Geomorphology and Sedimentary Dynamics of the Tunis Gulf Mouths

To characterize the flux of detritic sediments through the hydrographic network toward the Mediterranean Sea, five 45 cm deep cores and 18 surface samples were taken at the mouths of the wadis of Tunis Golf (wadis Majerda, Meliane, El Bey, and Abid). The description of the five drill cores made at the wadi mouths is based on the texture or type of facies, the size of particles of biological origin (fauna and flora), the color of sediments, and the distribution of fractions above 63 µm. The Majerda Delta lithologic profile is divided into three levels of silty clay. New estuary deposits are as typical as old estuary deposits. The profile of wadi Meliane is formed by sand columns of the same texture but different fauna colors and sizes. Wadi El Bey’s profile shows a series of black and grayish sand horizons. At the mouth of wadi Abid, a series of sand horizons distinguishes this profile from other profiles. It is noted here that there is abundant coarseness, equivalent to 90% of the total sediment from 15 cm. The influx of detritic inputs into the Mediterranean Sea in the Gulf of Tunis through the water network is formed by strongly carbonized quartz deposits northeast and slightly south of the bay. These inputs are finer in the Majerda Delta, more uniform in particle size, and rich in hyperfine fractions (<2 µm), but vary from moderate to moderate in the south of the bay (wadis El Bey and Abid). Sediments are characterized by “graded suspension” type. It refers to classified substances transported by undercurrents and leads to the deposition of typical river channels. X-ray diffraction mineralogical analysis identified the following non-clay minerals: quartz, calcite, halite, and hematite. All sediments are rich in calcite and quartz. Halite and hematite are found in minimal amounts at the mouth of the Medjerda Delta. Clay mineral are composed by smectite, illite, and kaolinite.