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This paper presents research results for Holocene sedimentary processes and controlling factors in Datça and Hisarönü Bays located in south west Turkey. For this purpose, we collected seafloor grab samples (upper 30 cm) from 71 stations and seismic profiles (only one sample is used to explain sedimentary process) from Hisarönü and Datça Bays with the MTA-SELEN research ship. According to the seismic profile, the continental self edge or threshold is found at depths of -90/-120 m and displays seismic facies parameters showing sea level variations from the Quaternary period. According to radiocarbon dating calculations, the sediment samples began to be deposited 2694-14700 years before present. The seafloor sediments comprise 1-18% gravel, 7-85% sand, 2-30% silt and 6-69% clay size clastic material. Although mud of mixed silt and sand composition is the most common sediment type, there are significant sand and gravel amounts. As well as discussing regional differences in grain size distribution, the presence of residual (relict) sediments is noted. The total amount of heavy mineral-rich black sand is mostly below 2%, reaching 13% in ophiolite-and chromite-rich central and eastern regions. Inorganic geochemistry of sediments includes relatively significant amounts of ophioliticsourced Mg, Cu, Ni and Fe. Regional variations in river drainage system, bay morphology, terrestrial source rock lithology and marine waves and currents affect not only sediment grain size distribution, but also total heavy mineral content and the main element composition.

The 23 October 2011 Van Earthquake (Mw: 7.2) was generated by the Van Fault Zone (VFZ) with reverse fault characteristics. The earthquake on the fault caused surface deformation with 10 cm displacement observed in engineering structures. On land the VFZ has general E-W strike and 28 km length. The western end of the fault is within Lake Van. This study aimed to determine the tectonic structures and evolution in the Quaternary of Edremit Bay using detailed mapping of the VFZ with land and underwater research methods, investigation of its continuation into Lake Van and common assessment of land and underwater data. Continental data showed the presence of E-W fold axes affecting Quaternary units in the hanging-wall and footwall of the VFZ. Offshore studies using shallow seismic profiling (GeoAcoustics) and multibeam bathymetric data acquisition determined that the underwater section of the VFZ had similar characteristics to those on land. Quaternary successions on the lake floor observed on seismic sections clearly showed folds in both blocks of the fault with axes parallel to the strike of the fault. The underwater ridge that is an extension of Çarpanak Cape coincides with the ridge structure on the hanging-wall block of the fault on land. Surface deformation related to the 23 October 2011 earthquake developed in a broad zone of the hanging wall of the VFZ. The research findings show the deformation along the VFZ in the Quaternary is in accordance with the deformations developing during the last earthquake.

Within the scope of this paper, seismic reflection and bathymetry studies were carried out in the shallow marine area forming the westernmost part of the Tekirdağ Basin using the R/V Selen Research Ship within the MTA Marine Research Department. In the study area, ~ 500 km length shallow seismic and bathymetry data were collected along 41 lines. By means of the data, tectonic structures and deformation textures of the North Anatolian Fault System (NAFS) in the marine area of Gaziköy were examined. As a result of the processing and interpretation of the seismic lines, compression structures occurring due to the SW rotation of the NAFS in the study area, the morphology of the Ganos depression that formed as a result of faulting and also three different stratigraphic units were distinguished. These units are separated from each other by distinct unconformity surfaces and each unit presents different deformation structures. One of the most significant results obtained from the seismic data is that the unconformity surface that separates the current sediments of the seafloor from the older units is represented by the overlapping structures indicate sea level changes. It has been assessed that this situation occurred as a result of the erosional process developed during sea level fall.

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