engleski

Paleoenvironmental reconstruction of Holocene sediments in Novigrad Sea and Karin Sea

Based on geoacoustic geophysical survey and high resolution multiproxy analysis of long sediment cores, it was possible to create palaeoenvironmental reconstruction of the whole Holocene sediment sequence and partially of underlying Pleistocene sediments in the Novigrad and Karin Sea. Palaeoenvironmental reconstruction includes terrestrial sediments predating Holocene flooding by the Adriatic Sea and marine sediments that span for last 11500 years. Marine transgression is determined at 9870-10750 cal BP. Sediment cores show a sediment influenced by the increased terrestrial influx which started at approximately 1.900 cal. yr BP. Similar event is evident in Krupa river floodplain (Zrmanja catchment), where high organic peat-like sedimentation is sharply replaced by high terrigenous input due to deforestation in the surrounding slopes. Evidence of anthropogenic changes with pronounced erosion due to deforestation in the catchments is evident in sediment as elevated magnetic susceptibility (MS), changes in color due to influx of red terra rossas visible as high a* and b*, elevated heavy metals (Pb, Cu), lithogenic elements, TOC, C/N and decreased carbonates. Significant influx of terrigenous material is visible from 720 cal BP at Zrmanja river mouth, 515 cal BP in Karin sea and 240 cal BP in Velebit channel. Highest erosion period in all locations is similar, and lasts from 160 to 265 cal BP. Thickness of Holocene marine sediments according to subbottom profiler data is up to 16, 5 m in Novigrad Sea and up to 9 m in Karin Sea. Due to the sea-level rise (as elaborated in DAY2 description), shallow and isolated Karin Sea bay (15 m deep) shows evidence of a brackish lake/marsh system in the period from 7.480 to 8.500 cal. yr. BP. It is recognized by high Ca concentration and low siliciclastic input typical for karstic lake sedimentation, low Sr/Ca ratio, elevated Sr/Ba, Pb/Al, Mg/Al ratios, elevated C/N, pollen and foraminiferal assemblages. This period is followed by sedimentation of fine grained dominantly silty sediments with dominance of calcite and quartz. Dark, sediment with low MS, TOC, C/N, Sr/Ca, Mg/Al and Mn/Fe ratios is typical for marine sedimentation, which lasts until today.

Holocene, sea level rise, marine sedimentation, anthropogenic influence

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