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    Crustal flow driving twin domes exhumation and low-angle normal faulting in the Menderes Massif of western Anatolia
    (Elsevier, 2023) Bodur, Ömer; Gögüs, Oğuz Hakan; Brune, Sascha; Şengül Uluocak, Ebru; Glerum, Anne; Fichtner, Andreas; Sözbilir, Hasan
    Lower crustal flow in regions of post-orogenic extension has been inferred to explain the exhumation of metamorphic core complexes and associated low-angle normal (detachment) fault systems. However, the origin of detachment faults, whether initially formed as high-angle or low-angle shear zones, and the extension is symmetric or asymmetric remains enigmatic. Here, we use numerical modeling constrained by geophysical and geological data to show that symmetric extension in the central Menderes Massif of western Anatolia is accommodated by the crustal flow. Our geodynamic model explains how opposite dipping Gediz and Buyuk Menderes detachment faults are formed by -40 & DEG; footwall rotation. Model predictions agree with seismic tomography data that suggests updoming of lower crust beneath the exhumed massifs, represented as twin domes and a flat Moho. Our work helps to account for the genetic relation between the exhumation of metamorphic core complexes and low-angle normal faulting in both Cordillera and Aegean orogenic regions and has important implications on crustal dynamics in extensional provinces.
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    The Role of Upper Mantle Forces in Post-Subduction Tectonics: Plumelet and Active Rifting in the East Anatolian Plateau
    (Amer Geophysical Union, 2024) Şengül Uluocak, Ebru; Pysklywec, Russell N.; Sembroni, Andrea; Brune, Sascha; Faccenna, Claudio
    The spatiotemporal interaction of large- and regional-scale upper mantle forces can prevail in collisional settings. To better understand the role of these forces on post-subduction tectonics, we focus on mantle dynamics in the East Anatolian Plateau, a well-documented segment of the Arabian-Eurasian continental collision zone. Specifically, we analyze multiple forces in the upper mantle, which have not been considered in previous studies in this region. To this end, we use a state-of-the-art 3D instantaneous geodynamic model to quantify the dynamics of thermally defined upper mantle structures derived from seismic tomography data. Results reveal a prominent SW-NE-oriented mantle flow from the Arabian foreland to the Greater Caucasus–a plumelet–through a lithospheric channel under the East Anatolian Plateau. This plumelet induces localized dynamic topography (∼500 m) around the extensional Lake Van province, favoring NE-directed compression and westward escape of the Anatolian plate. We suggest that the Lake Van region is an active magma-rich intraplate rift in the Africa-Arabia-Anatolian plume-rift system. The rift zone was probably initiated by Neotethyan subduction-related forces and has been reactivated and/or sustained by the plumelet-induced convective support. Our findings are consistent with numerous observations, including the recent low-ultralow seismic velocities with a SW-NE splitting anisotropy pattern, geochemical and petrological studies, and local kinematics showing upper mantle-induced extensional tectonics in the collisional region.