Zermatt–Saas-Fee-Decke
Back to Zermatt–Saas Fee nappeRepresentation and status
- Index
- ZS
- Color CMYK
- N/A
- Color RGB
- R: 241 G: 239 B: 237
- Rank
- tectonic unit
- Validity
- Unit is in Use
- Status
- valid
Nomenclature
- Deutsch
- Zermatt–Saas-Fee-Decke
- Français
- Nappe de Zermatt–Saas Fee
- Italiano
- Falda Zermatt–Saas Fee
- English
- Zermatt–Saas Fee Nappe
- Origin of the Name
- Historical Variants
-
Groupe de Zermatt (Argand 1908, Bartholmès 1920, Rutsch et al. 1966), branche de Saas (Argand 1911b), Muldenzone Zermatt-Saas = Zermatter-Mesozoikum = Zermatterzone (Eichenberger 1926), Saaserzüge (Roesli 1946), Ophiolith-Decke von Saas-Zermatt (Güller 1947), Zone von Zermatt-Saas-Fee (Bearth 1952), Ophiolithzone Zermatt-Saas-Fee (Bearth 1953, Kopp 1974), Zone de Zinal-Zermatt (Trümpy 1976), Eastern Piemonte Zone = Zermatt-Saas Zone (Compagnoni et al. 1977), Zermatt-Saas ophiolite zone (Barnicoat & Fry 1986, Barnicoat 1988), Zermatt-Saas-Decke (Froitzheim), zone de Zermatt-Saas Fee (Ganguin 1988, Vannay & Allemann 1990), unità inferiore della Zone Piemontese = unità di Zermatt-Saas (Dal Piaz et al. 1992), Zermatt-Saas ophiolitic nappe (Bill et al. 2001), Zermatt-Saas unit (Babist et al. 2006, Ellis et al. 2016), Zone of Zermatt-Saas Fee (Berger & Mercolli 2007), Lower ophiolitic unit = Zermatt-Saas unit (Dal Piaz et al. 2015), Zermatt–Saas Fee Nappe (TK500, Gouffon et al. 2024)
Description
- Description
-
Die Zermatt-Saas-Decke besteht aus ozeanischer Kruste (Serpentinit, Gabbro, Basalt mit pillow-lavas, Ophikarbonat) die im Mittleren Jura entstand. Radiolarite und kalkig-pelitische Sedimente treten auch auf. Im Eozän, während der alpinen Orogenese, wurden die Gesteine der Zermatt-Saas-Decke eklogitfaziell (inkl. Ultrahochdruck bis 25-30 kbar) metamorph überprägt.
la zone de Zermatt est fortement affectée par un métamorphisme éclogitique d'âge crétacé (BEARTH 1973 et 1974, DAL PIAZ et al. 1972, HUNZIKER 1974) => amphibolites à grenat, compactes et à grain fin (fond de la vallée de Zermatt, gorges du Trift), amphibolites/prasinites chloriteuses, serpentines
Bill et al. 2001: The Antrona and Zermatt-Saas ophiolitic nappes are found in a structurally low position. They are affected by high-P metamorphism (eclogite facies) followed by greenschist to amphibolite grade metamorphism (Bearth, 1974; Dal Piaz, 1974b; Hunziker, 1974; Dal Piaz and Ernst, 1978; Colombi, 1989; Steck, 1989; Vannay and Allemann, 1990; Reinecke, 1991; Amato et al., 1999).
Hierarchy and sequence
- Upper boundary
-
nappe du Mont Rose
- Lower boundary
-
nappe du Tsaté
Age
- Age at top
-
- Cretaceous
- Age at base
-
- Middle Jurassic
Palaenography and tectonic
- Paleogeography
- Piemont Basin
- Tectonic unit (resp. main category)
- Kind of protolith
-
- ophiolitic
- Metamorphism
- monocyclic
- Metamorphic facies
-
- greenschist facies (epizone)
- amphibolite facies
- eclogite facies
- Note on metamorphism
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Hochdruck- bis Ultrahochdruck-Metamorphose.
References
- Definition
-
(1908) :
Carte géologique du Massif de la Dent Blanche (moitié septentrionale) 1:50 000. Mat. Carte géol. Suisse (N.S.) 23, carte spéciale n° 52
Eclogites et amphibolites grenatifères p.p. à glaucophane, avec masses restreintes de prasinites amphiboliques.
- Definition
-
(2024) :
Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern
p.68: The Zermatt - Saas Fee Nappe consists of rocks derived from the Piemonte-Liguria Ocean. They are mostly large bodies of serpentinites, metagabbros (Middle – Late Jurassic, Rubatto et al. 1998) and metabasalts in which pillow structures are locally well preserved. Oceanic sediments overlie these ophiolites, in particular metacherts (metaradiolarites). All of these rocks display relics of Early Eocene high-pressure metamorphism in eclogite facies (Barnicoat & Fry 1986, Rubatto et al. 1998).
- Important Publications
-
(1988) : Contribution à la caractérisation du métamorphisme polyphasé de la zone de Zermatt-Saas Fee (Alpes valaisannes). Thèse ETHZ N°8731, 321 p.