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Impact-induced devolatilization and hydrogen isotopic fractionation of serpentine: Implications for planetary accretionImpact-induced devolatilization of porous serpentine was investigated using two independent experimental methods, the gas recovery and the solid recovery method, each yielding nearly identical results. For shock pressures near incipient devolatilization, the hydrogen isotopic composition of the evolved H2O is very close to that of the starting material. For shock pressures at which up to 12 percent impact-induced devolatilization occurs, the bulk evolved gas is significantly lower in deuterium than the starting material. There is also significant reduction of H2O to H2 in gases recovered at these higher shock pressures, probably caused by reaction of evolved H2O with the metal gas recovery fixture. Gaseous H2O-H2 isotopic fractionation suggests high temperature isotopic equilibrium between the gaseous species, indicating initiation of devolatilization at sites of greater than average energy deposition. Bulk gas-residual solid isotopic fractionations indicate nonequilibrium, kinetic control of gas-solid isotopic ratios. Impact-induced hydrogen isotopic fractionation of hydrous silicates during accretion can strongly affect the long-term planetary isotopic ratios of planetary bodies, leaving the interiors enriched in deuterium. Depending on the model used for extrapolation of the isotopic fractionation to devolatilization fractions greater than those investigated experimentally can result from this process.
Document ID
19880013582
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Tyburczy, James A. (Arizona State Univ. Tempe., United States)
Krishnamurthy, R. V. (California Inst. of Tech. Pasadena., United States)
Epstein, Samuel (California Inst. of Tech. Pasadena., United States)
Ahrens, Thomas J. (California Inst. of Tech. Pasadena., United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1988
Subject Category
Inorganic And Physical Chemistry
Report/Patent Number
NASA-CR-182877
NAS 1.26:182877
Accession Number
88N22966
Funding Number(s)
CONTRACT_GRANT: NGL-05-002-105
CONTRACT_GRANT: NAG9-46
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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