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 5 Representative analysis of main minerals of garnet-bearing gneiss (ZR4)

Mineral	Grt1a	Grt1b	Grt2	Grt3	Wm1	Wm2	Wm3	Jd1	Ep1	Ep2	Gln1	Ttn1
SiO₂	37.98	37.47	38.14	38.2	45.61	52.48	50.33	58.68	37.38	38.14	56.6	30.7
TiO₂	0.01	0.06	0.15	0.17	0.39	0.07	0.07	0	0.24	0.06	0.01	38.33
Al₂O₃	21.24	20.82	21.19	20.99	35.88	24.83	27.84	22.88	25.81	27.92	11.17	2.5
FeOt	34	35.88	25.37	19.52	1.03	3.46	3.73	1.63	9.43	6.85	17.37	0.48
NiO	0	0	0	0	0	0	0	0	0.01	0	0	0
MnO	3.23	4.94	1.66	3.36	0	0	0.07	0.01	0.13	0.06	0.1	0
MgO	4.12	0.84	0.54	0.21	0.56	2.47	2.94	0.34	0.16	0	5.25	0.01
CaO	1.04	1.94	13.99	17.48	0.01	0.07	0.04	0.66	23.2	23.17	0.29	28.03
Na₂O	0	0	0.02	0.01	0.37	0.48	0.2	15.37	0.02	0	7.28	0.03
K₂O	0.03	0	0.02	0.07	9.47	10.3	10.61	0.01	0.01	0.08	0.03	0.12
Cr₂O₃	0.04	0	0.01	0	0.02	0	0	0	0.03	0	0	0.05
TOT	101.69	101.95	101.09	100.02	93.35	94.16	95.83	99.57	96.41	96.27	98.1	100.26
Si	2.99	3.01	3	3.01	3.07	3.55	3.36	1.99	2.96	3	7.99	4
Al_IV	0.01	0	0	0	0.93	0.45	0.64	0.01	0.04	0	0.01	0.38
Al_VI	1.97	1.97	1.96	1.95	1.92	1.53	1.56	0.9	2.36	2.58	1.85
Ti	0	0	0.01	0.01	0.02	0	0	0	0.01	0	0	3.76
Fe²⁺	2.21	2.39	1.64	1.25	0.06	0.2	0.21	0	0	0.04	2
Fe³⁺	0.03	0.02	0.03	0.04				0.05	0.62	0.41	0.05	0.05
Mg	0.48	0.1	0.06	0.03	0.06	0.25	0.29	0.02	0.02	0	1.1	0
Mn	0.22	0.34	0.11	0.22				0	0.01	0	0.01
Na	0	0	0	0	0.05	0.06	0.03	1.01	0	0	1.94	0.01
Ca	0.09	0.17	1.18	1.48	0	0.01	0	0.02	1.97	1.95	0.04	3.91
K	0	0	0	0.01	0.81	0.89	0.9	0	0	0.01	0.01	0.02
Cr	0	0	0	0	0	0	0	0	0	0	0	0
SUM	8	8	7.99	8	6.92	6.94	6.99	4	7.99	7.99	15	12.13