Silica lime

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The name Kieselkalk for a lithostratigraphic unit of the Alps, later also Helvetic Kieselkalk , was introduced into stratigraphic literature in 1867 by Franz Joseph Kaufmann .

He put the type locality on the Lopperberg , which belongs to the Pilatus chain . As Hanspeter Funk found out in 1969, this profile is unsuitable because the lower limit is below the lake level and the profile is also heavily obstructed by the motorway. So he defined a new type profile on the North Pilatus.

The rocks originated in the Lower Cretaceous ( Hauterivium ) and belong to the Helvetic layer sequence. In the lying position they are limited by the Betliskalk or the Diphyoideskalk . In the hanging wall , the Drusberg layers form the boundary.

Characteristic of the Kieselkalk are often a "wall formation", the spongy weathering and the numerous scuffing marks. The "small wall formation" is an alternating layer of 15–40 cm thick, silica-sand-limestone horizons, with 2–10 cm thick, dark, weathering, marbled silica slates. Some of these layers are bulbous and have chert deposits . It does not seem to be a boudinage , but rather selective solution processes during diagenesis . The dark marl slates were subsequently influenced by weak tectonic processes. The quartz content of the silica lime is 20-30% and it was used as railway ballast because of its hardness.

Its thickness is very variable. In the Axen Nappe ( Helvetikum ) it is 70–120 m and reaches a maximum of over 700 m in the Drusberg Nappe (Helvetikum).

Individual evidence

  1. ↑ Franz Joseph Kaufmann: Geological Description of Pilatus . Contributions to the geological map of Switzerland, 5 [text volume], Bern 1867
  2. ↑ Hanspeter Funk: Type profiles of the Helvetian silica limestone formation and the Altmann layers. Eclogae Geologicae Helvetiae Vol. 61 (1968). Basel, pp. 192-203
  3. ↑ Lithostratigraphic Lexicon of Switzerland ( Memento of the original from October 28, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (www.stratigraphie.ch) @1@ 2Template: Webachiv / IABot / www.stratigraphie.ch
  4. ^ R. Trümpy: Geology of Switzerland . Basel. 1980
  5. ↑ Hanspeter Funk: On the stratigraphy and lithology of the Helvetic silica limestone and the Altmann layers in the Säntis-Churfirsten group (northeastern Switzerland). Eclogae Geologicae Helvetiae Vol. 64 (1971)
  6. ↑ Geology of the Canton of Uri. Altdorf 2011, ISBN 978-3-033-02916-3 , p. 66