A new example of polyphase basin formation in western Anatolia: Plio-Quaternary Tavşanlı Graben, Kütahya

Abstract

ABSTRACT The southwestern part of Turkey is called the ‘western Anatolia Extensional Province‘. Today, there is an approximately N-S-oriented extension in this area. The seismically active region is characterized by E-W and N-S-trending grabens. The tectonism and evolution of Tavşanlı Graben, one of these grabens, during the Plio-Quaternary period are the main subjects of this study. The Tavşanlı Graben, about which there is no information in the literature, has been defined for the first time in this study, and the geometrical and kinematic properties, relative ages, and interrelationships of some Neogene-aged faults, especially Quaternary-aged faults, have been presented in the manuscript. The data obtained indicate strike-slip faulting in the late Pliocene in the region. These E-W striking faults and the basin they formed are the first in western Anatolia with these features. In the Quaternary, E-W-oriented normal faults were formed in the region. The asymmetric topography of the graben area is consistent with the other E-W-oriented grabens in western Anatolia. Late Cretaceous basement rocks and Miocene-aged units are observed at the margins of the graben, which are fragmented by faults. The fill of the graben is Quaternary-aged fan deposits and alluvium. In this study, it was determined that the Tavşanlı Basin, which started to form with a transtensional mechanism at the end of the Pliocene, was transformed into the Tavşanlı Graben in the Pleistocene. The basin formation, which started with directional faulting in the late Pliocene, evolved into a graben in the Quaternary, and reached its present form by completing its development in two phases, supports the views that adopt the multi-stage deformation of western Anatolia in the late Cenozoic. In addition to contributing to the literature on this subject, the article will also serve as a basis for future paleoseismological studies.