Abstract The study area is located in and around Umm Ar Razam village, about 50 Km east of Darnah city, north-eastern Libya. In this study many claystone sections were studied. These claystones belong to the lowermost part of Al Faidiyah formation of Upper Oligocene – Lower Miocene age. The studied sections consist of claystone beds ranging in thickness about 10 meters. These bentonitic clays are generally grey to greenish grey in colour, with popcorn – like appearance. They have a waxy character and are exposed sporadically in this area as isolated outcrops. They might be deposited in lagoonal, lacustrine or shallow marine environment. The main purpose of this thesis is to study the origin and to evaluate the Umm Ar Razam bentonitic clays. For example, lithology, mineralogy, the chemical composition, crystal forms and habits, physical properties, industrial uses and treatment will be investigated. The Results showed that these clays consist of the minerals Na- montmorillonite, Kaolinite, and Illite. Non – clay minerals includes quartz, calcite, dolomite, gypsum, halite, muscovite, rutile, sanidine, and tridymite. Moreover, clay mineral fraction studies using the different techniques showed that these bentonitic clays were formed due to in situ alteration of volcanic ash in subaquous environment. Evidences for such an occurrence include mineralogical evidence as the existence of high temperature minerals as sanidine, rutile, and tridymite. The existence of unaltered volcanic ash as seen from SEM photomicrographs also supports this origin. Furthermore, XRF results showed downward depletion of silica right below these bentonitic clays 6 in calcarenite beds of Al Abraq formation. XRF results also showed that the Umm Ar Razam bentonites are in accordance with the American bentonites and the parent material of such bentonites came from basic volcanic ash materials. In addition, the viscosity and the filtration of Umm Ar Razam bentonite is nearly identical with the international bentonite by adding (Soda Ash) and (Na2 SiO3 ) with special treatment method. The cost of the Enhanced Umm Ar Razam bentonite is less than of the imported bentonite cost. Based on the physical and chemical properties these bentonites can be used in many industries especially as building materials and drilling fluids.
فيصل عياد أبو سهمين (2009)

Abstract As part of the NE-trending Mourizidie Shear Zone in south-central Libya (south of Mourizidie pass), four units representing Preccambrian basement rocks (metasediments) were mapped during field work: phyllites (metaclaystone); metapelites (metasiltstone); pasmmites (metasandstone) and Quartzites. Granitic bodies of various sizes (few meters to hundreds of meters) are found throughout the study area. The metasediments and granites are both intruded by veins and dikes having an overall NE trend. Four Palaeozoic sedimentary units were mapped within the study area. The concidence of the S1 foliation with the S0 of the original bedding of the protolith is a proof that the S1 foliation is caused by deep burial. The petrographic description of the minerals in thin section shows an assemblage of sericite, muscovite and biotite, all representing a sub-greenschist facies to greenshcist facies. This low grade metamorphism helped in preseving the original sedimentary structures of the protolith, thus helping in identifying the original bedding plane S0. Faults observed in the field or traced on aerial photograhs belong to three major trend: NE, NNE, and ENE. Folds are extremely diverse in shape, attiude and tightness, thus their classification is equally diverse. This diversity is observed in the field even within a distance of no more than few meters. The isostatic rebound of the basement could have caused this great difference in the attitude of the folds, especially at considerable depths characterised by a kinematically ductile, restricted and contained settingAt least two phases of deformation are present in the area. D1 is marked by the generation of S1, while D2 is marked by the first folding F1 caused by the isostatic rebound he generation of S2 foliation as fan cleavage is directly related to the F1 folding. Some folds underwent refolding, which lead to an F2 phase of folding.Sequential schematic structural model is proposed to explain the structural history of the study area. This model should be tested through intensive detailed field work large scale map in nearby areas.
مسعودة محمد حنبولة (2015)

Abstract The Sirt Basin is one of the youngest sedimentary basins in Libya and covers an area of approximately 600.000 km² in north central Libya. It is located on the northern margin of the African plate, with approximate coordinates 14°00`- 20°00`E and 28°00`-31°00`N. The Late Jurassic-Early Cretaceous as Sarir Sandstone in the Sirt Basin evolved as a consequence of the interplay between global eustasy and regional tectonics. As Sarir Sandstone of the eastern Sirt Basin is composed mainly of sandstones and shales resting unconformably on a basement complex of igneous and metamorphic rocks. It is unconformably overlain by the Upper Cretaceous sediments of Maragh, Lidam and Etel formations. It has been subdivided into three members. The upper member consists mainly of sandstones with intercalations of siltstones and shales of variable thickness. The middle member consists of shale and silty shale. The basal part of the formation, which rests directly on the crystalline basement represents the lower member. It is comprised of sandstone with subordinate intercalations of siltstones and shale. Two main facies have been recognized on the basis of lithological features and types of stratifications: which consist mainly of shale and intercalation of silt and sand. The Middle Shale Member consists mainly of shallow lake deposits, containing black shale facies. Continental Fluvial Deposits represent most of the cored interval and it belongs to the Upper as Sarir Sandstone. These facies have been subdivided into braided and meandering lithofacies: The braided depositional system, has been recognized in three different intervals of the studied cores; classified as subfacies (1), subfacies (2) and subfacies (3). The meandering depositional system, represents three sub-environments including point bars, abandoned channels and over-bank deposits. The reservoir characteristics of these sediments are studied on the basis of porosity, permeability and reservoir zonation. The reservoir quality of As Sarir Formation is largely controlled by primary sedimentary features associations, which were shaped by the depositional environments. Meandering Lithofacies are formed from continuous sand successions and show good porosities, up to 18.51%, and permeabilities up to 125.5mD. The Braided Lithofacies also show good reservoir quality, but the effective porosity and permeability are lower, because of associated shales. The most important diagenetic features responsible for a reduction in reservoir quality are those resulting from compaction, cementation, and the diagenesis of clay minerals.
صلاح الدين محمد الوحيشي (2014)