الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The study area is characterized by the presence of many geomorphological coastal landforms including headers, bays, wadis, coastal groves, sabkhas and dunes. These are common features in the coastal area of Al-Dafna plateau which extends from the mouth of Wadi Omm El-Shawash, in the west (east of Tobruk City), to Bir Al Ramla Well in the eastern border of Libya with Egypt for about 130 km long. Sabkha samples were collected from the intertidal and supratidal zones in two seasons; summer and winter in 2017 and 2018. Six sites in the coastal area of Al-Dafna were chosen for collecting samples from the intertidal and supratidal zones at the Wadis mouths and at areas behind the stretching sand dunes. These include; Wadi Omm El-Shawesh, Alaqila, Wadi Al-Ain, Omm Rukbah, Wadi Rizk and Wadi Al-Sawani. Forty three samples were chosen from the cores representing the intertidal and the supratidal zones. The texture, composition and origin of the coastal sabkha sediments are determined through analyzing the samples for carbonate, sand, and mud composition as well as sand, silt, and clay contents for textural characteristics. The mineralogical composition of twenty three bulk powdered samples has been determined from X-ray diffraction. Clay minerals present are identified in the separated fractions from fourteen mud samples and thoroughly examined by the X-ray diffraction technique. Twenty sabkha samples were chemically analyzed by XRF technique for determination of their major oxides concentrations. This study revealed that there is two types of sabkhas present in the coastal area of Al Dafna plateau. The first type is developed at the wadi mouths where sea water enter the wadis through high tides, these include; Omm El-Shawesh sabkha, Wadi Al-Ain sabkha and Wadi Rizk sabkha. The second type is formed behind the shore sand hummocks where sea water seepage mixed with groundwater then raised to the surface through capillary action and evaporated. However, it was subjected also to flooding of wadis through rainy season. These include; Alaqila, Omm Rukbah and Wadi Al-Sawani sabkhas.