Swistsprung

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The Swistsprung is a 28 km long geological fault in the east of the Lower Rhine Bay . It has been proven that it extends from Erftstadt in the north-west to the south-east to Meckenheim and thus forms the border between the Cologne plaice in the north-east and the sinking Erft plaice in the south-west. It is believed that the Swistsprung continues in the southeast to the Ahr . In the northwest it is replaced by the fault system of the Erftsprings.

Swistsprung in the Flerzheim gravel pit

Geological structure

The base of the Lower Rhine Bay is built up from Paleozoic layers, which mainly belong to the Devonian and Carboniferous and partly to the Permian . Among other things, Triassic layers are also present on the Erft-Scholle.

The tertiary filling layers are preserved in various facies . These are purely marine deposits in the north and north-west. In the center of the Lower Rhine Bay, these pass into lagoon deposits and are replaced in the south by marshy-terrestrial to limnic - fluvial deposits. In addition to gravel and sand , lignite in particular is of economic importance .

The Quaternary sediments are characterized by fluvial and aeolian- glacial deposits. The development of the Rhine and Meuse led to the sedimentation of thick layers of gravel, which can be seen today along the Swistsprung.

Tectonic movement

The Lower Rhine Bay is part of the Cenozoic West European Rift System , which extends from the east coast of Spain through France and Germany to the North Sea of the Netherlands . The tectonic activity, which continues today, is caused by the subsidence of the rift system, which is caused , among other things, by the rise of mantle plumes into the lithosphere and the resulting earth crust bulging of Central and Western Europe. In addition, deformation impulses emanate from the divergent plate boundary on the Mid-Atlantic Ridge and from the convergent plate boundary of the African and Eurasian plate, which extend into the Lower Rhine Bay and lead to stresses and discharges.

The first faults in this area are due to the early Tertiary rift movement, even before the bay was actually formed. This division of the basin into north-east and south-west clods also persisted during tectonically highly active phases. As a result, the separation manifested itself in a long fault system, which consists of swist and erft cracks in the southern area and a fault of up to 400 m in the main seam . On average, the throwing height of the Swistsprung is approx. 20 m. As part of geoscientific work by the Steinmann Institute at the University of Bonn , the Swistsprung is being investigated as a topographical hurdle in the construction of the Eifel aqueduct by the Romans in the 1st century AD. To cross the fault, it was necessary to build a 1.4 km long aqueduct . Using geoarchaeological findings, an attempt is made to quantify the disturbance activity of the Swistsprung over the past 1800 years. The result was that at the time the aqueduct was used, earthquakes must have occurred in the southern Lower Rhine Bay. Movements along the Swistsprung could not be detected due to the geoarchaeological evidence, but they could not be excluded either. However, damage to modern buildings indicates differential movements of the subsurface.

Measurements of the terrain surface have confirmed these tectonic movements along the Swistsprung. The largest movements can be detected south of Metternich in the Dünstekoven and Buschhoven area.

The Swisttal belongs to earthquake zone 2 as well as subsoil class T. The earthquake zone 2 comprises areas to which an intensity interval of 7.0 to <7.5 is assigned according to the underlying risk level. The associated design value of the ground acceleration is 0.6 m / s² in this earthquake zone.

In addition, the lignite mining is currently changing the tension in the region and thus, for example at Buschhoven, a settlement rate of 3 mm per year.

Individual evidence

  1. ↑ a b Ludwig Ahorner: Investigations on the quaternary fracture tectonics of the Lower Rhine Bay . In: Ice Age and the Present . tape 13 . Öhringen 1962, p. 24-105 .
  2. ^ A b Roland Walter: Geology of Central Europe . 7., completely rework. Edition Schweizerbart, Stuttgart 2007, ISBN 978-3-510-65225-9 .
  3. ^ Hans Hager: Peat accumulation and syngenetic clastic sedimentation in the Tertiary of the Lower Rhine basin (FR Germany) . In: Mémoires de la Société géologique de France . tape 149 . Paris 1986, p. 51-56 .
  4. ↑ a b K. Skupin, K. Buschhüter, H. Hopp, K. Lehmann, R. Pelzing, J. Prüfert, M. Salamon, G. Schollmayer, A. Techmer, V. Wrede: Paleoseismic investigations in the area of ​​the Lower Rhine Bay . In: Scriptum . tape 17 . Krefeld 2008, p. 72 .
  5. ^ Hans-Wilhelm Quitzow: The storage conditions . In: Geological and mining overview of the Rhenish lignite district . Krefeld 1966, p. 5 - 11 .
  6. ^ Gösta Hoffmann: Römerkanal project. In: Environmental Geology Bonn. University of Bonn, accessed on July 6, 2018 .
  7. ^ Hoffmann, G., Kummer, S., Márquez, R. Valdivia Manchego, M .: The Roman Eifel Aqueduct: archaeoseismological evidence for neotectonic movement at the transition of the Eifel to the Lower Rhine Embayment . In: International Journal of Earth Sciences . August 29, 2019, doi : 10.1007 / s00531-019-01766-y .
  8. ↑ Doris Pfaff: Swistsprung lets the walls tear down. Generalanzeiger, December 28, 2006, accessed on September 14, 2019 .
  9. ↑ Alexander Quante: Environmental report on the FNP reorganization Swisttal - on behalf of the municipality of Swisttal . Grünplan - Office for Landscape Planning, Dortmund 2016.
  10. ↑ A. Shepherd, T. Utescher, M. Valdivia-Manchego, M. Klett, F. Eichhorst, F. by the Hocht: The Cenozoic Lower Rhine Basin - rifting, sediment input, and cyclic stratigraphy . In: Geologische Rundschau . tape 94 , p. 621-639 .