Karsdorf disorder

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The Karsdorfer disorder (also Karsdorfer rejection ) is a North-South-East trending , steeply Northeast incident tectonic fault on the eastern edge of the Ore Mountains . It is named after the place Karsdorf near Rabenau (Saxony) on the southeastern edge of the Döhlen basin , which was also called Wendischcarsdorf in the past , and is therefore also referred to in historical literature as the Wendischcarsdorfer fault or Wendischcarsdorfer fault .

The Karsdorfer fault has the character of a postponement , whereby the northeast wing has been raised. This offset, the jump height of which is only vaguely quantified in the geological literature as “over 100 m” to “at least 300 m”, is expressed in the landscape and the like. a. in the form of a striking ridge that crosses the northeastern roof of the Osterzgebirge between the valleys of the Rote Weißeritz and the Lockwitzbach and towers above it by about 80 to 120 m. In contrast, the course of the actual fault line, a few 100 m southwest of the ridge, is barely perceptible in the terrain.

Tectogenesis and delimitation

The Karsdorf Fault is sometimes represented in the literature as a section of the so-called Central Saxon Fault , where the southeastern part of the Elbe zone is pushed up or pushed over to the southwest against the Eastern Ore Mountains. Usually, however, the term “Central Saxon disturbance” summarizes those disturbances that a. separate the Eastern Ore Mountains Crystalline from the units of the Elbe Valley Slate Mountains and were already active in the late high phase of the Variscan Orogeny , presumably in the course of extensive right-handed shear movements . In contrast, the Karsdorf fault runs about two kilometers southwest of this line within the Eastern Ore Mountains Crystalline and its formation is dated at the earliest in the Upper Cretaceous . The Karsdorf fault is considered to be the result of a northeast-directed compression of the Saxon-Bohemian crust as a result of the long-range effects of the formation of the Alps .

Surface geology and geomorphology around the fault

View from the southeast over the Hirschbachgrund and the Hirschbachheide to the raised northeast wing of the Karsdorfer Fault (from left to right: Quohrener Kipse, Hermsdorfer Berg, Wilisch).
View from the northeast wing to the south over the Hirschbachheide to the Pultscholle of the Ore Mountains. The dark conifers mark the extent of the sandstone table; the Karsdorf fault runs roughly along its front edge.

The southwestern edge area of ​​the deferred northeastern wing of the Karsdorf Fault is characterized in the landscape by a northwest-southeast-trending ridge that is visible from afar and consists of the following mountains:

The northwestern part of this ridge is located in the Döhlen Basin , a geological structure whose southwestern edge runs about 250 to less than 100 meters northeast of the Karsdorf fault. The rocks of the Döhlen basin originate from the processing of the “Ur-Erzgebirge” in the early Permian and are assigned to the Rotliegend series . They were lifted out of the underground as a result of the shifting of the southeastern section of the Elbe zone towards the Eastern Ore Mountains. The conglomerates occurring on the southwestern edge of the Döhlen Basin are more resistant to erosion than the fine-grain Rotliegend rocks further inside the basin. The summit of the Quohrener Kipse consists entirely of such conglomerates. To the southeast, the ridge leaves the Döhlen basin and changes into an orthogneiss ("red gneiss"), which is also relatively resistant to erosion. The fact that the Wilisch is the highest mountain on the ridge at 476 m is likely to be related to the fact that a fossil volcanic vent made of particularly resistant basaltoid rock bites in its summit region . It goes back to a volcanic episode in the Tertiary and is therefore significantly younger than the gneisses and Rotliegend rocks. A narrow strip stretches between the Karsdorfer fault and the ridge, the subsurface of which consists of a two-mica paragneiss ("gray gneiss"). This paragneiss is clearly more prone to erosion than the Rotliegend conglomerates and the red gneiss, because the area immediately northeast of the Karsdorf fault is morphologically rather inconspicuous.

On the south-western wing of the Karsdorf Fault there are several island-like occurrences of Cretaceous sandstones , which are several dozen meters thick, surrounded by and subordinate to the Ore Mountain Crystalline . These are equivalents of the Elbe sandstone . The oldest layers of these deposits are among the oldest deposits of the Upper Cretaceous in the Dresden area ( Niederschöna Formation , Middle to Upper Cenomaniac ). They are separated from the actual Elbe Chalk by the Karsdorf Fault or the Döhlen Basin. The Elbe sandstones that once also existed on the northwest wing of the Karsdorf Fault have been completely removed .

The wooded "sandstone islands" are called Dippoldiswalder Heide , Hirschbacher Heide and Reinhardtsgrimmaer Heide and are of regional importance for the natural water balance. The almost flat area is drained by the Oelsabach and the Hirschbach and the Lockwitzbach .

Pleistocene loess loam occurs in patches and enables agricultural use of the soil between Hermsdorf and Reinberg, which is otherwise waterlogging and poor in nutrients south of the Karsdorf Fault.

literature

  • Dietrich Franke: Regional Geology East. Geological online reference work for East Germany with around 2500-page encyclopedia (PDF; 19 MB) and separately downloadable maps and tables
  • W. Alexowsky, EA Koch, M. Kurz, JW Schneider, K.-A. Tröger, L. Wolf: Explanations for sheet 5048 Kreischa. 3rd edition, Freiberg 1999, in:
    • Saxon State Office for Environment and Geology (ed.): Geological map of the Free State of Saxony 1: 25000, sheet 5048 Kreischa. 3rd edition, Freiberg 1999
  • R. Beck: Explanations of the special geological map of the Kingdom of Saxony. No. 82, sheet Kreischa. Leipzig 1917 ( digitized version ), p. 87
    • P. Kossmat, K. Pietzsch: Special geological map of the Kingdom of Saxony. No. 82 sheet Kreischa. 2nd edition, published by the Royal Ministry of Finance, Dresden 1912 ( digital version of the map can be downloaded as a .jpg file. Note: The map shows the southeastern part of the Döhlen basin in shades of brown. The Karsdorf fault is on or near the southwestern edge of the Basin, "Wendischcarsdorf" tangent, drawn as a slightly thicker black line.)
  • Kurt Pietzsch: Outline of the geology of Saxony. 2nd edition, VEB Deutscher Verlag der Wissenschaften, Berlin 1956
  • Ulrich Sebastian: The geology of the Ore Mountains. Springer Spectrum, Berlin · Heidelberg 2013

Individual evidence

  1. ↑ Hans-Jürgen Berger, Manfred Felix, Sascha Görne, Erhard Koch, Ottomar Krentz, Andrea Förster, Hans-Jürgen Förster, Heinz Konietzky, Christian Lunow, Katrin Walter, Holger Schütz, Klaus Stanek, Steffen Wagner: Tiefengeothermie Sachsen. 1. Work stage 09/2009 - 07/2010. Series of publications by the State Office for the Environment, Agriculture and Geology. Issue 9/2011, p. 67 f. ( online )
  2. ↑ W. Pälchen, H. Walter (ed.): Geology of Saxony. Geological structure and history of development . Stuttgart 2008. pp. 316-319 ISBN 978-3-510-65239-6
  3. ^ Jens Weber, Christian Jentsch, Christian Zänker: The Wendischcarsdorfer rejection and the Wilisch. In: Green League Osterzgebirge (Ed. :) Naturführer Ost-Erzgebirge. Volume 3: Natural history hiking destinations. Sandstein Verlag, Dresden 2007, ISBN 978-3-942422-48-2 , p. 345 ( HTML version )