New mineralogical and geochemical data from a suite of glass ± from the mantle (Deines & Gold, 1973; Nelson et al., 1988). However, controversy remains as to whether such apatite ± amphibole ± phlogopite ± carbonate-bearing spinel magmas represent (1) direct partial melts of carbonatewehrlite, lherzolite and harzburgite xenoliths from the Newer Volbearing mantle peridotite (i.e. primary carbona...

The Piquiri Syenite Massif, southernmost Brazil, is part of the post-collisional magmatism related to the Neoproterozoic Brasiliano-Pan-African Orogenic Cycle. The massif is about 12 km in diameter and is composed of syenites, granites, monzonitic rocks and lamprophyres. Diopside-phlogopite, diopside-biotite-augite-calcic-amphibole, are the main ferro-magnesian paragenesis in the syenitic rocks...

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...

Chemical weathering indices (one-dimensional/1D index values) and accompanying ternary plots (two-dimensional/2D compositional space) facilitate quantitative comparison of whole-rock mineral major-element data, empirical chemical trends with predicted vectors. However, data analysis in is restricted by poles grouping elements that are hosted different minerals or influenced selectively later al...

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...