FLUCTUATIONS OF SEA-LEVEL DURING THE PAST 400 000 YEARS - THE RECORD OF SINAI, EGYPT (NORTHERN RED-SEA)

Morphological features such as emerged and submerged terraces and wave-cut notches, as well as modern and dated fossil coral reefs along the coasts of the Red Sea in southern Sinai, provide a record of ten high- and low-stand sea-level events. These events are correlated with peaks in the Milankovitch orbital cycles and with the deltaO-18 curve. The ten Sinai sea-level events correspond to the deltaO-18 substages 1.1, 2.2, 4.2, 5.1, 5.2, 5.3, 5.4, 5.5, 7.1, and 9.3, respectively. The coral reef belt is developed on the margin of a lateral moving lithosphere, which is part of the Dead Sea transform system. Based on the regional tectonics of southern Sinai, and assuming a sea-level of 6.5 m above the present sea-level during the last interglacial high stand (substage 5.5), an average uplift rate of 0.085 mm/year is estimated. By removing the tectonic uplift effect, a sea-level curve for the past 400 000 years is obtained. On this curve, the calculated elevations (m, in relation to the present sea-level), the isotopic substages and the ages (in ka = thousands of years) of the events 1 through 10, detected in Sinai, are: (1) substage: 1.1, age: 6ka, elevation: + 0.5(+/- 0.2); (2) 2.2, 18 ka, - 122(+/- 10); (3) 4.2, 64 ka, -65 (+/- 3); (4) 5.1, 79 ka, + 0.3(+/- 1); (5) 5.2, 91 ka, -28(+/- 5); (6) 5.3, 99 ka, -1.5(+/- 1); (7) 5.4, 111 ka, -29(+/- 5); (8) 5.5, 124 ka, + 6.5(+/- 2); (9) 7.1, 193 ka, -1.4(+/- 2); and event (10) substage: 9.3, age: 331 ka, elevation: + 2.9(+/- 2). Ages of events (1), (8), (9) and (10) are based on U-Th dating; others are deduced from correlations and conceptual models. Elevations are based on field data from onshore and offshore the Sinai.