Falda della Margna

Rappresentazione e statuto

Colore CMYK

N/A

Colore RGB

R: 241 G: 239 B: 237

Rango

falda

Uso

Unità in uso.

Status

valido

Nomenclatura

Deutsch

Margna-Decke

Français

Nappe de la Margna

Italiano

Falda della Margna

English

Margna Nappe

Origine del nome

Piz da la Margna (GR)

Varianti storiche

Margnadecke (Staub 1917b, Wilhelm 1933, Staub 1934, Spillmann 1993), Margna-Decke bzw. Margna-Zug (Staub 1946), Falda Margna (Godenzi 1963), Margna-Decke (Schmutz 1976), Margna-Decke = Margna nappe (Hermann & Müntener 1992), Margna Nappe (TK500 / Gouffon et al. 2024)

Descrizione

Descrizione

Kontinentaler Ursprung (bzw. intra-oceanic high). Heutige Position zwischen zwei ophiolitische Einheiten: Malenco-Avers (unten) und Platta-Decke (oben).

Gerarchia e successione

Unità di rango inferiore

• Maloja-Teildecke
• Fedoz-Mulde
• Fora-Teildecke

Limite superiore

Ostalpin

Limite inferiore

Malenco-Forno-Lizun-Decke

Geografia

Estensione geografica

Bernina-Massiv, Val Poschiavo. Nordwestlich der Engadiner Linie findet sich die Margna-Decke (resp. Maloja-Teildecke) und die Fex-Schuppenzone im Gebiet des westlichen Silser Sees wieder. Die Margna-Decke keilt am Septimerpass zwischen den Lizun-Grünschiefern und der Platta-Decke, mit denen sie verfaltet ist, aus (Liniger 1992).

Paleogeografia e tettonica

Paleogeografia

margine continentale adriatico :

southern continental margin / platform

Termini generici

• Margna

Tipo di origine

• tettonico

Referenze

Definizione

Staub R. (1918) : Geologische Beobachtungen am Bergellermassiv. Vjschr. Natf. Ges. Zürich 63, 1-18

Revisione

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

p.82: The Margna Nappe is thrust over the ophiolitic Malenco-Forno-Lizun Nappe and is divided into two W-facing flat-lying antiformal basement cores separated by a thrust fault highlighted by a thin Triassic sedimentary band (Liniger & Guntli 1988, Spillmann 1993, Spillmann & Trommsdorff 2007). The nappe reached epidote-amphibolite-facies conditions during Late Cretaceous deformation (Guntli & Liniger 1989). The basement cores include upper crustal granitoids and paragneisses, as well as lower crustal pelitic pre-Alpine granulites and Permian gabbros. The exhumation of the lower crustal parts of the basement is due to hyperextension at an ocean-continent transition between the ophiolites of the Malenco-Forno-Lizun Nappe and the continental basement of the future Margna Nappe (Hermann & Müntener 1996). The Mesozoic cover of the Margna Nappe is mainly developed at the top of the nappe, where it forms a syncline that is believed to link the Margna Nappe to the overlying Sella Nappe. However, the contact between the sediments of the overturned limb and the basement of the Sella Nappe is marked by a thrust fault.