Constraints on rates of granitic magma transport from epidote dissolution kinetics

Science

Volumn 271, Issue 5257, 1996, Pages 1845-1848

  Brandon, Alan D ^a   Creaser, Robert A ^b   Chacko, Thomas ^b  

^a GEOPHYSICAL LABORATORY   (United States)

^b UNIVERSITY OF ALBERTA   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

DISSOLUTION KINETICS; DYKE; EPIDOTE; GRANITE; MAGMA TRANSPORT;

EID: 0029749211     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.271.5257.1845     Document Type: Article

References (38)

1. H. Ramberg, J Geophys. Res. 77, 877 (1972); C F Miller, E. B. Watson, T M. Hamson, Trans. R. Soc. Edinburgh 79, 135 (1988).
2. H. Ramberg, J Geophys. Res. 77, 877 (1972); C F Miller, E. B. Watson, T M. Hamson, Trans. R. Soc. Edinburgh 79, 135 (1988).
3. K. I. Mahon, T. M. Harnson, D. A. Drew, J. Geophys. Res 93, 1174 (1988).
4. R. F. Weinberg and Y. Podladchikov, ibid. 99, 9543 (1994).
5. J. D Clemens and C. K. Mawer, Tectonophysics 204, 339 (1992); N Petford, R. C. Kerr, J. R. Lister, Geology 21, 845 (1993). N Petford, J Geophys. Res. 100, 15735 (1995).
6. J. D Clemens and C. K. Mawer, Tectonophysics 204, 339 (1992); N Petford, R. C. Kerr, J. R. Lister, Geology 21, 845 (1993). N Petford, J Geophys. Res. 100, 15735 (1995).
7. J. D Clemens and C. K. Mawer, Tectonophysics 204, 339 (1992); N Petford, R. C. Kerr, J. R. Lister, Geology 21, 845 (1993). N Petford, J Geophys. Res. 100, 15735 (1995).
8. R Scandone and S. D Malone, J Volcanol. Geotherm. Res. 23, 239 (1985); W W. Chadwick, R. J. Archuleta, D A. Swanson, J Geophys. Res. 93, 4351 (1988), M J Rutherford and P. M Hill, ibid. 98, 19667 (1993)
9. R Scandone and S. D Malone, J Volcanol. Geotherm. Res. 23, 239 (1985); W W. Chadwick, R. J. Archuleta, D A. Swanson, J Geophys. Res. 93, 4351 (1988), M J Rutherford and P. M Hill, ibid. 98, 19667 (1993)
10. R Scandone and S. D Malone, J Volcanol. Geotherm. Res. 23, 239 (1985); W W. Chadwick, R. J. Archuleta, D A. Swanson, J Geophys. Res. 93, 4351 (1988), M J Rutherford and P. M Hill, ibid. 98, 19667 (1993)
11. E-an Zen and J. M. Hammarstrom, Geology 12, 515 (1984)
12. M. T. Naney [Am. J Sci. 283, 993 (1983)] synthesized epidote in granodiorite melts at 800 MPa but not at 200 MPa, and the derived epidote stability curve intersects the granite melting curve at 600 MPa (6) M. W Schmidt [Contnb. Mineral. Petrol. 110, 304 (1992)] experimentally produced epidote only at >750 MPa in granodiorite and at >600 MPa in tonalite. Schmidt (11) experimentally produced epidote only at ≥600 MPa in near-solidus experiments with natural tonalite. Schmidt and A. B. Thompson (Am. Mineral., in press) show that the hypersolidus stability field of epidote can be extended to 400 MPa, but only at exceptionally oxidizing conditions (hematitemagnetite buffer) close to the solidus (680°C).
13. M. T. Naney [Am. J Sci. 283, 993 (1983)] synthesized epidote in granodiorite melts at 800 MPa but not at 200 MPa, and the derived epidote stability curve intersects the granite melting curve at 600 MPa (6) M. W Schmidt [Contnb. Mineral. Petrol. 110, 304 (1992)] experimentally produced epidote only at >750 MPa in granodiorite and at >600 MPa in tonalite. Schmidt (11) experimentally produced epidote only at ≥600 MPa in near-solidus experiments with natural tonalite. Schmidt and A. B. Thompson (Am. Mineral., in press) show that the hypersolidus stability field of epidote can be extended to 400 MPa, but only at exceptionally oxidizing conditions (hematitemagnetite buffer) close to the solidus (680°C).
