Helvetic nappes

The Helvetic system, even briefly Helvetikum and called in French Alps Dauphiné region is, together with the Ultrahelvetikum next to the South and Austroalpine and Penninic the one of the great geological ceiling systems in the Alps. The ceiling of the Helvetic primarily consist of Cretaceous and lower Tertiary sediments that are folded repeatedly. Proportion of the Helvetic layer sequence but also Upper Jurassic and older rocks that range into the crystallizer massifs of Switzerland and France at least until well into the Carboniferous.

Named after the Helvetic Switzerland (Latin Helvetia ), where this system was first described. Many Type localities of the Helvetic located in Switzerland.

Deposition and formation

Originally, the rocks of the Helvetic were deposited on the European shelf. According to the respective original position takes the thickness of the layers of the Helvetic from north to south ( in the Western Alps from west to east ) to: near the existing coastal deposits are low powerful, often incomplete and influenced by the country, the initially coast distant layers in south are characterized by powerful limestone consequences. The layers of Ultrahelvetikums come from the adjoining the Helvetic, extreme southern shelf edge of Europe, marking the transition to the Penninic Ocean.

When alpidischen orogeny the rocks were Helvetic including some crystalline massifs sheared off from its base camp and pushed the most northern part of the Alpine stack north on the European continent. The originally deposited horizontally layers were folded and disrupted in a complicated manner.

Occurrence

In France, the Helvetic forms ( here also called Dauphiné ), the western half of the Alps, between Cannes over Grenoble to Mont Blanc. The highest peaks are the gneisses and granites of the crystalline massifs of Pelvoux, Belle Donne, the Mont Blanc and the Aiguilles Rouges. You are upstream to the west, the Helvetian limestone massifs of the Provencal Alps, the Dauphiné Alps and Savoy Alps.

In Switzerland, the Helvetic forms along with its crystallizer shares the northern half of the Alps. Apart from the gneisses and granites of the Aar and Gotthard massif is in them upstream to the north Bernese and Glarus Alps of siliceous limestone due to its resistance to the weathering of Hauptgipfelbildner. Excellent open-minded is the Helvetic in the field of Santis and Churfirsten.

The Ostschweizer systems stretch across Vorarlberg ( Bregenz Forest ) until the Allgäu ( area around Oberstdorf and the Ifen ).

In the rest of the Helvetic Alps as a whole is barely open, as it mostly from the flysch zone about the following ( rhenodanubischer flysch ) is pushed over there. To the north of Salzburg, the ceiling comes to light again, from there it takes place against the Northern Limestone Alps as often interrupted band of small-scale tectonic scales within the Rhenodanubian Flyschzone to the westerly boundary of the Vienna Basin. The rocks of the Helvetic enter here the terrain is not particularly prominent.

Tectonics and metamorphism

The Helvetic shows an intricate ceiling structure. Roughly divided into:

  • Ultrahelvetische ceilings and ultrahelvetischer flysch
  • Above or südhelvetische ceiling
  • Under - or ceiling nordhelvetische

Some geologists reckon part of the Tauern Window to the Helvetic.

Stratigraphy

Eastern Switzerland / Vorarlberg / Allgäu

The main elements of the layer in the Eastern Allgäu are from Old ( Lying ) by Jung ( hanging style ) as follows:

Belledonne Aarmassif Bernese Alps Hohe Tauern window Bad Heilbrunn
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