strati.ch - Lessico lithostratigrafico della Svizzera

Rappresentazione e statuto

Colore CMYK: siehe Betlis-Fm.
Colore RGB: R: 160 G: 210 B: 120

Rango: Strato litostratigrafico
Uso: Unità in uso.
Status: termine locale (informale)

Nomenclatura

Deutsch: Büls-Bank
Français: Banc de Büls
Italiano: Strato di Büls
English: Büls Bed

Origine del nome: Hinterbüls (SG), Churfristen

Varianti storiche: Cephalopodenbank (Arn. Heim 1916), Ammonitenhorizont an der Basis des Valanginienkalkes (Haus 1937 in: Rutsch et al. 1966), Büls-Schichten (Kuhn 1997), Büls Beds = Büls Member (Föllmi et al. 2007)

Descrizione

Potenza: Max. 5 m (Föllmi et al. 2007)

Componenti

Fossili

ammoniti

Gerarchia e successione

Unità di rango superiore

Betliskalk s.s.

Unità sovrastante

Unità sottostante

Età

Geomorfologia

Primo Valanginiano

Osservazioni sul tetto

Stephanophorus Zone / frühe campylotoxus-Zone (Wyssling 1986, Kuhn 1996)

Età alla base

Primo Valanginiano

Osservazioni sulla base

späte Pertransiens-Zone

Metodo di datazione: Ammoniten-Biostratigraphie (Wyssling 1986, Kuhn 1996, Föllmi et al. 2007).

Geografia

Estensione geografica: Vorarlberg, Ost- und Zentralschweiz.

Paleogeografia e tettonica

Neocomiano
Kreide (Helv.)

Paleogeografia

North Tethyan Shelf (Helv.) :
marge continentale européenne

Termini generici

Helvetic

Tipo di origine

sedimentaria

Referenze

Definizione: Kuhn Oliver (1996) : Der Einfluss von Verwitterung auf die Paläozeanographie zu Beginn des Kreide-Treibhausklimas (Valanginian und Hauterivian) in der West-Tethys. Diss. ETH Zürich

Die Phosphoritbildung der neudefinierten Büls-Schichten findet innerhalb der Pertransiens und Stephanophorus-Zone statt (Unter Valanginian), ...

Revisione: Föllmi Karl B., Bodin Stephane, Godet Alexis, Linder Pascal, van de Schootbrugge B. (2007) : Unlocking paleo- environmental information from Early Cretaceous shelf sediments in the Helvetic Alps: stratigraphy is the key! Swiss J. Geosci. 100, 349-369

p.354: In distal parts of the platform, the lower Betlis Limestone is overlain by an up to 5 m thick and heterogeneous succession, which consists of sandy, glauconitic, hemipelagic carbonates and marl, which include a discrete level of phosphate nodules or a phosphatized hardground (Fig. 2; Fig. 3). This unit is identified both in different regions in Vorarlberg (Austria), as well as in eastern and central Switzerland (Hauswirth 1913; Heim 1910–1916; Haus 1937; Strasser 1979; Felber and Wyssling 1979) and has been defined as “Büls Beds” by Kuhn (1996).

The Büls Member is underlain either by sediments of the Vitznau Formation or of the lower Betlis Limestone (Fig. 2) and overlain by sediments of the hemipelagic Sichel Limestone of the Diphyoides Formation. In the case this latter member is absent, the Büls Member bundle with the overlying Gemsmättli Bed and forms a single phosphate-rich bed (Kuhn 1996). This is the case for example at the type locality of the Gemsmättli Bed in the Pilatus region (Wyssling 1986).

The Büls Member includes the oldest drowning unconformity within the Helvetic platform succession, and documents a first phase of highly reduced carbonate production on the platform (Föllmi et al. 1994, 2006). Its age is constrained by ammonite biostratigraphy in occurrences in Vorarlberg and eastern Switzerland and encompasses the late pertransiens and early campylotoxus zones (Wyssling 1986; Kuhn 1996).

Büls-Bank