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Anistotropic yielding of rocks at high temperatures and pressures

Technical Report ·
DOI:https://doi.org/10.2172/6912914· OSTI ID:6912914
The anisotropic deformation of foliated and linealed rocks has been investigated, primarily to predict the mechanical response of rocks surrounding buried magma chambers to the stress fields generated by deep drilling. The principal application in this regard has been to evaluate, the scientific feasibility of extracting geothermal energy from buried magma chambers. Our approach has been to perform triaxial extension and compression tests at temperatures and pressures representative of the borehole environment on samples cored along six selected orientations and to fit the data to an orthohombric yield criterion. We have investigated Four-Mile gneiss (a strongly layered gneiss with well defined lineation), a biotite-rich schist, and Westerly granite (using a block oriented with respect to the granite's rift, grain, and hardway). Progress has been made in three areas: the experimental determination of strength anisotropies for the three starting materials, theoretical treatment and modeling of the results, and characterization of fabrics surrounding magma bodies resulting from their diaperic emplacement into shallow portions of the Earth's crust. In addition, results have been obtained for the tensile fracture of quartzite, basal slip and anisotropy of biotite single crystals, and anisotropic flow of bedded rocksalt.
Research Organization:
Texas A and M Univ., College Station, TX (United States). Center for Tectonophysics
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
FG05-87ER13711
OSTI ID:
6912914
Report Number(s):
DOE/ER/13711-T1; ON: DE93004363
Country of Publication:
United States
Language:
English