Single-crystal elastic properties of lawsonite and theirvariation with temperature

Frank R. Schilling, Stanislav V. Sinogeikin, Jay D. Bass

Research output: Contribution to journalArticlepeer-review


We have measured the elastic wave velocities and single-crystal elastic moduli of lawsonite (CaAl2(Si2 O7)(OH)2·H2O) by Brillouin spectroscopy at high temperatures to 450 °C and at room pressure. Lawsonite is generally characterized by high longitudinal (vP) and shear (vS) elastic wave velocities. A number of the elastic properties increase with increasing temperature, including the shear modulus, G (∂G /∂T=+2.01 GPa/100 K), and the aggregate velocities vP and vS. These anomalous properties are likely related to a displacive phase transition at ∼0 °C. This is supported by the small value of the elastic modulus c 66 (18(1) GPa at room temperature), and the fact that c 66 softens as temperature is decreased approaching the ∼0 °C phase transition. The anomalous behavior in c 66 leads to a decrease in vP/vS and Poisson's ratio with increasing temperature at 1 atm pressure. Our results show that the aggregate bulk modulus (KS=125(2) GPa at 21 °C) decreases monotonically with increasing temperature ( ∂K S / ∂ T =-1.8 GPa/100 K), in contrast to the results of Daneil et al. (1999) who observed a minimum in the bulk modulus at ∼230 °C. In general, the aggregate elastic wave velocities of lawsonite under high P - T conditions of a subducted slab are expected to remain comparable to those of anhydrous mafic silicates. This observation reinforces the notion that other hydrous minerals persist in subducted oceanic crust to considerable depth (∼250 km), in order to explain the low velocity layers observed in some subduction zones (e.g. Helffrich, 1996; Abers, 2000).

Original languageEnglish (US)
Pages (from-to)107-118
Number of pages12
JournalPhysics of the Earth and Planetary Interiors
Issue number1-2
StatePublished - Apr 15 2003


  • Elastic properties
  • High temperature
  • Hydrous minerals
  • Lawsonite

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science


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