Laufen-Member

Représentation et statut

Couleur CMYK

siehe Balsthal-Formation

Couleur RGB

R: 170 G: 195 B: 215

Rang

Membre lithostratigraphique (Sous-formation)

Usage

Ce terme est en usage.

Status

terme formel valide

Nomenclature

Deutsch

Laufen-Member

Français

Membre de Laufon

Italiano

Membro di Laufen

English

Laufen Member

Origine du nom

Laufen (BL)

Variantes historiques

Laufenerstein, Kalksteine von Laufen = Sequan (de Quervain 1969), Laufen-Schichten (Gygi 1995 S.13), Roche de Laufon = Laufner Kalk (Bollin 1996), Laufen Member (Gygi 2000c), Membre de Laufon, Calcaire de Laufon (Wildi et al. 2020)

Remarques nomenclatoriales

Untere Balsthal-Formation

Description

Description

Das Laufen-Member besteht aus sehr variablen, geschichteten Kalksteinen der Balsthal-Formation: Mikrite, Oolithe, dolomitische Onkolithe bis zu koralligenen Kalken. Onkoide treten an der Basis vor («akzessorische Mumienbänke»). Häufige Fossilien: Bivalven und Brachiopoden, keine Ammoniten.

Épaisseur

16 m and der Typlokalität (Gygi 2000b/c), bis 25-30 m auf Bl. Chasseral (Aufranc et al. 2017)

Composants

• ostréidés
• brachiopodes
• échinoïdes
• bivalves

Pholadomya, Serpulidae, Zeillerina astartina, Lithacosphinctes (Gygi 1995)

Hiérarchie et succession

Unité hiérarchiquement supérieure

• Balsthal-Formation

Unités hiérarchiquement subordonnées

• «Akzessorische Mumienbänke»

Unités sus-jacentes

• Verena-Member

Unités sous-jacentes

• Steinibach-Member

Âge

Âge au sommet

• Oxfordien tardif

Âge à la base

• Oxfordien tardif

Méthode de datation

Klastische Schüttungen (Gygi & Persoz 1986) und Sequenz-Stratigraphie (Gygi et al. 1998).

Géographie

Extension géographique

Nordwestschweiz.

Région-type

Laufental (BL)

Localité-type

• Laufen (BL)
  Particularités du site
  • typische Fazies
  Accessibilité du site
  • Steinbruch, Tongrube
  Coordonnées
  • (2604950 / 1252150)
  Note
  • Tal der Schachtele Nördlich Laufen (Gygi 2000c Profil RG457)

Typusprofil

• Liesberg (BL)
  Particularités du site
  • typische Fazies
  Accessibilité du site
  • Steinbruch, Tongrube
  Coordonnées
  • (2600430 / 1250338)
  Note
  • Zement-Steinbruch (Gygi 2000b Fig.35 und Pl.32)

Point of interest

• Gorges de Court
  Particularités du site
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Coordonnées
  • (2594580 / 1238050)
  Note
  • Hug 2001, Wetzel & Strasser 2001

Paléogéographie et tectonique

• Malm du Jura

Paléogéographie

plateforme carbonatée nord-téthysienne :
Plateforme de Bourgogne, ... = Northern Tethyan Carbonate Platform (NTCP)

Termes génériques

• Jura :
  Juragebirge

Type de protolithe

• sédimentaire

Métamorphisme

non métamorphique

Références

Définition

Gygi R. A. (1995) : Datierung von Seichtwassersedimenten des Späten Jura in der Nordwestschweiz mit Ammoniten Eclogae Geol. Helv. 88/1, 1-58

S.13

Révision

Gygi R. A. (2000) : Annotated index of lithostratigraphic units currently used in the Upper Jurassic of northern Switzerland. Eclogae geol. Helv. 93/1, 125-146

p.135: Laufen Member (Gygi 1995) ; Member of the Balsthal Formation ; Synonymy: Gygi (2000b. p. 62) The name Laufen Member was proposed by Gygi (1995 p.13). It is derived from the small medieval city of Laufen in Canton Baselland. LK 1087 Passwang. The upper part of the member is currently being quarried as a well-known building stone in the small valley of Schachlete north of Laufen, on the territory of the village of Dittingen (unpublished section RG 457 at coordinates 604.530/253.070). Complete sections of the member close to Laufen are above the cantonal road east of the former cement works at Liesberg (figured by Gygi 2000b. Fig. 35) and in the limestone quarry of the former Liesberg cement works (Gygi 2000b. Pl.32). Gygi (2000b, p. 62) proposed that beds no. 27-48 in this quarry be the type section of the Laufen Member. The member is 16 m thick in this section and is made up of bedded micritic limestone with oncoids near the base. The lithology of the Laufen Member is very variable. Micrite. pelmicrite. oncolite. oolite, oolitic oncolite. dolomitic oncolite or even coral limestone can occur. The Laufen Member is very fossiliferous in some places (Gygi 2000b. Fig. 19). Ostreid bivalves and ribbed brachiopods (Septaliphoria) are common. One ammonite has been found in the upper part of the member in the quarry Schmidlin in the Schachlete valley near Dittingen, Canton Baselland, by J. Jermann. Gygi (1995. Fig. 20) figured this Lithacosphinctes. but he could not identify it. It is only by means of mineral stratigraphy (Gygi & Persoz 1986) and sequence stratigraphy (Gygi et al. 1998) that the member can be dated at the Bimammatum and Hauffianum Subchrons of the Bimammatum Chron. The Laufen Member occurs in northwestern Switzerland. It grades laterally into the Oolithe rousse and into the lower La May Members in the proximal direction. The boundary to the lower Holzflue Member in the distal direction is also a transition.