{"id":60,"date":"2007-09-28T00:00:11","date_gmt":"2007-09-27T15:00:11","guid":{"rendered":"http:\/\/sasakitakanori.com\/en\/?p=60"},"modified":"2011-01-27T10:37:01","modified_gmt":"2011-01-27T01:37:01","slug":"t-sasaki-y-abe-eps-2007","status":"publish","type":"post","link":"http:\/\/sasakitakanori.com\/en\/archives\/60","title":{"rendered":"T. Sasaki &#038; Y. Abe, EPS (2007)"},"content":{"rendered":"<p><span style=\"text-decoration: underline;\">Takanori Sasaki<\/span> &amp; Yutaka Abe, Rayleigh-Taylor Instability after Giant Impacts: Imperfect equilibration of Hf-W system and its effect on the core formation age, <em>EPS<\/em>, <strong>59<\/strong>, 1035-1045 (2007).<\/p>\n<p><strong>Abstract<\/strong><\/p>\n<p>Hf-W chronometry provides constraints on the timing of planetary accretion and differentiation, as the segre- gation of a metal core from silicates should induce strong fractionation of Hf from W. In most previous studies, it was assumed that a giant impact would perfectly reset the Hf-W chronometer. Here, we show the difficulty of achieving perfect equilibration of the Hf-W system. Perfect equilibration requires iron to split into small droplets. However, since the sedimentation velocities of small droplets are low, the Rayleigh-Taylor instability between the upper metal-containing and lower metal-free layers results in quick overturning of the layers, unless iron droplets were uniformly distributed in the entire mantle. Therefore, the lower metal-free layers cannot be equilibrated. We calculated the isotopic evolution of the Hf-W system, taking into account the partial resetting of this chronometer. Our study led to three conclusions: (1) collision conditions and the number of giant impact events affect the age estimation of core formation, (2) the Earth\u2019s W isotope ratio indicates that more than two-tenths of the volume of the protoearth\u2019s mantle must have been equilibrated at each giant impact, and (3) Mars should have experienced a late, extensive equilibration event; it could have been a single giant impact.<\/p>\n<p> <a title=\"eps_2007_hf-w.pdf\" href=\"http:\/\/sasakitakanori.com\/wp-content\/uploads\/2007\/10\/eps_2007_hf-w.pdf\">Read the full article<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<div class=\"mh-excerpt\"><p>Takanori Sasaki &amp; Yutaka Abe, R <a class=\"mh-excerpt-more\" href=\"http:\/\/sasakitakanori.com\/en\/archives\/60\" title=\"T. Sasaki &#038; Y. Abe, EPS (2007)\">[&#8230;]<\/a><\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":{"0":"post-60","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-recent_publications"},"_links":{"self":[{"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/posts\/60","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/comments?post=60"}],"version-history":[{"count":2,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/posts\/60\/revisions"}],"predecessor-version":[{"id":63,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/posts\/60\/revisions\/63"}],"wp:attachment":[{"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/media?parent=60"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/categories?post=60"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/sasakitakanori.com\/en\/wp-json\/wp\/v2\/tags?post=60"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}