DIFFERENTIAL STRESS DETERMINED FROM DEFORMATION-INDUCED MICROSTRUCTURES OF THE MOINE THRUST ZONE.

The dislocation structure, recrystallization, and elongation of quartz grains in tectonites from three localities along the Monie thrust fault have been analyzed by transmission electron and optical microscopy. The dislocation density, 5 multiplied by 10**8cm** minus **2, and the grain size after recrystallization, 15 mu m, in the basal quartzite unit at the Stack of Glencoul are independent of distance from the fault, to the maximum sampling distance of similar 100 m. A quantitative estimate of the strain, based on the aspect ratios of the relict quartz grains, as a function of distance from the fault has been used to calculate strain rate and temperature profiles. The small size of the grains after recrystallization, highly serrated grain boundaries, and large densities of free dislocations suggest that very little static recovery followed the plastic deformation event.