TY - JOUR
T1 - Fractionation in the solar nebula, II. Condensation of Th, U, Pu, and Cm
AU - Boynton, William V.
N1 - Funding Information:
The author is grateful to S.R. Taylor, H. Palme and F. Podosek for permission to cite their unpublished data. Helpful comments from A. Navrotsky and anonymous reviewers are also appreciated. This was was supported in part by NASA grant NSG-7335.
PY - 1978/6
Y1 - 1978/6
N2 - Reasonable assumptions concerning activity coefficients allow the calculation of the relative volatility of the actinide elements under conditions expected during the early history of the solar system. Several of the light rare earths have volatilities similar to Pu and Cm and can be used as indicators of the degree of fractionation of these extinct elements. Uranium is considerably more volatile than either Pu or Cm, leading to fractionations of about a factor of 50 and 90 in the Pu/U and Cm/U ratio in the earliest condensates from the solar nebula. Ca, Al-rich inclusions from the Allende meteorite, including the coarse-grained inclusions, have a depletion of U relative to La of about a factor of three, suggesting that these inclusions may have been isolated from the nebular gas before condensation of U was complete. The inclusions, however, can be used to determine solar Pu/U and Cm/U ratios if the rare earth patterns are determined in addition to the other normal measurements.
AB - Reasonable assumptions concerning activity coefficients allow the calculation of the relative volatility of the actinide elements under conditions expected during the early history of the solar system. Several of the light rare earths have volatilities similar to Pu and Cm and can be used as indicators of the degree of fractionation of these extinct elements. Uranium is considerably more volatile than either Pu or Cm, leading to fractionations of about a factor of 50 and 90 in the Pu/U and Cm/U ratio in the earliest condensates from the solar nebula. Ca, Al-rich inclusions from the Allende meteorite, including the coarse-grained inclusions, have a depletion of U relative to La of about a factor of three, suggesting that these inclusions may have been isolated from the nebular gas before condensation of U was complete. The inclusions, however, can be used to determine solar Pu/U and Cm/U ratios if the rare earth patterns are determined in addition to the other normal measurements.
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U2 - 10.1016/0012-821X(78)90074-2
DO - 10.1016/0012-821X(78)90074-2
M3 - Article
AN - SCOPUS:0005443412
SN - 0012-821X
VL - 40
SP - 63
EP - 70
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 1
ER -