engleski

Tectonic influences on late Holocene relative sea levels from the central-eastern Adriatic coast of Croatia

Differential tectonic activity is a key factor responsible for variable relative sea-level (RSL) changes during the late Holocene in the Adriatic. Here, we compare reconstructions of RSL from the central-eastern Adriatic coast of Croatia with ICE-7G_NA (VM7) glacial-isostatic model RSL predictions to assess underlying driving mechanisms of RSL change during the past ~ 2700 years. Local standardized published sea-level index points (n ¼ 23) were combined with a new salt-marsh RSL reconstruction and tide-gauge measurements. We enumerated fossil foraminifera from a short salt-marsh sediment core constrained vertically by modern foraminiferal distributions, and temporally by radiometric analyses providing subcentury resolution within a Bayesian age-depth framework.We modelled changes in RSL using an Errors- In-Variables Integrated Gaussian Process (EIV-IGP) model with full consideration of the available uncertainty. Previously established index points show RSL rising from 1.48mat 715 BCE to 1.05m by 100 CE at 0.52 mm/yr (0.82-1.87 mm/yr). Between 500 and 1000 CE RSL was 0.7m below present rising to 0.25mat 1700 CE. RSL rise decreased to a minimum rate of 0.13 mm/yr (0.37-0.64 mm/yr) at ~1450 CE. The salt-marsh reconstruction shows RSL rose ~0.28m since the early 18th century at an average rate of 0.95 mm/yr. Magnitudes and rates of RSL change during the twentieth century are concurrent with long-term tide-gauge measurements, with a rise of ~1.1 mm/yr. Predictions of RSL from the ICE-7G_NA (VM7) glacial-isostatic model (0.25mat 715 BCE) are consistently higher than the reconstruction (1.48mat 715 BCE) during the Late Holocene suggesting a subsidence rate of 0.45 ± 0.6 mm/yr. The new salt-marsh reconstruction and regional index points coupled with glacial-isostatic and statistical models estimate the magnitude and rate of RSL change and subsidence caused by the Adriatic tectonic framework.

Relative sea level, Adriatic, Croatia, Late Holocene, Glacial isostatic adjustment, Tectonic subsidence, Salt marsh, Foraminifera

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