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Equation of state of antigorite, stability field of serpentines, and seismicity in subduction zones
Author(s) -
Hilairet Nadège,
Daniel Isabelle,
Reynard Bruno
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024728
Subject(s) - equation of state , diamond anvil cell , geology , compression (physics) , phase (matter) , compressibility , thermodynamics , anisotropy , phase transition , mineralogy , high pressure , chemistry , physics , quantum mechanics , organic chemistry
Antigorite, the high‐pressure variety of serpentine, is a major water carrier in subduction zones. Its equation of state, which controls its stability field at high pressure, was determined at ambient temperature up to 10 GPa by in situ synchrotron X‐Ray diffraction in a diamond‐anvil cell. No amorphization, phase transition or hysteresis were detected during compression or decompression. Compression is anisotropic, with the c axis twice as compressible as the others. A fit to the second order Birch‐Murnaghan equation of state gave V 0 = 2926.23(50) Å 3 and K 0 = 67.27(123) GPa. In antigorite the atomic assemblage is denser than in lizardite, which may influence phase stability. The antigorite K 0 value obtained here is significantly higher than currently assumed in thermodynamic databases. Antigorite P‐T stability field is re‐evaluated, with major dehydration reaction (and associated potential earthquake) loci occurring at lower pressures, and is found to be consistent with the latest experimental results.