Nappe du Tsaté

Representation and status

Index

Ts

Color CMYK

N/A

Color RGB

R: 241 G: 239 B: 237

Rank

nappe

Validity

Unit is in Use

Status

valid

Status discussion

Nomenclature

Deutsch

Tsaté-Decke

Français

Nappe du Tsaté

Italiano

Falda del Tsaté

English

Tsaté Nappe

Origin of the Name

Alpage du Tsaté (VS)

Historical Variants

nappe du Tsaté (Sartori 1987, Escher et al. 1988, Marthaler & Stampfli 1989), zone du Combin auct., Upper ophiolitic units = Combin Zone Auct. = Tsaté nappe (Dal Piaz et al. 2015), Tsaté nappe (Steck et al. 2015), «zone du Combin» auct., Tsaté Nappe (TK500, Gouffon et al. 2024)

Description

Description

Unité tectonique la plus élevée du domaine pennique de Suisse occidentale, constituée de serpentinites (métapéridotites), gabbros et basaltes (ophiolites piémontaises), surmontés de radiolarites et d'une épaisse série de calcschistes dont la succession stratigraphique a été largement chamboulée lors de l'orogenèse alpine.

Cf. Sartori & Marthaler 1994, Escher et al. 1997

The Tsate nappe overthrusts the Zermatt-Saas nappe and is affected by blueschist to greenschist facies metamorphism. Ophiolitic rocks are represented by slices and lenses imbricated with calcschists (Marthaler, 1984; Lagabrielle, 1987; Kunz, 1988).

Hierarchy and sequence

Subordinate units

• unité de la Luette
• unité du Pleureur

Upper boundary

Chevauchement de la nappe de la Dent Blanche.

Geography

Geographical extent

Métapéridotites: Pointe du Tsaté, Cabane des Dix.

Palaenography and tectonic

Paleogeography

Piemont Basin

Tectonic unit (resp. main category)

• Tsate

Kind of protolith

• tectonic

Metamorphism

monocyclic

Metamorphic facies

• greenschist facies (epizone)
• blueschist facies

Note on metamorphism

Pas de témoins d'une phase de haute pression, contrairement à la Zone de Zermatt-Saas.

References

Definition

Sartori Mario (1987) : Structure de la zone du Combin entre les Diablons et Zermatt (Valais). Eclogae geol. Helv. 80/3, 789-814

Definition

Gouffon Yves (Editor) (2024) : Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern

p.70: The Tsaté Nappe crops out in southern Valais and in the Valle d’Aosta. It comprises oceanic metasediments, mainly calcschists and black shales of Cretaceous age, and ophiolitic rocks of Jurassic age. They originate from the Piemonte-Liguria Ocean. This nappe is characterized by a chaotic aspect and metamorphism under conditions of blueschist facies followed by greenschist facies. It is interpreted as the result of the formation of an accretionary wedge at the foot of the active Adriatic margin and the subsequent subduction below this continental plate (Marthaler & Stampfli 1989, Stampfli et al. 1998, 2002). Depending on the location, the Tsaté Nappe overlies the Mont Fort, Siviez-Mischabel or Zermatt - Saas Fee nappes, in some cases with small units (Theodulgletscher and Etirol-Levaz slices, Mont Emilius Nappe and Châtillon-St-Vincent Slices) between the two nappes. It is overlain by the Dent Blanche Nappe west of Valtournanche (lateral valley of the Valle d’Aosta) and by the Sesia Nappe further east.
Some authors (e. g., Bucher et al. 2004, Dal Piaz 1988, 1999, Dal Piaz et al. 2015, Pleuger et al. 2007) group the Tsaté Nappe with the Frilihorn, Gornergrat and Cimes Blanches nappes under the term “Combin Zone”, which was defined by Argand (1909) in an even broader sense.

Important Publications

Kunz Pierre (1988) : Ophiolites penniques et sédiments associés dans la région d'Arolla (val d'Hérens, Valais, Suisse). Eclogae geol. Helv. 81/1, 115-124

Marthaler Michel, Stampfli Gérard M. (1989) : Les Schistes lustrés à ophiolites de la nappe du Tsaté : un ancien prisme d'accrétion de la marge active apulienne? Schweiz. Min. Petr. Mitt. 69/2, 211-216

Material and varia