LINK<\/strong><\/a><\/p>\n“Highlights
\n\u2022 Ratios of Cu, S, Se, Te, Re, Pt and Pd in Martian meteorites are relatively constant.
\n\u2022 Martian meteorites show very limited eruptive losses of volatile Re, S, Se and Te.
\n\u2022 The parent magmas of most Martian meteorites were sulfide-undersaturated.
\n\u2022 Martian mantle and core have a low sulfur content.
\n\u2022 Low Te\/PGE ratios in Martian meteorites reflect a strongly volatile element-depleted Martian late veneer.”<\/p>\n
“It is generally believed that the Martian mantle and core are rich in sulfur and that shergottites originated from sulfide-saturated magma. However, recent work suggests that the high FeO contents would require very high S concentrations in shergottite parent magmas at sulfide saturation. Here we combine new and published data on chalcophile elements in shergottites, nakhlites and ALH84001 to constrain the sulfide saturation state of the parent magmas and the chalcophile element concentrations in their mantle sources.<\/p>\n
Regardless of the MgO content and the long-term depletion history of incompatible lithophile elements as indicated by initial \u03b5143Nd, different groups of shergottites display limited variations in ratios of Pt, Pd, Re, Cu, S, Se and Te. The emplacement of most shergottites within the crust and limited variations of ratios of chalcophile elements with substantial differences in volatility during eruption (e.g., Cu\/S, Cu\/Se and Pt\/Re) indicate little degassing losses of S, Se, Te and Re from shergottites. Limited variations in ratios of elements with very different sulfide\u2013silicate melt partition coefficients and negative correlations of chalcophile elements with MgO require a sulfide-undersaturated evolution of the parent magmas from mantle source to emplacement in the crust, consistent with the FeO-based argument. Sulfide petrography and the komatiite-like fractionation of platinum group elements (PGE) in shergottites also support this conclusion. The absence of accumulated sulfides in the ancient Martian cumulate ALH84001 results in very low contents of PGE, Re, Cu, Se and Te in this meteorite, hinting that sulfide-undersaturated magmas may have occurred throughout the Martian geological history. The negative correlation of Cu and MgO contents in shergottites suggests approximately View the MathML source2\u00b10.4(1s) \u03bcg\/g Cu in the Martian mantle. The ratios of Cu, S, Se and Te indicate 360\u00b1120 \u03bcg\/g360\u00b1120 \u03bcg\/g (1s) S, 100\u00b127 ng\/g100\u00b127 ng\/g (1s) Se and 0.50\u00b10.25 ng\/g0.50\u00b10.25 ng\/g (1s) Te in the Martian mantle. At such low S concentrations, all S in Martian mantle sources may dissolve in basaltic melts that form at >5 % partial melting.<\/p>\n
Assuming equilibrium metal\u2013silicate partitioning, and provided that the compositional model of the Martian mantle based on SNC meteorites is correct, Martian mantle inventories of Cu, S and Se were mostly established by core formation and the Martian core should contain <5\u201310 wt.% S only (depending on the choice of metal\u2013silicate partition coefficients). The low S content in the Martian interior is consistent with the low Zn content in the Martian mantle, which indicates about 5 wt.% S in the core. In contrast, the highly siderophile PGE, Re and Te were added to the mantle by late accreted material after the Martian core formed. The near chondritic PGE ratios and the very low ratio of volatile Te to refractory PGE reflect a strongly volatile element-depleted late veneer and imply that the delivery of Martian water, presumably from carbonaceous chondrite like materials, must have occurred before accretion of the late veneer, likely within 2\u20133 million years after formation of the solar system.\"\n<\/p>\n","protected":false},"excerpt":{"rendered":"
Zaicong Wang, Harry Becker Earth and Planetary Science Letters Volume 463, 1 April 2017, Pages 56\u201368 LINK “Highlights \u2022 Ratios of Cu, S, Se, Te, Re, Pt and Pd in Martian meteorites are relatively constant….<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3180,122,42,44,43],"tags":[2194,3641,642,1858,1830,1829],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11596"}],"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=11596"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11596\/revisions"}],"predecessor-version":[{"id":11598,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11596\/revisions\/11598"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11596"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11596"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11596"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}