The provenance of beach sediments on Rhodes, southeastern Greece, indicated by sediment texture, composition and roundness

Abstract

The texture, composition, provenance, and transport of beach sediments and the roundness of sediment grains were studied on the coasts of the island of Rhodes in southeastern Greece. All the studied beaches are intermediate or high-carbonate beaches where the texture and mineral composition of beach sediments and roundness of sediment grains display some degree of local variation. Beach sediments consist mainly of medium and coarse sand and granule gravel, being moderately or poorly sorted, symmetrical or negatively skewed and leptokurtic or very leptokurtic. On pocket beaches the mineral composition is closely related to nearby exposed coastal formations (sea cliffs, bluffs and rocks), the grain-size frequency distributions of beach sediments being nearly normal, and the roundness of sediment grains good. Where rivers discharge on to the beach or near to it, the mineral content of these beaches is related both to the formations situated inland in the catchment basins of the rivers and to coastal formations. River sediments (55–60%) and coastal abrasion sediments (40–45%) on shores are mixed by waves and littoral drift. Low-Mg calcite and quartz are the most common minerals in the beach sediments of Rhodes. The other common minerals are dolomite, feldspars, olivine, and magnetite; the sources being mainly the ophiolites on the mountains of northern Rhodes. The direction of net littoral drift is determined mainly by the predominant wind and waves approaching from the direction of the greatest fetch. These same waves determine, to a large extent, the direction of seasonal littoral drift in the beach and swash zones, whereas in the surf zone on the NW coast of Rhodes, it is determined mainly by the prevailing wind and waves.