Re and Os concentrations in arc basalts: The roles of volatility and source region fO2 variations

摘要: Olivine and spinel compositions, major elements (including ferric ferrous iron), S, Re Os contents have been measured for a suite of primitive (most >6 wt% MgO) basalts from the Trans Mexican Volcanic Belt (TMVB), including western volcanic belt, Michoacan-Guanajuato Field, Sierra Chichinautzin, Pico de Orizaba region, Palma Sola, San Martin Tuxtlas, eastern alkaline province (EAP). Sulfur at sulfide saturation were calculated to determine whether S are representative saturated liquids. Most samples much lower than expected saturation. A few higher perhaps due presence sulfate in total sulfur (i.e., more oxidized samples). Comparison TMVB along with previously analyzed MORB, OIB, BABB arc reveals continuum that is best explained by variation oxygen fugacity—and thus stability—in source region. High magmatic suites derivation melting mantle, where no longer stable behave incompatibly, whereas low derived relatively reduced mantle stable, compatibly. Intermediate examples abound, magmas span wide range concentrations fO2 during genesis magmas. Low furthermore potentially affected volatility which can factor 3–5.