Marnes de Saxel
Representation and status
- Color CMYK
- N/A
- Color RGB
- R: 125 G: 125 B: 125
- Rank
- lithostratigraphic unit
- Validity
- Unit is not in Use
- Status
- junior synonym (disused)
Nomenclature
- Deutsch
- Saxel-Mergel
- Français
- Marnes de Saxel
- Italiano
- Marna di Saxel
- English
- Saxel Marls
- Origin of the Name
- Historical Variants
-
Marnes de Saxel (Ujetz 1996, Charollais et al. 1998, Coppo 1999), Saxel Marls (Ospina-Ostios et al. 2013)
Description
- Description
-
Les Marnes de Saxel sont des marnes grises, à patine beige ou brunâtre, coupées de petits bancs de grès. Leur épaisseur apparente dépasse largement les 1000 m. Ces marnes sont datées du Lutétien supérieur-Bartonien et affleurent dans la zone liguro-piémontaise au niveau de la Nappe de Gurnigel.
- Thickness
- Plus de 1000 m (série fortement replissée).
Age
- Age at top
-
- Bartonian
- Age at base
-
- late Lutetian
Geography
- Type area
- Les Voirons (France)
Palaenography and tectonic
- Tectonic unit (resp. main category)
- Kind of protolith
-
- sedimentary
References
- Definition
- (1996) : -
- Definition
-
(2013) :
Planktonic foraminifer biostratigraphy as a tool in constraining the timing of flysch deposition: Gurnigel flysch, Voirons massif (Haute-Savoie, France). Sedimentology 60, 225–238
This formation is exposed on the eastern flank of the Vouan ridge and on the Tête du Char (Fig. 2). The Saxel Marls are predominantly composed of metre-thick layers of greenish-grey marls, displaying a light brown alteration colour, and separated by centimetre-thick to decimetre-thick beds of fine-grained sandstone (Fig. 5E). The CaCO3 content of these marls varies between 21% and 31%, but values up to 40% have been reported by van Stuijvenberg & Jan du Ch^ene (1981). Mica, pyrite and glauconite were observed in washed sediment fractions. The sandstone beds are rather homogenous and consist of calcite-cemented lithic arkose (Fig. 3) characterized by the occurrence of numerous fragments of micritic limestone. Beds of arenaceous limestone are also common, but conglomerate layers are missing in this succession, except near its base. This succession is over 1000 m thick, but might be affected by tectonic folding (Coppo, 1999). The thin sandstone beds exhibit sharp upper and lower contacts, and are commonly laminated (Fig. 5F). Flute casts, ripple laminations and convolute bedding have been observed at the base and within sandstone beds, respectively. However, complete Bouma sequences are uncommon. These beds could be interpreted as Facies F9 (Mutti et al., 2003). Most samples collected from the Saxel Marls yielded poor planktonic foraminiferal assemblages spanning the Middle to Upper Eocene stages. However, the best preserved assemblage contains Catapsydrax globiformis, Catapsydrax martini, Catapsydrax howei, Catapsydrax unicavus, Turborotalia cerroazulensis cerroazulensis, Tenuitellinata angustiumbilicata (Fig. 6B), Globigerina officinalis (Fig. 6C), Pseudohastigerina micra, Subbotina linaperta, Subbotina angiporoides, Subbotina utilisindex (Fig. 6F and G), Subbotina eocaena, Acarinina echinata, Acarinina mcgowrani ?, Acarinina rotundimarginata, Acarinina spinuloinflata, Globorotaloides suteri, Globigerinatheka rubriformis and Globotruncana (reworked). This well-preserved assemblage corresponds to the upper Middle Eocene to Lower Oligocene stage (planktonic foraminiferal zones P13 to P20).