Deformation record and revised tectonic evolution of the Nízke Tatry Mts. in the Tatric – Veporic junction area: Insights from structural analysis

Abstract

: The Nízke Tatry Mts. is a mountain range located in the central part of the Western Carpathians. Throughout history, the studied area has been affected by at least two orogenetic cycles – Variscan and Alpine. Based on structural analyses, it is possible to determine several deformation events. The older deformations ( D V ), which were accompanied by the Variscan higher-grade metamorphism, are characterised by penetrative tectonic foliations, such as schistosity and gneissic banding, and go hand in hand with folds and lineations. In contrast, the younger deformations ( D A ) are marked by structural evolution under low-grade (retrograde) metamorphism, phyllitic foliations, crenulation foliation, cataclasis, and minor recrystallisation. The Variscan deformation ( D 2 V ) is the earliest pervasive deformation with pronounced evolution of S 2 V metamorphic foliation, locally with preserved isoclinal and rootless folds of S 1 V planar fabric. Stretching and mineral lineations ( L 2 V ) are usually oriented in the ENE–WSW direction. The fabric of D 2 V is intensively affected by folds ( F 3 V ) and, in many places, marked by development of S 3 V axial planes. The Alpine deformation ( D 1 A ) was accompanied by low-grade metamorphism and depicted by space to zonal with pervasive foliation ( S 1 A ) in some areas. This deformation is characterised by a typical crenulation cleavage, where S 2 V planes are folded and produced S 1 A foliation. The crenulation and intersection lineations ( L 1 cA ) have NE–SW to E–W trends. The D 1 A deformation is also accompanied by pronounced evolution of NNW–SSE groove, stretching, and mineral lineation ( L 1 tA ). Shortening in the NNW–SSE direction is also evidenced by asymmetric folds with an ENE–WSW orientation of fold axes ( F 1 A ) and line intersections ( L 1 cA ) with pronounced top-to-the-NNW tectonic transport. The youngest observed Alpine deformation ( D 2 A ) is related to an extension of the Tatric crystalline basement with top-to-the-east transport defined by Alpine lineations ( L 2 A ) on spaced planar structures ( S 2 A ) and correspond to C surfaces.