Table 1 Structural units of the South Cottian Alps (see map Fig. 3)
Acro-nyms | Name of tectonic units | Paleogeographic domain | Main lithologies | Metamorphic facies |
|---|---|---|---|---|
QN | Queyras nappe | Piemonte-Liguria Ocean | Radiolarites, marbles and calcschists with ophiolite bodies | Blueschist |
MV | Monviso ophiolite complex | |||
Mainly ophiolites with minor metasediments | Eclogite | |||
VG | Val Grana unit | “Prepiemonte” – type facies of the Briançonnais s.l. distal margin | Mesozoic metasediments (Ladinian-Pliensbachian) | Blueschist |
VM-S | Val Maira – Sampeyre unit | Permian-Mesozoic metasediments (Upper Permian-Ladinian) | Blueschist | |
(cf. GS further N) | (cf. Giulian-Sea Bianca unit) | |||
CLSZ | Cima Lubin shear zone | Shear zones representing tectonic mélanges of oceanic and margin units | Mesozoic metasediments (dolostones, calcschists) and minor ophiolite bodies | Blueschist |
SDSZ | San Damiano shear zone | Blueschist | ||
VPSZ | Valmala-Piasco shear zone | HT- blueschist | ||
Drn2 | Upper Dronero unit | Dora-Maira crystalline Massif representing part of the former basement of the Briançonnais s.l. distal margin | Polycyclic schists and monocyclic metased. and granites (Permian) | Quartz eclogite |
Drn1 | Lower Dronero unit | Polycyclic basement | Blueschist | |
R | Ricordone unit | Polycyclic basement | Quartz eclogite | |
RS | Rocca Solei unit | Polycyclic basement | Quartz eclogite | |
BI | Brossasco-Isasca unit | Polycyclic basement | Coesite eclogite | |
SP | Sanfront-Pinerolo unit | Monocyclic metasediments (Carboniferous- Triassic) + Permian felsic intrusives | Garnet blueschist to eclogite | |
AL | Units of the Acceglio- Longet band (Acceglio anticline, Rocca Corna and Pelvo d’Elva units) and their southern equivalents | Acceglio-type facies domains of the Briançonnais s.l. distal margin (Acceglio, "Ecailles intermédiaires" or Ultrabriançonnais auct.) | Monocyclic metasediments (Up. Carbon.-Up. Cretac.-Paleoc., with Middle Triassic—Liassic gap) + Permian felsites Polycyclic schists (scarce) | HT- blueschist |
CBR | Classical Briançonnais nappes or Briançonnais s. str. (various nappes, see Fig. 6) | Briançonnais proximal margin (= Briançonnais s.str. domain) | Cf. Acceglio units but with thick Middle ± Upper Triassic dolostones ± Lower Liassic (rare) + Eocene “Flysch noir” | Greenschist to LT- blueschist |
SBR | Subbriançonnais units | Valaisan and Subbriançonnais rift domains | Up. Triassic (evaporites) – Eocene sediments | Non- metamorphic |