Journal of Petrology Advance Access published online on December 3, 2004
Journal of Petrology, doi:10.1093/petrology/egh088
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 UNIVERSITÀ DEGLI STUDI DI MILANO, DIPARTIMENTO DI SCIENZE DELLA TERRA, VIA BOTTICELLI 23, 20133, MILANO, ITALY
* To whom correspondence should be addressed. Fluid-saturated subsolidus experiments from 2·0 to 6·5 GPa, and from 680 to 800°C have been performed on three model peridotites in the system Na2O-CaO-FeO-MgO-Al2O3-SiO2-H2O (NCFMASH). Amphibole and chlorite coexist up to 2·4 GPa, 700°C. Chlorite persists to 4·2 GPa at 680°C. Starting from 4·8 GPa, 680°C a 10 Å phase structure replaces chlorite in all compositions. The 10 Å phase structure contains significant Al2O3 (up to 10·53 wt %) deviating from the MgO-SiO2-H2O 10 Å phase (MSH 10 Å phase). A mixed layered structure (chlorite-MSH 10 Å phase) is proposed to account for aluminium observed. In the Tinaquillo lherzolite amphibole breakdown occurs via the reaction amphibole + olivine ± H2O = clinopyroxene + orthopyroxene + chlorite. Thermal stability of chlorite (chlorite + orthopyroxene = forsterite + garnet + H2O) is shifted towards lower temperatures, compared with the system MASH. Furthermore, the chlorite thermal breakdown is also related to the degenerate reaction chlorite + clinopyroxene = olivine + garnet(± orthopyroxene) + H2O. Chlorite and the Al-10 Å phase structure contribute significantly to the water budget in subduction zones in the depth range relevant for arc magmatism, whereas amphibole-related fluid release is restricted to the forearc region. Chlorite and Al-10 Å phase breakdowns might explain the occurrence of a double seismic zone by dehydration embrittlement.
Received February 29, 2004
Accepted October 6, 2004
Article
Experimentally Determined Phase Relations in Hydrous Peridotites to 6·5 GPa and their Consequences on the Dynamics of Subduction Zones
P. FUMAGALLI, E-mail: Patrizia.Fumagalli{at}unimi.it
Abstract 
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  K. Naemura, T. Hirajima, and M. Svojtka The Pressure-Temperature Path and the Origin of Phlogopite in Spinel-Garnet Peridotites from the Blansky Les Massif of the Moldanubian Zone, Czech Republic J. Petrology, October 1, 2009; 50(10): 1795 - 1827. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. F. Zanazzi, P. Comodi, S. Nazzareni, and G. B. Andreozzi Thermal behaviour of chlorite: an in situ single-crystal and powder diffraction study European Journal of Mineralogy, June 1, 2009; 21(3): 581 - 589. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hermann and C. J. Spandler Sediment Melts at Sub-arc Depths: an Experimental Study J. Petrology, April 1, 2008; 49(4): 717 - 740. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Comodi, F. Cera, S. Nazzareni, and L. Dubrovinsky Raman spectroscopy of the 10-A phase at simultaneously HP-HT European Journal of Mineralogy, October 1, 2007; 19(5): 623 - 629. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Kaeser, A. Kalt, and T. Pettke Crystallization and Breakdown of Metasomatic Phases in Graphite-bearing Peridotite Xenoliths from Marsabit (Kenya) J. Petrology, September 1, 2007; 48(9): 1725 - 1760. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. L. Phillips, H. E. Mason, and S. Guggenheim Hydrogen bonded silanols in the 10 A phase: Evidence from NMR spectroscopy American Mineralogist, August 1, 2007; 92(8-9): 1474 - 1485. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. P. Dobson, A. A. De Ronde, M. D. Welch, and P. G. Meredith The acoustic emissions signature of a pressure-induced polytypic transformation in chlorite American Mineralogist, February 1, 2007; 92(2-3): 437 - 440. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. D. Litasov and E. Ohtani Effect of water on the phase relations in Earth's mantle and deep water cycle Geological Society of America Special Papers, January 1, 2007; 421(0): 115 - 156. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P.F. Zanazzi, M. Montagnoli, S. Nazzareni, and P. Comodi Structural effects of pressure on triclinic chlorite: A single-crystal study American Mineralogist, November 1, 2006; 91(11-12): 1871 - 1878. [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]
|
|
|
|
 |
|
 J. R. Smyth Hydrogen in High Pressure Silicate and Oxide Mineral Structures Reviews in Mineralogy and Geochemistry, January 1, 2006; 62(1): 85 - 115. [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]
|
|
|
|
|
|
P. Comodi, P. Fumagalli, S. Nazzareni, and P.F. Zanazzi The 10 A phase: Crystal structure from single-crystal X-ray data American Mineralogist, May 1, 2005; 90(5-6): 1012 - 1016. [Abstract] [Full Text] [PDF]
|
|