engleski

Eastern Adriatic karst isolation basins, sea level changes and paleoenvironments during the Late Quaternary

Numerous karst depressions exist along the Croatian coast of the eastern Adriatic and many have been submerged due to the Holocene sea- level rise. They may be connected or isolated from the sea in relation to the variations in relative sea-level (RSL) and their sill depth. When RSL is lower than the sill depth, depressions become isolated from the direct marine influence and freshwater environments may form. As the sea level rises, brackish- water phase occurs due to the seawater intrusion through karst. When RSL reaches the sill depth, depressions become flooded and marine deposition starts. Thus, sediments preserved in karst depressions can be a valuable source of paleoenvironmental and RSL data. The coastal areas of the Mljet Island, Lošinj Channel and Pirovac Bay are typical examples of submerged karst environments with sills at different depths. We provide a sedimentological record based on the multi- proxy analysis of 10 piston cores, combined with high resolution seismic data. The dated sediment successions enabled differentiation of freshwater, brackish-water and marine environments that existed in the studied areas during the Late Pleistocene and Holocene. We observed ingression contacts (i.e., onset of marine deposition) in each analyzed sediment core. In the Lošinj Channel we dated the oldest ingression contact at 10.5 ky BP, with sill at depth of 50 m. In the Stupa Bay on the Mljet Island this contact was dated at 9.8 ky BP in a basin with a sill depth of 19 m. Smaller sub- basin in the Lošinj Channel was ingressed at 7.9 kyr BP, similar as Pirovac Bay. The youngest ingression contacts were recorded in sediment cores from small sub-basins with shallow sills in the Lošinj Cannel and Veliko jezero on the Mljet Island. The collected data enabled us to infer RSL by combining the radiocarbon dates from the ingression contacts and sill depths. Current and future work includes detailed investigations of the other locations along the eastern Adriatic coast (e.g., Telašćica Bay, Kornati Channel, Koločep Channel) which are characterized by similar geomorphology. The composite RSL record obtained from different locations can improve our understanding of the Adriatic RSL and palaeoenvironmental changes, especially at the beginning of the Holocene for which only few data exist in this area.

isolation basins, eastern Adriatic coast, Quaternary, paleoenvironments

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