Giuv-Syenit
Back to Aar MassifRepresentation and status
- Index
- sigma-G
- Color CMYK
- (0%,60%,47%,16%)
- Color RGB
- R: 215 G: 85 B: 115
- Rank
- lithostratigraphic Formation
- Validity
- Unit is in Use
- Status
- informal term
Nomenclature
- Deutsch
- Giuv-Syenit
- Français
- Syénite du (Piz) Giuv
- Italiano
- Sienite del (Piz) Giuv
- English
- Giuv Syenite
- Origin of the Name
-
Piz Giuv (UR)
- Historical Variants
-
Giuvsyenit = Giufsyenit (Rutsch et al. 1966), Piz Giuv syenite (Franks 1968), Giuv-Syenite [sic] (Purdy & Stalder 1973), Syenit vom Piz Giuf, syenite from Val Giuv, Giuf-Syenit, Giuv Syenite (Berger et al. 2017), Giuv-Syenit (Gisler 2018)
- Nomenclatorial Remarks
-
Müller 1865, Heim 1891, Weber 1904
Description
- Description
-
Mineralbestand (Hauptfazies): rund 50 Vol.% Mikroklin-mikroperthit, 10% Oligoklas-Albit, 7% Orthoklas und Mikroklin, 5% Quarz, 15% Hornblende, 10% Biotit und 3% Apatit, Titanit und Orthit.
- Thickness
- Ca. 13 km lang, mit eine Maximalbreite von 1 km in der Gegend des Piz Giuv.
Hierarchy and sequence
- Superordinate unit
Age
- Age at top
-
- Visean
- Age at base
-
- Visean
- Dating Method
-
334.0 +/-2.5 Ma (Schaltegger & Corfu 1992)
Geography
- Geographical extent
- Östlichen Aarmassiv zwischen Oberalppass und Brunnifirn (Schijenstock, Piz Giuv, Piz Ault).
References
- Definition
-
(2017) :
Geological Map of the Aar Massif, Tavetsch and Gotthard Nappes. Geological Special Map 1:100'000, Explanatory Notes 129
p.37: The Giuv Syenite forms a continuous elongated band stretching from the Oberalppass in the west to the Brunnifirn in the east (HUBER 1948). The mainly strongly foliated syenite to quartz monzonite has a central facies with large K-feldspar phenocrysts outlining magmatic flow structures (Fig. 5). Its southern margin is characterised by an increasing degree of deformation (LABHART 1977). WEBER(1904) and HUBER (1948) reported detailed petrographic descriptions of the Giuv Syenite and of a variety of dykes associated with it (Fig. 5). WEBER (1904) described an intrusive contact of the Central Aar Granite with the Giuv Syenite. SCHALTEGGER et al.(1991) defined the geochemical characteristics of the Giuv Syenite as ultrapotassic and linked this body genetically with the shoshonitic basic and acid rocks of the Punteglias Granite Complex. The age of the Giuv Syenite is 334±2 Ma (Fig. 4, SCHALTEGGER & CORFU 1992). The western termination of the syenite is characterised by its dissolution into apophysis and slices (WEBER 1904). It is therefore not unexpected that the Giuv Syenite wedges out at depth and was not encountered in the Gotthard Base Tunnel (GUNTLI et al. 2016).