Accretion of primitive planetesimals: Hf-W isotopic evidence from enstatite chondrites

Science

Volumn 288, Issue 5471, 2000, Pages 1629-1631

  Lee, Der Chuen ^a,b   Halliday, Alex N ^b  

^a UNIVERSITY OF MICHIGAN   (United States)

^b ETH ZURICH   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

ISOTOPE; TUNGSTEN;

ACCRETION; ENSTATITE CHONDRITE; PLANETARY EVOLUTION; PLANETESIMAL;

ARTICLE; ASTRONOMY; COSMOS; GAS; HALF LIFE TIME; PRIORITY JOURNAL; SAMPLING; SUN;

EID: 0034595771     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.288.5471.1629     Document Type: Article

References (33)

1. J. W. Larimer and M. Bartholomay, Geochim. Cosmochim. Acta 43, 1455 (1979).
2. G. W. Kallemeyn and J. T. Wasson, Geochim. Cosmochim. Acta 50, 2153 (1986).
3. R. N. Clayton, T. K. Mayeda, A. E. Rubin, Proc. Lunar Planet. Sci. Conf. 15, 245 (1984); R. N. Clayton and T. K. Mayeda, Geochim. Cosmochim. Acta 60, 1999 (1996).
4. R. N. Clayton, T. K. Mayeda, A. E. Rubin, Proc. Lunar Planet. Sci. Conf. 15, 245 (1984); R. N. Clayton and T. K. Mayeda, Geochim. Cosmochim. Acta 60, 1999 (1996).
5. J. V. Smith, J. Geol. 90, 1 (1982); M. Javoy, Geophys. Res. Lett. 22, 2219 (1995); M. Javoy, Chem. Geol. 147, 11 (1998).
6. J. V. Smith, J. Geol. 90, 1 (1982); M. Javoy, Geophys. Res. Lett. 22, 2219 (1995); M. Javoy, Chem. Geol. 147, 11 (1998).
7. J. V. Smith, J. Geol. 90, 1 (1982); M. Javoy, Geophys. Res. Lett. 22, 2219 (1995); M. Javoy, Chem. Geol. 147, 11 (1998).
8. A. Shukolyukov and G. W. Lugmair, Lunar Planet. Sci. 29 (abstract 1208) (1998) [CD-ROM].
9. G. W. Lugmair and A. Shukolyukov, Geochim. Cosmochim. Acta 62, 2863 (1998).
10. D. W. Sears, G. W. Kallemeyn, J. T. Wasson, Geochim. Cosmochim. Acta 46, 597 (1982); K. S. Weeks and D. W. Sears, Geochim. Cosmochim. Acta 49, 1525 (1985); J. T. Wasson and G. W. Kallemeyn, Philos. Trans. R. Soc. London Ser. A 325, 535 (1988).
11. D. W. Sears, G. W. Kallemeyn, J. T. Wasson, Geochim. Cosmochim. Acta 46, 597 (1982); K. S. Weeks and D. W. Sears, Geochim. Cosmochim. Acta 49, 1525 (1985); J. T. Wasson and G. W. Kallemeyn, Philos. Trans. R. Soc. London Ser. A 325, 535 (1988).
12. D. W. Sears, G. W. Kallemeyn, J. T. Wasson, Geochim. Cosmochim. Acta 46, 597 (1982); K. S. Weeks and D. W. Sears, Geochim. Cosmochim. Acta 49, 1525 (1985); J. T. Wasson and G. W. Kallemeyn, Philos. Trans. R. Soc. London Ser. A 325, 535 (1988).
13. P. Kong, T. Mori, M. Ebihara, Geochim. Cosmochim. Acta 61, 4895 (1997).
14. G. W. Wetherill, Geochim. Cosmochim. Acta 58, 4513 (1994).
15. _, in Origin of the Moon, W. K. Hartman, R. J. Phillips, G. J. Taylor, Eds. (Lunar Planetary Institute, Houston, TX, 1986), pp. 519-550; V. S. Safronov, Astron. Zh. 31, 499 (1954).
16. _, in Origin of the Moon, W. K. Hartman, R. J. Phillips, G. J. Taylor, Eds. (Lunar Planetary Institute, Houston, TX, 1986), pp. 519-550; V. S. Safronov, Astron. Zh. 31, 499 (1954).
17. D.-C. Lee and A. N. Halliday, Nature 378, 771 (1995).
18. _, Science 274, 1876 (1996).
