Basement lithostratigraphy of the Adula nappe: implications for Palaeozoic evolution and Alpine kinematics

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Etat: Public
Version: Final published version
ID Serval
serval:BIB_E293EE59C85D
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Basement lithostratigraphy of the Adula nappe: implications for Palaeozoic evolution and Alpine kinematics
Périodique
International Journal of Earth Sciences
Auteur(s)
Cavargna-Sani M., Epard J.-L., Bussy F., Ulianov A.
ISSN-L
1437-3254
Statut éditorial
Publié
Date de publication
2014
Peer-reviewed
Oui
Volume
103
Pages
61-82
Langue
anglais
Résumé
The Adula nappe belongs to the Lower Penni- nic domain of the Central Swiss Alps. It consists mostly of pre-Triassic basement lithologies occurring as strongly folded and sheared gneisses of various types with mafic boudins. We propose a new lithostratigraphy for the northern Adula nappe basement that is supported by detailed field investigations, U-Pb zircon geochronology, and whole-rock geochemistry. The following units have been identified: Cambrian clastic metasediments with abundant carbonate lenses and minor bimodal magmatism (Salahorn Formation); Ordovician metapelites associated with amphibolite boudins with abundant eclogite relicts representing oceanic metabasalts (Trescolmen Formation); Ordovician peraluminous metagranites of calc-alkaline affinity ascribed to subduction-related magmatism (Ga- renstock Augengneiss); Ordovician metamorphic volcanic- sedimentary deposits (Heinisch Stafel Formation); Early Permian post-collisional granites recording only Alpine orogenic events (Zervreila orthogneiss). All basement lithologies except the Permian granites record a Vari- scan ? Alpine polyorogenic metamorphic history. They document a complex Paleozoic geotectonic evolution consistent with the broader picture given by the pre- Mesozoic basement framework in the Alps. The internal consistency of the Adula basement lithologies and the stratigraphic coherence of the overlying Triassic sediments suggest that most tectonic contacts within the Adula nappe are pre-Alpine in age. Consequently, me ́lange models for the Tertiary emplacement of the Adula nappe are not consistent and must be rejected. The present-day structural complexity of the Adula nappe is the result of the intense Alpine ductile deformation of a pre-structured entity.
Création de la notice
28/11/2013 10:14
Dernière modification de la notice
20/08/2019 16:06
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