|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | FEEDBACK/COMMNET | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Articles |
GeoForschungsZenturm Potstdam, Division 4.1 Telegrafenberg, D-14473 Potsdam, Germany
* E-mail: wunder{at}gfz-potsdam.de
This paper was presented at the EMPG VIII meeting in Bergamo, Italy (April 2000)
The pressure and temperature dependence of antigorite polysomatism was investigated in the P, T-range of 350–710°C, 0.2–5.0 GPa within the system MgO-SiO2-H2O (MSH). TEM-study indicated that increasing temperature and decreasing pressure of MSH-antigorite formation are correlated with a shorter a-cell periodicity, i.e. smaller m, value (m = number of tetrahedra in a single chain along the wavelength a). For the P, T-conditions investigated, the compositional m-range of antigorite is rather narrow (14–18) corresponding to Mg2.79Si2O5(OH)3.57 Mg2.83Si2O5(OH)3.67. The change in the crystal structure of antigorite is combined with a gradual partial dehydration process and loss of MgO.
For the formulation of reactions that include antigorite, the P, T-dependence of the chemical composition of antigorite has to be considered. However, our results support the conclusion of Mellini et al. (1987) of the limited applicability of a modulation-dependent geothermobarometer, because equilibrium states of antigorite modulation are rarely observed in natural occurrences and have not been reached in our experiments.
The successive partial dehydration of antigorite during ongoing subduction of serpentine-bearing oceanic lithosphere probably influences its rheological properties.
Key-words: antigorite, polysomatism, high-pressure experiments, serpentine, TEM.
This article has been cited by other articles:
|
|
 |
|
  I. Ribeiro Da Costa, F. J.A.S. Barriga, C. Viti, M. Mellini, and F. J. Wicks Antigorite in deformed serpentinites from the Mid-Atlantic Ridge European Journal of Mineralogy, August 1, 2008; 20(4): 563 - 572. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-L. AUZENDE, S. GUILLOT, B. DEVOUARD, and A. BARONNET Serpentinites in an Alpine convergent setting: Effects of metamorphic grade and deformation on microstructures European Journal of Mineralogy, February 1, 2006; 18(1): 21 - 33. [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]
|
|
|
|
 |
|
 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]
|
|
|
|
|
|
G. Capitani, G. Capitani, and M. Mellini The modulated crystal structure of antigorite: The m = 17 polysome American Mineralogist, January 1, 2004; 89(1): 147 - 158. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. H. Hattori and S. Guillot Volcanic fronts form as a consequence of serpentinite dehydration in the forearc mantle wedge Geology, June 1, 2003; 31(6): 525 - 528. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. D. Bromiley, G. D. Bromiley, and A. R. Pawley The stability of antigorite in the systems MgO-SiO2-H2O (MSH) and MgO-Al2O3-SiO2-H2O (MASH): The effects of Al3+ substitution on high-pressure stability American Mineralogist, January 1, 2003; 88(1): 99 - 108. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-L. AUZENDE, B. DEVOUARD, S. GUILLOT, I. DANIEL, A. BARONNET, and J.-M. LARDEAUX Serpentinites from Central Cuba: petrology and HRTEM study European Journal of Mineralogy, October 1, 2002; 14(5): 905 - 914. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | FEEDBACK/COMMNET | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
