Effect of Hydration on the Single-crystal Elasticity of Fe-bearing Wadsleyite to 12 GPa
The single-crystal elastic properties of Fe-bearing wadsleyite with 1.93 wt% H{sub 2}O (Mg{sub 1.634}Fe{sub 0.202}H{sub 0.305}SiO{sub 4}) have been determined by Brillouin scattering. At ambient conditions, the aggregate bulk and shear moduli (K{sub S0}, G{sub 0}) of this wadsleyite are 156.2(5) and 98.0(3) GPa, respectively. Compared to the corresponding anhydrous wadsleyite, 1.93 wt% H{sub 2}O lowers K{sub S0} and G{sub 0} by 8.1% and 9.3%, respectively. High-pressure measurements up to 12 GPa show that the pressure derivative of the bulk modulus, K'{sub S0} = 4.8(1), is similar to that of the anhydrous Fe-wadsleyite with reported values of 4.6-4.74, but the addition of H{sub 2}O increases the pressure derivative of the shear modulus, G{sub 0}' from 1.5(1) to 1.9(1). This contrasts with the G{sub 0}' of Fe-free wadsleyite, which is the same within uncertainty for the hydrous and anhydrous phases. As a result, both the compressional- and shear-wave velocities (v{sub P}, v{sub S}) of hydrous Fe-bearing wadsleyite are about 200({+-}24) m/s slower than anhydrous Fe-bearing wadsleyite at transition zone pressures.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1041771
- Report Number(s):
- BNL-97449-2012-JA; AMMIAY; TRN: US201212%%183
- Journal Information:
- American Mineralogist, Vol. 96, Issue 10; ISSN 0003-004X
- Country of Publication:
- United States
- Language:
- English
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