Mélange di Robièi

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Representation and status

Color CMYK
(0%,0%,20%,2%)
Color RGB
R: 250 G: 250 B: 200
Rank
lithostratigraphic Group
Validity
Unit is in Use
Status
informal term

Nomenclature

Deutsch
Robièi-Melange
Français
Mélange de Robièi
Italiano
Mélange di Robièi
English
Robièi Mélange
Origin of the Name

Lago di Robièi (TI)

Historical Variants

Robièi Formation = Robiei meta-wildflysch (Masson 2002), wildflysch de Robiei (Matasci 2009), Robiei wildflysch = Robièi Formation (Matasci et al. 2011 p.265), Calcescisti conglomeratici e a blocchi = Formazione di Robiei (Della Torre & Maggini 2015)

Description

Description

Calcescisti conglomeratici e a blocchi (elementi di gneiss, anfibolite, micascisto e marmo in una matrice carbonatico-scistosa).

Age

Age at top
  • late Eocene
Age at base
  • middle Eocene

Geography

Geographical extent
Lepontin
Point of interest

References

Definition
Matasci Battista, Epard Jean-Luc, Masson Henri (2011) : The Teggiolo zone: a key to the Helvetic–Penninic connection (stratigraphy and tectonics in the Val Bavona, Ticino, Central Alps). Swiss J. Geosci. 104, 257–283

p.265: 3.5 Fourth sedimentary cycle: the Robiei wildflysch (Tertiary)

The upper part of the Teggiolo calcschists essentially consists in a uniform sequence of mm- to cm-thick beds or streaks of various fine-grained detrital rocks, mainly calcareous and micaceous siltstones to sandstones, garnet micaschists and quartzitic sandstones. Although the bedding is usually well marked at a cm- to m-scale, on a larger distance it becomes irregular and discontinuous, contorted, or blurred, and from afar the general aspect is rather massive, contrasting with the conspicuous and regular layering of the Mèdola quartzite. Towards the top of the sequence the calcschists become more homogeneous and are often poorer in calcite and richer in garnet. However, the main characteristic of this formation is that it frequently contains blocks of exotic rocks of variable size. The whole complex of these blocks embedded in a more or less disordered flyschoid matrix presents all the characteristics of a wildflysch, analogous to typical wildflysches of central Switzerland (e.g. Trümpy 2006), the Prealps (e.g. Caron 1966; Weidmann et al. 1982; Kindler 1988) and the Valais s.str. domain of the French Alps (Masson et al. 2008). This thick and rather complex stratigraphic unit has been named the Robièi Formation by Masson (2002). According to the nature of the blocks, it is possible to distinguish three different associations that have specific vertical and lateral distributions.

  • Mélange del Pizzo Castello

    Name Origin

    Pizzo Castello (TI)

    Rank
    lithostratigraphic Formation
    Status
    informal term
    In short

    Développement particulier du Wildflysch de Robiéi dans la région du Pizzo Castello, avec des blocs de taille gigantesque (hectométrique, voire kilométrique) constitués de gneiss gris clair, de grès calcaire grossier (cf. Grès de Sevinèra), de marbre blanc à jaunâtre (cf. Marbre de Sevinèra), ou d'une association de ces trois lithologies en succession stratigraphique.

  • Mélange di Tamier-Zött

    Name Origin

    Tamierpass (TI) et Lago del Zött (TI)

    Rank
    lithostratigraphic Formation
    Status
    informal term
    In short

    Partie supérieure du Wildflysch de Robièi, comprenant des blocs exotiques de gneiss de nature variable, parfois migmatitique et contenant fréquement des filons basiques. La taille des blocs augmente vers le haut.

  • Mélange dell'Alpe Tamia-Campo

    Name Origin

    Alpe Tamia (Italia), WSW Pizzo Mèdola

    Rank
    lithostratigraphic Formation
    Status
    informal term
    In short

    Partie inférieure du Wildflysch de Robièi, comprenant des blocs exotiques de marbre calcitique pur de couleur blanche (cf. Marbre de Sevinèra). La taille des blocs tend à augmenter vers le haut.

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