Bifertengrätli-Formation

Représentation et statut

Index

hB

Couleur CMYK

40 / 20 / 40 / 0

Couleur RGB

R: 160 G: 180 B: 160

Rang

Formation lithostratigraphique

Usage

Ce terme est en usage.

Status

terme formel valide

Discussion du statut

Nomenclature

Deutsch

Bifertengrätli-Formation

Français

Formation du Bifertengrätli

Italiano

Formazione del Bifertengrätli

English

Bifertengrätli Formation

Origine du nom

Bifertengrätli (GL), am Tödi

Variantes historiques

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…

Composants

• végétaux : 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)

Hiérarchie et succession

Unité hiérarchiquement supérieure

• Spät- bis postvariszische Sedimente und Vulkanite des Aar-Massivs

Unités hiérarchiquement subordonnées

• Sandalp-Rhyolith
• «Lacustrine Member»
• «Estuarine Member»
• Grünhorn-Member
• «Basiskonglomerat» (Bifertengrätli-Fm.)

Âge

Âge au sommet

• Pennsylvanien tardif

Note sur le sommet

frühestes Stephanien

Âge à la base

• Pennsylvanien tardif

Note sur la base

Westphalien D

Méthode de datation

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

Géographie

Extension géographique

Aarmassiv im Gebiet Sandalp-Bifertengrätli.

Région-type

Tödi (GL/GR)

Paléogéographie et tectonique

Paléogéographie

continent européen

Termes génériques

• Aar

Type de protolithe

• sédimentaire
• volcanique

Références

Révision

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.