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Swiss Journal of Geosciences
Fig. 4 | Swiss Journal of Geosciences

Fig. 4

From: 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)

Fig. 4

Microstructures in garnet-bearing gneiss (ZR4). a Grt1 and Jd1 porphyroclasts wrapped by the S2 mylonitic foliation marked by Wm3 and Ep2. Note Grt2 corona rimming Grt1. Plane polarized light. Long side of the microphotograph = 3.3 mm. b Back-Scattered Electron (BSE) image that shows Grt1 and Wm1 porphyroclasts rimmed by Grt2 corona and Wm2, respectively. The S2 mylonitic foliation is marked by Ep2 and Wm3 and wraps the porphyroclasts. c Porphyroclasts of Grt1 and Jd1 wrapped by the S2 foliation marked by Wm3, Grt2 and Ep2. Plane polarized light. Long side of the microphotograph = 0.86 mm. d Back-Scattered Electron (BSE) image of photograph c. Grt1 is rimmed by Grt2 corona and Wm2 grows within Grt1 fractures. Jd1 and Grt1 porphyroclasts are rotated and wrapped by the S2 foliation, which is marked by Wm3, Ep, Grt2 and rare Gln1. e The S2 mylonitic foliation is marked by Wm3, Ep2 and Qz layers. Jd1 occurs as porphyroclasts and within folded layers with unrooted fold hinges and axial plane (AP1) parallel to the S2 foliation. Plane polarized light. Long side of the microphotograph = 3.3 mm. f Back-Scattered Electron (BSE) of the area located by the white square in panel e, after 90-degree anti-clockwise rotation. The folded level consists of small Jd1 crystals. The S2 foliation is marked by Wm3, Ep2 and Qz. g Large Grt1 porphyroclast with Gln1 fibers growing within boudin necks of Grt1, parallel to the S2 direction. Plane polarized light. Long side of the microphotograph = 3.3 mm. h Grt1, Grt2 and Gln1 fibers parallel to the S2 direction. Plane polarized light. Long side of the microphotograph = 0.86 mm

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