Structural framework of the Gulf of Elat (AQABA), Northern Red Sea

Abstract

The Gulf of Elat (Aqaba) occupies the southern part of the Dead Sea rift. The rift is considered to be a plate boundary of the transform type (partially leaky) which connects seafloor spreading in the Red Sea with the Sagros‐Taurus zone of continental collision. The deep water in the Gulf of Elat, up to 1850 m, provides a rare opportunity to examine the process of continental rifting by marine geophysical techniques. The bathymetry alone provides much information about fault patterns in this area. The fragmentation of the once continuous Arabian‐African platform is a complicated process. It shapes the structure of the gulf which has developed through continuing tectonism, primarily consisting of faulting. Recent geophysical and geological studies of the Gulf of Elat including bathymetry, bottom photographs, continuous seismic profiles, seismic refraction, gravity, magnetics, heat flow, and coring provide new information about the shallow and deep crustal structure of this important segment of the world rift system. The shallow structure of the gulf is dominated by three elongated en echelon basins, which strike N20°–25°E. Undulations in the floors of the basins produce several distinct deeps. These basins are interpreted as pullaparts. The new data from the gulf suggest that classical models for the formation of these structures should be modified. Only one of the longitudinal faults of each depression is a strike‐slip fault, while the other is predominantly a normal fault. The situation with the other two sides of the basin which are supposed to be composed of normal faults may also be more complex than previously thought. At least in one case, one such boundary is composed of a strike‐slip fault while the other has no significant fault. Crustal models of the Gulf of Elat based on gravity data indicate that the basins are rather shallow and do not extend into the lower crust. The fill of the basins extends to about 5 km below the seafloor in. the northern and southern basins and less in the central basin. Most significant magnetic anomalies in the Gulf of Elat extend from land into the sea. None of them, however, extends from one coast to another across the gulf. This supports the geological evidence for a shear between the Arabia and Sinai plates. The magnetic field over the southern third of the gulf is rather smooth and markedly different from that of the other parts. The nature of the magnetics, the crustal structure of the western margin, and the heat flow values indicate a thinner crust and different tectonic processes in the southern part of the gulf. Overall, it seems that within the southern Gulf of Elat a transition occurs between crustal spreading that takes place in the Red Sea to a rifting without spreading that takes place along the Dead Sea transform. Spreading activity propagates from south to north. The most active place is the central basin which is being propagated northward into the shallow northern basin.

Development of recent faulting in the southern Dead Sea Rift according to GPR imaging

“…1b). This basin is one of several en-echelon tectonic basins bounded by subparallel left-stepping faults that are developed north of the Gulf of Elat (Ben-Avraham et al, 1979a, b;Ben-Avraham, 1985;Garfunkel, 1981;Freislander, 1994Freislander, , 1995aBartov et al, 1998). These basins are filled with fluvial sediments and range in depth from several hundred meters to a few kilometers (Ben-Gai et al, 1993a, b;Freislander, 1994Freislander, , 1995a.…”

“…Bartov, 1990). (b) Schematic illustration of the main faults of head of the Gulf of Elat and the southern Arava valley (based on data presented by Ben-Avraham, 1985;Reches et al, 1987;Ben-Avraham and Tibor, 1993;Shamir, 1996). The location of Fig.…”

“…The Evrona fault, which is a prominent left-lateral strike slip-fault of the DSR extends along the northwest part of the Gulf of Elat (Aqaba), from the Gulf's head across the coastline to the sedimentary basins of the southern Arava valley (Ben-Avraham et al, 1979a, b;Ben-Avraham, 1985;Reches et al, 1987;Ben-Avraham (1992); Ben-Avraham and Zoback (1992); Ben-Avraham and Tibor, 1993; Shamir, 1996; Galli, P., 1999; Fig. 1b).…”

Tectonics of strike-slip restraining and releasing bends

“…Releasing bends produce pull-apart basins and faultbounded troughs that comprise some of Earth's lowest topographic depressions, such as the Dead Sea (ten Brink et al 1999), Death Valley (ChristieBlick & Biddle 1985 and submarine basins underlying the Gulf of Aqaba (Elat; Ben-Avraham 1985), the Cayman trough (Leroy et al 1996, AAPG) and the Gulf of California (Persaud et al 2003).…”

Stress analysis and tectonic trends of southern Sinai Peninsula, using potential field data analysis and anisotropy technique

“…Other circular anomalies are observed and could be interpreted as uplifting basement or intrusion of dibasic dykes located in the region extended between Sant Kathrine and Sharm El Sheikh. The southern part of the map shows also several circular magnetic anomalies that could be related to strike-slip movements of the Gulf of Aqaba [51]. Whereas, the minor N-S of the East Africa trend system reflects the deformations of the Late and Early Paleozoic rocks…”