Origin of the sand population on the Sakarun Beach

U sklopu ovog rada analiziran je sediment plimne zone plaže Sakarun na Dugom otoku. Plaža Sakarun popularna je turistička destinacija Dugog otoka. Budući da istočnu obalu Jadranskog mora dominantno grade okršene karbonatne stijene pješčane plaže nisu česta pojava. Plaža Sakarun iz godine u godinu trpi velike gubitke sedimenta čime joj se površina smanjuje. Kako bi se spriječio daljnji gubitak sedimenta i kako bi se plaža zaštitila od nestanka, u sklopu ovog rada utvrđeno je porijeklo sedimenta plaže Sakarun. Analiziran je sediment s tri profila plaže iz plimne zone. Rezultati granulometrijske analize pokazali su da plažu grade relativno dobro sortiran pijesak te relativno dobro sortiran slabo šljunkoviti pijesak. Pijesak se najvećim dijelom sastoji od karbonatne komponente dok je siliciklastična podređena. Difrakcijom rengenskih zraka na prahu utvrđen je mineralni sastav u kojem dominiraju kalcit i magnezijski kalcit, a aragonit, kvarc i halit prisutni su u manjim količinama. Sediment plaže pregledan je pod mikroskopom, a mikroskopska analiza pokazala je da sediment grade ljušture organizama. Određivanjem udjela karbonatne komponente utvrđeno je da pijesak koji gradi Sakarun sadrži iznadprosječan udio karbonatne komponente što odgovara sedimentu koji nastaje u blizini obala i otoka. Poznavanjem porijekla i karakteristika sedimenta dobivamo jasniju sliku o regulaciji plaže i njenom očuvanju, budžetu sedimenta te njegovom donošenju i odnošenju.As part of this study the intertidal sediment of the Sakarun beach on the Dugi Otok Island has been analysed. Sakarun beach is a very popular tourist destination of the Dugi Otok Island. Since the eastern coast of the Adriatic Sea is dominantly built of karstified carbonate rocks, sandy beaches are not very common. Sand population of the Sakarun beach is declining which may cause general loss of beach. To prevent further sediment loss and protect the beach from extinction, the origin of the sediment of Sakarun beach was determined as a part of this work. The intertidal sediment along three beach profiles has been analysed. Granulometric analysis showed that beach is composed of moderately well sorted sand and moderately well sorted slightly gravelly sand. The sand is mostly composed of carbonate component, while siliciclastic component is present in traces. X-ray diffraction showed the mineral composition where calcite and magnesium calcite are dominant, while aragonite, quartz and halite occur in smaller amount. The sediment is analysed under the microscope. Analysis showed that sand is mostly composed of fragmented organism shells. Carbonate component analysis showed that sand from Sakarun beach contains an extremely high percentage of the carbonate minerals, which is a typical characteristic of the sediment that deposits near shores and islands. By knowing the characteristics and sediment origin, we are getting a clearer picture of beach regulations and their preservations, sediment budget and its input and output