19. _, Nature 388, 854 (1997); G. Quitté, J. L. Birck, C. J. Allègre, Lunar Planet. Sci. 31 (abstract 1441) (2000) [CD-ROM].
20. _, Nature 388, 854 (1997); G. Quitté, J. L. Birck, C. J. Allègre, Lunar Planet. Sci. 31 (abstract 1441) (2000) [CD-ROM].
21. D.-C. Lee, A. N. Halliday, G. A. Snyder, L. A. Taylor, Science 278, 1098 (1997).
22. D.-C. Lee and A. N. Halliday, Chem. Geol., in press.
23. C. L. Harper and S. B. Jacobsen, Geochim. Cosmochim. Acta 60, 1131 (1996); S. B. Jacobsen and C. L. Harper, in Earth Processes: Reading the Isotope Code, A. Basu and S. Hart, Eds. (American Geophysical Union, Washington, DC, 1996). pp. 47-74.
24. C. L. Harper and S. B. Jacobsen, Geochim. Cosmochim. Acta 60, 1131 (1996); S. B. Jacobsen and C. L. Harper, in Earth Processes: Reading the Isotope Code, A. Basu and S. Hart, Eds. (American Geophysical Union, Washington, DC, 1996). pp. 47-74.
25. M. F. Horan, M. I. Smoliar, R. J. Walker, Geochim. Cosmochim. Acta 62, 545 (1998).
26. All the samples were crushed with an aluminum oxide mortar under a laminar flow of high-efficiency particulate arresting (HEPA)-filtered air. Because of the very low W concentration in nonmetallic phases (mostly silicates and oxides), we treated all the nonmagnetic phases as a single fraction. Consequently, only three fractions-magnetic, bulk rock, and nonmagnetic-were analyzed, and the separation was performed with a hand magnet. Because abundant fine-grained silicates are intimately intergrown with the metal phases, mechanical separation is unable to provide a pure metallic fraction. Therefore, in addition to the bulk metal measurement some portions of the bulk metal separates from each sample were treated first with hot 6 M HCl to preferentially dissolve the metals. The solution was then decanted from the residue, and the residue was subsequently digested as another silicate/oxide-rich fraction with variable amounts of metal.
27. Web fig. 1 is available at www.sciencemag.org/ feature/data/1048497.shl.
28. Y. Guan, K. D. McKeegan, G. J. Macpherson, Lunar Planet. Sci. 31 (abstract 1744) (2000) [CD-ROM]; T. J. Fagan, K. D. McKeegan, A. N. Krot, K. Keil, Lunar Planet. Sci. 31 (abstract 1592) (2000) [CD-ROM].
29. Y. Guan, K. D. McKeegan, G. J. Macpherson, Lunar Planet. Sci. 31 (abstract 1744) (2000) [CD-ROM]; T. J. Fagan, K. D. McKeegan, A. N. Krot, K. Keil, Lunar Planet. Sci. 31 (abstract 1592) (2000) [CD-ROM].
30. Y. Guan, G. R. Huss, G. J. MacPherson, G. J. Wasserburg, Lunar Planet. Sci. 30 (abstract 1391) (1999) [CD-ROM].
31. E. Polnau, O. Eugster, U. Krähenbühl, K. Marti, Geochim. Cosmochim. Acta 63, 925 (1999).
32. D.-C. Lee and A. N. Halliday, Int. J. Mass Spectrom. Ion Proc. 146/147, 35 (1995).
33. We thank E, Hauri and K. Righter for their reviews; M. Johnson for technical assistance; R. Hewins, G. W. Lugmair, M. Prinz, B. Zanda, and G. J. Wasserburg for discussion; and M. Lindstrom, C. J. MacPherson, and M. Wadhwa for access to their meteorite collections at NASA, the Smithsonian Institution of Washington, and the Field Museum in Chicago. This work was supported by NSF and NASA.