• Schams-Deckenkomplex

    Origin of the Name

    Schams = Val Schons (GR), Hinterrheintal

    Rank
    nappe complex
    Status
    valid
    Age
    Carboniferous - Eocene
    In short

    The Schams Nappe Complex is a Middle Penninic tectonic unit of eastern Switzerland encompassing a set of small nappes, which were folded after their emplacement around the Tambo-Suretta pair during the Niemet-Beverin post-nappe folding. The Schams Nappe Complex also contains different mélanges: to the west, in the lower limb of the Niemet-Beverin Backfold, the Knorren Mélange is in contact with the Tambo Nappe, while the Areua-Bruschghorn Mélange marks the boundary with the Tomül Nappe; to the east, in the upper (overturned) limb of the Niemet-Beverin Backfold, the Martegnas Mélange is in contact with the Arblatsch Flysch belonging to the Tomül Nappe.

    The sedimentary sequences of the Schams Nappe Complex exhibit large facies variations and are rich in sedimentary syn-rift breccias of Middle Jurassic to Early Cretaceous age, indicating contemporaneous extension and sinistral strike-slip. The mid-Cretaceous to Cenozoic post-rift sediments are very similar to those found in the Falknis Nappe. Retrodeformation suggests that the Schams nappes formerly occupied an area north of the depositional area of the Tambo and Suretta Mesozoic. This is supported by facies arguments indicating that sediments in the originally northernmost paleogeographical position (now forming the Gelbhorn Nappe) suggest N-directed shedding of syn-rift breccias, and by the Subbriançonnais-type facies of the Triassic strata.

    Rueck_1995_f39
    Nomenclatorial Remarks

    cf. Schreurs 1990, Schmid et al. 1990

  • Gelbhorn-Decke

    Origin of the Name

    Gelbhorn = Piz Mellen (GR)

    Rank
    nappe
    Status
    valid
    In short

    The Gelbhorn Nappe is part of the Schams Nappe Complex. In the hanging wall of the Suretta Nappe (eastern Shams), the outer, fine-grained, calcareous limb of the unit (1b) is normal, while the inner, coarse-grained limb (1a) is overturned on the Tschera-Kalkberg Nappe. In the Westschams, and thus in the footwall of the Suretta Nappe, the structural situation is the other way round, i.e. the outer limb is overturned and the inner limb is normal.

  • Tschera-Kalkberg-Decke

    Rank
    nappe
    Status
    valid
    In short

    The Tschera-Kalkberg Nappe is a tectonically complex, mélange-like inner sheath of the Schams Nappe Complex. It is divided into three subunits based on lithological criteria.

  • Areua-Bruschghorn-Melange

    Origin of the Name

    Bruschghorn (GR)

    Rank
    tectonically bounded lithostratigraphic unit
    Status
    informal term
    Age
    Paleozoic - Early Triassic
    In short

    The Areua-Bruschghorn Mélange is a tectonic mélange situated in the lower limb of the Niemet-Beverin Backfold, at the contact between the Schams Nappe Complex and the Tomül Nappe.

    Nomenclatorial Remarks

    Das im Westschams vorkommende Areua-Bruschghorn-Melange lässt sich über das Scharnier der liegenden Niemet-Beverin-Falte mit dem Martegnas-Melange im Ostschams verbinden.

    • Bruschghorn-Schuppe

      Name Origin

      Bruschghorn (GR)

      Rank
      tectonic slice
      Status
      local name (informal)
      In short

      Gneis, Dolomit, Gips und Prasinit.

    • Burgruinen-Gneis

      Name Origin

      Burgruine Splügen (GR)

      Rank
      lithostratigraphic Formation
      Status
      informal term
      In short
      Hellgrauer, quarzreicher Orthogneis mit charakteristischen dunkelgrauen Feldspäten. Das Gestein ist von Quarzgängen (Pegmatit) durchsetzt.
  • Martegnas-Melange

    Origin of the Name

    Piz Martegnas (GR), Oberhalbstein

    Rank
    tectonically bounded lithostratigraphic unit
    Status
    local name (informal)
    In short

    The Martegnas Mélange is a tectonic mélange situated in the upper (overturned) limb of the Niemet-Beverin Backfold, at the contact between the Schams Nappe Complex and the Arblatsch Flysch (Tomül Nappe).

    Nomenclatorial Remarks

    Das im Ostschams vorkommende Martegnas-Melange lässt sich über das Scharnier der Niemet-Beverin-Falte mit dem Areua-Bruschghorn-Melange im Westschams verbinden.

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