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Table 2 Summary of metamorphic and deformational stages of the two Complexes and the Barmet Shear Zone

From: Internal geometry of the central Sesia Zone (Aosta Valley, Italy): HP tectonic assembly of continental slices

Internal complex Barmet Shear zone External complex
1. Pre-Alpine HT   1. Pre-Alpine HT
Minor, rare, pre-Alpine minerals relics   Large undeformed volumes, pre-Alpine minerals relics
2. Eclogite facies Pre-stage 4 HP (Eclo-Bs) 2. Epidote-blueschist facies
Pervasive foliation (S2~NW/45), local stretching lineation (L2~NW/SE) Mostly in fragments. Rare Gln in carbonate breccia matrix Epidote blueschist foliation (S2) parallel to compositional bands, stretching lineation (L2)
3. Retrograde blueschist to greenschist facies   3. Greenschist facies
Tight to isoclinal folds (F3, PA~N-NE/30), amplitude from dm to km   Tight to isoclinal folds (F3), amplitude 1–10 m
Local new axial planar foliation (S3)   Composite foliation developed (S2 + S3~SE/60)
4. Greenschist facies 4. Greenschist facies 4. Greenschist facies
Mylonitic foliation (S4~N-NW/70) Mylonitic greenschist foliation Mylonitic greenschist foliation (S4~SE/80)
Close to contact with External Complex (S4~SE/60), local stretching Close to contact with Internal Complex
Rare stretching lineation (L4~NW/30) lineation (L4~W/E) Local stretching lineation (L4~W/E)
5. Greenschist facies 5. Greenschist facies 5. Greenschist facies
Close to tight recumbent folds (F5, PA~NW/45), amplitude 1–20 m Close to tight recumbent folds (F5), amplitude of 1–20 m Close to tight recumbent folds (F5, PA~NE/45), amplitude 1–20 m
Local weak and spaced axial planar (S5)   Local and spaced foliation (S5) or fracture cleavage
6. Lower greenschist facies 6. Lower greenschist facies 6. Lower greenschist facies
Rare open to tight upright folds (F6), amplitude some metres, fracture cleavage in the hinge zone Rare open to tight upright folds (F6), amplitude of some metres Rare open to tight upright folds (F6), amplitude some metres
7.   7.
Emplacement of dykes   Emplacement of dykes
Rare dykes 0.5–1 m thick   Rare dykes reported by Lanza (1977), not found in mapped area
8.   8.
Brittle fracturing   Brittle fracturing
Rare brittle fractures (B8) with S-C features top to east sense of shear   Rare brittle fractures (B8)
  1. PA axial planes