After their experimental data were re-explained in terms of the maximum-effective-moment （MEM） criterion, Gomez-Rivas and Griera （2015） challenge the validity of the MEM-Criterion in terms of shear fractures, whic...After their experimental data were re-explained in terms of the maximum-effective-moment （MEM） criterion, Gomez-Rivas and Griera （2015） challenge the validity of the MEM-Criterion in terms of shear fractures, which have mixed up with shear fractures and shear bands. The two features are similar in appearance but different in deformation mechanism （s）. The MEM-criterion proves that ±55° to σ1era are the maximum effective moment directions and the shear bands that formed by mate- rial-line （beddings or fabrics） rotation mechanism have a constant conjugate angle of 110°. Theoretically, the 55° or 110° is a material-invariant, and practically, a statistic-invariant or preferred direction with average deviation of -10°. By this angle, shear bands can be easily recognized from shear fractures with conjugate angle never over 90°. The High-strain deformation in the lozenges usually predates the surrounding shear bands. Two stress states can not coexisted simultaneously in the same place and the resolving cr1＇ normal to the related shear zone represents 0-100% deformation partitioning, depending on the original kinematic vorticity of the shear zones.展开更多
基金supported financially by the Project from Geological Survey of China(Grant No.12120115027101)
文摘After their experimental data were re-explained in terms of the maximum-effective-moment （MEM） criterion, Gomez-Rivas and Griera （2015） challenge the validity of the MEM-Criterion in terms of shear fractures, which have mixed up with shear fractures and shear bands. The two features are similar in appearance but different in deformation mechanism （s）. The MEM-criterion proves that ±55° to σ1era are the maximum effective moment directions and the shear bands that formed by mate- rial-line （beddings or fabrics） rotation mechanism have a constant conjugate angle of 110°. Theoretically, the 55° or 110° is a material-invariant, and practically, a statistic-invariant or preferred direction with average deviation of -10°. By this angle, shear bands can be easily recognized from shear fractures with conjugate angle never over 90°. The High-strain deformation in the lozenges usually predates the surrounding shear bands. Two stress states can not coexisted simultaneously in the same place and the resolving cr1＇ normal to the related shear zone represents 0-100% deformation partitioning, depending on the original kinematic vorticity of the shear zones.
