Olivine-Pyroxene-PtFe Alloy as an Oxygen Geobarometer
| Autor: | H. E. Jamieson, A. H. Grant, P. L. Roeder |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | The Journal of Geology. 100:138-145 |
| ISSN: | 1537-5269 0022-1376 1300-1450 |
| DOI: | 10.1086/629577 |
| Popis: | An equilibrium assemblage of olivine, Ca-free pyroxene, and PtFe alloy can be used to calculate oxygen fugacity at a known temperature and pressure. This oxygen geobarometer has been tested T = 1300-1450°C, P = 1 bar and 10 kbar. The calculated log $$fO_{2}$$ may be compared with that determined by the $$CO_{2}-H_{2}$$ mixture used to control the furnace atmosphere in the 1 bar experiments and, in the case of the 10 kbar experiments, the log $$fO_{2}$$ determined from the graphite-fluid equilibrium. The average deviation of the calculated log $$fO_{2}$$ and that determined by other means is 0.2; the maximum absolute difference is 0.4. The distribution coefficient ($$K_{d}$$) for Fe and Mg between coexisting olivine and pyroxene was found to range from 1.14 at $$X_{Fe{2}SiO_{4}}^{ol} = 0.164$$ to $$X_{Fe{2}SiO_{4}}^{ol} = 0.655$$, and varies systematically with the Fe/(Fe + Mg) of the phases. |
| Databáze: | OpenAIRE |
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