Falda del Monte Rosa
Back to Breithorn-ZoneRepresentation and status
- Index
- MR
- Color CMYK
- N/A
- Color RGB
- R: 241 G: 239 B: 237
- Rank
- nappe
- Validity
- Unit is in Use
- Status
- valid
Nomenclature
- Deutsch
- Monte-Rosa-Decke
- Français
- Nappe du Mont Rose
- Italiano
- Falda del Monte Rosa
- English
- Monte Rosa Nappe
- Origin of the Name
- Historical Variants
-
pli-nappe du Mont Rose = nappe V (Argand 1911b), Gneisdecke des Monte Rosa = Monte Rosadecke = Gneismassiv des Monte Rosa (Eichenberger 1926), massif du Mont Rose (Huang 1935), Ricorpimento M. Rosa-Arceza-G. Paradiso-Ambin (Hermann 1937), Monte Rosa-Zone = Wurzelzone der Mischabel-Decke = Locarno-Zone (Blumenthal 1952), Monte Rosa-Teildecke (Bearth 1952), Serie Mte Rosa-Arceza (Bearth), falda del Monte Rosa (Dal Piaz et al. 1992a), Monte Rosa basement fold nappe = Monte Rosa unit (Steck et al. 2015), Monte Rosa unit (Ellis et al. 2016), Monte Rosa Nappe (TK500, Gouffon et al. 2024)
Description
- Description
-
Spät- bis postvariszische Granitoide die ein älteres, variszisch amphibolitfaziell metamorphes bis migmatitisches Kristallin intrudierten. Lokal tritt eine reliktische Sedimentbedeckung (Meta-Arkosen und Sandsteinen ; Perm - Frühe Trias). Die Monte-Rosa-Decke wurde alpin sukzessiv eklogitfaziell (Eozän), amphibolitfaziell und grünschieferfaziell überprägt.
Recumbent gneiss fold nappe of the Penninic zone of the Central Alps witnessing high-pressure regional metamorphism followed by Barrovian metarmophism.
Hierarchy and sequence
- Units at roof
- Units at floor
Geography
- Geographical extent
- inkl. Dufourspitze (4634 m)
Palaenography and tectonic
- Tectonic unit (resp. main category)
- Kind of protolith
-
- tectonic
- Metamorphism
- polycyclic
- Metamorphic facies
-
- greenschist facies (epizone)
- amphibolite facies
- migmatitisation
- eclogite facies
References
- Definition
-
(2024) :
Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern
p.67: The Monte Rosa Nappe comprises mainly crystalline basement made up of polycyclic paragneisses and orthogneisses that represent granitic intrusions of Carboniferous and Permian age. This basement is subdivided in two parts by the thick Stellihorn Shear Zone. A sedimentary series, known as the “Furgg Zone”, surrounds the crystalline basement in a discontinuous manner. It separates in particular the Monte Rosa gneisses from those of the Portjengrat Nappe and consists of Permian to Jurassic metasediments, which are crosscut by mafic sills and dykes. However, the “Furgg Zone” is considered as an allochthonous cover of the Monte Rosa Nappe (Steck et al. 2015) because these intrusion veins do not intersect the underlying gneisses and the contact between the “Furgg Zone” and the Monte Rosa gneisses is typically of tectonic nature. The allocation of the “Furgg Zone” remains a matter of controversy, with some authors considering it as a cover of the Portjengrat Nappe (Bearth 1957, Keller & Schmid 2001) or even as a mélange zone (Froitzheim 2001).
All the rocks of the Monte Rosa Nappe have undergone a metamorphism with higher pressure (eclogite facies) than those of the Siviez-Mischabel and Mont Fort nappes (high-greenschist to blueschist facies), indicating a deeper burial in a subduction zone. Two hypotheses may explain this feature: 1) The Monte Rosa Nappe has a more internal paleogeographic origin than the Siviez-Mischabel and Mont Fort nappes, all three were caught in the same underthrusting surface as the Piemonte-Liguria Ocean, whereby the Monte Rosa Nappe went deeper (Steck et al. 2015); 2) the Monte Rosa Nappe has a more external origin than the other two and was caught in the same subduction zone as that of the oceanic Valaisan Basin – from which the origin of the Antrona Nappe is hypothesized in that case – thus below the Siviez-Mischabel and Mont Fort nappes (Pleuger et al. 2005).
- Important Publications
-
(2002) : Structural evolution of the Penninic units in the Monte Rosa region (Swiss and Italian Alps). Diss. Universität Basel