Triaxial stress and failure modes in hydrothermal mineral systems

Blenkinsop, T. G. ORCID: https://orcid.org/0000-0001-9684-0749 2023. Triaxial stress and failure modes in hydrothermal mineral systems. Australian Journal of Earth Sciences 70 (7) , pp. 947-957. 10.1080/08120099.2023.2210637

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Abstract

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

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	Taylor and Francis Group
ISSN:	0812-0099
Funders:	NERC
Date of First Compliant Deposit:	11 May 2023
Date of Acceptance:	29 April 2023
Last Modified:	09 Sep 2023 02:27
URI:	https://orca.cardiff.ac.uk/id/eprint/159421

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