Strain Localization at Constant Strain Rate and Changing Stress Conditions: Implications for Plate Boundary Processes in the Upper Mantle

We present results from a natural deformed shear zone in the Turon de Técouère massif of French Pyrenees that directly addresses processes involved strain localization, topic has been investigated for last 40 years by structural geologists. Paleopiezometry indicates differential stresses are variable both spatially across zone, and temporally during exhumation. have, however, also calculated rate, which remains constant despite changes stress. This result appears to be at odds with recent experimental deformation on monophase (olivine) rocks, indicate localization occurs dominantly as hypothesize massif—and many zones—strain reactions, decrease grain size promote activation sensitive mechanisms. From tectonics perspective, this study rate particular plate boundary is relatively uniform. Stress, varies accommodate deformation. viewpoint consistent boundary, but it not typical way we interpret localization.