Paleostress analysis in the Jakubčovice quarry (the Nízký Jeseník Upland) - an example of results affected by folding


Authors: Havíř J

Published in: Bulletin of Geosciences, volume 76, issue 3; pages: 169 - 177;

Keywords: Brittle deformation, Stress analyses, Culm, Nízký Jeseník region, Variscan compression,

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The orientations of fault planes with striations were studied in the Culm rocks in the quarry near Jakubčovice and used for the computation of orientations of the principal paleostress axes. For the seven groups of data, seven different results of the paleostress analyses were found. Three results represent the paleostress fields with nearly horizontal orientations of the σ1 axis as well as σ3 axis. Other results show either the WNWESE compression or a seeming WNW-ESE extension. Computed orientations of the seemingly extensional paleostress fields were strongly affected by rotation during the Variscan folding. The back-rotated orientations of the principal paleostress axes show the actual WNW-ESE compression passing off during the movement along the fault planes. This result of the analysis represents a very good example of a close relation between folding and the activity of reverse faults, which also partially balanced the shortening of space. If the possible subsequent rotation during folding is not taken into account, the interpretation of the result of paleostress analysis can be strongly deceitful.