14. M. T. Naney [Am. J Sci. 283, 993 (1983)] synthesized epidote in granodiorite melts at 800 MPa but not at 200 MPa, and the derived epidote stability curve intersects the granite melting curve at 600 MPa (6) M. W Schmidt [Contnb. Mineral. Petrol. 110, 304 (1992)] experimentally produced epidote only at >750 MPa in granodiorite and at >600 MPa in tonalite. Schmidt (11) experimentally produced epidote only at ≥600 MPa in near-solidus experiments with natural tonalite. Schmidt and A. B. Thompson (Am. Mineral., in press) show that the hypersolidus stability field of epidote can be extended to 400 MPa, but only at exceptionally oxidizing conditions (hematitemagnetite buffer) close to the solidus (680°C).
15. 2 conditions of natural epidote-bearing magmas (6, 16) Quenched experimental charges were sectioned longitudinally, polished, and examined with reflected-light microscopy and backscattered electron imaging Rim widths were measured with an optical microscope equipped with a graduated ocular lens; the rim widths reported are the average of 20 to 30 measurements. Rim width data are as follows: experiment Ep-10, f = 51 17 hours, rim width = 2.74 ± 09 μm; experiment Ep-12, t = 141.20 hours, rim width = 4 95 ± 0.8 μm; and experiment Ep-11, t = 378.78 hours, rim width = 8.18 ± 1.3 μm.
16. 2 conditions of natural epidote-bearing magmas (6, 16) Quenched experimental charges were sectioned longitudinally, polished, and examined with reflected-light microscopy and backscattered electron imaging Rim widths were measured with an optical microscope equipped with a graduated ocular lens; the rim widths reported are the average of 20 to 30 measurements. Rim width data are as follows: experiment Ep-10, f = 51 17 hours, rim width = 2.74 ± 09 μm; experiment Ep-12, t = 141.20 hours, rim width = 4 95 ± 0.8 μm; and experiment Ep-11, t = 378.78 hours, rim width = 8.18 ± 1.3 μm.
17. D C. Rubie and A J Brearley, in High-Temperature Metamorphism and Crustal Anatexis, J R. Ashworth and M. Brown, Eds (Unwin Hyman, London, 1988), pp. 57-86. See also G. W. Fisher, Geochim. Cosmochim Acte 42, 1035 (1978).
18. D C. Rubie and A J Brearley, in High-Temperature Metamorphism and Crustal Anatexis, J R. Ashworth and M. Brown, Eds (Unwin Hyman, London, 1988), pp. 57-86. See also G. W. Fisher, Geochim. Cosmochim Acte 42, 1035 (1978).
19. D R Baker, Contrib. Mineral. Petrol. 106, 462 (1991)
20. -1 can be estimated.
21. 2O (10), which spans the range of natural granitic melt water contents [J. D. Clemens, Lithos 17, 273 (1984)], and diffusivity differences of this magnitude have little significance for the conclusions drawn here.
22. 2O (10), which spans the range of natural granitic melt water contents [J. D. Clemens, Lithos 17, 273 (1984)], and diffusivity differences of this magnitude have little significance for the conclusions drawn here.
23. -1 was used (10).
24. W. Johannes, Contrib Mineral. Petrol 86, 264 (1984).
25. B. W Evans and J. A. Vance, ibid. 96, 178 (1987); R. L. Dawes and B. W. Evans, Geol. Soc Am. Bull. 103, 1017 (1991)
26. B. W Evans and J. A. Vance, ibid. 96, 178 (1987); R. L. Dawes and B. W. Evans, Geol. Soc Am. Bull. 103, 1017 (1991)
