CLAY MINERAL DISTRIBUTIONS TO INTERPRET NILE CELL PROVENANCE AND DISPERSAL .2. COASTAL-PLAIN FROM NILE-DELTA TO NORTHERN ISRAEL

This study identifies clay mineral assemblages between the eastern Nil e delta and northern Israel to complement and refine interpretations o f modern sediment provenance and dispersal patterns in the SE Mediterr anean. Previous petrological investigations indicate that the River Ni le has been the dominant source of sediment transported to the Levant Sea, whereas sediment contributions from Sinai, Gaza and Israeli river s and coastal cliff exposures in this region have been minor. However, this sediment dispersal pattern, modelled as the Nile littoral cell, is now being altered as a response to the High Dam at Aswan, barrages along the Nile valley and in the Nile delta, and water diversion by th e high-density canal system in the Nile delta. As a result, Nile sedim ent input identified by high proportions of smectite is presently deri ved from erosion of the delta margin rather than from direct dispersal by the river proper. The present investigation records important perc entages of kaolinite in the clay fraction of samples recovered in coas tal cliff exposures, from east of Bardawil lagoon and Wadi El Arish to the Lebanon-Israel border. Clay mineral assemblages in the fluvial ch annels on the coastal plain east of the Nile delta are considerably mo re variable: those west of El Arish are smectite-rich, while those on the plain east and north to the Tel Aviv region are kaolinite-rich; cl ay assemblages between Tel Aviv and Atlit are smectite-rich; still far ther north, locally between Atlit and Haifa, assemblages in some fluvi al channels comprise high percentages of illite, and those from north of Haifa to the Lebanese border record large proportions of kaolinite and illite. These laterally variable clay assemblages on the Sinai, Ga za and Israeli coastal margins are more closely related to the differe nt source terrains in highlands that back the coastal plain than to di stal Nile provenance. Modern clay minerals near the coast are derived from (1) rivers that flow seasonally from highlands in Sinai and Israe l, (2) seasonally variable winds that carry dust from arid and semi-ar id regions toward the coast, and (3) wave current erosion of coastal e xposures. As the amount of distal Nile-derived clay from Egypt is redu ced, these more proximal sources will likely to account for increasing proportions of clays supplied to Sinai and the SE Levant margin.