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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.

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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.

The Western Black Sea basin formed during the rifting of the Moesian Platform in Early Cretaceous. The closure of the Neotethys Ocean in the Middle Eocene resulted in the formation of the Pontide fold and thrust belt in northern Turkey. During this study, eight seismic reflection profiles were interpreted to determine the subsurface structural geometry and tectono-stratigraphic evolution of the offshore Akçakoca-Amasra area. The stratigraphy of the study area is determined based on a composite wireline well log of the Akçakoca-1 wildcat well, which was also used to construct a velocity model based on sonic data. We suggest that a major décollement surface was developed during the Eocene Pontide Orogeny. The decollement is located at the limestone clay-shale intraformational transition within the Late Cretaceous (Maastrichtian)-Paleocene Akveren Formation. Normal faults formed during the Cretaceous rifting in the region are located below the décollement surface. They provide tectonic ramps along the décollement surface and allow the decollement to develop ramp-flat thrust fault geometry. A well-developed duplex structure is also present along the seismic lines. The décollement surface serves as the floor thrust of the duplex structure. The roof thrust of the duplex is in the Pliocene Sarıkum Formation, dominantly composed of claystone.