Experimental oxygen isotope fractionation between siderite-water and phosphoric acid liberated CO sub 2 -siderite

Journal Article · Sat Oct 01 04:00:00 UTC 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90302-X· OSTI ID:5207913

Carothers, W W; Adami, L H; Rosenbauer, R J ^[1]

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1. Geological Survey, Menlo Park, CA (USA)

The equilibrium fractionation of O isotopes between synthetic siderite and water has been measured at temperatures ranging from 33{degree} to 197{degree}C. The fractionation between siderite and water over this temperature range can be represented by the equation: 10{sup 3} 1n {alpha} = 3.13 x 10{sup 6}T{sup minus 2} {minus} 3.50. Comparison between the experimental and theoretical fractionations is favorable only at approximately 200{degree}C; at lower temperatures, they generally differ by up to 2 permil. Siderite was prepared by the slow addition of ferrous chloride solutions to sodium bicarbonate solutions at the experimental temperatures. It was also used to determine the O isotope fractionation factors between phosphoric acid liberated CO{sub 2} and siderite. The fractionation factors for this pair at 25{degree} and 50{degree}C are 1.01175 and 1.01075, respectively. Preliminary results of the measured C isotope fractionation between siderite and CO{sub 2} also indicate C isotopic equilibrium during precipitation of siderite. The measured distribution of {sup 13}C between siderite and CO{sub 2} coincides with the theoretical values only at about 120{degree}C. Experimental and theoretical C fractionations differ up to 3 permil at higher and lower temperatures.

• OSTI ID: 5207913
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:10; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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58 GEOSCIENCES
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BENCH-SCALE EXPERIMENTS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONATE MINERALS
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IRON ORES
ISOTOPES
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MINERALS
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OXIDES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOSPHORIC ACID
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SEPARATION PROCESSES
SIDERITE
SYNTHETIC MATERIALS
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TEMPERATURE EFFECTS
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WATER