Equation of State for Natural Almandine, Spessartine, Pyrope Garnet: Implications for Quartz-In-Garnet Elastic Geobarometry

The equation of state (EoS) a natural almandine74spessartine13pyrope10grossular3 garnet typical composition found in metamorphic rocks Earth’s crust was obtained using single crystal synchrotron X-ray diffraction under isothermal room temperature compression. A third-order Birch-Murnaghan EoS fitted to P-V data and the results are compared with published for iron, manganese, magnesium, calcium compositional end-members. This comparison reveals that ideal solid solution mixing can reproduce this intermediate garnet. Additionally, new used calculate geobarometry on sample from same rock, which collected Albion Mountains southern Idaho. Quartz-in-garnet elastic pressures quartz inclusion entrapment alternative methods both hydrostatic Grüneisen tensor approaches. QuiG barometry overlap within uncertainty when calculated pure end-member almandine, weighted averages EoS, presented study. tensors produce apparent higher relative method, but large uncertainties.