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SUPERFICIAL SEDIMENTS OF NORTHERN RED SEAMAHMOUD KH. EL-SAYEDDepartment of Oceanography, Faculty of ScienceAlexandria University, Alexandria, A.R. EgyptINTRODUCTIONAs one of the youngest oceanic zones on Earth - an Ocean in the making - the Red Sea is ofenormous interest in understanding the structural and tectonic phenomena related to ocean floorspreading and in reconstructing the history of global tectonics. Although investigation of the Red Seagoes back into the 19th century, the mid-1960s mark the true beginning of its scientific exploration,with oceanic studies increasing both in number and diversity (THIESSE et al., 1983). However,most of these investigations, particularly those in marine geology, have been associated with brinearea in the central axial valley (near 21"N), and zones characterized by metalliferous sediments.Numerous studies have been made concerning the paleontology, mineralogy and geochemistry ofrecent Red Sea sediments (see STOFFERS and ROSS, 1974).Although some geological information of the northern Red Sea has been published, thesurficial sediments in this area received little attention. Much of the available information on thetexture, mineralogy, chemistry and paleontology of the surface sediments of the northern Red Seacomes from the ,fifty sediment samples collected during the Egyptian Preliminary Expedition to thenorthern Red Sea in the R.R.S. MABAHITH in 1934-1935. Studies of these samples were carriedout by SHUKRI and HIGAZY (1944a,b); MOHAMED (1949); SAID (1949, 1950a,b, 1951);SHUKRI (1953); EL-DEEB (1978) and CHERIF et al. (1983). Some sediment samples from theGulf of Suez and the Gulf of Aqaba also were studied within these investigations. Subsequently,both gulfs were investigated intensively, particularly the Gulf of Suez, after the reopening of the SuezCanal for navigation in the late 1970s (MOHAMED, 1979,1980; STANLEY et al., 1982; NAWAR,1983). Supplementary information on the sediments of the northern Red Sea was recently obtainedfrom deep drilling in this area.The major sedimentary constituents of the northern Red Sea sediments revealed from variousinvestigations in the area will be summarized and critically reviewed. Sediments from the two gulfsare excluded.GEOLOGIC SETTING OF THE NORTHERN RED SEAThe Red Sea extends in a northwesterly direction from the narrow strait of Bab-El-Mandab atits southern end to the tip of Sinai Peninsula, a distance of about 1930 km. It cuts across a hugedome of Precambrian basement rocks (Arab-Nubian Massif) flanked by epicontinental and marinesediments. At its southern end, the Red Sea is connected to the Gulf of Aden which trendsENE-WSW, opening into the Indian Ocean and separating the southern part of the Arabian Peninsulafrom the Somali Plateau. At the northern end, the Red Sea bifurcates into the Gulfs of Suez andAqaba, creating the triangular Sinai Peninsula (ABDEL-GAWAD, 1969) (Fig. 1). The northern RedSea prober (excluding the two Gulfs) lies north of about 24'N.The geology of the northern Red Sea was previously reported by ABDEL-GAWAD (1969),SAID (1969), COLEMAN (1977) and many others. From the southern tip of Sinai to Ras Benas andAbu-Madd, the Red Sea is characterized by relatively straight and parallel coasts (Fig. 1). Accordingto HALL (1976) these straight coasts suggest the absence of typical sea floor spreading anomalies inthe northern Red Sea, as the magnetic lineations are poor and often non-existent in this region.According to STOFFERS and ROSS (1974) wells drilled around the edge of the Red Sea basingenerally reach evaporites of Miocene and younger ages. Three wells in the northern Red Sea(Fig. 2) did not hit any evaporites, but bottomed in granite.341