Triaxial stress and failure modes in hydrothermal mineral systems

Rock mechanics experiments show that the magnitude of intermediate principal stress significantly affects rock failure. Since triaxial states (no is zero) are ubiquitous in crust, and polyaxial axial (all three stresses different) general, should have an important effect on hydrothermal mineralisation. For example, extensional veins or dykes vein-hosted gold porphyry deposits may multiple orientations when least similar magnitudes, single maximum similar. The Griffith-Murrell fracture criterion with a tensile cutoff can be used to illustrate effects At lowest values mean stress, suggests only failure occur. low–intermediate either shear occur: favoured magnitudes. higher stresses, will occur at lower pore fluid pressure differential magnitudes minimum