian volcanic history, and the potential for life-bearing environments on the surface of the red planet. Although several Martian meteorites, representing the planet’s crust, have been analyzed before for this assessment, little is known about the effect of shock on recorded hydrogen (H) in their mineral phases. Here, hydrogen contents and isotopes are measured by secondary ion mass spectrometry (SIMS) in an enriched olivine-phyric shergottite, Larkman Nunatak (LAR) 06319, containing impact-melted zones. Systematic 100 \u03bcm-long traverses in pyroxene and maskelynite grains reveal decreases of hundreds of \u00b5g\/g H2O and increases in \u03b4D of thousands of \u2030 towards the contact with impact-melted zones, which is interpreted as H diffusive loss during shock-melting. Diffusion modeling reveals that temperatures high enough to permit H diffusion following shock were maintained near the impact-melted zone for a few minutes. By comparison, the interior of pyroxenes > 200 \u03bcm away from impact-melted zones have some of the highest H content with 170-480 \u00b5g\/g H2O and the lowest \u03b4D with \u223c300 \u2030. The latter values, obtained on the most Mg-rich, i.e. earliest crystallized pyroxenes, are used to estimate that the enriched shergottite mantle source contains 300-1000 \u00b5g\/g H2O and has a \u03b4D of \u223c300 \u2030. This \u03b4D is similar to that of depleted shergottite and nakhlite mantle sources, but higher than Earth\u2019s upper mantle, suggesting slightly different water source materials for the two planets. The enriched shergottite mantle source has \u223c10 times more water than that inferred for the depleted shergottite source and for Earth\u2019s upper mantle. The high water content and wide range of \u03b4D in olivine (from 90 \u00b5g\/g H2O and 2700\u2030 to 1350 \u00b5g\/g H2O and -14\u2030) is interpreted as overprinting by a combination of Martian and terrestrial surface alteration. Finally, the high \u03b4D recorded in the impact-melt produced glass (3350-4700 \u2030), its moderate water content (100-230 \u00b5g\/g H2O), and the presence of vesicles, are likely the result of incorporation of Martian surficial material (ice and atmospheric gases) and degassing during shock melting. This study shows that shock can induce H loss from minerals, accompanied by > 1000 \u2030 \u03b4D increases. Additionally, although it confirms that the Martian mantle may be heterogeneous in its water content, it implies that the Martian mantle is homogeneous within uncertainties for \u03b4D.”<\/p>\n","protected":false},"excerpt":{"rendered":"
J.-M. Dudley, A.H. Peslier, R.L. Hervig Geochimica et Cosmochimica ActaAvailable online 28 October 2021 LINK “Assessing the water abundance and hydrogen isotopic signature (\u03b4D) of the Martian interior dictates our understanding of the formation of…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[122,43],"tags":[3760,4652,192,2276,1920,1829],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29360"}],"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=29360"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29360\/revisions"}],"predecessor-version":[{"id":29361,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/29360\/revisions\/29361"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29360"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29360"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29360"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}