We report the results of an experimental calibration of oxygen isotope fractionation between quartz and zircon. Data were collected from 700 to 1000 C, 10–20 kbar, and in some experiments the oxygen fugacity was buffered at the fayalite–magnetite–quartz equilibrium. Oxygen isotope fractionation shows no clear dependence on oxygen fugacity or pressure. Unexpectedly, some high-temperature data (9...

Wherry discussed the origin of this material and on the basis of mineralogical and structural evidence suggested its derivation from aan original sedimentary type. He concluded that the presence of sillimanite indicated a noteworthy alumina content of the original sediment and thought that very likely the material w’as originally an argillaceous sandstone. The present writer” has discussed the ...

The thermal diffusivity of Teflon, sodium chloride, quartz, and silica glass was measured at 40øC to pressures of 35, 18, 30, and 36 kbar, respectively. A transient line source method was modified for use in a piston-cylinder high-pressure c ll. Pressure gradients were determined by experiments with bismuth foils. The pressure dependence of the thermal diffusivity at 40øC for the substances stu...

In water-bearing porous rocks, pore pressure variations play a major role in deformation, through dissolution?precipitation and fracturing processes. An often-overlooked variation where falls to negative or tension can operate whenever aquifer formations dry out, for instance, deep storage (nuclear industrial wastes, long-term CO 2 mitigation, short-term energetic resources, etc.). This generat...

An interconnecting technique, the "PDMS connection method", for quartz microchips in a high-pressure system is presented. The connection between quartz microchips is an essential technology for modular microfluidic devices, such as microchip-HPLC. PDMS was applied to the seal material, being spread on the seal side of the chips, and set into the metal housing. The characteristics of the PDMS co...

As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably α-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of α-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the tra...

Post-entrapment modifications reduce the reliability of fluid inclusions to determine trapping conditions in rock. Processes that may modify fluid inclusion properties are experimentally identified in this study using synthetic fluid inclusions in quartz with a well-defined composition and density. Modifications are characterized with microthermometry (homogenization and dissolution temperature...

Theoretical calculations are performed to study transformations in silica as a function of nonhydrostatic stress. Molecular-dynamics calculations reveal a crystalline-to-crystalline transition from a-quartz to a phase with five-coordinated silicon (Si) at high pressure in the presence of deviatoric stress. The phase, which appears for specific orientations of the stress tensor relative to the c...