- Aarmassif
The Aarmassif or Aaremassif (German: "Aarmassiv") is a geologic
massif in theSwiss Alps . It contains a number of large mountain chains and parts of mountain chains.Name
The massif is called after the
Aar , a river that has its source in the massif.Geography
The Aarmassif crops out in the eastern part of the
Bernese Alps and theLepontine Alps , roughly formLeukerbad in the west to theTödi in the east. Further east the massif only appears in small windows like the "Vättner window" betweenGigerwald andVättis in Sankt Gallen and at theLimmerensee in the same canton.Tectonics and lithology
The Aarmassif is part of the
Helvetic zone of the Alps, which consists of material originally from the Europeantectonic plate . The Aarmassif has lithologies common forPaleozoic basement rocks all over Europe, deformed and metamorphosed during theVariscan orogeny . YoungerMesozoic sedimentary rock s were eroded from this basement as athrust fault brought the basement to the surface in theAlpine orogeny . Other places where the European basement crops out in the Helvetic zone are the mountain chains of theMassif des Écrins and ofMont Blanc in the French and Italian Alps.The lithologies of the basement rocks are mainly
gneiss es,schist s andamphibolite s. These were in some places intruded byPermian granite s after theVariscan orogeny , called Aare granite. During a late phase in the Alpine orogeny in theTertiary the Aarmassif was uplifted in the form of a large elongated dome structure. The overlying limestones of theHelvetic nappes now have a very high dip angle, forming a ridge that appears at theEiger and south of theJungfrau .ee also
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Infrahelvetic complex
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