Abstract
At 11 outcrops within 100 km of Blue Mountain Lake, New York, we measured strain relaxation during overcoring of 'surface', 'doorstopper', and Bureau of Mines borehole deformation gauges. To confirm further the orientation of in situ stress, at two sites, vertical fractures were induced at borehole walls using a packer-fracturing technique. Several cores from each site were then tested for mechanical anisotropy using ultrasonic, compressibility, and thin section analyses. The orientations of mechanical anisotropy had a poor correlation with the preferred orientation of microcracks observed in thin section. The various techniques for measuring in situ stress orientations gave internally consistent results were epsilon1 generally aligned with topographic contours and often the mechanically stiff direction of the core. We interpret the alignment of epsilon1 and other structures to be the result of a feedback between the contemporary tectonic stress and the process of jointing during the development of local topography. Hence epsilon1 is controlled by local structures and is a reflection of the contemporary tectonic stress but not a direct measure of it. -from Authors
Original language | English (US) |
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Pages (from-to) | 9333-9349 |
Number of pages | 17 |
Journal | Journal of Geophysical Research |
Volume | 89 |
Issue number | B11 |
DOIs | |
State | Published - 1984 |
All Science Journal Classification (ASJC) codes
- Geophysics
- Forestry
- Oceanography
- Aquatic Science
- Ecology
- Water Science and Technology
- Soil Science
- Geochemistry and Petrology
- Earth-Surface Processes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
- Palaeontology