Axen-Decke

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

Axen-Decke

Français

Nappe de l'Axen

Italiano

Falda dell'Axen

English

Axen Nappe

Origine del nome

Axen-Kette (UR), östlich des Urnersees

Varianti storiche

Axen-Teildecke (Schmidt & Preiswerk 1908), Axendecke, --- (Oberholzer 1933), Axen-Decke (Lienert et al. 2003, Hantke et al. 2019)

Descrizione

Descrizione

Oberhelvetische Decke der zentralschweizerischen Alpen (Trias-Paläogen). Hauptmerkmal der Axen-Decke ist der mächtige Malm mit der Schilt-Formation und dem Mergelband zwischen Unterem und Oberem Quintner Kalk.

"Hauptmerkmal der Axen-Decke ist der mächtige Malm mit der Schilt- Formation und dem Mergelband zwischen Unterem und Oberem Quintner Kalk. In der Abfolge der Helvetischen Gesteine sind die weiche, inkompetente Zementstein-Formation und die Öhrli-Mergel ideale Gleithorizonte, auf denen die Kreide als Teildecken (Bächistock-Decke und Silberen-Decken) abgeschert und nach Norden verfrachtet wurde." (Lienert et al. 2003 S.18)

Gerarchia e successione

Unità di rango inferiore

• Toralp-Schuppe
• Silberen-Schuppen
• Bächistock-Schuppe
• Radstock-Schuppen
• Axen-Südschuppe
• Axen-Nordschuppe
• Wissberg-Schuppe
• Schächentaler Windgällen-Schuppen
• Höch Turm-Schuppe
• Friteren-Schuppe
• Bränd-Schuppe

Unità sottostante

• Glarner Deckenkomplex

Età

Geomorfologia

• tardo Eocene

Osservazioni sul tetto

Stad-Formation

Età alla base

• Triassico Medio

Osservazioni sulla base

Röti-Dolomit

Geografia

Estensione geografica

Zwischen Kandertal und Linthal: Buntstock bzw. Kiental/Schilthorn, Brünigpass, Melchtal, Engelberg, Uri Rotstock, Bisital, Klöntal und Glärnisch.

Paleogeografia e tettonica

Termini generici

• Axen

Tipo di origine

• tettonico

Referenze

Definizione

Buxtorf Aug., Künzli E., Rollier Louis (1908) : Geologische Beschreibung des Weissensteintunnels und seiner Umgebung. Beitr. geol. Karte Schweiz (N.F.) 21

Revisione

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

p.40: From the Kander Valley, the Axen and Drusberg nappes represent the eastward continuation of the Wildhorn Nappe Complex. The transition is caused by a synsedimentary fault (Bachli-Giesenen Fault, Hänni & Pfiffner 2001), which led to the development in the east of a very thick marl sequence (earliest Cretaceous Palfris Formation) that acted as décollement layer during Alpine nappe stacking.

Up to the Engelberg Valley, the stratigraphic series of the Axen Nappe and that of the Drusberg Nappe are practically complementary. The Axen Nappe is composed of a Jurassic series with some Triassic fragments in its base and Cretaceous and Paleogene sediments in the eastern part of the area. The Drusberg Nappe consists only of Cretaceous to Paleogene sediments. Between the Engelberg Valley and the Klöntal, where the Axen Nappe series is complemented by overlying Paleogene sediments, the internal structure of the nappe becomes more complex due to the presence of numerous thrusts following additional décollement levels which split the nappe into several slices. In contrast, the stratigraphic series of the Drusberg Nappe does not change. However, three slices of Late Jurassic limestone (Quinten Formation) are present at its base; one is located in the Muotatal and underlies the Palfris Formation (Wissenwand Slice, Hantke et al. 2013), the other two crop out between the Engelberg Valley and the Vierwaldstättersee, intercalated into the Palfris Formation (Maisander Slices, Menkveld 1995); the latter are considered part of the Axen Nappe.

Between the Thunersee and the Vierwaldstättersee, the Drusberg Nappe contains a large-scale open synformal structure which preserves tectonically higher units in its core, from bottom to top: the Habkern Mélange Zone, the Lower Penninic Schlieren Nappe and klippen of the Middle Penninic Préalpes Médianes Nappe. The internal structure of the Axen Nappe changes abruptly across the Engelberg Valley (Pfiffner et al. 2010, Pfiffner 2011) owing to a fault perpendicular to the fold axes and active during nappe formation. In a similar manner, a fault must be assumed along the southeastern part of the Vierwaldstättersee which explains the very different nappe structure of the Axen and the Drusberg nappes on both sides of the lake (Pfiffner et al. 2010, Pfiffner 2011).

East of the Vierwaldstättersee, the two nappes can be traced all the way up to the Linth Valley. On the western flank of this valley, they are underlain by the Glarus Nappe Complex (including the Mürtschen Nappe), while they are replaced by the Glarus Nappe Complex and the Säntis Nappe on the eastern flank. A major N – S oriented fault is assumed to be present along the Linth Valley in order to explain the dramatic change in internal structure of the Helvetic nappes on either side of the valley.