Coastal changes from open coast to present lagoon system in Histria region (Danube delta)

Abstract

Preoteasa, L., Vespremeanu-Stroe, A., Hanganu, D, Katona, O.,Timar-Gabor, A., 2013. In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Coastal changes from open coast to present lagoon system in Histria region (Danube delta). Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 564-569, ISSN 0749-0208. Histria (Istros) is a Milesian colony founded on the Black Sea coast during the 7th c.BC. Nowadays, the remains of the ancient city are located 8 km inland form the Black Sea coast, on the continental edge of the Razelm-Sinoe lagoon system which forms the southern part of the Danube Delta. Significant environmental changes occurred during and after the ancient city’s lifetime, particularly related to dramatic shoreline displacement. The present study deals with the Late-Holocene coastal landscape transformation from the open-coast stage to the present-day lagoon system. Our research includes stratigraphic records by Ground Penetrating Radar scanning of the beach ridges, cores in lagoons and beach ridges and absolute age determination of the paleoshorelines. The study shows that the ancient city decoupling from the sea was due to the beach ridge plain development southward and eastward of the acropolis. The decline of the Histria city, documented during the 7th c. AD, temporally coincides with the decoupling of the city from the open coast as a consequence of the shoreline progradation. Discontinuous chronology and discordant stratigraphy obtained by OSL dating and GPR scanning of successive ridges document intense neotectonic movements which affected Saele-Chituc beach ridge plain. The seismic activity led to the recent drowning of its central part and the formation of the Sinoe lagoon; the same processes acted at the downdrift part of the Dunavat lobe and also in the areas presently occupied by Histria and Nuntasi Lakes. Several areas containing archeological remains are currently below sea-level due to local neotectonics.