Formation de Courgenay

Rappresentazione e statuto

Index

i6C

Colore CMYK

40 / 10 / 10 / 0

Colore RGB

R: 160 G: 200 B: 220

Rango

Formazione litostratigrafica

Uso

Unità in uso.

Status

termine formale valido

Discussione del statuto

Nomenclatura

Deutsch

Courgenay-Formation

Français

Formation de Courgenay

Italiano

Formazione di Courgenay

English

Courgenay Formation

Origine del nome

Courgenay (JU)

Varianti storiche

Humeralis-Kalke auct., Courgenay-Formation (Gygi 1995 S.12), Courgenay Formation (Gygi 2000b, Gygi 2000c)

Links

Synonymi

Formation de Court

Descrizione

Descrizione

La formation est constituée d’une succession de calcaires micritiques lités (Membre de la May) et de calcaires massifs de couleur blanchâtre plus ou moins crayeux, parfois décrits comme calcaires massifs oolithiques (Membre de Ste-Vérène). Ils forment très souvent des parois ou des falaises.

Geomorfologia

Forme très souvent des parois ou des falaises.

Potenza

30-40 m, max. 50 m à la transition avec la Fm. de Balsthal (Aufranc et al. 2016).

Gerarchia e successione

Unità di rango inferiore

• Membre de Porrentruy
• Membre de la May

Unità sovrastante

• Formation de Reuchenette

Unità sottostante

• Formation de Vellerat

Limite superiore

Formation de Reuchenette

Limite inferiore

Marnes du Membre de Bure (Formation de Vellerat)

Età

Geomorfologia

• Primo Kimmeridgiano

Età alla base

• Oxfordiano tardo

Osservazioni sulla base

Zone à Bimammatum: Sous-zone à Hauffianum

Metodo di datazione

Minéralogie des argiles (Gygi & Persoz 1986 Pl.1a).

Geografia

Estensione geografica

Ajoie, Canton du Jura.

Regione-tipo

Ajoie (JU)

Località-tipo

• Courgenay/Iennsdorf (JU)
  Coordinate
  • (2576450 / 1250200)

Sezione-tipo

• Courgenay (JU)
  Caratteristiche del sito
  • typische Fazies
  Agibilità del sito
  • Strassenanschnitt / Bahnanschnitt
  Coordinate
  • (2573790 / 1247100)
  Nota
  • Chemin Paulin, 4 km SW Courgenay (Gygi 2000b Pl.19 Profil RG350, Gygi 2000c)

Paleogeografia e tettonica

• Malm

Termini generici

• Jura :
  Juragebirge

Tipo di origine

• sedimentaria

Condizioni di formazione

Plateforme interne, faciès lagunaire.

Metamorfismo

non metamorfo

Referenze

Definizione

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

S.12

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.129: Courgenay Formation (Gygi 1995) ; Previously: "Humeralis-Kalke" ; Synonymy: Gygi (2000b, p. 60) Gygi (1995. p. 12) proposed the Courgenay Formation for the lagoonal limestones between the marly Vellerat Formation below and the Reuchenette Formation above. The name refers to the village of Courgenay in the southern Ajoie region of Canton Jura. The type section is RG 350 along the road called Chemin Paulin (name not indicated on the map) 4 km southwest of the village at coordinates 573.790/247.100. LK 1085 St-Ursanne. The section is represented as plate 19 in Gygi (2000b). The Courgenay Formation has two members. The La May Member below is a well-bedded micritic limestone with a thickness of 31 m in the section RG 350 at Chemin Paulin. Above follows the Porrentruy Member, an almost pure white, massive micritic limestone which is 13 m thick in the reference section that is RG 350. No ammonites were found to date in the Courgenay Formation. It is only with clay minerals that it can be shown that the Porrentruy Member is coeval with the Letzi Member in Canton Aargau (correlation K by Gygi & Persoz 1986. Pl. 1 A). The Letzi Member can be dated with ammonites as earliest Kimmeridgian. The Courgenay Formation grades distally, between St-Ursanne and Glovelier, Canton Jura, into the oolitic Balsthal Formation that includes the "Court Formation" of Bolliger & Burri (1970. p. 73). Gygi (2000b. p. 61 showed that the Court Formation is a junior synonym of the Balsthal Formation and is therefore a superfluous term.

Materiale e vario

15200003