View source for Aarmassif

{{Short description|Geologic massif in the Swiss Alps}}
{{unreferenced|date=September 2009}}
{{Geology of the Alps}}
The '''Aarmassif''' or '''Aaremassif''' (German: ''Aarmassiv'') is a [[geology|geologic]] [[massif]] in the [[Swiss Alps]]. It contains a number of large [[mountain chain]]s and parts of mountain chains.

==Name==
The massif is named after the [[Aar]], a river that has its source in the Aarmassif.

==Geography==
The Aarmassif [[outcrop|crops out]] in the eastern part of the [[Bernese Alps]] and the [[Lepontine Alps]], roughly form [[Leukerbad]] in the west to the [[Tödi]] in the east. Further east the massif only appears in small [[window (geology)|windows]] like the ''Vättner window'' between Gigerwald and [[Vättis]] in [[Canton of St. Gallen|Sankt Gallen]] and at the [[Limmerensee]] in the same [[Cantons of Switzerland|canton]].

==Tectonics and lithology==
The Aarmassif is part of the [[Helvetic zone]] of the Alps, which consists of material originally from the European [[tectonic plate]]. The Aarmassif has [[Lithology|lithologies]] common for [[Paleozoic]] [[basement (geology)|basement]] rocks all over Europe, [[deformation (geology)|deformed]] and [[metamorphism|metamorphosed]] during the [[Variscan orogeny]]. Younger [[Mesozoic]] [[sedimentary rock]]s were [[erosion|eroded]] from this basement as a [[thrust fault]] brought the basement to the surface in the [[Alpine orogeny]]. Other places, where the European basement crops out in the Helvetic zone, are the mountain chains of the [[Massif des Écrins]] and of [[Mont Blanc]] in the [[France|French]] and [[Italy|Italian]] Alps.

The [[Rock (geology)|lithologies]] of the basement rocks are mainly [[gneiss]]es, [[schist]]s and [[amphibolite]]s. These were in some places intruded by [[Permian]] [[granite]]s after the [[Variscan orogeny]], called '''Aare granite'''. During a late phase in the Alpine orogeny in the [[Tertiary]] the Aarmassif was [[tectonic uplift|uplifted]] in the form of a large elongated [[dome (geology)|dome structure]]. The overlying limestones of the [[Helvetic nappes]] now have a very high [[Strike and dip|dip]] angle, forming a ridge that appears at the [[Eiger]] and south of the [[Jungfrau]] mountain.

==See also==
*[[Infrahelvetic complex]]

==References==
{{reflist}}

{{coord missing|Switzerland}}

[[Category:Geology of the Alps]]
[[Category:Geology of Switzerland]]
[[Category:Lepontine Alps]]


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