27. D. A. Archibald, T E Krogh, R. L. Armstrong, E. Farrar, Can J. Earth Sci. 21, 567 (1984); A. D. Brandon and R. St. J Lambert, ibid. 30, 1076 (1993)
28. D. A. Archibald, T E Krogh, R. L. Armstrong, E. Farrar, Can J. Earth Sci. 21, 567 (1984); A. D. Brandon and R. St. J Lambert, ibid. 30, 1076 (1993)
29. A. D Brandon and R St. J. Lambert, J. Petrol. 35, 239 (1994) Only the outer margin of the batholith (zone 1 to 3 km thick) has abundant epidote (from 0 1 to 3%). The middle-zone granodiorite has only minor or no epidote (less than 0.1%). The two-mica granite, for which there is geochemical evidence that it is derived from a different crustal source, has no epidote. The latter two zones are >60% of the areal exposure Epidote in these inner zones was either completely resorbed or was never stable in these more felsic magmas
30. J E Reesor, Geol Sun Can. Mem. 292 (1958).
31. 26-29) overlaps the magmatic range (Table 1)
32. Epidote-bearing granodiorites from the White Creek Batholith have mineral assemblages appropriate for use of the Al-hornblende geobarometer [J M. Hammarstrom and E-an Zen, Am. Mineral. 71, 1297 (1986)] based on recent experimental calibrations [M. C. Johnson and M. J. Rutherford, Geology 17, 837 (1989) = PJR below; M. W. Schmidt (7) = PS below]. See Table 1 for a typical hornblende analysis. For this analysis, we obtained pressures of 240 and 360 MPa, respectively, using the PJR and PS geobarometers For 16 hornblende analyses from samples WC-18 and WC-19, we obtained a range of 210 to 280 MPa and a mean of 240 MPa (depth of 8.4 km) using the PJR geobarometer, and a range of 320 to 400 MPa and a mean of 360 MPa (depth of 12 6 km) using the PS geobarometer
33. Epidote-bearing granodiorites from the White Creek Batholith have mineral assemblages appropriate for use of the Al-hornblende geobarometer [J M. Hammarstrom and E-an Zen, Am. Mineral. 71, 1297 (1986)] based on recent experimental calibrations [M. C. Johnson and M. J. Rutherford, Geology 17, 837 (1989) = PJR below; M. W. Schmidt (7) = PS below]. See Table 1 for a typical hornblende analysis. For this analysis, we obtained pressures of 240 and 360 MPa, respectively, using the PJR and PS geobarometers For 16 hornblende analyses from samples WC-18 and WC-19, we obtained a range of 210 to 280 MPa and a mean of 240 MPa (depth of 8.4 km) using the PJR geobarometer, and a range of 320 to 400 MPa and a mean of 360 MPa (depth of 12 6 km) using the PS geobarometer
34. H. Nekvasil, Am Mineral. 73, 966 (1988).
35. C. R. Vyhnal, H Y. McSween, J. A. Speer, ibid 76, 176 (1991), A. J. Tulloch, Geology 14, 186 (1986), R. H. Moench, ibid., p. 187.
36. C. R. Vyhnal, H Y. McSween, J. A. Speer, ibid 76, 176 (1991), A. J. Tulloch, Geology 14, 186 (1986), R. H. Moench, ibid., p. 187.
37. C. R. Vyhnal, H Y. McSween, J. A. Speer, ibid 76, 176 (1991), A. J. Tulloch, Geology 14, 186 (1986), R. H. Moench, ibid., p. 187.
38. We thank B. Evans and R Dawes for sample material, R. W. Luth for laboratory facilities, M Walter for initial experiments, A. Locock for the epidote sample, P. Wagner for electron microprobe assistance, and P Resultay for timely polishing of the charges, and R. W. Luth, J Farquhar, D. R M. Pattison, and three anonymous reviewers for helpful comments. Supported by Natural Sciences and Engineering Research Council of Canada research grants to R A C. and T C A.D.B. is supported by a Carnegie Institution Post-Doctoral Fellowship.