Modes of active tectonics in Gokceada island, northern Aegean Sea

Category Tectonic & Seismotectonic
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Koral, Hayrettin; Ozturk, Huseyin; Hanilci, Nurullah
Holding Date 11 October 2008

Gokceada (formerly Imbros) Island lies in the northern Aegean Sea in close proximity of the Saroz Tough along the seismically active North Anatolian Fault (NAF). It has a high and rough topography along its western shore that diminishes towards the north and east with a depression in the middle. The peaks reach up to 673 m in the northwestern half of the island which has a water division line along a NE orientation asymmetrically proximal to the western coast. The island possesses a variety of morphological and coastal features such as paleo-coastal notches, hanging valleys, waterfalls, springs and travertine formation, all evidences of active tectonics. Fault segments parallel to the NAF in NE-SW orientations coincide with many of these morphotectonic features and truncate the sequence in the island which comprises more than 2 km thick Tertiary sedimentary strata over underlying metamorphic rocks. The exclusive exposure of the metamorphics at the base of the Tertiary strata in the island and their total absence on the surface in the adjacent Thrace basin, together with evidence of morphotectonic, geological and tectonic features, suggest an alternative setting of strike-slip transpressional fault within the reported extensional tectonic setting of the strike-slip North Anatolian Fault (NAF). Considering the metamorphic rocks presently lie at a water depth of more than 1000 m in the Saroz Trough we could suggest that a few kilometers of vertical displacement must have occurred to acquire their present position on the island. Hence, the NAF exhibits modes of dip-slip along with strike-slip movements. This is consistent with the thrust and normal-slip components in recorded in the seismic events of the region.