The Full Wiki

More info on Nappe

Nappe: Wikis

Advertisements
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

Schematic overview of an eroded thrust system. The shaded material is the nappe. The erosional hole is called a window or fenster. The klippe is the isolated block of the nappe overlying autochthonous material.

In geology, a nappe is a large sheetlike body of rock that has been moved more than 2 km (1.2 miles)[1] or 5 km[2] from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart. The resulting structure is a large-scale recumbent fold. The term stems from the French word for tablecloth.

Nappes or nappe belts are a major feature of the European Alps, Carpathians and Balkans[3]. The concept was developed by the French geologists who unraveled the complex tectonic history of the Alps, led by M.A. Bertrand, who identified the feature as nappe de charriage. In Switzerland it was A. Escher von der Linth and M. Lugeon. At the same time, nappe structure was investigated in northwestern Scotland by Ch. Lapworth. The Austroalpine nappes of the eastern Alps consist of a series of three thrust-faulted nappe stacks which overlie the three older Penninic nappes in this very complex system[4].

Structure of the nappe

Klippe of Choč nappe, Vápeč, Strážovské vrchy Mts., Slovakia

Numerous signs can be determined on the frame of the word 'nappe'. The frontal part in the direction of movement is called the leading edge of the nappe. Numerous folds and secondary thrusts and duplexes are common here. These features are commonly called digitations. The surface on which a nappe moves is called the decollement plane. An area in which the nappe is completely separated from its substratum is designated a 'root area'. A root area of the nappe is often compressed and reduced, even underthrust below the surrounding tectonic units, resulting in a specific structure called suture. A nappe the root area of which is not known is called a 'rootless' nappe.

Areas with a nappe structure often contain two types of geological features:

  • Fault inlier, fenster or window – is of autochthonous basement uncovered by erosion, but continuously surrounded by the body of nappe. A typical example: Hohe Tauern window in the Alps.

Classification of nappes

According to petrographical composition, two basic types of nappes are known:

References

  1. ^ Howell, J.V. (Editor) 1960: Glossary of geology and related sciences. American Geological Institute, Washington D.C., 325 p.
  2. ^ Marko, F., Jacko, S., 1999: Structural geology (General and systematic). ISBN 80-88896-36-3 Vydavateľstvo Harlequin, Košice, p. 81 - 93 (Slovak)
  3. ^ Gamkrelidze, I.P. 1991: Tectonic nappes and horizontal layering of the Earth’s crust in the Mediterranean belt (Carpathians, Balkanides and Caucasus). Tectonophysics, 196, p. 385-396
  4. ^ Schmid, S. M., Fügenschuh, B., Kissling, E, and Schuster, R. 2004: Tectonic Map and Overall Architecture of the Alpine Orogen. Eclogae geologicae Helvetiae v. 97, Basel: Birkhäuser Verlag, pp. 93–117, ISSN 0012-9402
Advertisements

Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message