Highly Siderophile Element and 187Os Signatures in Non-cratonic Basalt-hosted Peridotite Xenoliths: Unravelling the Origin and Evolution of the Post-Archean Lithospheric Mantle

摘要: The highly siderophile elements (HSE) consist of the Platinum Group Elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) along with rhenium and gold. These transition show relative chemical inertness high market values, which respectively earned them additional names noble metals precious metals. The HSE a very pronounced affinity for iron metal, translates into metal/silicate partition coefficients similar to or higher than 10,000 over large ranges both pressure temperature (e.g., O’Neill et al. 1995; Borisov Palme 2000; Ertel 1999, 2001, 2006, 2008; Fortenfant 2003, 2006; Brenan 2005; Cottrell Walker McDonough 2009; Laurenz 2010; Mann 2012; see 2016, this volume detailed review). Consequently, are thought have been efficiently sequestered within metallic core our planet during metal–silicate differentiation Earth, leaving silicate counterpart almost HSE-barren. Investigations mantle peridotites since 1970s revealed ng.g−1 level abundances as well close-to-chondritic proportions (Chou 1978; Jagoutz 1979; Mitchell Keays 1981; Sun Becker Fischer-Godde 2011). Such inter-HSE fractionations not predicted Earth left after separation low- high-pressure core–mantle (see volume). close agreement between osmium isotopic compositions fertile those chondritic meteorites (Walker 2002a), requires nearly identical Re/Os ratios in these two reservoirs, provides particularly convincing evidence that mantle’s content cannot simply represent residue formation. …