Geological and kinematic evolution of the western part of the North Anatolian Fault system: an analogue modelling investigation

Sibel Uskuplu

Research output: ThesisDoctoral Thesis

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The right-lateral North Anatolian Fault (NAF) appears to be an exceptional example of a continental strike-slip fault that extends in an east-west direction for more than 1200 km dividing the Eurasian and Anatolian plates. To the east the plate boundary is localized along a single fault system while toward the west the fault branches into three segments. The Sea of Marmara lies along the western part of the NAF, and it is a key geodynamical region characterised by transtension accommodating both the strike-slip motion between Anatolia and Eurasia and the extensional deformation present in the adjacent Aegean region. Although it has been, and still is an intensively studied area, the NAF geometry and kinematics, and their relationship with the geology and geodesy within the Sea of Marmara are not entirely constrained.
To investigate the geometry and the evolution of pull-apart basins and of the Sea of Marmara in particular, I used crustal-scale 3D analogue models and GPS-derived strain rate field. The analogue models consisted of two different rheological layers, upper and lower crust, while the geometry of the fault was reproduced by a releasing bend adjacent to a restraining bend subject to dextral movement. The crustal thickness and the length and orientation of the releasing-restraining bend pair in the analogue model were scaled according to the western part of the NAF. In the experiments, we used dry- quartz sand and silicon putty to simulate the rheological behaviour of the upper and lower crust, respectively. The experimental methods further illustrate the characteristics of the analogue models and techniques used to elaborate their data. We compared the models to different regions in the Sea of Marmara at different scales. The analogue models reproduced the overall basin characteristics and showed how the basin evolved to attain subsidence along the releasing bend and uplift over the restraining bend. Topography and slip transfer along different parts of the fault system were analysed. The findings of this study contribute to the understanding of the geometry of each segment of western NAF that influences the overall geodynamic evolution of the area of the Sea of Marmara.
In the last years dense campaign GPS – Global Positioning System - measurements constrained modern deformation in western Anatolia and the Sea of Marmara. I elaborated these data to obtain the strain rate pattern over this area, including the orientation and the magnitude of its principal horizontal components and dilation. This last analysis allowed us to gain an overall perspective on the deformation trend of the Sea of Marmara resulting from the interaction of Anatolia with the Nubian slab rollback in the Aegean Sea. The result showed the different strain accumulation in the Anatolia and Eurasia plates, but also an extensional neotectonics regime possibly linked to the Aegean extension.
In this thesis, the analogue models are compared with the western part of the North Anatolian Fault -Sea of Marmara. However, these models also have general applicability to complex strike slip fault systems where the interaction of restraining/releasing bend (double-bend) are even less clearly understood than in the Sea of Marmara. This general applicability is the result of our “geometrical” approach which can be compared to other natural examples that show a reasonable fit.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Vannucchi, Paola, Supervisor
  • Morgan, Jason, Advisor
Award date1 Feb 2021
Publication statusUnpublished - 2019

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