Rekonstrukcija paleookolja Tr žaškega zaliva v holocenu z uporabo geokemijskih metod -Reconstruction of the Holocene palaeoenvironmentof the Gulf of Trieste by using geochemical methods

The reconstruction of the Holocene paleoenvironment was performed in the Gulf of Trieste by geochemical analysis of four boreholes (V-3, MK -6, V-5 in V-6) from the offshore region and three cores dated with 14C (GT 1, GT 2 in GT 3) taken in the North and central part of the gulf. During the Würm regression the present Northern Adriatic continental shelf together with the Gulf of Trieste was a wide fluvio-lacustrine plain, where rivers coexisted with swamps and bogs forming peat soils. The cross-section of the Holocene sediment in MK -6 at a depth of 48 m below the present sea level indicates that the early Holocene – late Glacial sediment occurred about 10,000-11,000 years BP, when the sea started to enter the Rižana valley. At that time the eastern part of the Bay of Koper was still covered by the Rižana fluvial deposits. Marine sedimentation prevailed over brackish sedimentation during the most intensive marine transgression at the depth of 26 m in all four boreholes. The marine sediment is present at the depth of 1.6 m, 2.1 and 1.0 m in GT 1, GT 2 and GT 3 cores in the central part of the Gulf of Trieste, respectively indicating the lower rate of sedimentation compared to offshore regions. In the lower part of these sediments the fluvial-brackish sediment prevails, dated to 9030 ± 70 BP in GT 1, 9380 ± 40 BP in GT 2 and 9160 ± 50 BP in GT 3. These data are in good agreement with the general sea-level rise in the northern Adriatic in the Holocene