Liesberg-Member

Torna a Alto Reno, parta nord

Rappresentazione e statuto

Index
i5L
Colore CMYK
(3%,0%,31%,31%)
Colore RGB
R: 170 G: 175 B: 120
Rango
Membro litostratigrafico (Sotto-formazione)
Uso
Unità in uso.
Status
termine formale valido
SCS nota
Die Zuordnung des Members zu zwei Formationen stellt einen Kompromiss dar um verschiedenen Experten gerecht zu werden.

Nomenclatura

Deutsch
Liesberg-Member
Français
Membre de Liesberg
Italiano
Membro di Liesberg
English
Liesberg Member
Origine del nome

Liesberg (BL), Naturschutzgebiet Tongrube Andil

Varianti storiche
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)
Nota sul nome
Terrain à chailles siliceux, Rauracien inférieur, Glypticien, Glypticus-Schichten, Florigemma-Schichten, Fringeli-Schichten, Thamnastreen-Schichten

Descrizione

Descrizione

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.

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

Componenti

Fossili
  • coralli
  • crinoidi
  • echinoidi

Gerarchia e successione

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

Età

Geomorfologia
  • Oxfordiano medio
Osservazioni sul tetto

Transversarium-Z., Antecedens-Sz.

Età alla base
  • Oxfordiano medio
Osservazioni sulla base

Transversarium-Z., Antecedens-Sz.

Metodo di datazione

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

Geografia

Estensione geografica
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).
Regione-tipo
Birstal/Movelierkette, Berner Jura
Sezione-tipo
  • Hinter Chestel (BL)
    Caratteristiche del sito
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Agibilità del sito
    • Steinbruch, Tongrube
    Coordinate
    • (2599675 / 1249525)
    Nota
    • Tongrube Liesbergmühle bei Liesberg (Ziegler 1962, Pl.1 Nr.1, Gygi 2000b Pl.31 Profil RG306 Schichten 99-106)
Sezione di riferimento
  • Tongrube Andil (BL)
    Caratteristiche del sito
    • Obergrenze
    • Untergrenze
    • typische Fazies
    Agibilità del sito
    • Steinbruch, Tongrube
    Coordinate
    • (2598950 / 1249970)
    Nota
    • Komplettes Referenzprofil nördlich Liesberg

Paleogeografia e tettonica

  • Malm
Paleogeografia
Northern Tethyan Carbonate Platform (Jura > Helv.) :
Plateforme de Bourgogne, ... = Northern Tethyan Carbonate Platform (NTCP)
Termini generici
Tipo di origine
  • sedimentaria
Sequenza
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)
Metamorfismo
non metamorfo

Referenze

Revisione
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.

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

Materiale e vario

Immagini
Liesberg_typlok
  • «Kalkiges Liesberg-Member»

    Name Origin

    Liesberg/Irtiemont (BL)

    Rango
    unità litostratigrafia
    Statuto
    termine scorretto (informale)
    In breve

    Oberer, mergelig-kalkiger Teil des Liesberg-Mb.

    Age
    Oxfordiano medio
  • «Mergeliges Liesberg-Member»

    Name Origin

    Liesberg/Irtiemont (BL)

    Rango
    unità litostratigrafia
    Statuto
    termine scorretto (informale)
    In breve

    Unterer, vorwiegend mergeliger Teil des Liesberg-Mb.: graue Mergel mit Einlagerungen von hermatypen Korallen, Brachiopoden, Bivalven und Echinodermen. Viele Fossilien sind silifiziert.

    Age
    Oxfordiano medio
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