The compatibility of vanadium (V) during mantle melting is a function of oxygen fugacity (fO2): at high fO2’s, V becomes more incompatible. The prospects and limitations of using the V content of peridotites as a proxy for paleo-fO2 at the time of melt extraction were investigated here by assessing the uncertainties in V measurements and the sensitivity of V as a function of degree of melt extr...

The Emperor Seamount-Hawaiian island chain is thought to originate from melting of a heterogeneous mantle plume, but the composition of the plume has always been inferred from the compositions of the erupted lavas. It has been suggested that recycled (i.e. previously subducted) basaltic oceanic crust (with or without sediments) is part of this plume and responsible for the enriched isotopic com...

Two dives of the DSV Shinkai 6500 in the Mariana Trough back-arc basin in the western Pacific sampled back-arc basin mantle exposures. Reports of peridotite exposures in back-arc basin setting are very limited and the lack of samples has hindered our understanding of this important aspect of lithospheric evolution. The Mariana Trough is a slow-spreading ridge, and ultramafic exposures with asso...

V/Sc systematics in peridotites, mid-ocean ridge basalts and arc basalts are investigated to constrain the variation of fO2 in the asthenospheric mantle. V/Sc ratios are used here to ‘ see through’ those processes that can modify barometric fO2 determinations in mantle rocks and/or magmas: early fractional crystallization, degassing, crustal assimilation and mantle metasomatism. Melting models ...

The intrinsic oxygen fugacities of homogeneous, inclusion-free, megacryst ilmenites from the Frank Smith, Excelsior, Sekameng and Mukorob kimberlite pipes in southern Africa, and the aln6itic breccia in the Solomon Islands have been determined. Similar measurements have been made of the type A and B spinel peridotites from San Carlos in Arizona. The type A peridotites are characterised by oxyge...

The source regions of mid-ocean ridge basalts (MORB) are heterogeneous, consisting of chemically and lithologically distinct domains of variable size. Partial melting of such heterogeneous mantle sources gives rise to diverse isotopic compositions of MORB and abyssal peridotites. Variations in radiogenic isotope ratios in MORB are attributed to mixing of melts derived from enriched and depleted...

Title of Dissertation: CREATION AND DESTRUCTION OF LITHOSPHERIC MANTLE BENEATH THE NORTH CHINA CRATON Jingao Liu, Ph.D., 2011 Dissertation directed by: Professor Roberta L. Rudnick, Geology Professor Richard J. Walker, Geology Mantle peridotites carried in volcanic rocks provide a window into the composition, age and origin of deep lithospheric mantle. Previous studies of mantle peridotites hav...

We apply a tool based on element distribution between orthopyroxene and clinopyroxene for quantifying rare earth element (REE) disequilibria in ultramafic rocks in the subsolidus state. We present case studies of the REE contents of mineral cores in mantle xenoliths and abyssal peridotites using in situ analytical tools. Even when only mineral cores are measured (to avoid enriched rims), equili...