Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Crichton, W. A. Articles by Ross, N. L. Search for Related Content GeoRef GeoRef Citation

Equations of state of dense hydrous magnesium silicates: results from single-crystal X-ray diffraction

European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble cedex, France
Department of Geosciences, Virginia Tech., Derring Hall, Blacksburg, VA 24061, USA

^* E-mail: crichton{at}esrf.fr

The equations of state of dense hydrous magnesium silicates (DHMS), determined from high-pressure single-crystal X-ray diffraction are reviewed, including hydroxylchondrodite, hydroxylclinohumite, phase A, phase B (anhydrous and hydrous), superhydrous phase B and phase E. The phases along the forsterite–brucite join, Mg₂SiO₄–Mg(OH)₂, display near (increasing) linearity in compressibility with respect to water content and increasing bulk moduli (K_T) with density. Such trends allow prediction of the as yet unknown bulk moduli of phases such as OH-Mg norbergite. The addition of water also reduces the bulk modulus of the B-phases and the anisotropy observed in axial compression. The alternating layers of octahedra and octahedra + tetrahedra completely control compression of the B phases, with the stacking direction becoming more compressible with addition of water. The enigmatic Phase E has the highest K_T' yet measured for a hydrous silicate and one of the lowest K_T. In contrast with other DHMS, Phase E is only slightly anisotropic in axial compression and we attribute this to the role of the intralayer cations in the structure. The degree of hydration and the vacancy concentration appear to be coupled in Phase E.

KEYWORDS: compressibility measurements, equation of state, phase A, anhydrous phase B, phase B, superhydrous B, phase E, hydroxylclinohumite, hydroxylchondrodite, XRD data: single crystal data at high pressure, DHMS

This article has been cited by other articles:

				S. D. Jacobsen Effect of Water on the Equation of State of Nominally Anhydrous Minerals Reviews in Mineralogy and Geochemistry, January 1, 2006; 62(1): 321 - 342. [Full Text] [PDF]