Origin and distribution of clay minerals in the Alexandroupolis Gulf, Aegean Sea, Greece

The mechanisms of clay mineral distribution in Alexandroupolis Gulf are stu died. The annual solid supply of the Evros River, flowing into the Gulf, am ounts to at least 1 000 000 m(3). The surficial bottom sediments are common ly fine-grained and are distributed along zones almost parallel to the coas tline. In the central part of the Gulf clay-silt size sediments predominate . The main clay minerals in the size fractions (2-1, 1-0(.)25 and <0(.)25 m u m) are illite, smectite, kaolinite and in small amounts interstratified i llite/smectite. Quartz, feldspars, amphiboles and chlorite occur in traces in the coarser fraction (2-1 mu m) of some samples. All the above minerals are the weathering products of the Evros River drainage basin, as well as o f the Neogene and Quaternary unconsolidated sediments of the coast. The hyd rodynamic regime and physical grain size are the main mechanisms, which con trol the distribution of the clay minerals in the Gulf. The low content of kaolinite in all samples and the presence in traces of chlorite and amphibo les in some coarse clay fractions may be due to the unfavourable climatic a nd physicochemical conditions, as well as to the rapid transport and deposi tion of freshly weathered material. (C) 2000 Academic Press.