A review of possible eustatic, isostatic and tectonic contributions in eight late-Holocene relative sea-level histories from the Mediterranean area

Abstract

This paper consists of a comparison between eight late-Holocene sea-level histories investigated by the author in different Mediterranean areas and sea-level predictions in the same areas made by global isostatic models. The areas include three regions that are generally considered as tectonically relatively stable: (1) the southern coast of France, (2) Sardinia, and (3) the southern coasts of Tunisia, where late-Holocene evidence may be either of submergence, or of emergence. Also considered are: (4) a subsidence region in the northern Adriatic, and actively uplifting areas: (5) in Calabria, and (6) in Nisyros Island (Greece). Lastly, case studies in areas affected by repeated coseismic vertical displacements include: (7) western Crete and Antikythira Island in the Hellenic Arc, and (8) the Levant coasts of Turkey, Syria and the Lebanon. In each case the question of whether the evidence available may or may not be consistent with gradual isostatic or eustatic displacements has been explored. It appears that in non-tectonic areas the hydro-isostatic effects have been overestimated (Sardinia) or underestimated (southern Tunisia) by the same models. In the northern Adriatic, the closest Mediterranean area to the former Scandinavian ice sheet, glacio-eustatic effects are suspected to be almost absent. Our analysis failed to quantify isostatic effects in areas of rapid tectonic uplift (Calabria and Nisyros), but rejected predictions of significant isostatic subsidence in the Hellenic Arc and on the Levant coast. Finally, several data from tectonic and non-tectonic areas are consistent with nearly stable global eustasy since 6000 BP, thus challenging the assertion of significant additional melting of Antarctica after the complete melting of the former Northern Hemisphere ice caps.