Quaternary Evolution of Cinarcik Basin, Marmara Sea, Turkey from structural and stratigraphic interpretation of multiple resolutions of seismic reflection data
Abstract
Marmara Sea in western Turkey is an active subsiding marine basin forming along the North Anatolian Fault (NAF). The NAF is 1500 km-long and in northwest Turkey accommodates the current GPS-derived ~25 mm/yr westward motion of the Anatolian platelet relative to Asia. The Marmara Sea contains three subbasins with water depths reaching 1250 m, called from west to east the Tekirdag, Central and Cinarcik basins. These basins are separated by shallower topographic highs, the Western and Central highs. The NAF has two main branches and multiple strands within Marmara Sea and Cinarcik basin is a wedge-shaped active transtensional basin located along the northern branch of the NAF. We use exisiting deep-penetration, low-resolution migrated multichannel seismic reflection (MCS) data and our new migrated high-resolution MCS data for seismic stratigraphic interpretations in Cinarcik basin. This basin has a thick and not uniformly distributed sediment fill, with a maximum sediment thickness of 6 km or more (Carton et al., 2007). We used all seismic reflection data to correlate five stratigraphic horizons from the Imrali basin to the south, which contains stacked low-stand shelf-edge deltas. Our age model assigns these horizons to glacial maxima separated by 100 ka. The age of the deepest horizon is older than 500 ka using our stratigraphic-age model for Imrali basin (Sorlien et al., in review). We used a simple 3D velocity model based on stacking velocities and refraction velocities (Dessa et al., 2007). Gridded digital horizons were depth-converted and subtracted from each other to produce isochore maps (vertical thickness) between horizons including the sea floor. Volumes were calculated for each isochore grid and combined with isochores for the basin to the south. Assuming a constant rate of deposition in the two basins, the near constant interval volumes support the age model. The east ends of depocenters for each ~100 ka interval migrate westward with respect to the footwall north of the south-dipping Northern NAF. This assumes subsidence initiates at a fixed footwall bend at the southeast end of a releasing segment in this fault (The Tuzla Bend). Using the age model, the depocenter migrates at about 2 cm/year with ongoing right-lateral displacement. This supports steady-state fast slip on the northern NAF and not the young reorganization of it that has been proposed. Published models include right-normal oblique slip on a non-vertical northern NAF accommodating all extension across the releasing segment. Other publications include partitioned normal faults along southern Cinarcik basin accommodating 10 mm/yr extension. Our interpretation using the age model supports only 2 mm/yr of extension, and these normal faults are localized along only the SE part of the releasing segment supporting the right-normal oblique slip model.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.T31F..08K
- Keywords:
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- 3025 MARINE GEOLOGY AND GEOPHYSICS / Marine seismics;
- 3045 MARINE GEOLOGY AND GEOPHYSICS / Seafloor morphology;
- geology;
- and geophysics;
- 8111 TECTONOPHYSICS / Continental tectonics: strike-slip and transform;
- 8150 TECTONOPHYSICS / Plate boundary: general