Membre de la Forclaz

Retour à nappe du Niesen

Représentation et statut

Couleur CMYK
(0%,11%,26%,31%)
Couleur RGB
R: 175 G: 155 B: 130
Rang
Membre lithostratigraphique (Sous-formation)
Usage
Ce terme est en usage.
Status
terme formel valide
Discussion du statut

Nomenclature

Deutsch
Forclaz-Member
Français
Membre de la Forclaz
Italiano
Membro della Forclaz
English
Forclaz Member
Origine du nom

Ruisseau de la Forclaz (VD), Ormont-Dessous

Variantes historiques

Marnes et calcaires du torrent de la Forclaz (Badoux & Homewood 1978, Badoux & Gabus 1991), Forclaz member (Ringgenberg et al. 2001)

Description

Épaisseur
30-50 m (Ringgenberg et al. 2001)

Composants

Fossiles
  • foraminifères
  • bivalves

Bositra buchi (Roemer 1836)

Hiérarchie et succession

Unité hiérarchiquement supérieure
Unités sus-jacentes
Unités sous-jacentes

Âge

Âge au sommet
  • Bathonien
Âge à la base
  • Bathonien
Méthode de datation

Foraminifères: Protopeneroplis striata (Weynschenk), Archeosepta platierensis (Wernli) (Badoux & Homewood 1978).

Géographie

Région-type
Vallée de la Grande Eau, entre Le Sépey et la Forclaz

Paléogéographie et tectonique

  • Dogger
Type de protolithe
  • sédimentaire

Références

Révision
Ringgenberg Yann, Tomassi Alexander, Stampfli Gérard M. (2001) : The Jurassic sequence of the Niesen nappe in the region of Le Sépey - La Forclaz (Swirtzerland): witness of the Piemont rifting in the Helvetic paleogeographic domain. Bull. Soc. vaud. Sci. nat. 87/4, 353-372

p.360: 2.1.5. Forclaz member (Bathonian) Good outcrops of this member are only found in La Forclaz stream (map 1:25'000 n°1285, Les Diablerets, geographic coordinates: 571'600/133'325 to 571 '775/133'650). It is 30 to 50 m thick and composed of turbiditic sandy limestones which alternate with marls. The proportion sand/marls is 1:1 and Tabe sequences are present. The detritic elements point to a more basinal environment than for the other members: limestones with little quartz, feldspars and white micas but a lot of spicules, recrystallized echinoderms, Lenticulina, Nodosoaria and little or no resedimented platform fragments. Marls interbeds are sometimes full of Posidonia bronni or bositra and ichnofossil imprints. Homewood and Badoux (1978) found Protopeneroplis striata (WEYNSCHENK) and Archeosepta platierensis (WERNLI) which indicate a Bathonian age. The transition to the Langy member is gradual, the bed thickness and the detritic fraction increase upward.

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