Topography controlling the wind regime on the karstic coast: late Pleistocene coastal calcareous sands of eastern mid-Adriatic, Croatia

Aeolian dunes controlled by regional climate have been formed in many coastal areas of the Mediterranean Sea during the Quaternary. Generally, they are formed under a landward-blowing wind, and comprise numerous reworked penecontemporaneous shallow-marine carbonate grains. Along the eastern mid-Adriatic Sea, late Pleistocene aeolian and alluvial sands occur as isolated patches in karstic depressions on several islands and the Peljesac Peninsula. At most localities, the sands consist of a mixture of mostly carbonate rock fragments and siliciclastic material. A higher proportion of shallow-marine bioclasts was found only at one locality. The terrestrial material was transported to the coastal area by at least two rivers: paleo-Cetina and paleo-Neretva River, and was subsequently reworked and transported by wind, resulting in aeolian deposition. Sandy units of various thicknesses exhibiting sharp erosional bedding planes and cross-bedding are interpreted as representing aeolian dunes and sand sheets controlled by a complex wind regime. The mineralogical composition at almost all localities indicates near-river flood plains as the main sand source. Although the area was affected by strong winds blowing landward and parallel to the coast, they significantly deviated due to the local topography produced by the tectonically deformed and karstified carbonate basement. In this way, the late Pleistocene aeolian deposits on the mid-Adriatic islands differ from deposits from most Quaternary Mediterranean coastal aeolian belts, as they contain very small quantities of penecontemporaneous shallow-marine carbonate grains and were deposited by winds blowing in varying directions instead of prevailing landward-blowing winds.