Zone de mélange du Pillon

Representation and status

Color CMYK

N/A

Color RGB

R: 241 G: 239 B: 237

Rank

tectonic

Validity

Unit is in Use

Status

informal term

Nomenclature

Deutsch

Pillon-Melangezone

Français

Zone de mélange du Pillon

Italiano

Zona di mélange del Pillon

English

Pillon Mélange Zone

Origin of the Name

Col du Pillon (VD)

Historical Variants

complexe du Pillon (McConnell 1951), Complexe du Pillon (Lombard 1975), Pillon Mélange Zone (Gouffon et al. 2024)

Description

Description

Série ultrahelvétique triasico-aalénienne à lentilles turoniennes.

Badoux 1963 p.7: Le complexe du Pillon, montrant entre le Trias et l'Aalénien ou parfois dans le Trias un chapelet de lentilles généralement turoniennes et qu'il avait baptisé en 1929 la zone du Rard.

Hierarchy and sequence

Subordinate units

• Cornieule de Retaud
• Zone des Roseyres
• Zone du Rard
• Trias du Col de la Croix

Palaenography and tectonic

Tectonic unit (resp. main category)

• Ultrahelvetic

Kind of protolith

• tectonic

References

Definition

McConnell R.B. (1951) : La nappe du Niesen et ses abords entre les Ormonts et la Sarine. Matér. Carte géol. Suisse (N.S.) 95, 107 pages

Definition

Gouffon Yves (Editor) (2024) : Tectonic Map of Switzerland 1:500000, Explanatory notes. Federal Office of Topography swisstopo, Wabern

p.42: The Pillon Mélange Zone consists of a chaotic system of discontinuous slivers – some of them of several kilometers long, often described as “nappes” – in a few matrix. This mélange zone is known in the literature as the “Ultrahelvetic nappes”. The paleogeographic origin of the slivers is located south of that of the Wildhorn Nappe Complex, i.e., in the most distal part of the European continental shelf (see p. 38). These slivers were thrust onto the sediments of the Helvetic platform, most likely at the base of the Penninic units during their emplacement onto the southern European continental margin. They underwent later deformation during the formation of the Helvetic nappes. The mélange zone can be subdivided into lower mélanges, associated with a specific Helvetic nappe, and upper mélanges, related to the base of the Prealps nappes (Mosar et al. 2001; more details in Jeanbourquin et al. 1992, Jeanbourquin 1994). It is located on top of the Lower and Upper Helvetic nappes and forms a wide band between the Helvetic units and the Penninic units of the Prealps; this band was formerly called the “Zone des Cols” (“Sattelzone”) or “Internal Prealps”.
The matrix part of the mélanges is relatively poorly developed; little “wildflysch” is found between the slivers. However, a chaotic deposit dominated by block-in-matrix fabrics – the Plaine Morte Mélange (Jeanbourquin 1994) – directly overlies many Lower and Upper Helvetic units (Aiguilles Rouges Massif, Morcles and Jägerchrüz nappes, Wildhorn Nappe Complex). In many cases, this mélange lies directly above the Helvetic flysch and has therefore occasionally been considered as the top of the Helvetic sedimentary series.