Western Anatolia, at the boundary between the Aegean and Anatolian microplates, is considered a type-locationfor the significant transition between compressional and extensional tectonics. The region is marked by diversetectonic events from the Paleoproterozoic through the Cambrian, Devonian, and Late Cretaceous, recorded byits suture zones, metamorphic rocks, and igneous intrusions. Extension initiated in a complex collage of multiplesutured crustal fragments. Today, the region is transitioning or has transitioned to a stress regime dominated bystrike-slip tectonics. Control for extension in Western Anatolia is widely accepted as the rollback of the African(Nubian) slab along the Hellenic arc. Outstanding questions include the timing and geometry of the Hellenic arcand connections to other subduction systems. Slab tear is proposed for many regions across the Anatolianand Aegean microplates. This process impacts lithospheric dynamics, generates economic and energy deposits,facilitates lithospheric thinning, and influences the onset of transfer zones that accommodate deformation andprovides magma conduits. The role of magma in facilitating extension and where and why switches in stressregimes occurred are still under consideration. The correlation between Aegean and Anatolian tectonic eventsalso requires a better understanding of the metamorphic history recorded in Western Anatolia rocks.

Transfer zones, locations where strain is transferred from one structural element to another, are common features in the Aegean and Anatolian microplates. These features link fault systems and accommodate broader-scale tectonic processes in the area, including the extrusion of the microplates and extension driven by the rollback of the African (Nubian) subduction slab. Transfer zones outcrop at local scales, where transfer faults activate due to regional tectonic forces (e.g., in the Sea of Marmara, Thrace Basin, and Menderes Massif). Broader transfer zones are more complex and may have different origins, connections, and overlaps. Two regional-scale Western Anatolian transfer zones, the İzmir–Balıkesir Transfer Zone and Uşak-Muğla Transfer Zone, are depicted as ~150 km long strike-slip faults. However, their specific dimensions and relationship to fault systems exposed within the zones they encompass are debated. Here, we identify and describe transfer zones mapped in specific locations in Western Anatolia. These zones are significant across diverse geological processes, from identifying hazards to regions of hydrocarbon deposition and mineralizations. In addition, they shed light on lithosphere dynamics as the microplates experience the fundamental tectonic processes of rollback, slab tear, extension, and extrusion.

The North American Cordilleran metamorphic core complex belt provides insight into the tectonometamorphic evolution of North America. Garnet-bearing assemblages have been used to generate pressure-temperature (P-T) constraints on the metamorphic history in its northern and central segments. Such datasets are scarce in its southern segment. We review existing metamorphic conditions and timing for these core complexes. Conditions from the Whipple detachment shear zone in southeastern California were also ascertained using conventional and isopleth thermobarometry. A sample from the easternmost Whipple Mountains shows monazite in reaction with allanite trapped in garnet. The monazite was dated in situ using an ion microprobe and yield 62±9 Ma, 67±7 Ma, and 80±6 Ma (Th-Pb dates, ±1s). P-T conditions recorded by garnet and matrix minerals from an adjacent rock are high-grade (rim, 680-750°C and 7-9.4 kbar and core, 750-800°C and 6.2-7.8 kbar). The results suggest exhumation from depths deeper than previously thought. With this new information, a new pressure-temperature-time path may be established for the rocks in the Whipple detachment and may suggest a deeper initiation or multiple metamorphic events not previously analyzed.