Val-Gliems-Formation

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Representation and status

Index
P-Gl
Color CMYK
(23%,0%,13%,39%)
Color RGB
R: 120 G: 155 B: 135
Rank
lithostratigraphic Formation
Validity
Unit is in Use
Status
informal term

Nomenclature

Deutsch
Val-Gliems-Formation
Français
Formation du Val Gliems
Italiano
Formazione della Val Gliems
English
Val Gliems Formation
Origin of the Name

Val Gliems (GR), Sumvitg

Historical Variants

Vals Gliems Metasediments (Franks 1968), Val-Gliems-Formation (Böhm 1986, Gisler 2018), Val Gliems Formation (Berger et al. 2017)

Nomenclatorial Remarks

Knotenschiefer, Konglomeratgneis

Hierarchy and sequence

Superordinate unit
Units at roof
Upper boundary

Sandpass-Formation bzw. Mesozoische Sedimente des Autochtons

Lower boundary

Altkristallin im Norden, Südlicher Aaregranit im Süden.

Age

Age at top
  • Early Carboniferous (= Mississipian)
Age at base
  • Early Paleozoic
Dating Method

Prä-Viséen (intrudiert durch der Tödi-Granit).

Geography

Geographical extent
Chrüzlital, oberes Val Strem/Calmut, Val Cavardiras, Val Russein, Val Gliems.

References

Definition
Böhm C. (1988) : Vulkanoklastite im östlichen Aarmassiv (Val Russein, Graubünden). Schweiz. mineral. petrogr. Mitt. 68/3, 501–508
Definition
Berger Alfons, Mercolli Ivan, Herwegh Marco, Gnos Edwin (2017) : Geological Map of the Aar Massif, Tavetsch and Gotthard Nappes. Geological Special Map 1:100'000, Explanatory Notes 129

p.34: BÖHM (1988) defined the Val Gliems Formation. He was the first to recognise the volcanic and volcaniclastic character and described in detail the internal stratigraphic relationships. The Val Gliems Formation can be subdivided into two sequences: a volcaniclastic sequence, and a metasedimentary (metapelitic) sequence (BÖHM 1988). The metapelitic sequence is identical to the “phyllite unit” of EUGSTER (1951), whereas the “banded psammitic schists and black pelitic schists” of EUGSTER (1951), as well as the “upper and the lower conglomerate layer” of FRANKS(1968 b) all correspond to the volcaniclastic sequence of BÖHM (1988). The volcanic rocks vary in composition from dacitic to rhyodactic and show a calc-alkaline affinity (BÖHM 1988). On the base of its stratigraphic reconstruction, BÖHM (1988) interpreted the structural organisation of the Val Gliems Formation as a large fold with a steeply plunging fold axis. The upper age limit of the Val Gliems Formation is defined by the age of the granite intruding along its northwestern margin. This granite is the western continuation of the Visean Tödi Granite (pers. comm.C.Gisler) and not the eastern end of the Asselian Central Aar Granite, as proposed by EUGSTER (1951) and VÖGELI (1988). Thus, the situation in the Val Gliems is the same as in the Bifertenfirn area where the granitoids of the Tödi Granite Complex intrude the metasedimentary and volcaniclastic rocks of the Bifertenfirn Formation. Besides lithological and structural similarity of the Bifertenfirn Formation and Val Gliems Formation (FRANKS 1968 b, BÖHM 1988), these intrusive relationships confirm the pre-Visean age of the Val Gliems Formation and justify the attribution of the two formations to the Cavardiras Group.

  • Metapelitische Abfolge (Val-Gliems-Fm.)

    Rank
    petrographic facies
    Status
    informal term
    In short
    Metapelitische Einlagerungen in der Val-Gliems-Formation.
    Age
    Early Paleozoic
  • Metavulkaniklastische Abfolge (Val-Gliems-Fm.)

    Rank
    petrographic facies
    Status
    informal term
    In short
    Regelmässig aufgebaute, zyklische vulkanoklastiche Abfolge der Val-Gliems-Formation : basale konglomeratische Lage, dacitischer Tuff, ignimbritischer Tuff (Schlacken-Fiamme). Diese Abfolge wird durch die Einlagerung von Peliten unterbrochen.
    Age
    Early Paleozoic
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