REE (LREE) into the glass with respect to clinopyroxene, but the A group of chrome-spinel peridotite upper-mantle xenoliths from the reverse for Sr and Y, in both mica-bearing and mica-free parageneses. Lashaine volcano, northern Tanzania, differs from other xenoliths In a mica-bearing melt pocket, Rb and Ba partition preferentially at this locality in containing glassy melt pockets. Modal, min...

A new diapiric model for kimberlite genesis takes into account recent interpretations of peridotiteCO2-H20 melting relationships. A minor thermal perturbation at depth might trigger release of reduced vapors with major components C-H-O. Where these volatile components cross the estimated solidus boundary near 260 km, partial melting occurs, the density inversion causes diapiric uprise along adi...

Talc formation via silica-metasomatism of ultramafic rocks is believed to play key roles in subduction zone processes. Yet, the conditions talc remain poorly constrained. We used thermodynamic reaction-path models assess at slab-mantle interface and show that it restricted a limited set pressure–temperature conditions, protolith, fluid compositions. In contrast, our predict chlorite ubiquitous ...

Abstract The timing and processes of ductile deformation metasomatism can be documented using apatite petrochronology. We integrated microstructural, U-Pb, geochemical analyses grains from an exhumed mylonitic shear zone in the St. Barthélémy Massif, Pyrenees, France, to understand how are recorded by U-Pb dates patterns. Electron backscatter diffraction (EBSD) documents crystal plastic charact...

The nature of PGE-Re (PGE Pt, Pd, Os, Ir, Ru) behavior in subcontinental lithospheric mantle was investigated using new, high precision PGE-Re abundance measurements and previously published Re-Os isotopic analyses of peridotite xenoliths from the Sierra Nevada and Mojave Province, California. Ru/Ir ratios and Ir concentrations are constant over a wide range in S content and major-element ferti...

a r t i c l e i n f o Keywords: silica-undersaturated volcanism 238 U-230 Th-226 Ra-210 Pb series disequilibria magma transport and residence time carbonate metasomatism volcanic hazard assessment The silica-undersaturated Nyiragongo volcanics, located in the East African Rift, have globally unique chemical compositions and unusually low viscosities, only higher than carbonatite lavas, for terr...

The morphology of resorbed diamond crystals is a valuable source information on the composition and ascent rate kimberlite magmas, as well possible redox conditions in protolith. Previously, resorption was thoroughly investigated at P–T–fO2 parameters magma ascent. In this study, we using unaltered group I model carbonatite that are typical peridotite magmas subcontinental lithospheric mantle. ...