Vojtko R. & Kriváňová K., 2024: Cretaceous collision and thrusting of the Veporic Unit onto Tatric Unit in the Nízke Tatry Mts. revealed from structural analysis. Acta Geologica Slovaca, 16, 1, 19–31.

Cretaceous collision and thrusting of the Veporic Unit onto Tatric Unit in the Nízke Tatry Mts. revealed from structural analysis

Rastislav Vojtko & Katarína Kriváňová

Department of Geology and Paleontology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia; rastislav.vojtko@uniba.sk, katarina.krivanova@uniba.sk

Abstract

The Nízke Tatry Mts. is a significant mountain range in the middle part of the Central Western Carpathians which is divided into two important sub-units, the eastern part is composed of the Veporic crystalline basement (Kráľovohoľské Tatry), which is thrust onto the Tatric crystalline basement (Ďumbierske Tatry) located in the western part during the Eo-Alpine (Cretaceous) tectogenesis. Both basements are characterised by well-developed Variscan pervasive planar structural elements, which originate from the syn-metamorphic crystallisation of rock-forming minerals and their parallel alignment. This Variscan foliation is an important marker for understanding the Alpine deformation, which was accompanied by low-grade metamorphism, mylonitisation, and cataclasis, especially in the microscale, originating during the simple shear deformation mechanism with the evolution of spaced, crenulation and mylonitic foliations. On a map scale, the Alpine structure is indicated by individual thrust shear zones, that are composed of mylonites with ENE – WSW strike and predominantly intermediate SE dip. The internal structures of these shear zones have pronounced asymmetry characterised by asymmetrically deformed objects, such as quartz lenses and asymmetry of macro-folds, porphyroblasts, shear bands stretching, and mineral lineations referring to top-to-the-NNW transport (average azimuth of 343 degrees). The geometric relationships of the planar structures and lineations define the top-to-the-NNW tectonic transport of the Veporic Unit onto the Tatric Unit along the Čertovica thrust during the Eo-Alpine tectogenesis.

Key words: Western Carpathians, Variscan structure, Alpine structure, fabric, folds, thrust, kinematics

Manuscript received: 2024-05-09

Revised version accepted: 2024-06-14