Membre de Delémont

Representation and status

Color CMYK

N/A

Color RGB

R: 125 G: 125 B: 125

Rank

lithostratigraphic Member (Subformation)

Validity

Unit is in Use

Status

incorrect name (though informally used)

Scs Note

Wegen der möglichen Verwechslung mit dem "Delémontien" wurde das Delémont-Member (Gygi 2000b) in Chestel-Member umbenannt.

Status discussion

Nomenclature

Deutsch

Delémont-Member

Français

Membre de Delémont

Italiano

Membro di Delémont

English

Delémont Member

Origin of the Name

Chapelle de Vorbourg, NW Delémont (JU)

Historical Variants

Couches de Delémont, Delémont-Schichten, Delémont Member (Gygi 2000b, Gygi 2000c), Membre de Delémont (Comment & Ayer)

Nomenclatorial Remarks

Name des Delémont-Members leitet sich ab vom Profil RG 366 (Schichten 1 bis 9), Chapelle du Vorbourg, nahe Delémont (Gygi 2000a, 56).

Description

Thickness

24 m à Chestel ; 40 m (Comment & Ayer)

Hierarchy and sequence

Superordinate unit

• Formation de St-Ursanne

Units at roof

• Membre de Buix

Units at floor

• Liesberg-Member

Upper boundary

Membre de Buix

Lower boundary

Membre de Liesberg

Stratigraphic discussion

Das Delémont-Member verzahnt sich lateral mit dem Grellingen-Member (Gygi 2000a/b).

Age

Age at top

• middle Oxfordian

Note about top

Transversarium-Zone, Antecedens-Subzone

Age at base

• middle Oxfordian

Note about base

Transversarium-Z., Antecedens-Sz.

Dating Method

Ammonitenbiostratigraphie (indirekt): Funde aus dem Hangenden (Buix-Mb.) und Liegenden (Sornetan-Mb.), siehe Gygi (2000b, 130), Mineralostratigraphie.

Geography

Geographical extent

4 bis 8 km breiter Gürtel, der sich von Ocourt am Doubs nach St-Ursanne (JU), Delémont und Liesberg, Dittingen und Blauen/BL entlangzieht.

Type locality

• Chapelle de Vorbourg (JU)
  Site particularities
  • Obergrenze
  • typische Fazies
  Site accessibility
  • Strassenanschnitt / Bahnanschnitt
  Coordinates
  • (2593870 / 1247660)
  Note
  • route NW de la chapelle de Vorbourg (Gygi 2000b p.55 Profil RG 366, Schichten 1-9, Gygi 2000c)

Reference profiles

• Chestel (BL)
  Site particularities
  • Obergrenze
  • Untergrenze
  • typische Fazies
  Site accessibility
  • Steinbruch, Tongrube
  Coordinates
  • (2599690 / 1249570)
  Note
  • Gygi 2000b S.56 Profil RG306 Schichten 107-110

Palaenography and tectonic

Tectonic unit (resp. main category)

• Jura :
  Juragebirge

Kind of protolith

• sedimentary

Conditions of formation

"rauracien"

Metamorphism

non metamorphic

References

Definition

Gygi R. A. (2000) : Integrated stratigraphy of the Oxfordian and Kimmeridgian (Late Jurassic) in northern Switzerland and adjacent southern Germany. Denkschriften der Schweizerischen Akademie der Naturwissenschaften 104, 152 S.

S.55

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.129: Delémont Member (Gygi 2000b) ; Member of the St-Ursanne Formation ; Synonymy: Gygi (2000b. p. 55) The Delémont Member of the lower St-Ursanne Formation was renamed by Gygi (20(X)b. p. 55). The name refers to Delémont. the capital of Canton Jura (LK 1086 Delémont). where the member crops out along the road northwest of Vorbourg chapel in section RG 366 (see plate 23 in Gygi, 2000b, beds 1-9). Gygi (2000b, p. 56) selected as reference section of the member RG 306, beds 107-110. in the quarry of Chestel at Liesberg, Canton Baselland, at coordinates 599.690/249.570, LK 1086 Delémont. The Delémont Member forms a 4-8 km wide belt within the lower St-Ursanne Formation. This belt runs from Ocourt on the Doubs river to St-Ursanne. Canton Jura. Delémont, and Liesberg, Dittingen and Blauen in Canton Baselland. The member is made up mainly by carbonate oolite and is 24 m thick in the reference section. There are hermatypic corals and oncoids at the base. Northeast of St-Ursanne the oncoids become so concentrated that they form an oncolite. This local facies was called Caquerelle pisolite by Ziegler (1962. p. 18). This must be distinguished from the Couches de la Caquerelle of Rollier (1892. p. 282). a synonym of the Buix Member (see above). The Caquerelle oncolite was figured by Pümpin (1965 Fig. 6 and 7). At present the oncolite is well exposed in the unpublished section RG 338 at the locality Côte du Frêne near Asuel. Canton Jura. LK 1085 St-Ursanne. at coordinates 581.950/247.990 along a forest road 400 m southwest of Les Malettes. The Delémont Member grades to the northwest and to the southeast into biomicritic limestone with hermatypic corals and coral bioherms. the Grellingen Member. No ammonites were found in the Delémont Member. There are ammonites of the early Antecedens Subchron in the upper Sornetan Member below and ammonites from the boundary between the Antecedens and Luciaeformis Subchron in the Buix Member above (Gygi, 1995. Fig. 2). The age of the Delémont Member can therefore be assigned to the Antecedens Subchron.