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Öğe Geodynamics of East Anatolia-Caucasus Domain: Inferences From 3D Thermo-Mechanical Models, Residual Topography, and Admittance Function Analyses(John Wiley and Sons Inc, 2021) Şengül Uluocak, Ebru; Göğüş, Oğuz H.; Pysklywec, Russell N.; Chen, BoWe investigate anomalous topography in the Anatolia-Caucasus domain of the Arabian-Eurasian plate convergence zone. To achieve this aim, we use three-dimensional (3D) geodynamic modeling in addition to analyses of the non-isostatic components of surface topography based on residual topography and free-air gravity admittance functions. The numerical experiments are based on two different temperature models obtained from P-wave tomography data that are sensitive respectively to large and small-scale variations of upper mantle structures. Our results suggest a long-wavelength convective support of topography, which is in general agreement with the uncompensated pattern of residual topography and free-air admittance values, as well as previous modeling studies. At shorter wavelengths, we provide new constraints on the regional dynamic processes related to 3D variations of the upper mantle flow vectors and associated surface deflections. Positive dynamic topography is found over the East Anatolian Plateau (∼400 m to ∼1.2 km) that is consistent with inferred lithospheric thinning processes pertinent to the tectonic evolution of the Tethyan orogenic system. We further show dynamic topography in the plateau (≥500 m) that may account for extensional tectonics in the Lake Van region interpreted from local kinematic and geophysical studies. In conjunction with the observations, negative anomaly patterns are estimated in the western part of the Black Sea (∼−2 km), the eastern Pontides arc (∼−200 m), and the northeast Arabian Plate (∼−1 to −2.3 km). Our model results also suggest a link between large-scale mantle flow and SW-NE-directed general pattern of the SKS-based anisotropy beneath the region. © 2021. American Geophysical Union.Öğe Multistage lithospheric drips control active basin formation within an uplifting orogenic plateau(Nature Portfolio, 2024) Andersen, A. Julia; Gogus, Oguz Hakan; Pysklywec, Russell N.; Uluocak, Ebru Sengul; Santimano, TascaAccording to GNSS/INSAR measurements, the Konya Basin in Central Anatolia is undergoing rapid subsidence within an uplifting orogenic plateau. Further, geophysical studies reveal thickened crust under the basin and a fast seismic wave speed anomaly in the underlying mantle, in addition to a localised depression in calculated residual topography (down to 280 m) over the Konya Basin, based on gravity-topography considerations. Using scaled laboratory (analogue) experiments we show that the active formation of the Konya Basin may be accounted for by the descent of a mantle lithospheric drip causing local circular-shaped surface subsidence. We interpret that the Konya Basin is developing through a secondary drip pulse that is contemporaneous with broad plateau uplift caused by a larger-scale lithospheric drip since the Miocene. The research reveals that basin evolution and plateau uplift may be linked in a multistage process of lithospheric removal during episodic development of orogenic systems. Active subsidence of the Konya region, Turkiye, is attributed to descent of a lithospheric drip into the mantle, according to analogue models, and suggests that major tectonic events may be linked to multistage dynamic flow processes in the mantle.Öğe Symptomatic lithospheric drips triggering fast topographic rise and crustal deformation in the Central Andes(Springernature, 2022) Andersen, Julia; Gogus, Oguz H.; Pysklywec, Russell N.; Santimano, Tasca; Sengul Uluocak, EbruThe basin and plateau regions of the Central Andes have undergone phases of rapid subsidence and uplift during the last similar to 20 Myr in addition to internal tectonic deformation. Paleoelevation data and the presence of high seismic wave speed anomalies beneath the Puna Plateau suggest that these tectonic events may be related to lithospheric foundering. Here, we study the geodynamic processes in the region using three dimensional, scaled, analogue models and high-resolution optical image correlation techniques. The analogue experiments show how a gravitational instability of the mantle lithosphere developing into a lithospheric drip may form a circular sedimentary basin in the crust that undergoes subsidence and subsequently reverses to uplift, while simultaneously undergoing internal crustal shortening. The model results reveal that drips may be symptomatic where the crust is well coupled to the sinking mantle lithosphere and manifests tectonic deformation at the surface, or poorly coupled asymptomatic drips with weak crustal surface manifestations. Overall, the physical models suggest that the formation of the Arizaro Basin and nearby Central Andean basins are caused by symptomatic lithospheric dripping events and highlight the significant role of non-subduction geodynamic mechanisms in driving surface tectonics.Öğe The Role of Upper Mantle Forces in Post-Subduction Tectonics: Plumelet and Active Rifting in the East Anatolian Plateau(Amer Geophysical Union, 2024) Uluocak, Ebru Senguel; Pysklywec, Russell N.; Sembroni, Andrea; Brune, Sascha; Faccenna, ClaudioThe 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 (similar to 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. Our goal is to better understand the active deformations of post-subduction tectonics. To this end, we ran a 3D thermomechanical model of the East Anatolian Plateau, one of the most intriguing segments of the Arabian-Eurasian continental collision zone. The model integrates seismically defined upper mantle structures and uses an open-source code (ASPECT). Results reveal the significant role of large- and regional-scale upper mantle forces in the study region. At long wavelengths, we find SW-NE-oriented mantle flow and associated dynamic topography. We interpret that such flow-a plumelet (regional upper-mantle plume migration with neither a significant tail extending to the lower mantle nor a mushroom head reaching the hot spots on the surface)-is linked to the large-scale mantle flow from the Arabian plate to the Greater Caucasus. At short wavelengths, we find localized dynamic topography and high stress and strain anomalies in the Lake Van zone. We argue that the plumelet, which became more forceful after the removal of the subducted Neotethyan slab, may have generated mantle tractions that contribute to magma-rich-intraplate rifting in the Lake Van region. Our results are in good agreement with local kinematics, low-speed seismic velocities with SW-NE anisotropy patterns, and geochemical-petrological studies. We present the 3D numerical model and observations related to the Africa-Arabia-Anatolian plume-rift system Our thermomechanical model provides new insight into the magma-rich intraplate active rifting in collisional settings Integrated analyses from the 3D geodynamic model and observations reveal a SW-NE-oriented plumelet and its regional implicationsÖğe The surface tectonics of mantle lithosphere delamination following ocean lithosphere subduction: Insights from physical-scaled analogue experiments(Amer Geophysical Union, 2011) Gogus, Oguz H.; Pysklywec, Russell N.; Corbi, Fabio; Faccenna, ClaudioMany postulated lithospheric removal events occur in regions with an earlier history of subduction, but the relationship between the two processes has not been explored. In this work, we use physical-scaled analogue experiments to investigate the evolution from ocean lithosphere subduction to collision and possible delamination of the mantle lithosphere from the crust. We test how varying the magnitude of plate convergence alters the behavior of the subduction-delamination model. Our experiments show that a retreating ocean proplate can evolve to continental mantle lithosphere delamination. Negative surface topography is supported at the delamination hinge, and this migrates back with the peeling lithosphere. With high plate convergence, delamination is suppressed. Rather, the crust and mantle lithosphere split at the collision zone in a form of flake tectonics as oncoming procrust is accreted on top of the retroplate and the promantle lithosphere subducts below. Localized high topography develops at this zone of crustal accretion and thickening. The results suggest that delamination may be a continental continuation of plate retreat and that lithospheric removal is triggered by the transition from one process to another.
