High Temperature Elasticity of Pyroxenes

Isaak 0073989了解地球上地幔的矿物学需要知道所有候选矿物的弹性特性。然而，斜方辉石，特别是单斜辉石在高温高压下的弹性数据库中存在着虚拟的空白。本工作的主要目的是测量的弹性模量的单晶单斜辉石的温度依赖性，使用共振超声光谱（罗斯）。这一目标需要完成以下中间目标：1）发展适合于单斜晶体对称性的罗斯理论和计算机程序; 2）在室温下比较计算光谱和测量光谱时进行模式识别; 3）获得不同Mg、Fe、Ca组成的三种单斜辉石的高温共振光谱;以及4）将在升高的温度下的单斜辉石共振数据减少到适当的Cij对T。这项工作的第二个目标是测量两个斜方辉石矿物的高温弹性使用斜方罗斯计划，是早期开发和应用于橄榄石弹性测量。这些目标的成功完成将为高温下辉石的研究提供必要的数据，为地球上地幔矿物学提供新的约束条件，并为罗斯在测量低对称性单斜晶体弹性方面提供新的应用。

Isaak 0073989 Understanding the mineralogy of Earth's upper mantle requires that the elastic properties of all candidate minerals are known. There are, however, virtual gaps in the elasticity database at elevated pressure and temperature for orthopyroxene and especially clinopyroxene. The primary objective of this work is to measure the temperature dependencies of the elastic moduli of single-crystal clinopyroxene using resonant ultrasound spectroscopy (RUS). This objective requires completing the following intermediate goals: 1) developing the RUS theory and computer code appropriate for monoclinic crystal symmetry; 2) making mode identification when comparing calculated and measured spectra at room temperature; 3) obtaining resonance spectra at high temperature for three clinopyroxenes of varying Mg, Fe, Ca compositions; and 4) reducing the clinopyroxene resonance data at elevated temperature to appropriate Cij vs. T. The secondary objective of this work is to measure the high temperature elasticity of two orthopyroxene minerals using the orthorhombic RUS scheme that was developed earlier and applied to olivine elasticity measurements. Successful completion of these objective will provide needed data on pyroxenes at high temperature, new constraints for the mineralogy of Earth's upper mantle, and new applications of RUS for measuring elasticity of low symmetry monoclinic crystals.