In situ observation of the formation of 10 Å phase from talc + H2O at mantle pressures and temperatures

Science

Volumn 286, Issue 5441, 1999, Pages 940-942

  Chinnery, Nicholas J ^a   Pawley, Alison R ^a   Clark, Simon M ^b  

^a UNIVERSITY OF MANCHESTER   (United Kingdom)

^b DARESBURY LABORATORY   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

TALC;

HIGH PRESSURE; HIGH TEMPERATURE; MANTLE; TALC;

AQUEOUS SOLUTION; ARTICLE; CHEMICAL REACTION; GEOLOGY; HIGH TEMPERATURE; PRIORITY JOURNAL; REACTION ANALYSIS; THERMODYNAMICS;

EID: 0033615614     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.286.5441.940     Document Type: Article

References (27)

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2. A. E. Ringwood and A. Major, Earth Planet. Sci. Lett. 2, 130 (1967); L.-G. Liu, Phys. Earth Planet. Inter. 42, 255 (1986); M. Kanzaki, Phys. Earth Planet. Inter. 66, 307 (1991).
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6. A. R. Pawley and B. J. Wood, Am. Mineral. 80, 998 (1995). The upper pressure limit of 10 Å phase stability has not been determined, but it is at least 8 GPa (2).
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12. D. Walker, M. A. Carpenter, C. M. Hitch, Am. Mineral. 75, 1020 (1990); D. Walker, Am. Mineral. 76, 1092 (1991). We used tungsten carbide anvils with 12-mm truncated edge lengths.
13. T. Irifune et al., Science 272, 1468 (1996).
14. 2O content during our experiments.
15. The Ti content of a sample run at 6.5 GPa and 700°C for 4 hours was determined by electron microprobe analysis. At a distance of 10 μm from the Ti wall, the Ti content was 0.25 weight %, and at a distance of 90 μm, it was <0.01 weight %.
16. N. J. Chinnery, thesis, University of Manchester, Manchester, UK (1999).
17. 2O in the capsule.
18. J. F. Bauer and C. B. Sclar, Am. Mineral. 66, 576 (1981).
19. The convention that the repeat length of the unit cell along the z crystallographic axis in 10 Å phase is half that in talc results in (001) in 10 Å phase being equivalent to (002) in talc.
20. The relation between energy E, d spacing and detector angle 8 is given by the equation d = 6.199/(E sin θ).
21. 4.00.
22. 2O at these conditions.
23. 2O = 10 Å phase was found to extend from 73°C at 5.3 GPa to 580°C at 7 GPa [B. Wunder and W. Schreyer, Lithos 41, 213 (1997)].
24. A. K. Miller, S. Guggenheim, A. F. Koster van Groos, Am. Mineral. 76, 106 (1991).
25. 2O per formula unit of 10 Å phase is released in the reaction.
26. 2O per formula unit of 10 Å phase is released in the reaction.
27. This work was supported by Natural Environment Research Council (NERC) studentship GT4/95/223/E to N.J.C. and NERC grants GR3/10308 and GR3/ 11181 to A.R.P. We thank M. Henderson for helpful discussions and R. Jones for technical assistance.