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Published September 1980 | public
Journal Article

Actinide crystal-liquid partitioning for clinopyroxene and Ca_3(PO_4)_2

Abstract

Using fission and alpha track radiography techniques, we have measured partition coefficients (D) for the actinide elements Th, U and Pu between diopsidic clinopyroxene, whitlockite [β-Ca_3 (PO_4)_2] and silicate liquid at 20kbar. Equilibrium partitioning at the crystal-liquid interface is assumed, and corrections for actinide zoning have been applied to the measured D values. Reproducibility for both actinide and minor element D values is carefully examined as a criterion for crystal-liquid interface equilibrium. The data are mostly compatible with interface equilibrium except for experiments at high cooling rates ( ⪸ 30 deg/hr). Partition coefficients for Th/U/Pu of about 0.002/0.002/0.06 are measured for clinopyroxene and 1.2/0.5/3.4 for whitlockite. At an oxygen fugacity of 10^(−8.5), Pu is much more readily incorporated into the crystalline phases than is U or Th because of the importance of trivalent Pu. The D_(Pu)(cpx) is similar to D(cpx) of the light rare earths supporting the concept of Pu/(rare earth) dating.

Additional Information

© 1980 Pergamon Press Ltd. Received 20 August 1980, Accepted 15 April 1981, Available online 4 April 2003. WE acknowledge profitable discussions with J. JONES and B. O. MYSEN and thoroughly reviews by J. A. PHILPOTTS, W. BOYNTON and A. J. IRVING. This research was supported by NASA grant NSG-7202.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023