LINK<\/strong><\/a><\/p>\n“Geochemical models describing the behaviour of niobium during Earth\u2019s growth rely on the general paradigm that niobium was delivered by Earth\u2019s asteroidal building blocks at chondritic abundances. This paradigm is based on the observation that niobium is traditionally regarded as a refractory and strongly lithophile element, and thus stored in the silicate portions of Earth and differentiated asteroids. However, Earth\u2019s silicate mantle is instead selectively depleted in niobium, in marked contrast to the silicate mantles of many asteroids and smaller planets that apparently lack any significant depletion in niobium. Here we present results of high-precision measurements for niobium and other lithophile elements in representative meteorites from various small differentiated asteroids. Our data, along with the results of low-pressure experiments, show that in more reduced asteroids\u2014such as Earth\u2019s first building blocks\u2014niobium is moderately chalcophile and more so than its geochemical twin tantalum by an order of magnitude. Accordingly, niobium can be sequestered into the cores of more reduced asteroids during differentiation via the segregation of sulfide melts in a carbon-saturated environment. We suggest that the niobium deficit in Earth\u2019s silicate mantle may be explained by the Earth\u2019s silicate mantle preferentially accreting the silicate portions of reduced asteroidal building blocks.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Carsten M\u00fcnker, Ra\u00fal O. C. Fonseca & Toni Schulz Nature Geoscience doi:10.1038\/ngeo3048 LINK “Geochemical models describing the behaviour of niobium during Earth\u2019s growth rely on the general paradigm that niobium was delivered by Earth\u2019s asteroidal…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[78,131,28,77,112,214],"tags":[1819,3218,1874,822,4243,4242,4244],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13798"}],"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=13798"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13798\/revisions"}],"predecessor-version":[{"id":13799,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/13798\/revisions\/13799"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13798"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13798"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13798"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}