AN IMPROVED FRAMEWORK FOR THE ASSESSMENT OF HOLOCENE RELATIVE SEA-LEVEL CHANGES ALONG THE MEDITERRANEAN AND BLACK SEA COASTS: PROXIES, VARIABILITY AND THE CLIMATOLOGICAL IMPLICATIONS

After the analysis of more than 1200 radiocarbon dated Relative Sea-Level (RSL) data-points we present here the first quality-controlled database constraining the Holocene sea-level histories along the Mediterranean and Black Sea coasts. We reviewed and standardized the geological RSL data-points using a new multi-proxy methodology based on: (1) modern taxa assemblages in Mediterranean lagoons and marshes; (2) beachrock characteristics (cement fabric and chemistry, sedimentary structures); and (3) the modern distribution of Mediterranean fixed biological indicators (Vacchi et al., 2016b). These RSL data-points were coupled with the large number of archaeological RSL indicators available for the Mediterranean and Black Sea coasts. Such standardized methodology allowed the robust assessment of the spatial variability of RSL histories among the different regions and the comparison with the ICE-5G (VM2) Glacial Isostatic Adjustment (GIA) model (Spada and Stocchi, 2007). In the western Mediterranean, RSL rose continuously for the whole Holocene with a sudden slowdown at ∼7.5 ka BP and a further deceleration during the last ∼4.0 ka BP, after which time observed RSL changes are mainly related to variability in isostatic adjustment (Vacchi et al., 2016a,b). The sole exception is southern Tunisia, where data show evidence of a mid-Holocene high-stand compatible with the isostatic impacts of the melting history of the remote Antarctic ice sheet. In the eastern Mediterranean, we depicted the role of the right-lateral North Anatolic Fault in controlling the Late Holocene RLS variation in Northern Aegean Sea (Vacchi et al., 2014) and we better constrain the subsidence rates in the broad Nile delta area (Khan et al., 2015). Current analysis are focused on Black Sea coasts where compaction-related subsidence plays a major role in controlling the Holocene sea-level variability, notably in the Danube delta and in the Taman peninsula (Giaime et al., 2016) Our results indicate that late-Holocene sea-level rise was significantly slower than the current one. First estimates of GIA contribution indicate that, at least in the northwestern sector, it accounts at least for the 25-30% of the ongoing sea-level rise recorded by Mediterranean tidal gauges (Vacchi et al., 2016b). Such contribution is less constrained at lower latitudes due to the lower quality of the late Holocene index points. Future applications of spatio-temporal statistical techniques are required to better quantify the gradient of the isostatic contribution and to provide improved context for the assessment of 20th century acceleration of sea-level rise along the coasts of Mediterranean and Black Sea.