Experimental diopsidite: Implications for natural diopsidite genesis through fluid-melt-mantle peridotite reaction

Trapped Melt in the Josephine Peridotite: Implications for Permeability and Melt Extraction in the Upper Mantle

Tabular dunites in the Josephine peridotite of southwestern Oregon represent conduits for melt extraction from the upper mantle. The amount of melt trapped within these channels during cooling and exhumation of the peridotite massif was calculated using a mass-balance approach. These calculations suggest that no more than 0·1^0·2 vol. % melt could have been trapped within these dunites after cr...

Wetting of mantle olivine by sulfide melt: implications for Re=Os ratios in mantle peridotite and late-stage core formation

This study investigates the effects of variations in the relative fugacities of oxygen and sulfur on the wetting of mantle olivine by molten sulfide. Experiments were performed on mixtures of San Carlos olivine and synthetic FeS at 1 bar and 1350oC. Crucibles were fabricated from San Carlos olivine, and the fugacities of oxygen and sulfur were controlled by mixing CO2, CO, and SO2 gases. Experi...

Microtomography of partially molten rocks: three-dimensional melt distribution in mantle peridotite.

The permeability of the upper mantle controls melt segregation beneath spreading centers. Reconciling contradictory geochemical and geophysical observations at ocean ridges requires a better understanding of transport properties in partially molten rocks. Using x-ray synchrotron microtomography, we obtained three-dimensional data on melt distribution for mantle peridotite with various melt frac...

Equations of state of the high-pressure phases of a natural peridotite and implications for the Earth’s lower mantle

To help determine the chemical composition of the Earth’s mantle, we characterised the high-pressure mineral assemblage of an undepleted natural peridotite—thought to be representative of the Earth’s upper-mantle—to 107 GPa using high-resolution X-ray diffraction. At lower-mantle conditions, the peridotite transforms to the assemblage 76 (F 2)% (Mg0.88Fe0.05 2 + Fe0.01 3 + Al0.12Si0.94)O3 ortho...

Calculating melting temperatures and pressures of peridotite protoliths: Implications for the origin of cratonic mantle