Nappe du Tsaté

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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

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)
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
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.

Material and varia

Images
  • unité de la Luette

    Name Origin

    La Luette (VS), Val d'Hérémence

    Rank
    tectonically bounded lithostratigraphic unit
    Status
    informal term
    Valid term
    Graue-Serie (Tsate) Garda-Bordon-Formation
    In short

    Unité la plus interne de la nappe du Tsaté, constituée de calcschistes à dominance calcaire ou pélitique, riches en roches vertes.

  • unité du Pleureur

    Name Origin

    Le Pleureur (VS)

    Rank
    tectonically bounded lithostratigraphic unit
    Status
    informal term
    Valid term
    Rousse_Serie (Tsate)
    In short

    Marbres phyllitiques clairs, brèches sédimentaires à composants calcaires et dolomitiques, calcschistes quartzo-micacés à surface d'altération rougeâtre (nappe du Tsaté).

    Age
    Cretaceous
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