Abstract

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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