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Cenozoic convergence between the Eurasian and African plates and concurrent slab roll-back processes have produced a progressive extension in back-arc areas, such as the Aegean region and western Anatolia. There is still a long-standing controversy as to whether this was a continuous or stepwise process. To shed light on this controversy and on the driving mechanism of regional extension, we present palaeomagnetic and geochronological results from the Söke Basin located at the southeastern rim of the İzmir-Balıkesir Transfer Zone. Our improved geochronology shows that volcanic activity in the region occurred between 11.66 and 12.85 Ma. Middle to late Miocene palaeomagnetic data for the Söke Basin show a c. 23° clockwise rotation, whereas early Miocene data show a c. 28° counterclockwise rotation. The primary nature of the magnetization is indicated by a positive tilt test. The resulting c. 51° counterclockwise rotations during the middle Miocene signify a major tectonic reorganization, during a period when an interruption of exhumation of metamorphic massifs has been reported. We suggest that the İzmir-Balıkesir Transfer Zone is the main driver of the reorganization in the region. The regional fingerprint of this tectonic reorganization coincides with the acceleration of trench retreat and illustrates the surface impact of tearing of the Hellenic slab. [ABSTRACT FROM AUTHOR]

Sillimanite- and staurolite-grade metamorphic rocks exhumed along the Pangong fault, the NE branch of the right-lateral Karakoram strike-slip fault in northern Ladakh, NW India, show multiple episodes of metamorphism and fabric development. Debate has centred on whether these metamorphic rocks were formed as a result of shear heating during strike-slip faulting, or whether they are exhumed earlier metamorphic rocks unrelated to movement on the Karakoram fault. Here we constrain the burial and exhumation history of the Pangong Metamorphic Complex combining the pressure-temperature evolution with accessory phase geochronology. Sillimanite-grade metamorphism in graphitic pelites was superseded by the preserved P-T conditions of a Bt + Ms + St + Grt + Qtz + Fsp assemblage at 585-605 °C and 6.05-7.25 kbar, equivalent to c. 20-25 km of burial. Laser ablation monazite U-Pb geochronology reveals that sillimanite-grade metamorphism occurred at 108.0 ± 0.6 Ma in rocks immediately adjacent to the Pangong strand of the Karakoram fault, implying that most metamorphic rocks along the Karakoram fault were not formed by shear heating during Miocene strike-slip faulting. This age correlates closely with the ages of the Hunza granite-granodiorite batholith, and the K2 orthogneiss in northern Pakistan, and confirms that some high-grade metamorphism occurred before collision and accretion of the Kohistan arc and the Indian plate to Asia; protracted high-grade metamorphism, and accompanying crustal thickening lasted at least 100 Ma along the South Asian plate margin. Our P-T and geochronology results also demonstrate the continuity of Cretaceous metamorphism across the Karakoram fault. [ABSTRACT FROM AUTHOR]