Investigation of the Black Sea outlet of Istanbul Strait

Shelf and continental slope region of southwestern Black Sea shelf in front of the Bosphorus outlet are investigated by using high resolution acoustic data. These data are correlated with analysis and dating of cores recovered from critical points on the shelf to determine recent sedimentation in relation with neotectonics, the horizons of sea level changes since Last Glacial Maximum (LGM) and to understand their effects on recent sediments. EM300 Multibeam Echosounder system provided most detailed bathymetric map of the area that ever obtained and extensive geomorphologic features such as continental slope, submarine canyons and slumps are determined. Very high resolution seismic (Chirp) system was used to determine recent sedimentation, active faulting, shallow gas accumulations and mud volcanoes.The triggering mechanisms for the formation of slumps, secondary canyons, gullies on the canyon walls at the continental slope and shelf incising canyon heads were discussed. The westerly abrupt turn of the canyon head, which is proceeding on the shelf, is associated with the North Border Fault. Also shallow gas accumulations observed at the shelf and shelf edge region. In piston coring which is recovered in the frame of European Assemblage project, the sediments are extremely disturbed due to gas existence. For the first time, Gas Hydrates were recovered in gravity core that was taken from NW part of the study area.The seismic startigraphy of the channel system at the exit of Istanbul Strait was betrayed. From the existence of the channel system at the exit of Bosphorus, it is concluded that, the entrance of Mediterranean water into Black Sea was originated in a high energy system before the two-way under water current system between Istanbul Strait and Black Sea was formed. On the basis of the catastrophic and anti-catastrophic hypotheses and sea level changes since last glacial maximum (LGM) in correlation with core dating, a scenario was developed to explain the last connection between Marmara Sea and Black Sea.