Mantle melting and basalt extraction by equilibrium porous flow

Science

Volumn 270, Issue 5244, 1995, Pages 1958-1961

  Lundstrom, C C ^a   Gill, J ^a   Williams, Q ^a   Perfit, M R ^b  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b UNIVERSITY OF FLORIDA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

BASALT; BASALT EXTRACTION; EQUILIBRIUM POROUS FLOW; MANTLE MELTING; MANTLE PROCESSES; MELTING; MORB; POROUS FLOW; URANIUM SERIES DISEQUILIBRIUM;

PACIFIC, JUAN DE FUCA RIDGE;

EID: 0029475541     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.270.5244.1958     Document Type: Article

References (43)

1. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
2. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
3. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
4. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
5. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
6. K. T. M. Johnson and H. J. B. Dick, J. Geophys. Res. 97, 9219 (1992); A. V. Sobolov and N. Shimizu, Nature 363, 151 (1993); K. Ross and D. Elthon, ibid. 365, 826 (1993); S. R. Hart, Proc. Natl. Acad. Sci. U.S.A. 90, 11914 (1993); D. McKenzie and M. J. Bickle, J. Petrol. 29, 625 (1989); K. T. M. Johnson, H. J. B. Dick, N. Shimizu, J. Geophys. Res. 95, 2661 (1990).
7. C. H. Langmuir, E. M. Klein, T. Plank, in Mantle Flow and Melt Generation at Mid-Ocean Ridges (American Geophysical Union, Washington, DC, 1992), pp. 183-280.
8. J. H. Natland, in Magmatism in the Ocean Basins, A. D. Saunders and M. J. Norry, Eds. (Blackwell Scientific, Oxford, 1989), pp. 41-70; R. Hekinian, D. Bideau, R. Hebert, Y. Niu, J. Geophys. Res. 100, 10163 (1995); D. J. Fornari et al., Earth Planet. Sci. Lett. 89, 63 (1988).
9. J. H. Natland, in Magmatism in the Ocean Basins, A. D. Saunders and M. J. Norry, Eds. (Blackwell Scientific, Oxford, 1989), pp. 41-70; R. Hekinian, D. Bideau, R. Hebert, Y. Niu, J. Geophys. Res. 100, 10163 (1995); D. J. Fornari et al., Earth Planet. Sci. Lett. 89, 63 (1988).
10. J. H. Natland, in Magmatism in the Ocean Basins, A. D. Saunders and M. J. Norry, Eds. (Blackwell Scientific, Oxford, 1989), pp. 41-70; R. Hekinian, D. Bideau, R. Hebert, Y. Niu, J. Geophys. Res. 100, 10163 (1995); D. J. Fornari et al., Earth Planet. Sci. Lett. 89, 63 (1988).
11. H. S. Waff and J. R. Bulau, J. Geophys. Res. 34, 6109 (1979); D. L. Kohlstedt, in (2), pp. 103-121.
12. H. S. Waff and J. R. Bulau, J. Geophys. Res. 34, 6109 (1979); D. L. Kohlstedt, in (2), pp. 103-121.
13. C. C. Lundstrom et al., Earth Planet. Sci. Lett. 128, 407 (1994).
14. M. Spiegelman and T. Elliott, ibid. 118, 1 (1993).
15. D. McKenzie, ibid. 74, 81 (1985).
16. R. W. Williams and J. Gill, Geochim. Cosmochim. Acta 53, 1607 (1989).
17. C. Richardson and D. McKenzie, Earth Planet. Sci. Lett. 128, 425 (1994).
18. P. D. Beattie, Nature 363, 63 (1993).
19. T. Z. LaTourrette, A. K. Kennedy, G. J. Wasserburg, Science 261, 739 (1993).
20. 230Th excesses in Hawaii through crystal-liquid Th-U fractionation alone; K. W. Sims et al., Science 267, 508 (1995). By using a modification of their equation 1 for Th and U. With the enriched-source partition coefficients of Fig. 1 and a value for F of 0.1, the fractionation of Th from U (αTh/U) is 1.018; this is almost within the uncertainty of the measurement. See also R. K. O'Nions and D. McKenzie, Philos. Trans. R. Soc. London 342, 65 (1993).
21. 230Th excesses in Hawaii through crystal-liquid Th-U fractionation alone; K. W. Sims et al., Science 267, 508 (1995). By using a modification of their equation 1 for Th and U. With the enriched-source partition coefficients of Fig. 1 and a value for F of 0.1, the fractionation of Th from U (αTh/U) is 1.018; this is almost within the uncertainty of the measurement. See also R. K. O'Nions and D. McKenzie, Philos. Trans. R. Soc. London 342, 65 (1993).
