Thermodynamic calculations of the volatility of the platinum group elements (PGE): The PGE content of fluids at magmatic temperatures

Journal Article · Sun Nov 01 00:00:00 EST 1987 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(87)90377-2· OSTI ID:5221834

Wood, S A ^[1]

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1. McGill Univ., Montreal, Quebec (Canada)

The volatilities of the platinum-group elements as metals, oxides and chlorides were calculated at temperatures of 800-1600 K. Only Pd is significantly volatile as the metal. At log f{sub H{sub 2}O} = 1 Kbar and 1200 K, the concentration (weight) of Pd in the vapor reaches 1 ppt and at 1600 K attains several ppb. The PGE oxides are extremely volatile at atmospheric oxygen fugacities. However, only Os and Ru have significant volatilities ({>=} 1 ppt) as oxides (OsO{sub 4}, RuO{sub 3}) at oxygen fugacities typical of magmatic PGE deposits (near QFM), and only at temperatures greater than 1400 K. Data on the volatility of PGE chlorides exist only for Pd and Ru, both of which are somewhat more volatile as chlorides than as oxides. At 1400 K, f{sub H{sub 2}O} = 1000 bars, f{sub HCl} = 100 bars and at QFM, the calculated vapor concentrations of PdCl{sub 2} and RuCl{sub 3} are 500 ppt and 20 ppt, respectively. However, higher concentrations of PGE may be attained at higher temperatures, higher f{sub O{sub 2}}, higher f{sub HCl} or lower f{sub H{sub 2}O}. Also, any interactions between water vapor and PGE vapor species would tend to increase the vapor concentration of PGE. Vapor transport of the more volatile PGE as chlorides may play some role in the transport of these metals in mafic igneous complexes such as the Stillwater or the Bushveld. However, under the conditions where the PGE are most volatile, the metals Fe, Ni and Cu are several factors of ten more volatile, so that enrichment of the PGe and Cu over Ni and Fe cannot be explained by chloride transport alone.

• OSTI ID: 5221834
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 51:11; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
IGNEOUS ROCKS
CHEMICAL COMPOSITION
OSMIUM COMPOUNDS
PLATINUM COMPOUNDS
RUTHENIUM COMPOUNDS
THERMODYNAMIC PROPERTIES
FLUID FLOW
GEOCHEMISTRY
LEAD COMPOUNDS
LIQUIDS
MAGMATISM
PETROGENESIS
PHASE STUDIES
VAPORS
VOLCANISM
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FLUIDS
GASES
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
ROCKS
TRANSITION ELEMENT COMPOUNDS
580000* - Geosciences