MORPHOTECTONIC EVOLUTION OF THE ARMUTLU PENINSULA AND SURROUNDINGS - NW ANATOLIA - TURKEY; SOME MAJOR CHARACTERISTICS OF EASTERN MARMARA REGION

Northwestern Anatolia is a region that has the most complex features of North Anatolian Fault System and intensive seismic activity. Because of this, there have been many neotectonic and seismologic investigations in this region. However, the morphotectonic researches that should be the first step of the neotectonic and seismologic studies are relatively less and insufficient. In this presentation, the Armutlu peninsula as a main morphotectonic entity of the northwestern Anatolia and its significance will be discussed.

Northwestern Anatolia is a mosaic composed mainly of different morphotectonic units that separated from each other with recent active or inactive structural elements. The main components of the mosaic are represented by Trakya-Kocaeli peneplain, Çamdað-Akçakoca plateau, Armutlu-Almacýk highland, Bursa-Bilecik plateau. These major morphotectonic units separated from each other some minor morphotectonic units such as Adapazarý-Karasu corridor, Adapazarý basin, Ýzmit-Sapanca corridor, and Gemlik-Pamukova corridor.

Investigation of internal structures and interrelations of these major and minor morphotectonic units reveals some important data on the neotectonic features of northwestern Anatolia. Common features of the morphotectonic units are having an Upper Miocene-Lower Pliocene sedimentary cover. The succession composed mainly of continental – fluviatile – lacustrine sediments is very critical because of its deposition on a peneplain topography just before the neotectonic period. The first data on the neotectonic activity of the northwestern Anatolia can be observed only in the uppermost level of this unit. In this period, the region was uplifted and a conjugate fault system developed NW and NE direction probably under N-S compressional stress. This conjugate fault system, which dissected the peneplain topography, was cut by the North Anatolian fault system and finally the recent morphotectonic units of the region were formed under this complex structural pattern. The members of NW and NE conjugate fault system most of which are inactive until recently, were reactivated under the effects of the North Anatolian fault system and some rotational block movements in Armutlu peninsula were developed along the boundary of major and minor morphotectonic units.