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Utilisateur:Pierre Granite

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Ridge made of Rotondo Granite.

The Rotondo granite is a late Variscan granitic intrusion located in the Saint-Gotthard Massif in Switzerland. Its name comes from the Pizzo Rotondo.

Description[modifier | modifier le code]

It shows as a fin to medium-grained granite. Unlike other granitic intrusions present in the Gotthard Massif (Gamsboden Granite and Fibbia Granite), the foliation is only very weakly developed[1] and is mostly visible in ductile shear zones. The intrusion was dated of an age of 294 Ma[2]. On surface, it outcrops over an area of 20-25 km2[3].

Significance[modifier | modifier le code]

Fresh Rotondo Granite surface in the Bedretto Tunnel.

The Bedretto Underground Laboratory for Geoenergies which is located in the Bedretto Tunnel, is performing research on deep geothermal energy in the Rotondo Granite. The site was selected, because of the similarities that this rock shows with rocks that are expected to be encountered at a depth of 4-5 km below the Swiss Plateau.

Références[modifier | modifier le code]

  1. Lützenkirchen, V., & Loew, S. (2011). Late Alpine brittle faulting in the Rotondo granite (Switzerland): deformation mechanisms and fault evolution. Swiss Journal of Geosciences, 104(1), 31-54.
  2. Sergeev, S. A., & Steiger, R. H. (1995). Caledonian and Variscan granitoids of the Gotthard massif: new geochronological and geochemical results, Schweizerische Mineralogische und Petrographische Mitteilungen, 75, 315-316.
  3. Labhart, T. (2005). Erläuterungen Zum Geologischen Atlas Des Schweiz 1:25000, Val Bedretto, Atlasblatt 68. ed. Bundesamt für Wasser und Geologie.

Bedretto-Fenster (de)