Fluctuations of sea level during the past 400 000 years: the record of Sinai, Egypt (northern Red Sea)

Abstract

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 δ¹⁸O curve. The ten Sinai sea-level events correspond to the δ¹⁸O 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 teetonics 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 400000 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: 6 ka, 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.