COASTAL EOLIAN DEPOSITS IN THE EASTERN ADRIATIC, CROATIA: WHY THEY ARE ATYPICAL?

Aeolian dunes controlled by regional climate have been formed on many coastal belts during the Quaternary. Generally, they are characterized by two main properties: (i) the wind regime that has caused landward dune progradation, and (ii) specific calcareous composition that comprises deflated shallow marine carbonate grains such as bioclasts, foraminifers, peloidal grains and ooids.

Pleistocene coastal aeolian deposits occur as isolated erosional patches on the islands of Hvar, Vis, Mljet, Lastovo and Korcula, as well as on the Peljesac peninsula in the eastern Adriatic. These islands represent parts of the Karst Dinarides, mountain chain connecting the Alps with Hellenides and Taurides along the NE Adriatic coast, composed in this part mostly of a thick pile of carbonates predominantly derived from the Mesozoic Adriatic Carbonate Platform. Studied islands are today surrounded by shallow sea, and during the major glacial relative sea-level falls in Pleistocene represented part of the mainland.

Coastal aeolian deposits in the eastern Adriatic have been found at different altitudes, up to 200 m a.s.l. They are mostly composed of very fine to medium grained sands exhibiting distinct cross-bedding, and are interpreted as dunes, megaripples and sand sheets formed in dry and cold climate. Due to climate change into wet and more warm, some of the sands were eroded and redeposited in local fluvial environments. Eolian sands represent mixture of variable share of calcareous and siliclastic detritus. However, carbonate component is composed exclusively of limestone lithoclasts derived from older limestones since they do not contain subrecent shallow marine carbonate grains, with exception of numerous bioclasts determined on the island of Lastovo. The complex wind regime that operated on the coast during deposition caused dune progradation seaward, landward and paralel to the coastline, unlike typical coastal aeolian deposits showing landward dune progradation.

Therefore, Pleistocene coastal aeolian deposits from the eastern Adriatic islands of Hvar, Vis, Mljet, Lastovo and Korcula and the Peljesac peninsula may be regarded as atypical since they (i) mostly do not contain any subrecent grains of marine origin, and (ii) were caused by a complex wind regime resulting in progradation of dunes in different directions.