Liesberg-Member

Representation and status

Index

i5L

Color CMYK

(3%,0%,31%,31%)

Color RGB

R: 170 G: 175 B: 120

Rank

lithostratigraphic Member (Subformation)

Validity

Unit is in Use

Status

valid formal name

Scs Note

Die Zuordnung des Members zu zwei Formationen stellt einen Kompromiss dar um verschiedenen Experten gerecht zu werden.

Nomenclature

Deutsch

Liesberg-Member

Français

Membre de Liesberg

Italiano

Membro di Liesberg

English

Liesberg Member

Origin of the Name

Liesberg (BL), Naturschutzgebiet Tongrube Andil

Historical Variants

Couches de Liesberg (Rollier 1888 p.71), Liesberg-Schichten (Rollier 1895, Ziegler 1962 S.29, Bolliger 1968, Bolliger & Burri 1970 S.69), Liesbergschichten (Pümpin 1965), Liesberg Member (Gygi & Persoz 1986 p.395, Gygi 2000c)

Nomenclatorial Remarks

Terrain à chailles siliceux, Rauracien inférieur, Glypticien, Glypticus-Schichten, Florigemma-Schichten, Fringeli-Schichten, Thamnastreen-Schichten

Description

Description

Graue Mergel mit Einlagerungen von hermatypen Korallen, Brachiopoden, Bivalven und Echinodermen. Viele Fossilien sind silifiziert. Mächtigkeit kalkiger Anteil: ca. 7m, mergeliger Anteil: ca. 8 m.

"graubraune Korallenkalke mit mergeligen Zwischenlagen" [Pümpin 1965 S.812]; "Im Unterschied zur St-Ursanne-Formation weisen die Liesberg-Schichten stellenweise einen starken Tonanteil auf." (Bolliger & Burri 1970 S.69); "blau-graue Mergel mit Kalkkonkretionen und Korallen" (Gygi 2000b S.135)

Bis zu 30% des Gesteinsvolumens werden von Lagen ellipsoidaler und dünner tellerförmiger Korallen («Schwarten») eingenommen. Typisch sind Verkieselungen in Form von massiven, länglichen Knollen, von ganzen Fossilien, z. B. Brachiopoden, oder von Bruchstücken davon.

Thickness

Durchschnittliche Mächtigkeit von 13 m (ca. 25 m an der Typlokalität) ; 10-25 m (Gygi 2000c).

Components

• corals
• crinoids
• echinoids

Hierarchy and sequence

Superordinate unit

• Formation de St-Ursanne
• Bärschwil-Formation

Subordinate units

• «Kalkiges Liesberg-Member»
• «Mergeliges Liesberg-Member»

Units at roof

• Formation de St-Ursanne
• Chestel-Member
• Grellingen-Member

Units at floor

• Bärschwil-Formation
• Membre de Sornetan

Upper boundary

Das Liesberg-Member endet mit der letzten Mergelzwischenlagerung. Nur einzelne Mergellagen treten noch in der St-Ursanne-Formation auf. Die Verkieselungen hingegen gehen nach oben weiter.

Lower boundary

Das Liesberg-Member beginnt mit dem ersten Einsetzen von Korallen über den Sornetan-Mb..

Age

Age at top

• middle Oxfordian

Note about top

Transversarium-Z., Antecedens-Sz.

Age at base

• middle Oxfordian

Note about base

Transversarium-Z., Antecedens-Sz.

Dating Method

Biostratigraphie: Ammoniten (indirekt): Funde aus dem Hangenden (St-Ursanne-Formation) und Liegenden (Sornetan-Member), siehe Gygi (2000b: 136)

Geography

Geographical extent

Nordwestschweiz. Dokumentiertes proximalstes Vorkommen befindet sich nahe Bure (JU). Die Lage des distalsten Vorkommens ist nicht genau bekannt (Gygi 2000a). Wahrscheinlich keilt die lithostratigraphische Einheit in den angrenzenden Biohermen der St-Ursanne-Formation aus (Gygi & Peroz 1986: pl. 1).

