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

Details

Ressource 1Request a copy Sous embargo indéterminé.
State: Public
Version: Final published version
Serval ID
serval:BIB_E293EE59C85D
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Basement lithostratigraphy of the Adula nappe: implications for Palaeozoic evolution and Alpine kinematics
Journal
International Journal of Earth Sciences
Author(s)
Cavargna-Sani M., Epard J.-L., Bussy F., Ulianov A.
ISSN-L
1437-3254
Publication state
Published
Issued date
2014
Peer-reviewed
Oui
Volume
103
Pages
61-82
Language
english
Abstract
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.
Create date
28/11/2013 11:14
Last modification date
20/08/2019 17:06
Usage data