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Effect of pressure, temperature, and oxygen fugacity on the metal-silicate partitioning of Te, Se, and S: Implications for earth differentiation
- Source :
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Geochimica et Cosmochimica Acta . Aug2009, Vol. 73 Issue 15, p4598-4615. 18p. - Publication Year :
- 2009
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Abstract
- Abstract: We have measured liquid Fe metal–liquid silicate partitioning (D i) of tellurium, selenium, and sulfur over a range of pressure, temperature, and oxygen fugacity (1–19GPa, 2023–2693K, fO2 −0.4 to −5.5 log units relative to the iron-wüstite buffer) to better assess the role of metallic melts in fractionating these elements during mantle melting and early Earth evolution. We find that metal-silicate partitioning of all three elements decreases with falling FeO activity in the silicate melt, and that the addition of 5–10wt% S in the metal phase results in a 3-fold enhancement of both D Te and D Se. In general, Te, Se, and S all become more siderophile with increasing pressure, and less siderophile with increasing temperature, in agreement with previous work. In all sulfur-bearing experiments, D Te is greater than D Se or D S, with the latter two being similar over a range of P and T. Parameterized results are used to estimate metal-silicate partitioning at the base of a magma ocean which deepens as accretion progresses, with the equilibration temperature fixed at the peridotite liquidus. We show that during accretion, Te behaves like a highly siderophile element, with expected core/mantle partitioning of >105, in contrast to the observed core/mantle ratio of ∼100. Less extreme differences are observed for Se and S, which yielded core/mantle partitioning 100- to 10 times higher, respectively, than the observed value. Addition of ∼0.5wt% of a meteorite component (H, EH or EL ordinary chondrite) is sufficient to raise mantle abundances to their current level and erase the original interelement fractionation of metal-silicate equilibrium. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 00167037
- Volume :
- 73
- Issue :
- 15
- Database :
- Academic Search Index
- Journal :
- Geochimica et Cosmochimica Acta
- Publication Type :
- Academic Journal
- Accession number :
- 42965806
- Full Text :
- https://doi.org/10.1016/j.gca.2009.04.028