The crustal structure of Egypt and the northern Red Sea region

Abstract

P-wave receiver functions from 26 stations in the Egyptian National Seismic Network (ENSN) have been modeled using the H-k stacking method and in a joint inversion method with Rayleigh wave group velocities to investigate crustal structure across Egypt and the northern Red Sea region. The new estimates of crustal structure, when combined with previous results, show that along the rifted margins of the Red Sea, Gulf of Suez and Gulf of Aqaba crustal thickness ranges from 25 to 30km, the average crustal Vp/Vs ratio is 1.77, and the average crustal shear-wave velocity is 3.6km/s. Beneath northern and central Egypt, including the Sinai Peninsula, crustal thickness ranges from 32 to 38km, the average crustal Vp/Vs ratio is 1.79, and the average crustal shear-wave velocity is 3.5km/s. Beneath southern Egypt, crustal thickness ranges from 35 to 40km, the average crustal Vp/Vs ratio is 1.76, and the average crustal shear-wave velocity is 3.7km/s. In southern Egypt, the crust is also characterized by a 10–20km thick mafic lower crust. These findings indicate that crust along the rifted margins of the northern Red Sea, and Gulfs of Suez and Aqaba have been thinned by about 5 to 10km. The thick mafic lower crust in southern Egypt can be attributed to suturing during the Neoproterozoic collision of east Gondwana against the Sahara metacraton. Overall, the structure of the crust in Egypt away from the northern Red Sea region is similar to the structure of Precambrian crust in many other parts of Africa.