THE PIENINY KLIPPEN BELT IN THE WESTERN CARPATHIANS OF NORTHEASTERN SLOVAKIA - STRUCTURAL EVIDENCE FOR TRANSPRESSION

The Pieniny Klippen Belt represents a 600-km-long but only a few kilom eters wide suture zone in the Carpathian orogenic belt. Based on a qua ntitative analysis along a part of its NW-trending segment in northeas tern Slovakia, we present structural data supporting transpression, th e continuous interaction of strike-slip shearing, horizontal shortenin g, and vertical lengthening, as a major deformation style in its polyp hase deformation history. Dextral transpression is expressed in the ma p scale and outcrop fault pattern, the oblique orientation of fold axe s to the faults bounding the Klippen Belt, and extension parallel to t he fold axes, The transpression-related strain field is described and quantified by the analysis of: (1) orientation of rotated fold axes (d isplaying an acute angle to the margins of the Klippen Belt); (2) orie ntation and geometry of paleostress derived from mesoscale fault-stria e analysis (E-trend of sigma3-trajectories and flattening geometry); a nd (3) the deformation history indicated by extension veins (non-coaxi al regime). Different techniques using fault-striae data quantify pale ostress and subdivide heterogeneous data sets mathematically into homo geneous subsets. The observed deformation history is modelled as a hom ogeneous transpression deformation. The best-fitting model requires a NW-trending (present-day orientation) external contraction direction ( e.g., plate-slip vector), and predicts 16% fold axes parallel extensio n and 23% axial plane normal shortening.