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Anisotropic yielding of rocks at high temperatures and pressures; Annual Progress Report, 1988-1989

Technical Report ·
DOI:https://doi.org/10.2172/5269644· OSTI ID:5269644
The experimental results we have obtained on Four-Mile gneiss have demonstrated that the yield behavior of quartzo-feldspathic rocks containing only a small percentage (10%) of mica can be markedly anisotropic, provided the mica minerals exhibit a strong crystallographic preferred orientation. Samples of gneiss oriented such that resolved shear stresses on the foliation plane are large are considerably weaker than granites of similar grain size and composition, and this weakness is attributed to enhanced nucleation of microcracks in quartz and feldspar adjacent to mica grains that are suitably oriented for slip. We expect the yield behavior of rocks containing a higher proportion of phyllosilicates to be influenced by the strongly anisotropic nature of these minerals as well, although the strengths, temperature and pressure dependencies, and flow-controlling mechanisms in such rocks may be significantly different.
Research Organization:
Texas A and M Univ., College Station, TX (USA)
Sponsoring Organization:
DOE/ER
DOE Contract Number:
FG05-87ER13711
OSTI ID:
5269644
Report Number(s):
DOE/ER/13711-3; ON: DE90004633
Country of Publication:
United States
Language:
English