Quattervals-Decke

Représentation et statut

Couleur CMYK

N/A

Couleur RGB

R: 241 G: 239 B: 237

Rang

tectonique

Usage

Ce terme est en usage.

Status

valide

Nomenclature

Deutsch

Quattervals-Decke

Français

Nappe du Quattervals

Italiano

Falda del Quattervals

English

Quattervals Nappe

Origine du nom

Piz Quattervals (GR)

Variantes historiques

Quatervals-Element (Schmid 1973), Quattervals unit (Furrer et al. 1985), Quatervals-Einheit (Dössegger 1987), Quattervals-Teildecke, Quattervals Nappe (TK500 / Gouffon et al. 2024)

Description

Description

Furrer et al. 1985: "An imbricated sheet of Upper Triassic carbonate rocks thrust to the SW or S over the Ortler sediments along the Trupchun-Braulio Line. The Quattervals nappe is part of the S-charl nappe affected by "back-thrusting". It is separated from the S-charl nappe by the complex fault (lag?) of the Gallo Line."

Géographie

Extension géographique

Engadiner Dolomiten (SE der Engadin-Störung).

Paléogéographie et tectonique

Type de protolithe

• tectonique

Références

Révision

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

p.97: The Quattervals Nappe comprises almost exclusively Late Triassic sediments, mostly dolomitic and calcareous formations of the Norian Hauptdolomit Group of considerable thickness overlain by Rhaetian deposits, which became detached from their former substratum along the Carnian Raibl Group during the Cretaceous orogeny (Somm 1965, Dössegg er 1987, Trümpy et al. 1997). The nappe consists of a series of NNE-dipping slices that overthrust the Ortler Nappe along the western part of the Trupchun-Braulio Thrust. These slices discordantly abut against the gently SSE-dipping cover of the “S-charl-Unterbau” located to the northwest along what is referred to as the “Gallo Line” in the literature (Karagounis 1962, Trümpy et al. 1997, see their cross-sections 2 and 3). This Gallo Fault was originally the basal thrust of the Quattervals Nappe and the Umbrail-Terza Slice Complex which were both thrust over the S-charl-Sesvenna Nappe (Schmid 1973, Conti 1997). In its present-day orientation, the Gallo Fault represents a late stage top-WSW normal fault that defines the southeastern limit of a large-scale anticlinorium centered in Val Müstair and the lower Spöl Valley and formed within the S-charl-Sesvenna Nappe to the WSW. Due to this normal faulting overprint, the Quattervals Nappe and Umbrail-Terza Slice Complex in the hangingwall, together with the underling Ortler Nappe became downthrown towards the south by a fault-perpendicular displacement of at least 3 km. According to Conti (1997), this normal fault is of Late Cretaceous age and reactivated a former WNW- directed Late Cretaceous thrust of the Quattervals Nappe over the S-charl-Sesvenna Nappe. According to this author, the provenance of the Quattervals Nappe most probably occurs east-southeast of its present-day outcrop area, having been transported to the WNW together with the Ortler Nappe along the Zebrù Thrust and then over the latter nappe along the Trupchun-Braulio Thrust (see discussion of alternative views in Trümpy et al. 1997). Hence, both the Ortler and Quattervals nappes represent considerably WNW-wards displaced (> 100 km) allochthons in the hangingwall of the Campo Nappe Complex and the S-charl-Sesvenna Nappe.