[1] We report some of the first noble gas data for in situ lower oceanic crust and shallow mantle. From a suite of gabbros and peridotites recovered from the Atlantis Bank oceanic core complex on the Southwest Indian Ridge, we measured He, Ne, Ar, Kr and Xe concentrations as well as He/He and Ar/Ar ratios, there by documenting the noble gas content and signature of oceanic lithosphere. Except f...

Abstract To unveil how forearc lithosphere cools and re‐equilibrates, we carried out a comprehensive geothermometric investigation of the New Caledonia ophiolite, which represents rare example proto‐arc section generated during subduction infancy. A large data set, including more than 80 samples (peridotites mafic‐ultramafic intrusives), was considered. Closure temperatures calculated for lherz...

The Re-Os isotope system is increasingly providing new insight into continental dynamics due to the fact that it is the only radiogenic isotope system that provides information on melt depletion events (hence lithosphere formation) in the uppermost mantle. Here we review application of the ReOs isotopic system to dating melt depletion in peridotites. In particular, we highlight examples of how ...

Zinc and Cd isotope compositions are presented for a comprehensive suite of terrestrial rocks to constrain the extent Zn fractionation during igneous processes better define ?66Zn ?114Cd values silicate Earth (the ? denote per mille deviations 66Zn/64Zn from JMC Lyon 114Cd/110Cd NIST SRM 3108 Cd). Analyses spinel lherzolites provide bulk (BSE) ?114CdBSE value –0.06 ± 0.03 ‰ (2SD). For Zn, perid...

Major elements, highly siderophile elements (HSE) and Re–Os isotope ratios were analysed in situ on individual sulfide grains in spinel peridotite xenoliths hosted by Miocene intraplate basalts from the Penghu Islands, Taiwan. The xenoliths represent texturally and compositionally different mantle domains, and the geochemical characteristics of the sulfides show changes in HSE distribution and ...

Ultramafic xenoliths from southeastern Arizona, USA, provide evidence for Cu-isotope heterogeneity in the lithospheric mantle. We report new data on Type I (Cr-, Mg-rich) peridotites, but also first Fe-Ti-Al-rich II pyroxenite (±amphibole) xenoliths. Whole rock ?65Cu values of pyroxenites and cryptically metasomatized lherzolites range to isotopically heavier compositions than asthenospheric ma...