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

Abstract

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 À1.48 m at 715 BCE to À1.05 m by 100 CE at 0.52 mm/yr (À0.82-1.87 mm/yr). Between 500 and 1000 CE RSL was À0.7 m below present rising to À0.25 m at 1700 CE. RSL rise decreased to a minimum rate of 0.13 mm/yr (À0.37-0.64 mm/yr) at~1450 CE. The salt-marsh reconstruction shows RSL rose~0.28 m 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 (À0.25 m at 715 BCE) are consistently higher than the reconstruction (À1.48 m at 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.

Coastal submersions in the north-eastern Adriatic during the last 5200 years

“…Bonaldo et al (2020) also showed a shift in directional wave-energy contributions in the northern Adriatic resulting in a possible local increase in wave climate severity along the northern and north-eastern coasts. This process could be aggravated in northern Croatia by coastal subsidence amounting to 0.4 mm per year (Faivre et al, 2019a(Faivre et al, , 2021, which is coherent with the estimated 0.45±0.6 mm per year subsidence in southern Croatia (Faivre et al, 2013;Shaw et al, 2018). Moreover, RSL changes for the last 1500 years along north-eastern coasts seem consistent with shifts in temperature and consequently with periods of rapid climate change (Faivre et al, 2019a).…”

Relative sea-level change and climate change in the Northeastern Adriatic during the last 1.5 ka (Istria, Croatia)

“…The northern Adriatic coast is generally considered to be a subsiding environment (Pirazzoli, 2005;Antonioli et al, , 2007Shaw et al, 2018). In order to estimate the ongoing contribution of land-level change and identify climate driven sealevel trends, we applied corrections for crustal movements associated with the spatially variable and ongoing GIA.…”

“…This quantitative approach has been used in several recent papers dealing with RSL change (e.g. Kemp et al, 2011Kemp et al, , 2013Shaw et al, 2018) providing data which can further be reliably compared (e.g. Kemp et al, 2015).…”

“…During the last two decades, this period has also been increasingly studied along the eastern Adriatic (e.g. Fouache et al, 2000;Faivre and Fouache, 2003;Benac et al, 2004;Pirazzoli, 2005, Antonioli et al, 2007Florido et al, 2011;Furlani et al, 2011aFurlani et al, , 2011bFurlani et al, , 2014Faivre et al, 2010aFaivre et al, ,b, 2011aShaw et al, 2018;Marriner et al, 2014;Evelpidou et al, 2014a, Evelpidou andPirazzoli, 2017;Vilibi c et al, 2017;Faivre and Butorac, 2018). Sea-level curves are obtained using various methods, from land and sea records, and are based on different markers (geomorphological, sedimentological, archaeological, historical and biological/ecological) which are often combined or used together (e.g.…”

Common Era sea-level budgets along the U.S. Atlantic coast

“…The 2274 individual data points in the database use proxies such as foraminifera, diatoms, testate amoebae, coral microatolls, archaeological evidence, and sediment geochemistry. We have updated the database (Supplementary Data) from Kemp et al (2018) to include 390 new RSL data points from northern New Jersey, USA (this study); Croatia 56 ; French Polynesia 57 ; Israel 58 ; Quebec 59 ; Connecticut 25 ; Maine 25 ; and Nova Scotia 25 . We compared the new northern New Jersey record with other published records along the U.S. Atlantic coast from southern New Jersey (Leeds Point and Cape May Courthouse 14 ), New York City 15 , Connecticut 60 , and North Carolina 45 to examine regional variability in magnitudes and rates of past RSL change, as well as variability in regional Common Era sea-level budgets.…”