Pseudokarst

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Cart formations in sandstone of the Upper Cretaceous in Saxon Switzerland

As pseudokarst is called geomorphological phenomena or parts of a landscape, the characteristics or features of a karst although their constituent rocks such as have, sandstone , quartzite or granite are considered non verkarstungsfähig. The demarcation of the pseudokarst from “real” karst in carbonate rocks ( limestone and dolomite ) on the one hand and non-karst landscape on the other is controversial.

Concept formation

The term pseudokarst alludes to the fact that the landscape is similar to that in a karst area , although the rock-forming minerals or soil-forming sediments are insoluble or hardly soluble. While the karst term was originally only used for landscapes that are formed by dissolving limestone and dolomite in carbonated water, it was later expanded to include anhydrite / gypsum and salt rocks, as these are also relatively easily soluble in water. However, since similar or identical features can be observed in some landscapes where the rocks or soil-forming sediments do not have this ability to dissolve, the term pseudokarst was established for these areas . A brief outline of the history of the term can be found u. a. in an article by István Eszterhás:

  • The first known use goes back to Walther von Knebel in his "Höhlenkunde mit dem Karstphänomene" from 1906.
  • A classification of the pseudo-karst phenomena in loess and clay sediments was carried out by FP Savarenskij in 1931.
  • In particular, Russian and Italian researchers worked and published in this field in the middle of the 20th century using the term, later also Bohemian geologists.

Today thermokarst , crevice and collapse caves (including the consequence caves , which are created by collapse from formerly artificial cavities) and lava caves are described under the generic term pseudokarst. Some authors group exclusively those forms that were not created by solution processes in the pseudokarst, while forms that are created by solution in gypsum rocks, quartzites and volcanic tuffs are referred to as parakarsts. Other researchers differentiate karst forms from classical karst according to the predominant rock, such as sandstone karst or quartzite karst.

The discussion of the classification of such phenomena in “real karst” and “pseudokarst” is still in flux. The role of the solution in the creation of the landscape has become established as a central feature for differentiation.

Origin and characteristics

In nature, all rocks are subject to destruction through various stresses. The forces of erosion in particular act here on the surface of the earth and in the immediate vicinity . Solution phenomena such as corrosion require a corresponding solubility in water. In principle, all minerals and thus the rocks that consist of them are soluble, but there are considerable differences between them in terms of the rate of dissolution, the dissolvable quantities per liter of water and the dissolution conditions. So apply z. B. basalt , quartzite and granite are simplified as insoluble or hardly soluble, while gypsum rock is easily soluble.

Manifestations

In pseudokarst all manifestations can be observed that even in the karst can be found: sinkholes , sinkholes , Bach seepage and sink-holes , sinkholes and underground drainage, carts , caves , however, takes place, etc. The emergence of these forms predominantly by tectonics , erosion, suffusion , etc. solving processes sometimes also take place, but play a subordinate role. Nevertheless, there are partially solution processes outside of the Karst. Exogenous forms can also be found in granite , which indicate signs of solution. In caves in sandstone or quartzite , such as the Muchimuk cave system and other caves of the South American tepuis , corrosive manifestations (solution hollow forms, sintered caves ) as well as speleothems caused by precipitation can also be detected. In many cases it is unclear whether the appearance of solution is the triggering process of the cavern formation or whether the solution only plays a subordinate, secondary role.

research

In 1982, Czech cave and karst researchers organized an independent pseudokarst symposium for the first time . Since then, these symposia have taken place in Europe on an international level every two years, most recently in 2010 in Saupsdorf (Saxon Switzerland / Germany). Since 1997 the World Association of Speleologists UIS has had an independent commission for the pseudokarst.

literature

  • W. von Knebel: Speleology with consideration of the karst phenomena. Friedrich Vieweg and son, Braunschweig 1906.
  • G. Florida: Un particolare fenomeno pseudocarsico manifeste da algune agrile. In: Bolletino della Societa ei Sciencia Naturale ed Economiche di Palermo. Volume 23, 1941, pp. 10-19.
  • HP Kosack: The spread of karst and pseudokarst phenomena over the earth. In: Petermanns Geographische Mitteilungen (B. 96.). Gotha 1952, pp. 16-22.
  • T. Striebel: Cave formation in “non-karstifiable” rocks: which forms are karst forms? In: Laichinger Höhlenfreund. 40 (1). Laiching 2005, pp. 31-52.

further reading

Web links

Individual evidence

  1. ↑ István Eszterhás: The History of the Pseudokarst Commission of the UIS. (No longer available online.) In: tu-dresden.de. Technische Universität Dresden , July 2008, archived from the original on December 6, 2017 ; accessed on October 26, 2018 .
  2. ↑ Urs Sandfuchs: Formerly iron ore - today natural gas . In: Underground . 2004, p. 45 ( sgh-lenzburg.ch [PDF; 576 kB ; accessed on November 8, 2018]).
  3. ↑ Luc Willems: Phénomènes karstiques en roches silicatées non carbonatées: cas des grès, des micaschistes, des gneiss et des granites en Afrique sahélienne et equatoriale . Dissertation Université de Liège , 2000, p. 4th ff. of the short version ( short version; PDF; 309 kB , index page of the complete version - comprehensive discussion of sandstone karst and terminological questions in this context).
  4. ↑ RH Winkelhöfer: The Elbe Sandstone Mountains are a sandstone karst area . In: The cave explorer . Journal for friends of speleology. Vol. 38, 2006, ISSN  0138-2519 , p. 50–53 ( geoberg.de - Memento in the Internet Archive from October 15, 2013).
  5. ^ A b Robert AL Wray: Quartzite dissolution: karst or pseudokarst? In: Cave and Karst Science . tape 24 , no. 2 , 1997, ISSN  0263-760X , p. 81–86 ( speleogenesis.info [PDF; 87 kB ; accessed on November 8, 2018] New publication at Speleogenesis and Evolution of Karst Aquifers. ).
  6. ↑ Roman Aubrecht, Tomáš Lanczos, Branislav Šmída, Charles Brewer-Carias, Federico Mayoral, Ján Schlögl, Ľubomír Kováčik, Miloš Gregor: Venezuelan sandstone caves: a new view on Their genesis, hydrogeology and speleothems . In: Geologia Croatica . tape 61 , no. 2–3 , 2008, ISSN  1330-030X , p. 346 ( srce.hr [PDF; 7 kB ]).