Membre de la May
Retour à Membre de PorrentruyReprésentation et statut
- Couleur CMYK
- cf. Formation de Courgenay
- Couleur RGB
- R: 155 G: 195 B: 215
- Rang
- Membre lithostratigraphique (Sous-formation)
- Usage
- Ce terme est en usage.
- Status
- terme formel valide
Nomenclature
- Deutsch
- La-May-Member
- Français
- Membre de la May
- Italiano
- Membro della May
- English
- La May Member
- Origine du nom
-
Petite vallée de La May, 2.5 km NE de St-Ursanne (JU)
- Variantes historiques
-
Humeralis-Kalke auct., La May-Schichten (Gygi 1995 S.12), La May Member (Gygi 2000c)
Description
- Description
-
Calcaire micritique, bien lité, pas d’ammonites mais des bivalves (Pholadomya). yellow, "spary-oolithic" limestone
- Épaisseur
- 20-30 m (Aufranc et al. 2016), 31 m à Courgenay (Gygi 2000c)
Composants
- brachiopodes
Hiérarchie et succession
- Unité hiérarchiquement supérieure
- Unités sus-jacentes
- Unités sous-jacentes
- Limite supérieure
-
Calcaire massifs du Mb. de Porrentruy. Limite supérieure difficile à repérer (év. lumachelle d'huîtres perforées, ecroûtées et teinteées de rouge).
- Limite inférieure
-
Marnes du Mb. de Bure (masqué)
Âge
- Âge au sommet
-
- Kimméridgien précoce
- Âge à la base
-
- Oxfordien tardif
- Méthode de datation
-
Coulée de débris
Géographie
- Extension géographique
- Nord de la suisse
- Région-type
- Canton du Jura
- Localité-type
-
-
La May (JU)
Particularités du site- typische Fazies
- (2580750 / 1247500)
- Petite vallée 2.5 km NE de St-Ursanne (Gygi 2000b/c Profil RG337)
-
La May (JU)
- Coupes de référence
-
-
Forage de La Coperie (JU)
Particularités du site- Obergrenze
- Untergrenze
- typische Fazies
- Bohrkern
- (2580900 / 1246230)
- <p>Forage d'exploration de la Transjurane (Gygi 2000b Pl.20 Profil RG443)</p>
-
Forage de La Coperie (JU)
Paléogéographie et tectonique
- Termes génériques
-
-
Jura
:
Juragebirge
-
Jura
:
- Type de protolithe
-
- sédimentaire
- Métamorphisme
- non métamorphique
Références
- Révision
-
(2000) :
Annotated index of lithostratigraphic units currently used in the Upper Jurassic of northern Switzerland. Eclogae geol. Helv. 93/1, 125-146
p.129: 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.
p.134: La May Member (Gygi 1995) ; Previously "Humeralis-Kalke". Member of the Courgenay Formation ; Synonymy: Gygi (2000b, p. 61)
The La May Member was named by Gygi (1995. p. 12). The name refers to the small valley called La May 2.5 km northeast of St-Ursanne in Canton Jura. LK 1085 St-Ursanne. where part of the member crops out at coordinates ca. 580.750/247.500 in the unpublished section RG 337. Below is the marl of the Bure Member which is covered, and above is a good outcrop of the massive Porrentruy Member. The only complete section of the La May Member was provided by the exploration well for the Transjurane superhighway near La Coperie farm 2 km east of St-Ursanne. This is section RG 443 which is represented as plate 20 in Gygi (2000b). The limestone of the La May Member is mostly micritic, well-cemented and well-bedded. Rounded lithoclasts of micrite grow to a diameter of 10 mm and are not rare. Macrofossils are Cycloserpula socialis (Goldfuss) and the bivalve Pholadomya. The thickness of the member is about 30 m in the borehole near La Coperie that Gygi (2000b p. 61) proposed to be the type section for lack of a complete outcrop at the surface. No ammonites have been found in the La May Member to date. The clay mineral stratigraphy by Gygi & Persoz (1986. Pl. 1A) indicates that the age of the La May Member ranges from the Hauffianum Subchron ofthe Bimammatum Chron to the lower Planula Chron (Gygi. 1995. Fig. 2). The La May Member occurs only in Canton Jura. The boundaries of the member with the Laufen and Verena Members are transitional.