Umbrail–Chavalatsch-Schuppen
Back to Umbrail-Chavalatsch SlicesRepresentation and status
- Color CMYK
- N/A
- Color RGB
- R: 241 G: 239 B: 237
- Rank
- tectonic slice
- Validity
- Unit is in Use
- Status
- valid
Nomenclature
- Deutsch
- Umbrail–Chavalatsch-Schuppen
- Français
- Écailles de l'Umbrail–Chavalatsch
- Italiano
- Scaglie dell'Umbrail–Chavalatsch
- English
- Umbrail–Chavalatsch Slices
- Origin of the Name
- Historical Variants
-
Engadiner-Dolomiten = Umbrail-Decke (Roesli 1927), Umbraildecke (Staub 1934), Umbrail-Decke (Staub 1946), Umbrail-Chavalatsch-Schuppenzone = Umbrail-Chavalatsch imbricate zone (Bl. Sta. Maria-Münstair, Schmid 1973), Schuppe des Umbrailgebietes (Trümpy 1972), zona a scaglie Umbrail-Chavalatsch (Montrasio et al. 2012), Umbrail-Chavalatsch Slices (TK500 / Gouffon et al. 2024)
- Nomenclatorial Remarks
-
(Piz) Lad Scholle (Van Loone 1960) [non: Unterengadiner Piz Lad !!!], Zone d'écailles de l'Umbrail-Chavalatsch (Ecaille de Terza incl.)
Description
- Description
-
Schuppen («imbricate zone») im liegenden des Ötztal-Kristallins, bestehend einerseits aus abgeschürfte spät-triassische Sedimente der «Engadiner Dolomiten» und andererseits aus vor-mesozoischen Kristallingesteinen.
Geography
- Type area
- Engadiner Dolomiten (GR)
Palaenography and tectonic
- Tectonic unit (resp. main category)
- Kind of protolith
-
- tectonic
References
- Definition
-
(1973) :
Geologie des Umbrailgebiets. Eclogae geol. Helv. 66/1, 101-210
p.101: The general structure is that of an imbricate zone ("Umbrail-Chavalatsch-Schuppenzone"), composed of two lithologically and tectonically separate units: 1. Upper Triassic sediments of the Engadine Dolomite facies ("Raibler Schichten" and "Hauptdolomit" formations) which are sheared off from their stratigraphical base and 2. pre-Mesozoic basement slices. This "Schuppenzone" represents a basal imbrication underneath and in the western front of a higher thrust complex, the "Ötztal" basement block, which overrode the sediments of the "Engadiner Dolomiten" shearing them off their stratigraphical base. The décollement horizon lies mainly in the "Raibler Schichten" formation. Geometrical evidence indicates that the relative displacement of the "Ötztal" basement was in a western direction during this phase. The tectonic interpretation is partly based on facies analysis derived from petrological studies of the basement rocks (part I) and stratigraphical studies of the Mesozoic sediments (part II). The main weight, however, is placed on a detailed description of the structure within and outside the main area of investigation (part III).
- Definition
-
(2024) :
Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern
p.97: This slice complex consists of two geographically separated parts. [...] The larger Umbrail-Chavalatsch Slices further to the east consist of a very complicated zone of imbrication (Schmid 1973), composed of two lithologically and tectonically separate units: firstly, of slices of Late Triassic sediments of the Raibl and Hauptdolomit groups, which were sheared off their original stratigraphical underpinnings, i.e., the S-charl-Sesvenna Nappe, and secondly, of pre-Mesozoic basement slices that are correlated with the tectonically higher basement of the Ötztal Nappe Complex that tectonically overlies the S-charl-Sesvenna nappe. Hence, these WNW-facing Umbrail-Chavalatsch Slices are interpreted as a basal imbrication underneath the Ötztal Nappe Complex, which overrode the sediments of the S-charl-Sesvenna Nappe, shearing them from their former stratigraphical base and imbricating them with basement slice pulled out of its base (Schmid 1973). In the east, this zone of imbrication with the Trupchun-Braulio Thrust at its base completely replaces the Quattervals Nappe and bends around into a NE–SW strike south of Sta. Maria. In the area of Piz Chavalatsch, the zone of imbrication directly overlies the Vinschgau Shear Zone of the Campo Nappe Complex and hence occupies a tectonic position identical to that of the Ötztal Nappe Complex (Conti 1997).