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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Experimental Study of the Solubility of Platinum (Pt) and Rhodium (Rh), with some Results for Chromium (Cr) Content at Chromite Saturation, in Molten Basalt-Rhyolite Mixtures

Turchiaro, Francesco 28 November 2013 (has links)
Pt, Rh and chromite solubility in basalt-rhyolite mixtures at 1400°C, 0.1 MPa, FMQ +3.4 and FMQ (fayalite-magnetite-quartz-buffer) is presented. Melt samples were equilibrated on Pt90Rh10 loops and in chromite crucibles for up to 100 hours. Pt/Rh solubility decreased 20 and 7-fold respectively, progressing to rhyolitic compositions. Cr solubility decreased 3-fold (FMQ+3.4) and 4-fold (FMQ) over the same compositional interval. At FMQ+3.4, reduced Cr solubility, compared to FMQ, reflects Cr3+ and Fe3+ exchange, stabilizing Fe3+-rich spinel. As SiO2 increases, decreasing Pt/Rh and Cr solubility is interpreted to result from low abundances of non-bridging oxygens and lack of octahedral sites for Cr3+.Numerically simulated diffusive exchange between basalt and rhyolite predicts rapid alloy saturation at high fO2, but undersaturated mixtures at low fO2. Magma mixing produced Fe3+-rich spinel at high fO2; chromite undersaturation occurs near FMQ. Combined chromite and Pt-rich alloy saturation does not appear to result from magma mixing near FMQ.
2

An Experimental Study of the Solubility of Platinum (Pt) and Rhodium (Rh), with some Results for Chromium (Cr) Content at Chromite Saturation, in Molten Basalt-Rhyolite Mixtures

Turchiaro, Francesco 28 November 2013 (has links)
Pt, Rh and chromite solubility in basalt-rhyolite mixtures at 1400°C, 0.1 MPa, FMQ +3.4 and FMQ (fayalite-magnetite-quartz-buffer) is presented. Melt samples were equilibrated on Pt90Rh10 loops and in chromite crucibles for up to 100 hours. Pt/Rh solubility decreased 20 and 7-fold respectively, progressing to rhyolitic compositions. Cr solubility decreased 3-fold (FMQ+3.4) and 4-fold (FMQ) over the same compositional interval. At FMQ+3.4, reduced Cr solubility, compared to FMQ, reflects Cr3+ and Fe3+ exchange, stabilizing Fe3+-rich spinel. As SiO2 increases, decreasing Pt/Rh and Cr solubility is interpreted to result from low abundances of non-bridging oxygens and lack of octahedral sites for Cr3+.Numerically simulated diffusive exchange between basalt and rhyolite predicts rapid alloy saturation at high fO2, but undersaturated mixtures at low fO2. Magma mixing produced Fe3+-rich spinel at high fO2; chromite undersaturation occurs near FMQ. Combined chromite and Pt-rich alloy saturation does not appear to result from magma mixing near FMQ.

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