Blueschist mylonitic zones accommodating syn-subduction exhumation of deeply buried continental crust: the example of the Rocca Canavese Thrust Sheets Unit (Sesia–Lanzo Zone, Italian Western Alps)

Swiss Journal of Geosciences

Table 1 Summary of deformation-metamorphic transformation stages with characteristic structures and mineral associations

Stage	Event	Structures	Mineral association
Grt-bearing gneiss
I	pre-1a	Coronitic	Wm1 + Grt1a + Qz
I	pre-1b	Microfractures	Grt1b
II	M1, D1	S1 discontinuous foliation	Wm2 + Grt2 + Jd1 + Qz + Ep1 ± Ttn1
III	M2, D2	S2 mylonitic foliation	Wm3 + Grt3 + Gln1 + Qz + Pl1 + Ep2 ± Ttn2
IV	M3, D3	AP3 folding	Cpx1
Grt-free gneiss
I	pre-1	Coronitic	Qz + Bt1
II	M1	Coronitic	Wm1 + Jd1 + Cpx1 + Qz + Ep1 ± Ttn1
III	M2, D2	S2 mylonitic foliation	Wm2 + Jd2 + Ep2 + Qz ± Ttn2 ± Gln1
IV	M3, D3	AP3 folding	Cpx2 + Qz + Pl1
Orthogneiss
I	pre-1	Coronitic	Kfs1 + Qz
II	M1	Coronitic	Wm1 + Grt1 + Jd1 + Qz ± Ttn1
III	M2, D2	S2 mylonitic foliation	Wm2 + Jd2 + Qz ± Ttn2
IV	M3, D3	AP3 folding	Cpx1