NEOGENNÍ ZPĚTNÁ ROTACE VRÁSOVO-NÁSUNOVÉ STAVBY VE SPODNÍM KARBONU KRY MALENÍKU

Abstract

In the frame of the geological mapping projects, geometry of the Variscan fold-thrust system of the Lower Carboniferous units on the SE margin of the Nízký Jeseník Highland and in the Maleník block was studied. This system consists of asymmetric kilometric folds and NW to WNW dipping thrusts. It is evident, that the fold geometry observed at sites on the SE margin of the Nízký Jeseník is almostthe same as the fold geometry studied in the quarries in the Maleník block. The only difference consist in north-westwards tilting of the fold geometry in the studied area with respect to situation on the NE margin of the Nízký Jeseník. This tilting corresponds to the up to 40° rotation around the sub-horizontal axis, which is sub-parallel to fold axes of the tectonic large (km) folds. It indicates that there is mutual relationship between the discussed rotation and the reactivation of the Variscan fold-thrust system. The main features of structural model are introduced in the article to explain the discussed rotation. The model supposes compressional back-rotation of the block connected with reactivation of Variscan thrusts. The block was steepened as a result of the shear movements associated with overthrust above the Lower Carboniferous units approximately from SE to NW. Known evidences of the Neogene reactivation of the Variscan thrusts allow assumption, that this overthrusting body was a frontal part of the Western Carpathian Nappe system.