Quartz-in-garnet (QuiG) under pressure: insights from in situ Raman spectroscopy

Abstract Elastic geothermobarometry relies on the contrast between thermal expansion and compressibility of a mineral inclusion its surrounding host, leading to residual pressure in ( P inc ) that may differ significantly from external pressure. Quartz-in-garnet (QuiG) inclusion-host systems are widely used elastic estimate entrapment conditions thus rock petrogenesis. To elucidate behaviour QuiG at elevated pressures, we have applied situ high-pressure Raman spectroscopy three samples having close 0 GPa room temperature. We demonstrate upon increase, garnet host acts as shield softer quartz inclusion. Consequently, increases with smaller rate compared Up 2.5 GPa, evolution calculated data agrees very well prediction equations state. Furthermore, relatively thin specimen was explored up pressures 7 GPa. Our results indicate shielding effect (even if only partial because insufficient distance surface) can keep inclusions thermodynamically stable about 2 above equilibrium quartz–coesite phase boundary. In addition, leads development anisotropic symmetry-breaking stresses undergo reversible crossover lower symmetry Given presence non-hydrostatic stress influence quartz-to-coesite boundary, especially temperatures relevant for conditions, our emphasize importance anisotropy systems, when occurs under coesite stability field.