Rapid subsidence and sedimentation from oblique slip near a bend on the North Anatolian transform fault in the Marmara Sea, Turkey

Abstract

Several basins are developing near bends on strands of the North Anatolian transform fault in northwest Turkey. Oblique slip on these faults, rather than strain partitioning, accounts for trans- tension and subsidence. These basins are asymmetric, and tilt and subside most rapidly at their narrow ends near the bends. The turbidite surface marking the floor of the Cinarcik Basin (eastern Marmara Sea) was mostly abandoned at a sudden drop in sedi- mentation, which was likely coincident with the 14 ka lake-sea transition, and is now a warped reference surface from which we can measure strain and sedimentation. Subsidence and tilt are rap- id, but do not require late Quaternary changes in regime. They are linked to transcurrent motion by slip parallel to an oblique bend on the North Anatolian fault and suggest tsunamogenic ver- tical motion in large Marmara Sea earthquakes.