An example of coeval development of ductile shear zones and folds in schistose terrains is documented by detailed mapping and structural analysis. Folds and shear zones were formed under retrogressive conditions after the peak of the regional Hercynian metamorphism, and both affect a previous regional schistosity. A gradual change in structural style, on a regional scale, is evidenced by the disappearance in higher grade domains of late folds and the preponderance of shear zones. Geometrical analysis reveals that the bulk structural pattern is compatible with a non-coaxial strain history. Structural variation reflects a gradual change in mechanical behaviour of schists, which show a marked variation in crystallinity, at the time of deformation. © 1987.
|Published - 1 Apr 1987