title: Coupled 186Os and 187Os evidence for core-mantle interaction
abstract: Osmium isotopic analyses of picritic lavas from Hawaii show enrichments in the osmium-186/osmium-188 ratio (186Os/188Os) of 0. 008 to 0.018%, relative to a chondritic upper mantle, that are positively correlated with enrichments in 187Os/188Os of 5.4 to 9.0%. The most viable mechanism to produce these coupled 186Os and 187Os enrichments is by addition of 0.5 to 1 weight percent of outer core metal to a portion of the D" layer and subsequent upwelling of the mixture. These data suggest that some plumes originate at the core-mantle boundary and that Os isotopes may be used to distinguish plumes derived from shallow versus deep mantle sources.
authors.affiliation: A. D. Brandon, R. J. Walker, J. W. Morgan, Isotope Geochemistry Laboratory, Department of Geology, University of Maryland, College Park, MD 20742, USA. J. W. Morgan, Department of Earth Resources, Colorado State University, Fort Collins, CO 80.
authors.initials: AD
authors.lastname: Brandon
authors.initials: RJ
authors.lastname: Walker
authors.initials: JW
authors.lastname: Morgan
authors.initials: MD
authors.lastname: Norman
authors.initials: HM
authors.lastname: Prichard