Late Pleistocene and Holocene sea-level change in Greece and south-western Turkey: a separation of eustatic, isostatic and tectonic contributions

Abstract

Sea-level change during Late Pleistocene and Holocene times is a combination of eustatic, isostatic and tectonic contributions. In the central Mediterranean Sea region of Greece and western Turkey, the isostatic components are important, due to the changing gravitational potential of the Earth, the readjustment of the crust upon the removal of the large ice sheets and the addition of the meltwater into the oceans, including the Mediterranean. Changes in relative sea-level due to these glacio-hydro-isostatic adjustments have reached amplitudes of 1 mm yr−1 during the last few thousand years. A model for the isostatic contribution to sea-level change, including the movement of shorelines due to the combined eustatic-isostatic changes, is developed, based on earth-model and ice-sheet parameters estimated from sea-level observations from other areas. Comparisons of this model with observations of sea-level change permit rates of vertical movement to be estimated for Late Holocene time. Allowance for the isostatic factors makes a significant difference to these rates. The plains of Argolis, Lakonia, Messinia and Navarine, in the southern Peloponnese, for example, appear to be tectonically stable on time-scales of a few thousand years and longer, consistent with the position of the Last Interglacial shoreline close to the present-day sea-level. The observations here, of a rising sea-level, are largely the consequence of the glacio-hydro isostasy and not of a long-term tectonic process. Crete as a whole is subject to tectonic uplift, but at variable rates, and forms part of an arcuate zone of uplift extending from Rhodes and Karpathos in the east to Kithera in the west at rates that locally exceed 4 mm yr−1. The southern shore of the Gulf of Corinthos is also subject to uplift at rates approaching 1.5 mm yr−1. These isostatically corrected estimates for the past few thousand years are in agreement with longer-term estimates based on the position of the Last Interglacial shoreline. Only on the Perachora Peninsula do the tectonic rates over these two time intervals appear to be in disagreement, with the Late Holocene rates being much higher than the long-term rates.