Mechanical Properties of Granular Silicates at Depth.
Final rept. 1 Jul 75-30 Jun 76,
STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF EARTH AND SPACE SCIENCES
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Granular silicates comprise a substantial part of the Earths crust, and yet there have been few attempts at determining their physical properties and flow processes experimentally. The goal of the research was to attempt to obtain these data, for a variety of granular silicates, at elevated temperatures and pressures, both in the presence and absence of pore fluids. The primary equipment to be used was Griggs-Heard 10 kb argon triaxial deformation apparatus because of the sensitivity required. Recrystallized grain sizes in wet quartzite deformed experimentally in the steady state show a marked inverse dependence on stress and are virtually independent of temperature and strain rate. This dependence, which is similar to that observed for dynamically recrystallized metals and olivine, is given by D 6.5 Sigma to the minus 1.4th power where D is the new grain size in microns and sigma is the differential stress in kilobars. If these preliminary observations are substantiated, stress magnitudes during creep of quartzite in the crust may be determined directly for the first time.
- Geology, Geochemistry and Mineralogy