Laufen-Member

Representation and status

Color CMYK

siehe Balsthal-Formation

Color RGB

R: 170 G: 195 B: 215

Rank

lithostratigraphic Member (Subformation)

Validity

Unit is in Use

Status

valid formal name

Nomenclature

Deutsch

Laufen-Member

Français

Membre de Laufon

Italiano

Membro di Laufen

English

Laufen Member

Origin of the Name

Laufen (BL)

Historical Variants

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)

Nomenclatorial Remarks

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.

Thickness

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

Components

• ostreids
• brachiopods
• echinoids
• bivalves

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

Hierarchy and sequence

Superordinate unit

• Balsthal-Formation

Subordinate units

• «Akzessorische Mumienbänke»

Units at roof

• Verena-Member

Units at floor

• Steinibach-Member

Age

Age at top

• late Oxfordian

Age at base

• late Oxfordian

Dating Method

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

Geography

Geographical extent

Nordwestschweiz.

Type area

Laufental (BL)

Type locality

• Laufen (BL)
  Site particularities
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2604950 / 1252150)
  Note
  • Tal der Schachtele Nördlich Laufen (Gygi 2000c Profil RG457)

Type profile

• Liesberg (BL)
  Site particularities
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2600430 / 1250338)
  Note
  • Zement-Steinbruch (Gygi 2000b Fig.35 und Pl.32)

Point of interest

• Gorges de Court
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Coordinates
  • (2594580 / 1238050)
  Note
  • Hug 2001, Wetzel & Strasser 2001

Palaenography and tectonic

• Malm of the Jura Mountains

Paleogeography

Northern Tethyan Carbonate Platform :
Plateforme de Bourgogne, ... = Northern Tethyan Carbonate Platform (NTCP)

Tectonic unit (resp. main category)

• Jura :
  Juragebirge

Kind of protolith

• sedimentary

Metamorphism

non metamorphic

References

Definition

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

S.13

Definition

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.