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Letter: Ion microprobe analysis of (231Pa)/(235U) and an appraisal of protactinium partitioning in igneous zircon

  • Axel K. Schmitt EMAIL logo
Published/Copyright: April 1, 2015
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American Mineralogist
From the journal American Mineralogist Volume 92 Issue 4

Abstract

Ion microprobe U-Pa measurements in zircon crystals from a Holocene rhyolite (Salton Buttes, California) are utilized to assess the partitioning of Pa and U between zircon and melt. The relative sensitivity factor (RSF) for ion microprobe U-Pa zircon analysis was calibrated on a natural high-U secular equilibrium zircon from Buff Peak (Nevada). Zircon crystals from Salton Buttes rhyolite show evidence for excess 231Pa with a weighted average (231Pa)/(235U) activity ratio of 1.9. From this ratio, model zircon-melt partition coefficient ratios DPa/DU = 0.9.2.2 are obtained, assuming plausible limits for (231Pa)/(235U)melt and correcting for the age of zircon crystallization (~15 ka). These values roughly fit lattice strain models for tetravalent cations, but are more than one order of magnitude lower than predictions for pentavalent Pa. Based on this appraisal of Pa partitioning, initial 231Pa disequilibrium caused by zircon-melt fractionation alone can produce minor discordance or excess 207Pb in Late Cenozoic zircon, but is insignificant for older U-Pb zircon ages.

Keywords: Pa-231; zircon; partition coefficients; uranium disequilibrium; rhyolites
Received: 2006-9-15
Accepted: 2006-10-25
Published Online: 2015-4-1
Published in Print: 2007-4-1

© 2015 by Walter de Gruyter Berlin/Boston

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  1. New constraints on metamorphic history of Adirondack diopsides (New York, U.S.A.): Al and δ18O profiles
  2. Hammadah al Hamra 193: The first amphibole-bearing winonaite
  3. Crystal chemistry of trioctahedral micas in alkaline and subalkaline volcanic rocks: A case study from Mt. Sassetto (Tolfa district, Latium, central Italy)
  4. Magnetic excitations and heat capacity of fayalite, Fe2SiO4
  5. The barometer tremolite + tschermakite + 2 albite = 2 pargasite + 8 quartz: Constraints from experimental data at unit silica activity, with application to garnet-free natural assemblages
  6. In-situ measurement of dissolution of anorthite in Na-Cl-OH solutions at 22 °C using phase-shift interferometry
  7. Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 °C
  8. Dissolution of the (001) surface of galena: An in situ assessment of surface speciation by fluid-cell micro-Raman spectroscopy
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  11. Clinoenstatite exsolution in diopsidic augite of Dabieshan: Garnet peridotite from depth of 300 km
  12. Heat-pulse calorimetry measurements on natural chlorite-group minerals
  13. Low-temperature behavior of NaGaSi2O6
  14. Single-crystal elasticity of zoisite Ca2Al3Si3O12(OH) by Brillouin scattering
  15. The effect of valence state and site geometry on Ti L3,2 and O K electron energy-loss spectra of TixOy phases
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  20. Transmission electron microscopy study of magnetites in a freshwater population of magnetotactic bacteria
  21. Anomalous behavior at the I2/a to Imab phase transition in SiO2-moganite: An analysis using hard-mode Raman spectroscopy
  22. The system Ag-Au-Se: Phase relations below 405 K and determination of standard thermodynamic properties of selenides by solid-state galvanic cell technique
  23. Rhombohedral (9R) and hexagonal (6H) perovskites in barium silicates under high pressure
  24. Structural effects of pressure on monoclinic chlorite: A single-crystal study
  25. Neptunium incorporation in sodium-substituted metaschoepite
  26. The effect of H2O on olivine crystallization in MORB: Experimental calibration at 200 MPa
  27. Symmetry and crystal structure of biaxial elbaite-liddicoatite tourmaline from the Transbaikalia region, Russia
  28. Letter: Onion morphology and microstructure of polyhedral serpentine
  29. Letter: Ion microprobe analysis of (231Pa)/(235U) and an appraisal of protactinium partitioning in igneous zircon
  30. Letter: Structural investigation of Mg local environments in silicate glasses by ultra-high field 25Mg 3QMAS NMR spectroscopy
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https://doi.org/10.2138/am.2007.2449
Keywords for this article
Pa-231; zircon; partition coefficients; uranium disequilibrium; rhyolites

