Russein-Diorit
Back to Aar MassifRepresentation and status
- Index
- delta-R
- Color CMYK
- (0%,51%,49%,16%)
- Color RGB
- R: 215 G: 85 B: 115
- Rank
- lithostratigraphic Formation
- Validity
- Unit is in Use
- Status
- informal term
Nomenclature
- Deutsch
- Russein-Diorit
- Français
- Diorite du Val Russein
- Italiano
- Diorite della Val Russein
- English
- Russein Diorite
- Origin of the Name
-
Untere Val Russein (GR)
- Historical Variants
-
Ruseindiorit (Wehrli 1896, Rutsch et al. 1966), Diorit von Val Russein (de Quervain 1969), Val Russein-Diorit, Russein Diorite (Berger et al. 2017), Russein-Diorit (Gisler 2018)
Hierarchy and sequence
- Superordinate unit
Age
- Age at top
-
- Middle Pennsylvanian
- Age at base
-
- Early Pennsylvanian
- Dating Method
-
347.3 +/-1.8 Ma (Schaltegger, unpubl.)
Geography
- Geographical extent
- Südöstlische Rand des Aar-Massivs im Gebiet des Val Russein.
References
- Definition
-
(1896) :
Das Dioritgebiet von Schlans bis Disentis im Bündner Oberland; geologisch-petrographische Studie mit einer geol. Karte. Beitr. geol. Karte Schweiz (N.F.) 6, 78 Seiten
S.21: a. Ruseindiorit.
Weitaus am häufigsten ist das Gestein des Ruseinstockes ein normaler massiger Hornblendediorit von feinem Korn. Grünlichgraue Feldspäte und schwarze, fast metallglänzende Hornblendekrystalle sind auf frischem Bruch zu erkennen. Pyrit ist ständiger Bestandteil und entweder schon von blossem Auge (Würfel bis 3 mm Seitenlänge) oder jedenfalls unter der Lupe sichtbar. Kleine Drusen mit gelblichem Verwitterungsmaterial (Chlorit und Epidot, sehr selten Quarz) sind charakteristisch. (...)
- Definition
-
(2017) :
Geological Map of the Aar Massif, Tavetsch and Gotthard Nappes. Geological Special Map 1:100'000, Explanatory Notes 129
p.40: Bodies of hornblende granite, porphyric granite and diorite of different dimensions have been mapped by WEHRLI (1896) and WEBER (1922) in the region of the Val Russein at the southeastern border of the Aar Massif. On the present map these different granitic bodies and the diorite were grouped into units called Munt Dado Granite and Russein Diorite, respectively. Both magmas intruded the Gärsthorn and Sogn Placi Gneiss Complexes of the Ausserberg-Avat Zone and the Late Carboniferous metasedimentary and volcaniclastic rocks of the Val Lumpegna Formation. Petrographic details on some of these bodies can be found in WEHRLI (1896). WEHRLI (1896) describes two types of diorite: (1) massive amphibole diorites and (2) foliated diorites. Towards the west, the diorites grade into greenschist (WEHRLI 1896, NIEDERER 1932, NIGGLI 1944). Despite this tectonic overprinting, it is possible to distinguish these intrusive rocks from the granitic gneisses and amphibolites of the polycyclic metamorphic basement of the Ausserberg-Avat Zone (Gärsthorn Gneiss Complex). A more complex zone of mafic rocks, forming layers of different thickness, occurs within the gneisses of the Ausserberg-Avat Zone north of Sedrun. This zone is characterised by a heterogeneous mingling of gabbroic, dioritic, granodioritic and syenitic rocks (HUBER 1948). These dioritic rocks are macroscopically slightly different from the Russein diorites of WEHRLI (1896); an affinity of these enclaves to the Curtin Monzodiorite (Rötifirn Group) cannot be excluded. However, on the present map sheet these enclaves were not depicted. In absence of robust dating of the Munt Dado Granite and the Russein Diorite, and based on the petrographic affinity with the Düssi Diorite, both
units were assigned to the Fruttstock Group.
The question arises if the Bugnei Granodiorite, formerly related by NIGGLI (1944) to the dioritic occurrences of the Val Russein, also belongs to the Fruttstock Group. This body with probable age similar to the plutonic rocks of the Fruttstock Group was strongly affected by intense deformation along the southeastern border of the Aar Massif (Clavaniev Zone, see p. 59 f.) at the contact with the Tavetsch and KELLER (1999), the Bugnei Granodiorite was assigned to the Clavaniev Zone.