|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Department of Earth Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
Correspondence: * E-mail: geoffrey{at}bromiley.uni-bayreuth.de. Present address: Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany
The high-pressure stability of antigorite in the systems MSH and MASH was investigated using two structurally and chemically well-constrained natural samples. Careful sample selection and characterization ensured that the only significant difference between the samples was Al content, one sample being essentially Al free, and the other containing 3.06(2) wt% Al2O3. In the system MSH, the reaction antigorite = forsterite + clinoenstatite + water was bracketed, under water-saturated conditions, between 630 and 650 °C at 1.6 GPa, between 620 and 660 °C at 2.5 GPa, between 620 and 660 °C at 3.9 GPa, and between 4.5 and 5.0 GPa at 520 °C. In the system MASH, the reaction antigorite = forsterite + clinoenstatite + chlorite + water was bracketed, under water-saturated conditions, between 660 and 700 °C at 2.0 GPa, between 660 and 680 °C at 2.9 GPa, and between 5.0 and 5.5 GPa at 600 °C. At pressures above 5.8 GPa, intersection of this reaction with the reaction chlorite + clinoenstatite = pyrope + forsterite + water leads to an additional reaction whereby the Al component of the antigorite is transferred to pyrope upon antigorite breakdown. The addition of a few weight percent Al2O3 into antigorite is shown to stabilize the antigorite structure to significantly higher temperatures and pressures, possibly by minimizing structural misfit among the component octahedral and tetrahedral sheets. This effect partially explains the considerable discrepancies noted between previous studies on the stability of antigorite at high pressure. In addition, antigorite breakdown in the system MASH transfers a significant volume of water to chlorite-bearing assemblages, thereby greatly increasing the range of temperatures over which water is tied up in hydrous phases relative to the system MSH.
This article has been cited by other articles:
|
|
 |
|
  T. Mizukami, H. Kagi, S. R. Wallis, and S. Fukura Pressure-induced change in the compressional behavior of the O-H bond in chrysotile: A Raman high-pressure study up to 4.5 GPa American Mineralogist, August 1, 2007; 92(8-9): 1456 - 1463. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. C. Hack, A. B. Thompson, and M. Aerts Phase Relations Involving Hydrous Silicate Melts, Aqueous Fluids, and Minerals Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 129 - 185. [Full Text] [PDF]
|
|
|
|
 |
|
 R. Hajialioghli, M. Moazzen, G. T. R. Droop, R. Oberhansli, R. Bousquet, A. Jahangiri, and M. Ziemann Serpentine polymorphs and P-T evolution of metaperidotites and serpentinites in the Takab area, NW Iran Mineralogical Magazine, April 1, 2007; 71(2): 203 - 222. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Melekhova, M. W. Schmidt, P. Ulmer, and E. Guggenbuhl The reaction talc + forsterite = enstatite + H2O revisited: Application of conventional and novel experimental techniques and derivation of revised thermodynamic properties American Mineralogist, July 1, 2006; 91(7): 1081 - 1088. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Reynard and B. Wunder High-pressure behavior of synthetic antigorite in the MgO-SiO2-H2O system from Raman spectroscopy American Mineralogist, February 1, 2006; 91(2-3): 459 - 462. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Kawamoto Hydrous Phases and Water Transport in the Subducting Slab Reviews in Mineralogy and Geochemistry, January 1, 2006; 62(1): 273 - 289. [Full Text] [PDF]
|
|
|
|
 |
|
 D. SMITH and W. L. GRIFFIN Garnetite Xenoliths and Mantle-Water Interactions Below the Colorado Plateau, Southwestern United States J. Petrology, September 1, 2005; 46(9): 1901 - 1924. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Bucher, Y. Fazis, C. de Capitani, and R. Grapes Blueschists, eclogites, and decompression assemblages of the Zermatt-Saas ophiolite: High-pressure metamorphism of subducted Tethys lithosphere American Mineralogist, May 1, 2005; 90(5-6): 821 - 835. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. FUMAGALLI and S. POLI Experimentally Determined Phase Relations in Hydrous Peridotites to 6{middle dot}5 GPa and their Consequences on the Dynamics of Subduction Zones J. Petrology, March 1, 2005; 46(3): 555 - 578. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
