Adula-Decke
Back to Soja-DeckeRepresentation and status
- Index
- As
- Color CMYK
- N/A
- Color RGB
- R: 241 G: 239 B: 237
- Rank
- nappe
- Validity
- Unit is in Use
- Status
- valid
- Scs Note
-
cf. Parco dell'Adula (BAFU)
Nomenclature
- Deutsch
- Adula-Decke
- Français
- Nappe de l'Adula
- Italiano
- Falda dell'Adula
- English
- Adula Nappe
- Origin of the Name
- Historical Variants
-
Aduladecke (Kündig 1926a, Weber 1966), Aduladecke = Schieferunterlage der Schamserdecken (Wilhelm 1933), Aduladecken (Staub 1934), Falda Adula (Godenzi 1963), Ricoprimento Adula = complesso Adula (Bianconi 1971), falda Adula (Sciesa 1991), unità di basamento dell'Adula-Cima Lunga (Dal Piaz et al. 1992a), Adula nappe (Partzsch & Meyre 1996, Cavargna-Sani 2013), Falda dell'Adula = Adula-Decke (Schenker, Bl. Osogna), Adula Nappe (TK500 / Gouffon et al. 2024)
Description
- Description
-
"Cette unité est caractérisée par une structure stratiforme très prononcée de son matériel ancien: des micaschistes, des paragneiss, des gneiss granitoïdes (à phengite dans la partie nord) et des amphibolites alternent à toutes les échelles (cm à plusieurs centaines de m). Dans la partie frontale, où la structure est nettement dominée par la tectonique en nappe, un laccolithe de granite vraisemblablement hercyniens (gneiss granitique de la Zervreila) a été incorporé au bâti alpin. Vers le sud, le cristallin Adula entre de plus en plus dans le domaine du métamorphisme intensif et de la déformation alpine de type profond des gneiss lépontiniques; entre la Mesolcina et la vallée de la Mera, il y a des roches migmatitiques." Trümpy 1970 p.14
- Thickness
- 2500-5000 m (Mayerat Demarne 1994)
Hierarchy and sequence
- Subordinate units
- Units at roof
- Units at floor
Geography
- Geographical extent
- Vals - Adula - Misox - Calanca
Palaenography and tectonic
- Paleogeography
-
Northern Tethyan Margin
:
Paleo-European Margin , South Helvetic Domain - Tectonic unit (resp. main category)
- Kind of protolith
-
- tectonic
- Metamorphism
- metamorphic
- Metamorphic facies
-
- eclogite facies
- amphibolite facies
- greenschist facies (epizone)
References
- Definition
-
(2024) :
Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern
p.53: The Adula Nappe consists of a Paleozoic crystalline basement made up of orthogneisses (Variscan and older), paragneisses (mostly clastic metasediments, containing also Paleozoic carbonate rocks) and lenses of mafic and ultramafic rock. Several mafic lenses experienced high-pressure Alpine metamorphism under eclogite-facies conditions, followed by decompression at Barrovian conditions between amphibolite to greenschist metamorphic facies. Relics of Variscan highpressure metamorphism have also been observed (Sandmann et al. 2014). Lithostratigraphic and tectonic studies of the Adula Nappe show a coherent structure dominated by large folds (e.g., Löw 1987, Cavargna-Sani et al. 2014b). This nappe was also interpreted as a slice complex created in a tectonic accretionary channel (e.g., Berger et al. 2005a, Pfiffner 2016).
In places, the basement contains a reduced series of Mesozoic sediments preserved in the cores of the synclines (Cavargna-Sani et al. 2014a, b); these Mesozoic sediments were earlier defined as the “internal Mesozoic” (e.g., Löw 1987). Mesozoic sediments may also cover the basement gneisses at the nappe border. From north of the Zervreilasee to San Bernardino, Triassic slices alternate with basement slices in a 300 m thick mélange zone known as the “Lower Vals Slices”, which is considered the top of the nappe. As in the other Lepontic units, these sediments are also typical for the most distal part of the thinned European margin (see p. 44).
The lower boundary of the Adula Nappe follows the shear zone on the top of the Simano Nappe (§ 5.8), the frontal part is bordered by the Soja and the Piz Terri-Lunschania nappes, up to the Valser Tal. From here to the south, the Adula Nappe is overlain by Lower Penninic units: first the Vals Slices (previously described as “Upper Vals Slices”), then the Aul Nappe and finally the Tomül Nappe.
- Important Publications
-
(1974) : Post-nappe folding in the western Lepontine Alps. Eclogae geol. Helv. 67/2, 333-348(2013) : The Adula nappe: stratigraphy, structure and kinematics of an exhumed high-pressure nappe. Thèse de doctorat, Université de Lausanne, 153 p.