Seabed Sedimentology and Elemental Geochemistry of the Aegean Sea

The Aegean Sea is a water body located in southeastern Europe and western Asia, between the Greek mainland and the western coast of Turkey. It is connected to the Mediterranean Sea to the south and the Sea of Marmara to the northeast. Its topography is complex and comprised of several alternating deep basins, ridges, and islands. Data on sedimentology (grain size) and inorganic elemental geochemistry have been compiled to present the most up-to-date knowledge of the region and to identify the major processes of sediment provenance and deposition.

The North Aegean Sea receives freshwater and sediment load from several rivers that drain the Balkans, Greece’s mainland, and Asia Minor. Sediment supply, along with bottom topography and local hydrological features are the controlling mechanisms that define the texture and geochemistry of surficial sediments. Fine aluminosilicate sediments occupy prodeltaic areas, parts of the extended continental shelf, and the deep basins. However, in areas where sedimentation rates are low, sediments deposited during the last sea transgression – relict sediments – prevail. The relict sediments are of a sandy texture with high carbonate contents associated with the biogenous component of the sediments. Most of the trace elements examined are associated with lithogenous aluminosilicates but elevated values are observed near industrialized sectors, and the river prodeltas, attributed to contamination from anthropogenic activities.

The main characteristic of the Central Aegean Sea is the shallow Cyclades Plateau which is comprised of many islands. The seabed is generally covered by coarse sandy sediments, rich in biogenous shells and their fragments. As such, major and trace elements are considerably diluted by carbonates, meaning they are substantially lower in content than those of the North Aegean Sea.

Overall, the abundance of elements and their variability in the Aegean Sea is regulated by the relative proportions of terrigenous vs biogenous components, grain size, and water depth. Sediments around the Hellenic Volcanic Arc islands display a different character but this is restricted to very near their sources. The South Aegean Sea is comprised of the Cretan Sea and the Dodecanese Islands. The limited information that is available for the region suggests finer sediment textures of a terrigenous element origin.

The Aegean Sea is a true oceanographic laboratory and rightfully has attracted the attention of the scientific community over the last decades. However, it is striking that large sectors of the Aegean have been largely under-sampled and thus remain unexplored for sedimentological and geochemical studies.