| Abstract: | Consistent arrangement of en-echelon gashes occurring within kink zones was observed and measured at several localities in the Lubec—Belleisle structural zone of southwestern New Brunswick.The special geometric relationship of both kinks and en-echelon fracture systems allow an interpretation of the regional and local stress orientations necessary to produce such combined features.Mohr-circle stress analysis of a modified direct shear model is used to postulate a mechanism whereby varying orientations of en-echelon tension gashes and boundary shears within kink zones can be explained. Using this analysis, the observed gash orientations can be generated by reduction in the local normal stress acting on original kink-zone boundaries, coupled with a corresponding increase in the normal stress acting transverse to such boundaries. These stress adjustments could be due to deflection of regional stress trajectories around local zones of yielding (by kinking) rock. |