22. H. Iwamori, Earth Planet. Sci. Lett. 125, 1 (1994).
23. f is higher for the enriched melt resulting in less decay during transport through spinel Iherzolite.
24. I. Reinitz and K. K. Turekian, Earth Planet. Sci. Lett. 94, 199 (1989).
25. S. J. Goldstein, M. T. Murrell, D. R. Janecky, J. R. Delaney, D. A. Clague, ibid. 107, 25 (1991).
26. S. J. Goldstein, M. T. Murrell, R. W. Williams, ibid. 115, 151 (1993).
27. A. M. Volpe and S. J. Goldstein, Geochim. Cosmochim. Acta 57, 1233 (1993).
28. 231 Pa analyses were performed on an NBS 1260 mass spectrometer at UCSC. Both instruments are equipped with ion counters whose linearity has been verified by repeated measurements on NBS standard U-010.
29. 231 Pa analyses were performed on an NBS 1260 mass spectrometer at UCSC. Both instruments are equipped with ion counters whose linearity has been verified by repeated measurements on NBS standard U-010.
30. The basalts from Endeavour have been described as E-MORBs (enriched) [J. L. Karsten, J. R. Delaney, J. M. Rhodes, R. A. Liias J. Geophys. Res. 95, 19235 (1990)] on the basis of their Zr/Y and Zr/Nb ratios.
31. 2O content. If a slower melting rate were used, the DM model for the enriched melt in Fig. 2B would move outward along a vector from EF to ES and beyond (Fig. 2B).
32. 2O content. If a slower melting rate were used, the DM model for the enriched melt in Fig. 2B would move outward along a vector from EF to ES and beyond (Fig. 2B).
33. The actual time of contact between the melt and the enriched source introduces some uncertainty. The EPF model treats the problem as continuous interaction throughout a depth range with a uniformly higher garnet mode, although the high velocity of melt relative to the solid would quickly separate melt from heterogeneously distributed enriched solid. However, our approach also applies to reactive flow where enriched melt interacts with unmelted peridotite to precipitate garnet and clinopyroxene during percolation. In a sense, we are assessing how residence time differences affect the relations between excesses in the two models.
34. It is likely that the U concentration of the enriched source greatly exceeds that of the depleted source; thus, only 1 to 5% of enriched melt by volume could create the observed range in disequilibria. Melting of depleted peridotite would then dominate crustal production.
35. 226Ra is 1600 years. Not only could significant decay occur after eruption and before collection, but there could also be significant decay during any transport from the last point of solid-liquid equilibration (which includes storage time in magma chambers).
36. 235U) (disequilibria) on eruption for chemically similar basalts.
37. 226Ra excess; K. H. Rubin and J. D. McDougall, Earth Planet. Sci. Lett. 101, 313 (1990).
38. x is the half-spreading rate and d is depth.
39. M. Spiegelman and P. Kenyon, Earth Planet. Sci. Lett. 109, 611 (1992).
40. Z. Jin, H. W. Green, Y. Zhou, Nature 372, 164 (1995).
41. 230Th (75,000 years).
42. H. Sato, I. S. Sacks, T. Murase, G. Muncill, H. Fukuyama, J. Geophys. Res. 94, 10647 (1989).
43. 231Pa analysis; Z. Palacz, D. Sampson, and W. Schillinger for technical support; and F. Hochstaedter, K. Rubin, and two anonymous reviewers for helpful comments. C.C.L., J.B.G., and Q.W. were supported by NSF and IGPP-LLNL. M.R.P. and collection of the southern JDF samples by ALVIN were supported by NSF grants OCE 8716827 and OCE 8918890.