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Elasticity of serpentines and extensive serpentinization in subduction zones
Author(s) -
Reynard Bruno,
Hilairet Nadège,
Balan Etienne,
Lazzeri Michele
Publication year - 2007
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 - 10.1029/2007gl030176
Subject(s) - chrysotile , geology , subduction , mantle (geology) , bulk modulus , compressibility , shear modulus , elasticity (physics) , mineralogy , mantle wedge , equation of state , seismology , thermodynamics , geophysics , materials science , composite material , tectonics , physics , asbestos
Elastic constants of lizardite [Mg 3 Si 2 O 5 (OH) 4 ] were computed using first‐principles quantum mechanical calculations within the density functional theory. The predicted c ‐axis compressibility is much larger than measured. Modeling of the weak O‐H⋯O interactions between layers must be improved in order to better predict layered hydrated mineral elastic properties. The large computed bulk modulus range is consistent with equation of state and seismic velocities in chrysotile‐lizardite serpentinites, but shear wave velocities are lower than the lowest theoretical estimate. The low seismic velocities measured for chrysotile serpentinites can be attributed to specific contribution of the nanotube‐textured chrysotile. For antigorite, the data from acoustic and EoS measurements are consistent. If used for interpreting seismic velocities, the inferred degrees of serpentinization of the mantle wedge are higher than with the commonly used calibrations using chrysotile‐serpentinite properties. Serpentine is likely a dominant phase in low velocity areas of the mantle wedge at 30–50 km depths.