Single-crystal elastic properties of Ca0.07Mg1.93Si2O6 orthopyroxene

Abstract The single-crystal elastic properties of Ca0.07Mg1.93Si2O6 orthopyroxene (space group Pbca) have been investigated by Brillouin spectroscopy at ambient conditions. The aggregate bulk and shear moduli, K0,S = 102.5 GPa (1.5) and μ = 74.2 GPa (1.1), respectively, are ~5% and ~3% lower than commonly accepted values for MgSiO3 end-member (K0,S = 107.6, μ = 76.8 GPa). These results indicate that the incorporation of small amount of Ca in the orthoenstatite structure does not greatly affect its elastic properties. As a consequence, the increase in bulk modulus reported in natural orthopyroxenes relative to the Mg-end-member is not related to the substitution of Ca in the M2 octahedral sites, but more probably to the substitution of Al in tetrahedral sites.

[1]  G. Gatta,et al.  The effect of Ca substitution on the elastic and structural behavior of orthoenstatite , 2006 .

[2]  Takeyuki Uchida,et al.  In situ measurements of sound velocities and densities across the orthopyroxene → high-pressure clinopyroxene transition in MgSiO3 at high pressure , 2004 .

[3]  S. Sinogeikin,et al.  Elasticity of single crystal and polycrystalline MgSiO3 perovskite by Brillouin spectroscopy , 2004 .

[4]  F. Nestola,et al.  High pressure behavior, transformation and crystal structure of synthetic iron-free pigeonite , 2004 .

[5]  M. Zema,et al.  Ca in orthopyroxene: structural variations and kinetics of the disordering process , 2003 .

[6]  F. Nestola,et al.  The structure of Pbca orthopyroxenes along the join diopside-enstatite (CaMgSi2O6-Mg2Si2O6) , 2003 .

[7]  I. Ohno,et al.  Elastic constants of chrome-diopside: application of resonant ultrasound spectroscopy to monoclinic single-crystals , 2002 .

[8]  R. Angel,et al.  Elasticity and equation of state of orthoenstatite, MgSiO3 , 2002 .

[9]  S. Sinogeikin,et al.  LETTERS. Elasticity of MgSiO3 orthoenstatite , 1999 .

[10]  R. Liebermann,et al.  Sound velocities of polycrystalline MgSiO3-orthopyroxene to 10 GPa at room temperature , 1998 .

[11]  Jennifer M. Brown,et al.  The elastic constants of an aluminous orthopyroxene to , 1997 .

[12]  R. Angel,et al.  Effect of Ca2+ and Fe2+ on the equation of state of MgSiO3 orthopyroxene , 1997 .

[13]  G. Molin,et al.  A crystal-chemical model for Pbca orthopyroxene , 1995 .

[14]  R. Angel,et al.  Equations of state and thermodynamic properties of enstatite pyroxenes , 1994 .

[15]  I. Jackson,et al.  The pressure dependence of the elastic moduli of single-crystal orthopyroxene (Mg0.8Fe0.2)SiO3 , 1993 .

[16]  M. Kanzaki.  Ortho/clinoenstatite transition , 1991 .

[17]  T. Gasparik,et al.  Reversals of the orthoenstatite‐clinoenstatite transition at high pressures and high temperatures , 1990 .

[18]  D. L. Anderson,et al.  Seismic velocities in mantle minerals and the mineralogy of the upper mantle , 1989 .

[19]  T. Duffy,et al.  Elasticity of enstatite and its relationship to crystal structure , 1986 .

[20]  Jay D. Bass,et al.  Elasticity of single‐crystal orthoferrosilite , 1984 .

[21]  James J. Simpson,et al.  A simple model of the 1982‐83 Californian "El Nino" , 1984 .

[22]  J. Papike,et al.  Structural and chemical variations in pyroxenes , 1981 .

[23]  D. Weidner,et al.  Elasticity of diopside , 1979 .

[24]  Herbert R. Carleton,et al.  Elasticity of coesite , 1977 .

[25]  Charles H. Whitfield,et al.  Elastic moduli of NaCl by Brillouin scattering at high pressure in a diamond anvil cell , 1976 .

[26]  T. Devenyi.  Quantitative evaluation of thin-layer chromatograms by video-densitometry. I. Determiniation of lysine in plant materials. , 1976, Acta biochimica et biophysica; Academiae Scientiarum Hungaricae.

[27]  A. L. Frisillo,et al.  Measurement of single‐crystal elastic constants of bronzite as a function of pressure and temperature , 1972 .

[28]  R. Hill.  Elastic properties of reinforced solids: some theoretical principles , 1963 .