Mélange di Robièi

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).

Hierarchy and sequence

Subordinate units

• Mélange del Pizzo Castello
• Mélange di Tamier-Zött
• Mélange dell'Alpe Tamia-Campo

Age

Age at top

• late Eocene

Age at base

• middle Eocene

Geography

Geographical extent

Lepontin

Point of interest

• Pizzo Cortefreddo (Italia), Valle Antigorio
  Site particularities
  • typische Fazies
  Site accessibility
  • Grat
  Coordinates
  • (2673000 / 1122000)
  Note
  • Della Torre & Maggini 2015 p.19
• Bocchetta Foglia = Hendar Furggu (TI)
  Site particularities
  • typische Fazies
  Site accessibility
  • Grat
  Coordinates
  • (2678850 / 1131950)
  Note
  • Della Torre & Maggini 2015 p.24 : zona del Bombogno
• Passo di Bosco = Guriner Furggu (TI)
  Site particularities
  • typische Fazies
  Site accessibility
  • Grat
  Coordinates
  • (2678000 / 1130620)
  Note
  • Della Torre & Maggini 2015 p.24 : zona del Bombogno

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.