«Unterer Betliskalk»

Rappresentazione e statuto

Colore CMYK

(0%,0%,0%,100%)

Rango

unità litostratigrafia

Uso

Unità non usata

Status

termine scorretto (informale)

Nomenclatura

Deutsch

«Unterer Betliskalk»

Français

«Unterer Betliskalk»

Italiano

«Unterer Betliskalk»

English

«Lower Betlis Limestone»

Varianti storiche

Unterer Teil des Valangienkalkes = brauner Echinodermenkalk (Arn. Heim 1916), Lower Betliskalk = lower Betlis member (Föllmi et al. 2006), lower Betlis Limestone (Föllmi et al. 2007)

Descrizione

Potenza

25-30 m (Heim 1916) ; max. 100 m (Föllmi et al. 2007).

Gerarchia e successione

Unità di rango superiore

• Betlis-Formation

Unità di rango inferiore

• Spitzern-Member

Unità sovrastante

• Büls-Bank

Limite inferiore

Föllmi et al. 2007: The switch-over from the deposition of the upper Oehrli Limestone to that of the overlying Betlis Formation near the Berriasian-Valanginian boundary represents a major turning point in the evolution of the Helvetic carbonate platform. The Berriasian photozoan mode of carbonate production is replaced by a heterozoan mode, which is repeatedly interrupted by episodes of incipient drowning (Fig. 2; Föllmi et al. 1994, 2006) and which lasted until the early Late Barremian.

The limit between these two carbonate units itself embodies a sequence boundary which on the platform is marked by karstified and iron-stained emersion horizons and perforated hardgrounds (Burger 1985, 1986; Mohr 1992a).

Età

Geomorfologia

• Primo Valanginiano

Osservazioni sul tetto

Unterhalb der Büls-Bank (pertransiens-Zone; Föllmi et al. 2007)

Età alla base

• Primo Valanginiano

Osservazioni sulla base

pertransiens-Zone

Metodo di datazione

Ammoniten in der hangende Büls-Bank (Kuhn 1996, Föllmi et al. 2007).

Geografia

Estensione geografica

Mürtschenstock, Säntis, Mattstock.

Paleogeografia e tettonica

Termini generici

• Helvetic

Tipo di origine

• sedimentaria

Referenze

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.353: On top of the thin unit of sandy marl [= Vitznau Formation] or directly on top of the upper Oehrli Member, a succession of platform carbonates is preserved (lower Betlis Limestone; Fig. 2; Strasser 1979, 1982; Burger & Strasser 1981; Kuhn 1996), which consists of maximally 100 m of a sandy grain- and packstone rich in echinoderms, bryozoans, bivalves, brachiopods, benthic foraminifera, and calcareous algae (Strasser 1979, 1982).