Original paper

Geochemical and micropaleontological investigations of tsunamigenic layers along the Thracian Coast (Northern Aegean Sea, Greece)

Mathes-Schmidt, Margret; Schwarzbauer, Jan; Papanikolaou, Ioannis; Syberberg, Fabian; Thiele, Annika; Wittkopp, Frederike; Reicherter, Klaus


In order to obtain more information on coastal evolution and the preservation of tsunamigenic and/or storm layers, several shallow boreholes were carried out along the shoreline of the Thracian Sea (northern Greece). In flat and southerly exposed coastal areas, sedimentary sequences provide evidence for past high-energy sedimentary events, which are interpreted as tsunamites. Earthquakes at the western end and along the northern strand of the North Anatolian Fault Zone (NAFZ) in the North Aegean Basin cause regular tsunamis. Several Holocene high-energy event layers have been found intercalated in clayey terrestrial, lagoonal, and sandy beach deposits. Through radiocarbon dating, geochemical, micropaleontological and sedimentological investigations, at least two possible events can be defined. These layers have erosive bases, show fining-up and thinning-up sequences, and include shell debris, foraminifera and rip-up clasts and characteristic variations in elemental content of Fe, K, Sr and Ca. However, the event layers cannot be assigned to any individual historic seismic or landslide event; the youngest event date is around AD 500 which is approximately 150 years after the closest (AD 344) documented historic event. We also introduce organic geochemical proxies as a tool for distinguishing tsunamigenic layers from normal lagoonal sediments.


foraminifersorganic and inorganic geochemistrythracian seatsunamites