Type area

Birstal/Movelierkette, Berner Jura

Type profile

• Hinter Chestel (BL)
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2599675 / 1249525)
  Note
  • Tongrube Liesbergmühle bei Liesberg (Ziegler 1962, Pl.1 Nr.1, Gygi 2000b Pl.31 Profil RG306 Schichten 99-106)

Reference profiles

• Tongrube Andil (BL)
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2598950 / 1249970)
  Note
  • Komplettes Referenzprofil nördlich Liesberg

Palaenography and tectonic

• Malm

Paleogeography

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

Tectonic unit (resp. main category)

• Jura :
  Juragebirge

Kind of protolith

• sedimentary

Sequence

The Liesberg Member displays three sedimentary cycles; they are marl-dominated at the base and then show an upward-increasing amount of platy corals and serpulids. Sequence boundary Ox4 is placed at the transition from coral limestones to lagoonal oncolites. (Wetzel & Strasser 2001)

Metamorphism

non metamorphic

References

Definition

Rollier Louis (1888) : Etude stratigraphique sur le Jura bernois: les facies du Malm jurassien. Eclogae geol. Helv. 1, 3-88

p.71

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.127: The overlying Liesberg Member is a gray marl with irregularly formed carbonate concretions and very abundant, mainly platy hermatypic corals and a thickness of 10-25 m. p.135: Liesberg Member (Rollier 1888) ; Member of the Bärschwil Formation ; Synonymy: Gygi (2000b. page 54) The name Liesberg Member (Couches de Liesberg) goes back to Rollier (1888. p. 71). It is derived from the village of Liesberg. Canton Baselland. LK 1086 Delémont. where there is a good section of the member in the clay pit of Hinter Chestel near Liesbergmüli. This is section RG 306 that is represented as plate 31 in Gygi (2000b). Gygi (2000b. p. 54) designated beds no. 99-106 of section RG 306 to be the type section of the Liesberg Member. The Liesberg Member is 25 m thick in the type section. The average thickness of the member is only about half as much. The matrix is a blue-gray marl that includes irregularly shaped nodules of calcium carbonate. The nodules can be partly chertified. As much as 30% of the rock volume are hermatypic corals that are mainly discoidal near the base and increasingly ellipsoidal (like bread loafs) towards the top. The corals are accompanied by a profusion of brachiopods. bivalves and echinoderms. Many of the macrofossils are partly chertified. The Liesberg Member occurs only in northwestern Switzerland. The distal boundary of the member is below the coral bioherms at the platform margin ofthe St-Ursanne Formation (Fig. 1). The base of the member is usually clear-cut and is drawn where the first hermatypic corals appear. The upper boundary can be transitional as in the landslide west of Vögeli farm at Bärschwil, Canton Solothurn, LK 1087 Passwang. This outcrop is the "Fringeli" of older authors and is represented as plate 34 in Gygi (2000b). Angela Coe found a large perisphinctid ammonite 2 m below the top of the member in the type section at Liesberg. Unfortunately, the specimen could not be identified. Nevertheless, it can be said that the Liesberg Member represents only a fraction of the Antecedens Subchron of the Transversarium Chron. because ammonites of the Antecedens Subchron have been figured from the Sornetan Member below (Duong 1974. PI. 3, Fig. 1 and Gygi 1995, Fig. 25): Gregoryceras romani (de Grossouvre) and from the upper St-Ursanne Formation above (Gygi 1995, Fig. 14): Perisphinctes (Dichotomosphinctes) dobrogensis Simionescu.

Important Publications

Bolliger W., Burri P. (1970) : Sedimentologie von Schelf-Carbonaten und Beckenablagerungen im Oxfordien des zentralen Schweizer Jura. Beitr. geol. Karte Schweiz N.F. 140, 112 Seiten

Ziegler M. A. (1962) : Beiträge zur Kenntnis des unteren Malm im zentralen Schweizer Jura. Mitt. geol. Inst. ETH und Univ. Zürich

Material and varia