Quartz deformation mechanisms in shear zones inferred by quantitative microstructural investigation: the case study of Kavala (Rhodope Massif, north-eastern Greece)

As it is known, the quantification of strain within shear zones improves our comprehension of crustal scale geological processes, like syn-shearing pluton emplacement. To this aim, we studied the Kavala (Symvolon) syn-tectonic pluton, which crops out in north-eastern Greece and is mainly composed of early-Miocene granodiorite. The pluton represents the south-western termination of the Rhodope Core Complex, which was exhumed as a result of large scale extension from mid-Eocene to mid-Miocene times. DINTER et alii (1995) constrain the intrusion and incipient mylonitization of the these granodiorites at 21-22 Ma (zircon and titanite U-Pb dates and hornblende Ar-40/Ar-39 dates), suggesting that the plutonic body resided at temperatures between 300 and 500 ¡C for 5-7 m.y., during which coaxial deformation may have continued. Field investigation highlighted the presence of a NE-SW monotone stretching lineation consistent with the shape elongation of the outcropping pluton, whose intensity in deformation increases towards the contact with the host gneiss. By taking into account the progressive deformation in the shear zone, we collected a sample suite of representative mylonitic rocks.