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    A Discussion on Geodynamic Modeling Methodology: Inferences from Numerical Models in the Anatolian Plate
    (Tmmob Jeoloji Muhendisleri Odasi, 2024) Uluocak, Ebru Sengul
    Numerical models have found widespread use in geosciences, mainly due to high-resolution datasets and the development of supercomputing facilities with powerful data processing and storage capabilities during the past two decades. Instantaneous and time-dependent geodynamic modeling studies were carried out in many regions of the Alpine-Himalayan orogenic belt, including the Anatolian Plate, to investigate mantle dynamics such as lower lithosphere deformation, upper mantle flow, and their surface implications. This study focuses on the instantaneous numerical modeling technique by considering multidimensional thermomechanical models in the Central and East Anatolian plateaus. To this end, conventional geodynamic modeling processes are explained with a conceptual flow chart that shows a feed-forward backpropagation modeling architecture which is nonlinearly fed by a large parameter space. While addressing a complex natural phenomenon controlled by variables on a wide range of space-time scales, the limitations as well as advantages of numerical models are analyzed. In addition to conventional techniques, systematic data improvement is discussed as a new strategy in data/ parameter-dependent numerical model design through an iterative process based on the Grounded Theory method for the construction of an explanatory theory from the model. This involves not refinement but (re)construction of the data (i.e., measurement/analysis/scaling) as an effective way to reveal theory/information grounded in data. It is speculated that this procedure, which includes problem-oriented data reconstruction accompanying the numerical modeling process, may provide an integrated perspective for instantaneous numerical modelling.
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    An Overview of Modeling in Earth Sciences; Inferences from Environmental Geophysics Applications
    (Tmmob Jeoloji Muhendisleri Odasi, 2024) Uluocak, Ebru Sengul; Ulugergerli, Emin Ugur
    In an earth science-related research study, while investigating geological or engineering problems, numerical modeling functions in two stages; i) prior to the fieldwork, obtaining the survey parameters (conceptual model), and ii) subsequent to the fieldwork, confirming the accuracy of the estimated subsurface structures with the help of the conceptual model. Although the numerical modeling process alone is not sufficient in both stages, it is possible to converge the numerical models into a realistic subsurface structure with additional information obtained from interdisciplinary studies. In this article, a workflow is proposed employing modeling studies used in earth sciences. Environmental pollution studies carried out on a now-unused open waste disposal site in Canakkale (Turkiye) are presented following this workflow. Accordingly, tomography measurements were made by using the electrical resistivity method along the profiles determined based on a conceptual model, and then a hypothetical two-dimensional (2D) combined solute transport model was produced by obtaining the porosity cross-section from the subsurface resistivity structure of the study area. The results show the spatial and temporal variation of pollution in the landfill during the years that geophysical measurements (i.e., 2004, 2008, and 2009) were taken, and the numerical modeling time (13,6 yrs). Besides, the numerical modeling results provide a conceptual model for future pollution studies in this area, with the length and depth of the possible survey profile (similar to 40-250 m and 0-25 m, respectively). The results emphasize the importance of evaluating geophysical studies together with numerical models sensitive to the spatial and temporal spread of the pollution cloud emitted from a polluting source, such as an open dumpsite.
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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, Omer; Gogus, Oguz Hakan; Brune, Sascha; Uluocak, Ebru Sengul; Glerum, Anne; Fichtner, Andreas; Sozbilir, 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.& COPY; 2023 Elsevier B.V. All rights reserved.
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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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    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, Tasca
    According 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.
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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.