S-charl–Sesvenna-Decke

Representation and status

Color CMYK

N/A

Color RGB

R: 241 G: 239 B: 237

Rank

nappe

Validity

Unit is in Use

Status

valid

Nomenclature

Deutsch

S-charl–Sesvenna-Decke

Français

Nappe de S-charl–Sesvenna

Italiano

Falda S-charl–Sesvenna

English

S-charl–Sesvenna Nappe

Origin of the Name

S-charl (GR)

Historical Variants

Falda di Scarl (Pozzi 1957), Unterengadiner Dolomiten = S-charl-Decke (Cadisch et al. 1968), S-charl–Sesvenna-Teildecke (Stutz & Walter 1983), Sesvenna-S-charl nappe (Furrer et al. 1985), Scarl-Decke (Gruber et al. 2010), S-charl–Sesvenna Nappe (TK500 / Gouffon et al. 2024)

Description

Description

Obere Decke der Unterengadiner Dolomiten (Oberostalpin). Besteht aus dem Sesvenna-Kristallin und seiner autochtone Sedimentbedeckung («S-charl-Decke s.s.»).

Hierarchy and sequence

Subordinate units

• Tavrü-Schuppe

Geography

Geographical extent

Engadiner Dolomiten (SE der Engadin-Störung).

Palaenography and tectonic

Tectonic unit (resp. main category)

• S-charl-Sesvenna

Kind of protolith

• tectonic

References

Definition

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

p.93: The basement of the S-charl-Sesvenna Nappe is commonly referred to as the Sesvenna basement and its cover as “S-charl-Unterbau” and “S-charl-Oberbau” (Dössegger 1987, Trümpy et al. 1997). The “S-charl-Unterbau” forms a series of NE–SW trending series of synclines and anticlines that affect both basement and cover without major detachments within the sedimentary sequence (Karagounis 1962). In contrast, the “S-charl-Oberbau”, referred to as Tavrü Slice, straddling the northeastern rim of the S-charl-Sesvenna Nappe neighbouring the Engadine Fault (see § 10.5), consists entirely of a Norian to Cretaceous succession, volumetrically dominated by an over 2 km thick Hauptdolomit. The Tavrü Slice is completely detached from the Carnian Raibl Group. This slice, separated from the tectonically higher Ötztal Nappe by the Schlinig Thrust, suffered substantial internal extension in a domino-style (see cross-sections in Trümpy et al. 1997); the cause of this extension, either by stretching below the basal thrust of the Ötztal Nappe (Schmid & Haas 1989) or by deformation during the Late Cretaceous extensional phase (Froitzheim et al. 1997), being a matter of debate.
Nowadays most authors agree that the S-charl-Sesvenna Nappe, including the Tavrü Slice, basically occupies the same tectonic position as the Silvretta Nappe, the two being only separated from each other by the Engadine Fault. In the area between Zernez and Scuol, the steeply SE-dipping Engadine Fault appears as a normal fault in cross-section (Trümpy et al. 1997) that shows more than 5 km vertical downthrow of the southeastern compartment (S-charl - Sesvenna Nappe) relative to the northwestern compartment (Silvretta Nappe). This extension was associated with sinistral strike-slip motion along the – in this area – sinistrally transtensive Engadine Fault (Schmid & Froitzheim 1993). As a consequence of this faulting, the Silvretta Nappe located north of this fault wedges out in a triangular area northeast of Zernez, only to reappear again in the form of the so-called “Oberer Gneiszug” (Eugs ter 1985) in map view. The latter is a narrow band of Sesvenna basement that rims the southeastern part of the Lower Engadine Window between Scuol and Nauders (Trümpy et al. 1997).