Oxygen fugacity has been calculated for rutile–ilmenite assemblages from the reaction 2Fe2O3 (in ilmenite) C 4TiO2 (rutile) D 4FeTiO3 (in ilmenite) C O2. The equation log f O2 D 22:59 25925=T 3:09 log T C 0:0016535P C 48:836P=T 4 log a FeTiO3 C 2 log a Fe2O3 C 4 log a TiO2 , where T is in kelvin and P is in kbar, was derived from available thermodynamic data. The hypothetical end-member rutile–...

The problem of heat–mass transfer in the permeable areas above asthenosphere zones was numerically studied based on an examination inclusion content minerals (olivine and clinopyroxenes) igneous metamorphic rocks lithospheric mantle Earth’s crust; evaluations thermodynamic conditions formation; experimental modeling influence hot reduced gases beneath Siberian craton. flow fluids a certain comp...

Volcanic rocks erupted among Pitcairn seamounts sample a mantle plume that exhibits an extreme Enriched Mantle-1 signature. The origin of this peculiar endmember remains contentious, and could involve the recycling marine sediments Archean or Proterozoic ages, delaminated units from lower continental crust, metasomatized peridotites lithospheric mantle. Here, we report sulfur multi-isotopic sig...

New Caledonia is one of the world’s best-exposed subduction/obduction complexes and central to understanding geodynamic evolution southwest Pacific region. We present new geochemical Ar/Ar age dates from in situ eruptive sequences La Conception basaltic-andesite lavas (ca. 29.12 Ma) correlate generation these with Saint Louis Koum/Borindi Massifs 24 provide information on magmatic processes ope...

Abstract The upper mantle is heterogeneous in Fe isotope compositions, but the origin of heterogeneity needs understanding. Recent studies on oceanic basalts demonstrate that results from low‐degree melt metasomatism. However, whether this hypothesis global significance testing continental settings. Here we present an isotopic study intraplate alkali China, which are shown to have derived conta...

Carbonatites, usually occurring within intra-continental rift-related settings, have strong light rare earth element (LREE) enrichment; they rarely contain economic heavy REE (HREE). Here, we report the identification of Late Triassic HREE-Mo-rich carbonatites in the northernmost Qinling orogen. The rocks contain abundant primary HREE minerals and molybdenite. Calcite-hosted fluid inclusions, i...

Carbonatite-associated rare-earth-element (REE) deposits are the most significant source of the world's REEs; however, their genesis remains unclear. Here, we present new Sr-Nd-Pb and C-O isotopic data for Cenozoic carbonatite-hosted giant REE deposits in southwest China. These REE deposits are located along the western margin of the Yangtze Craton that experienced Proterozoic lithospheric accr...

We report a new radiometric Rb–Sr age determination of 4.0370.04 Ga for high-Al basaltic clast 14321,1353, which is a Group B Apollo 14 high-Al basalt based on its whole-rock incompatible-traceelement chemistry. In addition, available literature Rb–Sr isotope data for Apollo 14 high-Al basalts were reprocessed using the same decay constant and data reduction protocol as used for sample 14321,13...