Periodic Reporting for period 1 - EASTMED-PALEOTSUNAMI (Towards a paleotsunami chronology in the southern Aegean and Levantine seas, Eastern Mediterranean)
Reporting period: 2016-06-20 to 2018-06-19
Normalization of element profiles like Ti, Fe, K and Zn by Ca is used to evaluate the changes in the balance between terrestrial clastic deposition and deposition of bio/chemical CaCO3 from water column. In all of the target sites of the project, Ca-normalized profiles show anomalies temporally correlating with the historical tsunamis in the eastern Mediterranean. This kind of geochemical trace is attributed to sudden increase in the amount of terrigenous sediment into the lagoons, which is swept from the sand spits of the lagoons due to marine overwash during tsunamis. During relatively sudden deposition of these clastics, there would be no time for bio/chemical CaCO3 precipitation from the water column that would result in a Ca-depleted intercalation within the background sedimentation. Above-mentioned geochemical fingerprints of tsunamis are relatively distinct compared to the physical sedimentary traces observed along u-channel radiographs. Catastrophic tsunamis are expected to transport significant amounts of coarse sediment and macro fossils from near-shore environment and sand barriers of the lagoon. However, this is not the case for the lagoons investigated within the scope of the project, because no obvious physical changes that are distinctly different from the background sedimentation were observed along the radiographs. It is probably because coarse-grained tsunami deposits could not reach to the coring locations, which are approximately 500 meters away from the sand barriers of the lagoons. Instead, only fine-grained sediment cloud could be transported to the coring locations, which can still be geochemically detected.