Membre de la Forclaz
Back to Niesen nappeRepresentation and status
- Color CMYK
- (0%,11%,26%,31%)
- Color RGB
- R: 175 G: 155 B: 130
- Rank
- lithostratigraphic Member (Subformation)
- Validity
- Unit is in Use
- Status
- valid formal name
- Status discussion
Nomenclature
- Deutsch
- Forclaz-Member
- Français
- Membre de la Forclaz
- Italiano
- Membro della Forclaz
- English
- Forclaz Member
- Origin of the Name
-
Ruisseau de la Forclaz (VD), Ormont-Dessous
- Historical Variants
-
Marnes et calcaires du torrent de la Forclaz (Badoux & Homewood 1978, Badoux & Gabus 1991), Forclaz member (Ringgenberg et al. 2001)
Description
- Thickness
- 30-50 m (Ringgenberg et al. 2001)
Components
- foraminifera
- bivalves
Bositra buchi (Roemer 1836)
Hierarchy and sequence
- Superordinate unit
- Units at roof
- Units at floor
Age
- Age at top
-
- Bathonian
- Age at base
-
- Bathonian
- Dating Method
-
Foraminifères: Protopeneroplis striata (Weynschenk), Archeosepta platierensis (Wernli) (Badoux & Homewood 1978).
Geography
- Type area
- Vallée de la Grande Eau, entre Le Sépey et la Forclaz
Palaenography and tectonic
-
- Dogger
- Kind of protolith
-
- sedimentary
References
- Definition
-
(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.