The tectono-metamorphic history of the Valaisan domain from the Western to the Central Alps: New constraints on the evolution of the Alps

Abstract

Research Article| February 01, 2002 The tectono-metamorphic history of the Valaisan domain from the Western to the Central Alps: New constraints on the evolution of the Alps Romain Bousquet; Romain Bousquet 1Department of Earth Sciences, Universität Basel, Bernoullistrasse 30, CH-4056 Basel, Switzerland Search for other works by this author on: GSW Google Scholar Bruno Goffé; Bruno Goffé 2Laboratoire de Géologie, École Normale Supérieure, UMR 8538, 24 rue Lhomond, F-75005 Paris, France Search for other works by this author on: GSW Google Scholar Olivier Vidal; Olivier Vidal 3LGCA, Université J. Fourier, 1381, rue de la Piscine, F-38400 St-Martin d'Hères, France Search for other works by this author on: GSW Google Scholar Roland Oberhänsli; Roland Oberhänsli 4Institut für Geowissenschaften, Universität Potsdam, Karl-Liebknecht-Strasse 24/H25, D-14476 Potsdam-Golm, Germany Search for other works by this author on: GSW Google Scholar Martin Patriat Martin Patriat 5DRO/GEM, B.P. 70, F-29280 Plouzané, France Search for other works by this author on: GSW Google Scholar Author and Article Information Romain Bousquet 1Department of Earth Sciences, Universität Basel, Bernoullistrasse 30, CH-4056 Basel, Switzerland Bruno Goffé 2Laboratoire de Géologie, École Normale Supérieure, UMR 8538, 24 rue Lhomond, F-75005 Paris, France Olivier Vidal 3LGCA, Université J. Fourier, 1381, rue de la Piscine, F-38400 St-Martin d'Hères, France Roland Oberhänsli 4Institut für Geowissenschaften, Universität Potsdam, Karl-Liebknecht-Strasse 24/H25, D-14476 Potsdam-Golm, Germany Martin Patriat 5DRO/GEM, B.P. 70, F-29280 Plouzané, France Publisher: Geological Society of America Received: 27 Nov 2000 Revision Received: 25 May 2001 Accepted: 26 Sep 2001 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2002) 114 (2): 207–225. https://doi.org/10.1130/0016-7606(2002)114<0207:TTMHOT>2.0.CO;2 Article history Received: 27 Nov 2000 Revision Received: 25 May 2001 Accepted: 26 Sep 2001 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Romain Bousquet, Bruno Goffé, Olivier Vidal, Roland Oberhänsli, Martin Patriat; The tectono-metamorphic history of the Valaisan domain from the Western to the Central Alps: New constraints on the evolution of the Alps. GSA Bulletin 2002;; 114 (2): 207–225. doi: https://doi.org/10.1130/0016-7606(2002)114<0207:TTMHOT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Petrographic and structural studies on metasedimentary rocks of the Valaisan domain from the Engadine window (Switzerland) to the Petit St. Bernard (France) show that this entire domain was subjected to high pressure–low temperature conditions during the Alpine orogeny. The pressure and temperature conditions increased from east to west. The metasedimentary rocks of the Engadine window and the Grisons area are characterized by blueschist-facies conditions (12–13 kbar, 350–400 °C, defined by Mg-carpholite and chloritoid occurrences). Toward the west, in the Petit St. Bernard and Versoyen units, the metamorphic conditions reached the eclogite facies (15– 16 kbar, 500 °C). The shortening direction associated with the high-pressure metamorphic event was oriented northwest- southeast all over the Valaisan domain. This direction is compatible with the direction of convergence between the European and Apulian plates in early Tertiary time (65–35 Ma).In the Eastern and Central Alps, blueschist-facies rocks occur below the Austroalpine nappes over an area of 300 × 20 km2 (from the Tauern window to the Grisons area) and have a thickness around 10 km. This volume of blueschist-facies rocks is in contrast with eclogite-facies rocks of Western Alps that form only a small slice with a thickness of 2 to 5 km. We interpret the difference in volume and metamorphic conditions from east to west as being due to a change of the subduction style. In the east, we assume the formation of a large wedge with a thickness of 40–50 km, such that rocks underwent blueschist metamorphism and were exhumed before collision between the European and Apulian plates. In the west, the Petit St. Bernard and the Versoyen units were metamorphosed and extruded in a subduction channel above the subducting slab. The data further allow us to conclude that the Valaisan domain was an ocean that was independent of the Piemontese Ocean and that had an important place in the youngest phase of the evolution of the Alps before the collision. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.