Bifertengrätli-Formation

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Representation and status

Index
hB
Color CMYK
40 / 20 / 40 / 0
Color RGB
R: 160 G: 180 B: 160
Rank
lithostratigraphic Formation
Validity
Unit is in Use
Status
valid formal name
Status discussion

Nomenclature

Deutsch
Bifertengrätli-Formation
Français
Formation du Bifertengrätli
Italiano
Formazione del Bifertengrätli
English
Bifertengrätli Formation
Origin of the Name

Bifertengrätli (GL), am Tödi

Historical Variants

Quarzporphyr auct., Bifertengrätliserie = Bifertengrätlischichten (Widmer 1949), Bifertengrätli-Serie (Rutsch et al. 1966), Bifertengrätli Formation (Franks 1968 p.59, Berger et al. 2017), Karbon?sedimente = Oberkarbon = Bifertengrätliformation (Pfiffner 1972), Bifertengrätliformation (Böhm 1986)

Description

Description

Vulkanische und sedimentäre Gesteine. Details siehe einzelne Members. Conglomerates, breccias and coarse sandstones are the most abundant sediments and many of these coarse clastic rocks contain a large amount of volcanic debris…

Components

Fossil Content
  • plants : Plantae

Calamites suckowi Bgt., Annularia stellata Schl., Pecopteris aus der Gruppe der P. cyathea Schl., P. arborescens Schl., P. plumosa Artis, Linopteris münsteri Eichw., Neuropteris ovata Hoffm., Cyclopteris cf. trichomanoides Bct. (Jongmans 1950)

Age

Age at top
  • Late Pennsylvanian
Note about top

frühestes Stephanien

Age at base
  • Late Pennsylvanian
Note about base

Westphalien D

Dating Method

Pflanzen des Westphalien-D bis frühestes Stéphanien am Tödi (Escher 1911, Jongmans 1950 und 1960).

Geography

Geographical extent
Aarmassiv im Gebiet Sandalp-Bifertengrätli.
Type area
Tödi (GL/GR)

Palaenography and tectonic

Paleogeography
European Continent
Tectonic unit (resp. main category)
Kind of protolith
  • sedimentary
  • volcanic

References

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.48: The Bifertengrätli Formation represents a key unit for the understanding of the lithostratigraphic architecture of the Late Carboniferous sequences and the evolution of the late Variscan deformation history (Fig. 6, HÜGI 1941, WIDMER 1949, FRANKS 1966, 1968 a, b). In addition to a detailed description of the stratigraphic sequence and the reconstruction of the different volcanic and sedimentary facies, FRANKS (1966, 1968 a, b) elaborated the age relationships between the different units outcropping in the Tödi area. Based on this study it was concluded that the Bifertengrätli Formation is younger than the Tödi Granite Complex, that the Bifertenfirn Formation (p. 34) is older than the Tödi Granite Complex as indicated by intrusive contacts, and that the Bifertenfirn Formation was deformed and metamorphosed before the intrusion of the Tödi Granite Complex. At this locality, the Variscan chronology in the Central Alps was constrained: fossil plants, dated by JONGMANS (1960) as Pennsylvanian (Westphalian D–Stephanian), were found in the sandstone of the Bifertengrätli Formation.

  • Sandalp-Rhyolith

    Name Origin

    Untere Sandalp (GL)

    Rank
    lithostratigraphic unit
    Status
    local name (informal)
    Age
    Gzhelian
  • «Lacustrine Member»

    Rank
    lithostratigraphic Member (Subformation)
    Status
    informal term
    Age
    Pennsylvanian
  • «Estuarine Member»

    Rank
    lithostratigraphic Member (Subformation)
    Status
    informal term
    Age
    Pennsylvanian
  • Grünhorn-Member

    Name Origin

    Grünhornhütte (GL)

    Rank
    lithostratigraphic unit
    Status
    informal term
    In short
    Unterer Teil der Bifertengrätli-Formation, bestehend aus grobklastischen, quarzreichen, konglomeratischen und brekziösen Gneisen, Quarziten und quarzitischen meist grünen Phylliten, sowie tuffitischen Lagen. Charakteristischen Brocken von schwarzem Tonschiefer.
    Age
    Late Carboniferous (= Pennsylvanian)
  • «Basiskonglomerat» (Bifertengrätli-Fm.)

    Name Origin

    Bifertengrätli (GL), Fridolinshütte / Ochsenstock ?

    Rank
    lithostratigraphic Bed
    Status
    informal term
    In short

    Grober Konglomerat, z.T. mit Effusivmaterial.

    Age
    Pennsylvanian
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