Sound velocities and elasticity of cordierite and implications for deep crustal seismic anisotropy

Abstract The elastic properties of cordierite, a common volatile-bearing metamorphic mineral, were measured using Brillouin spectroscopy under ambient conditions. We obtain a bulk modulus of KS =129(1) GPa, and a shear modulus of G=54.0(4) GPa. The bulk modulus of cordierite is much larger than thos...

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Bibliographic Details
Published in:Physics and chemistry of minerals 1999-04, Vol.26 (4), p.333-343
Main Authors: Toohill, K., Siegesmund, S., Bass, J. D.
Format: Article
Language:English
Subjects:
Anisotropy
Bulk modulus
Cordierite
Crystal structure
Diagnostic systems
Elastic anisotropy
Elastic properties
Elasticity
Feldspars
G ratio
Metamorphic rocks
Minerals
Olivine
Poisson's ratio
Preferred orientation
Seismic properties
Shear modulus
Silicates
Upper mantle
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Summary:Abstract The elastic properties of cordierite, a common volatile-bearing metamorphic mineral, were measured using Brillouin spectroscopy under ambient conditions. We obtain a bulk modulus of KS =129(1) GPa, and a shear modulus of G=54.0(4) GPa. The bulk modulus of cordierite is much larger than those of other crustal framework silicates (e.g., quartz and feldspars), but is similar to KS for denser upper mantle phases such as olivine. This is likely a result of the cordierite crystal structure, as suggested by a similarly high value of KS for minerals with closely related structures. Cordierite has an unusually high K/G ratio of about 2.4, and a Poisson’s ratio of 0.31,which may be a diagnostic seismic properties of areas in which cordierite-rich metamorphic rocks occur. The overall velocity anisotropy of cordierite is relatively low (
ISSN:0342-1791
1432-2021
DOI:10.1007/s002690050193