Burglary Basin

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Burglary basin is a geographical-geomorphological collective term for morphological basins that were created by subsidence of the earth's surface, regardless of the underlying mechanisms. In modern geosciences, however, the term is almost exclusively applied to geologically young, tectonically caused morphological basins. The size of such pools ranges from a few kilometers to several hundred, e.g. Sometimes even thousands of kilometers in length or diameter. The differences in height between the basins and their surroundings are also relatively variable, ranging from less than 100 to over 1000 meters. Since they are filled with sediments, the actual absolute amount of subsidence of such basin structures cannot be seen from the terrain morphology. It is sometimes several kilometers and can only be determined using geophysical methods. The reduction rates typically amount to a few millimeters per year.

Types of intrusion pools

Tectonic basins

Tectonic collapse basins are created by dynamic processes in the earth's interior, which cause a clod of the earth's crust to sink along fault surfaces, creating a hollow shape on the earth's surface. Depending on which tectonic mechanisms cause the subsidence, different variants of tectonic basins are distinguished. A typical variant is the rift valley . The term intrusion basin is often used synonymously with the term tectonic intrusion basin.

Volcanic tectonic basins

This type of collapse basin is based on material depletion in the subsurface of a volcanic area, e.g. B. an emptying magma chamber or the decrease in volume due to cooling of the melt in the magma chamber. As a result, the rock layers above slowly sag. Strictly speaking, the calderas are therefore also part of the volcanic tectonic basins. As a rule, such basins have smaller dimensions than the "pure" tectonic incursion basins.

Subrosion sinks

In the original meaning of the term intrusion basin, the so-called subrosion or collapse sinks are also included. These are also rather small and are also caused by material loss in the subsoil, which in this case is caused by the leaching ( subrosion ) of more or less water-soluble rocks such as limestone, gypsum or rock salt through groundwater, i.e. This means that the pool formation is triggered by processes that are relatively close to the surface. In addition, the basin is created by the coalescence of small-scale incursions over underground cavities ( sinkholes ) and not by the sinking of a larger block of rock. Subrosion sinks therefore differ fundamentally in their formation from tectonic and volcanic-tectonic basins. Therefore, they tend not to be included in modern geosciences.

Occurrences and examples

Since the term intrusion basin is primarily used in the geographical-geomorphological context, it is used almost exclusively for recent morphological basins. The following examples therefore relate to such pools. As a rule, these are geologically relatively young. Many of the larger basins in Europe were created by tectonic processes associated with the Alpid mountain formation in the Tertiary (65 to 3 million years before today).

Typical examples of tectonic intrusion basins are the Vienna Basin , the Horner Basin , the Lavant Valley and the Styrian Basin in Austria , the Upper Rhine Rift Valley and the Lower Rhine Bay with the Wahner Heide in Germany . The largest tectonic basin in the world is the East African Rift Valley .

A classic example of a volcanic-tectonic collapse basin is the Laacher See in the Eifel. The Eifel volcanism also has its origins in the Alpidic processes.

Most subrosion sinks can be found in limestone mountains, which is simply related to the fact that limestone is much more common in the upper crust than gypsum and rock salt. The technical term for a subrosion depression in a limestone mountain range is Polje . The typical area for Poljen is the Dinaric Mountains in the west of the Balkan Peninsula. In Germany, smaller subrosion sinks are particularly widespread in northern Hesse, southern Lower Saxony and Thuringia.

See also

Individual evidence

  1. ↑ a b Harald Zepp: Geomorphology. 4th updated and expanded edition. Verlag Ferdinand Schöningh, Paderborn, 2008 ISBN 978-3-8252-2164-5
  2. ^ Ferdinand Freiherr von Richthofen: Guide for explorers - instructions for observations on objects of physical geography and geology. Verlag von Gebrüder Jänecke, Hanover 1901 (reprint of the 1886 edition), p. 267

literature

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