Yazar "Gogus, Oguz H." seçeneğine göre listele

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    Long Wavelength Progressive Plateau Uplift in Eastern Anatolia Since 20 Ma: Implications for the Role of Slab Peel-Back and Break-Off
    (Amer Geophysical Union, 2020) Memis, Caner; Gogus, Oguz H.; Uluocak, Ebru Sengul; Pysklywec, Russell; Keskin, Mehmet; Sengor, A. M. Celal; Topuz, Gultekin
    Stratigraphic evidence is used to interpret that the East Anatolian Plateau with 2 km average elevation today was below sea level similar to 20 Ma and uplift began in the northern part. The presence of voluminous volcanic rocks/melt production across the plateau-younging to the south-corroborates geophysical interpretations (e.g., high heat flow and lower seismic velocities) that suggest progressive removal of the slab subducting under the Pontides. Here, we conduct numerical experiments that investigate the change in the surface uplift as a response to slab peel-back and potential break-off processes under subduction-accretionary complexes as well as continental lithosphere. Model results show similar types of tectonic behavior and magnitudes of uplift-subsidence in both oceanic and continental removal processes, and they satisfactorily explain 1.5 km of plateau rise and a similar to 280 km wide asthenospheric upwelling zone beneath Eastern Anatolia over 18 Myr timescale. Parametric investigation for varying plate strength and convergence velocities show that such model parameters control the amount of surface uplift (1 to 3 km), the width of the asthenospheric upwelling zone, and the potential timing/depth of break-off of the steepening/peeling slab. Experiments show that slab break-off develops during the terminal phase, which may correspond to only a few million years ago. Therefore, the long wavelength plateau uplift and magmatism over the Eastern Anatolian-Lesser Caucasus region since 20 Ma is controlled by progressive slab peel-back and resulting mantle dynamics. The slab break-off process (if it happened) has yet an indiscernible role.
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    Mantle flow uplift of western Anatolia and the Aegean: Interpretations from geophysical analyses and geodynamic modeling
    (Amer Geophysical Union, 2012) Komut, Tolga; Gray, Robert; Pysklywec, Russell; Gogus, Oguz H.
    The Western Anatolian and Aegean region demonstrates a complex geologic history of horizontal and vertical tectonics. Active normal faulting and exhumation zones indicate that Western Anatolia has experienced significant extension since the Oligocene-Early Miocene (similar to 30 Ma). Our geophysical analyses demonstrate that the region is also uplifted relative to an elevation that would be expected given an isostatic response to the lithosphere structure. Namely, topography residuals indicate a residual uplift of about 1500 m over similar to 200 km sections of Western Anatolia and the Aegean. Admittance functions between free-air gravity and topography indicate that the regional topography is isostatically uncompensated and as it approaches similar to 50 mGal/km at the longest wavelengths, the uncompensated topography is likely owing to an underlying mantle flow component. Using forward geodynamic modelling we consider an idealized section of Western Anatolian lithosphere based on tomographic inversions and examine the magnitude and pattern of surface topography to reconcile with the geophysical observables. The models consistently show a plateau-type uplift (and horizontal extension) through Western Anatolia with an amplitude and wavelength consistent with the residual topography calculations. Together, the geophysical analyses and modelling provide independent quantitative evidence that the thin Anatolian-Aegean lithosphere is being buoyed upwards by underlying mantle flow. The mantle flow may be associated with active lithosphere delamination beneath the region; a process that would also explain the ongoing crustal extension.
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    Present-day dynamic and residual topography in Central Anatolia
    (Oxford Univ Press, 2016) Uluocak, Ebru Sengul; Pysklywec, Russell; Gogus, Oguz H.
    The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of 'dynamic topography'. 2-D thermomechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along an N-S directional profile through the region (e.g. northern/Pontides, interior and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity and high surface heat flow/widespread geothermal activity. Model results suggest that there is similar to 1 km of mantle flow induced dynamic topography associated with the sublithospheric flow driven by the seismically inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myr. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.
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    Rapid surface uplift and crustal flow in the Central Andes (southern Peru) controlled by lithospheric drip dynamics
    (Nature Portfolio, 2022) Gogus, Oguz H.; Sundell, Kurt; Uluocak, Ebru Sengul; Saylor, Joel; Cetiner, Ugurcan
    The high flux magmatism, crustal shortening/extension and plateau formation in Cordilleran orogenic systems have been explained by removal of lithosphere (lower crust and the sub-arc mantle lithosphere) that develops beneath the magmatic arc and hinterland regions. However, the primary role of this process driving surface uplift, and crustal deformation is not well understood. Here, reconciling geodynamic model predictions with lithospheric structure and paleoelevation estimates, we suggest that viscous drip-type lithospheric removal from beneath the Central (Peruvian) Andes can explain several tectonic features: (1) double humped shaped/axisymmetric topographic profile and rapid surface rise (up to 1.2 km in similar to 4.31 Myrs); (2) thicker crust associated with the lower surface elevation of the Altiplano plateau (Lake Titicaca region) (negative residual topography) and higher topography and thinner crust of Western and Eastern Cordilleras (positive residual topography); and (3) faster wave speed (colder)/sub-Moho anomaly underlying the Altiplano, surrounded by slower speed anomalies on both western arc-forearc areas and parts of the eastern Cordillera and Sub-Andes. Our results emphasize the important role of lithospheric drip and associated mantle dynamics in the transient evolution of Andean orogeny controlling surface uplift and crustal flow and thickening.
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    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, Ebru
    The 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.
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    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, Claudio
    Many 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.