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Anionic Pt in Silicate Melts at Low Oxygen Fugacity: Speciation, Partitioning and Implications for Core Formation Processes on AsteroidsMost siderophile element concentrations in planetary mantles can be explained by metal/ silicate equilibration at high temperature and pressure during core formation. Highly siderophile elements (HSE = Au, Re, and the Pt-group elements), however, usually have higher mantle abundances than predicted by partitioning models, suggesting that their concentrations have been set by late accretion of material that did not equilibrate with the core. The partitioning of HSE at the low oxygen fugacities relevant for core formation is however poorly constrained due to the lack of sufficient experimental constraints to describe the variations of partitioning with key variables like temperature, pressure, and oxygen fugacity. To better understand the relative roles of metal/silicate partitioning and late accretion, we performed a self-consistent set of experiments that parameterizes the influence of oxygen fugacity, temperature and melt composition on the partitioning of Pt, one of the HSE, between metal and silicate melts. The major outcome of this project is the fact that Pt dissolves in an anionic form in silicate melts, causing a dependence of partitioning on oxygen fugacity opposite to that reported in previous studies.
Document ID
20170001741
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Medard, E. (Lunar and Planetary Inst. Houston, TX, United States)
Martin, A. M. (Lunar and Planetary Inst. Houston, TX, United States)
Righter, K. (NASA Johnson Space Center Houston, TX, United States)
Malouta, A. (Rice Univ. Houston, TX, United States)
Lee, C.-T. (Rice Univ. Houston, TX, United States)
Date Acquired
February 22, 2017
Publication Date
March 20, 2017
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-CN-38759
Meeting Information
Meeting: Lunar and Planetary Science Conference
Location: The Woodlands, TX
Country: United States
Start Date: March 20, 2017
End Date: March 24, 2017
Sponsors: Lunar and Planetary Inst.
Distribution Limits
Public
Copyright
Public Use Permitted.

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