Cretaceous collision and indentation in the West Carpathians: View based on structural analysis and numerical modeling

Abstract

[1] A model of indentation of a rigid promontory into weak metasedimentary rocks during Cretaceous convergence is suggested for tectonic evolution of southern part of West Carpathians. An early arcuate cleavage fan has developed in front of northward moving southern rigid basement block. The interaction of the moving indenter with western stationary basement promontory is responsible for development of the boundary-parallel shear zone along which the main southern indenter is shifted to the east. This results in development of a new steep transpressional cleavage overprinting the early fabric. Eastward displacement of the southern indenter causes the development of a thrust zone parallel to the margin of the eastern stationary promontory. A proposed numerical model of the deformation of a thin viscous sheet in front of oval rigid indenter reliably simulates the development of the observed deformation pattern. Modeled discrete partitioning between the western promontory and the indenting block fully agrees with the observed secondary cleavage associated with the transpressional shear zone. Our numerical model interconnects this complex kinematic frame with finite strain pattern, which was to date possible only for simple boundary conditions. In addition, the model explains the polyphase cleavage patterns in terms of complex shapes of promontories and changes in movements of indenting blocks.

Geological evolution of the southwestern part of the Veporic Unit (Western Carpathians): based on fission track and morphotectonic data

“…The Alpine tectono-metamorphic phase is characterised by Cretaceous amphibolite facies conditions in the structural footwall, which gradually decrease to greenschist facies conditions towards the structural hanging wall Jeřábek et al 2008a). The Cretaceous metamorphism was associated with the development of a subhorizontal mylonitic fabric, which developed during E-W orogen-parallel stretching induced by the northward overthrusting of the Gemeric Unit (Lexa et al 2003;Jeřábek et al 2007Jeřábek et al , 2012Bukovská et al 2013). With the ongoing collision, this fabric was folded.…”

Deformation history and nappe stacking in Rudabánya Hills (Inner Western Carpathians) unravelled by structural geological, metamorphic petrological and geochronological studies of Jurassic sediments

“…former accretionary wedge, the Meliata Unit (Inner Western Carpathians) which underwent very low-grade to blueschist facies metamorphism during the subduction and exhumation processes [22][23][24]. However, the knowledge is incomplete on the metamorphic conditions of similar tectonic units found in Hungary, in the Rudabánya Hills.…”

“…ern continent -fragments of it now located in NE Hungary (Bükk) -with the northerly lying West Carpathian domain (European plate) was described by [22], too. In this model the southern continent behaved as a rigid indenter controlling the deformation of all northerly foreland crustal units, and was actively moving toward the north (in recent coordinate system).…”

“…In this model the southern continent behaved as a rigid indenter controlling the deformation of all northerly foreland crustal units, and was actively moving toward the north (in recent coordinate system). The rheological assumptions between the Variscan Vepor basement, composed of gneisses and granites and the low-grade slates of Gemer Unit led to the formation of complex, polyphase cleavage patterns [22].…”

“…Although blueschist facies metasedimentary and metavolcanic rocks are present in the (tectonosedimentary) subduction mélange, and dismembered ophiolite suite is known in an evaporitic mélange, the internal structure of this orogen, the number and contents of nappes, stacking order, direction of subduction, still remain under discussion [19][20][21][22]. In addition to poor outcrop conditions and the lack of paleontological data from some stratigraphic units, the debate is fuelled by the lack of metamorphic petrological, structural and geochronological data from different low-grade metasediments which represent considerable part of the area.…”