The nature of a deformation zone and fault rock related to a recent rockburst at Western Deep Levels Gold Mine, Witwatersrand Basin, South Africa

摘要: Abstract In August 1998, a major deformation zone was exposed over several metres during mining operations on 87 Level (2463 m below surface) at Western Deep Levels Gold Mine, southwest of Johannesburg, providing unique opportunity to study the products recent rockburst. This consists three shear zones, with dip-slip displacements up 15 cm, that are oriented near-parallel advancing stope face. Jogs and highly pulverised, cataclastic ‘rock-flour’ developed displacement surfaces, sets secondary extensional fractures occur either side zones. A set pinnate (feather) joints intersects fault surfaces perpendicular slip vector. Microscopically, zones consist two joint exhibit fillings; quartz grains display intense intragranular fracturing. Secondary, intergranular extension associated joints. Extensional is also cause breccia fill The initial experienced by this brittle tensile, related stresses induced mining. has been masked later changes in stress field, which resulted shearing. does not appear be controlled pre-existing geological features and, thus, represents ‘burst fracture’, believed seismic event magnitude ML=2.1 recorded July epicentre located within 50 m locality.