Articles in the same Issue

  1. New constraints on metamorphic history of Adirondack diopsides (New York, U.S.A.): Al and δ18O profiles
  2. Hammadah al Hamra 193: The first amphibole-bearing winonaite
  3. Crystal chemistry of trioctahedral micas in alkaline and subalkaline volcanic rocks: A case study from Mt. Sassetto (Tolfa district, Latium, central Italy)
  4. Magnetic excitations and heat capacity of fayalite, Fe2SiO4
  5. The barometer tremolite + tschermakite + 2 albite = 2 pargasite + 8 quartz: Constraints from experimental data at unit silica activity, with application to garnet-free natural assemblages
  6. In-situ measurement of dissolution of anorthite in Na-Cl-OH solutions at 22 °C using phase-shift interferometry
  7. Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 °C
  8. Dissolution of the (001) surface of galena: An in situ assessment of surface speciation by fluid-cell micro-Raman spectroscopy
  9. An infrared spectroscopic study of the OH stretching frequencies of talc and 10-Å phase to 10 GPa
  10. Co2+-Cu2+ substitution in bieberite solid-solution series, (Co1-xCux)SO4·7H2O, 0.00 ≤ x ≤ 0.46: Synthesis, single-crystal structure analysis, and optical spectroscopy
  11. Clinoenstatite exsolution in diopsidic augite of Dabieshan: Garnet peridotite from depth of 300 km
  12. Heat-pulse calorimetry measurements on natural chlorite-group minerals
  13. Low-temperature behavior of NaGaSi2O6
  14. Single-crystal elasticity of zoisite Ca2Al3Si3O12(OH) by Brillouin scattering
  15. The effect of valence state and site geometry on Ti L3,2 and O K electron energy-loss spectra of TixOy phases
  16. Characterization of defects and the local structure in natural and synthetic alunite (K, Na, H3O)Al3(SO4)2(OH)6 by multi-nuclear solid-state NMR spectroscopy
  17. Using a mineral lifetime diagram to evaluate the persistence of olivine on Mars
  18. Complexity in 15- and 30-sectors polygonal serpentine: Longitudinal sections, intrasector stacking faults and XRPD satellites
  19. Light-induced alteration of arsenic sulfides: A new product with an orthorhombic crystal structure
  20. Transmission electron microscopy study of magnetites in a freshwater population of magnetotactic bacteria
  21. Anomalous behavior at the I2/a to Imab phase transition in SiO2-moganite: An analysis using hard-mode Raman spectroscopy
  22. The system Ag-Au-Se: Phase relations below 405 K and determination of standard thermodynamic properties of selenides by solid-state galvanic cell technique
  23. Rhombohedral (9R) and hexagonal (6H) perovskites in barium silicates under high pressure
  24. Structural effects of pressure on monoclinic chlorite: A single-crystal study
  25. Neptunium incorporation in sodium-substituted metaschoepite
  26. The effect of H2O on olivine crystallization in MORB: Experimental calibration at 200 MPa
  27. Symmetry and crystal structure of biaxial elbaite-liddicoatite tourmaline from the Transbaikalia region, Russia
  28. Letter: Onion morphology and microstructure of polyhedral serpentine
  29. Letter: Ion microprobe analysis of (231Pa)/(235U) and an appraisal of protactinium partitioning in igneous zircon
  30. Letter: Structural investigation of Mg local environments in silicate glasses by ultra-high field 25Mg 3QMAS NMR spectroscopy
  31. Letter: Entropies of mixing and subsolidus phase relations of forsterite–fayalite (Mg2SiO4–Fe2SiO4) solid solution
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