https://repository.uob.edu.ly/handle/123456789/1334 Sun, 25 Oct 2026 10:15:20 GMT 2026-10-25T10:15:20Z https://repository.uob.edu.ly/handle/123456789/1345 Description and characteristics of chert nodules in Appollonia Formation, Al Hmmeda road-cut, Al Jabal Al Akhdar, NE Libya Elfigih, Omar B; El Degheeli, AL- Moatasem Bellah K Physical, petrographic and bulk elements analysis of Chert Nodules in Appollonia Formation, Al Hmmeda road-cut were conducted and showed that the origin of these chert by replacement. The suspected siliceous organic matters are of low crystallized silica and were dissolved under the influence of increasing temperature and pH. Most of the chert was localized in the limestone and dolomitic limestone of Appollonia Formation (nodular zone) by percolation of silica-rich solution along microfractures and porous/permeability zones. This local porosity and permeability variations, mostly produced mixing of the diffused digenetic fluids. This process produces the nodular form of the cherts in the Appollonia mudstone facies in the nodular zone, while less marked permeability variations could have produced more regular tabular bodies of chert, which were not observed at least in the studied section. The absence of chert nodules in some adjacent rocks and even at higher elevation in the Appollonia stratigraphic section (nonnodular zone), might reflect effective exhaustion of the silica supply, fewer microfractures condition and perhaps dilution by the marine water of highly reduced silica-rich solution. Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1345 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1344 Geology of Ayn Al Majdoub Karstic Lake, Benghazi, NE Libya AlShible, Mousa S The major karstic area in Libya known as Ayn Zayanah system is a unique phenomenon of concentrated karstic surface and subsurface dolines and channels. By focusing on Al Majdoub Lake, as a case study, we can better understand how lithology, structure and hydrology contribute to the regional formation of the Karstic system. Geologically, the limestones of the middle Miocene, Benghazi Formation is forming the northern side of Benghazi region, which is characterized by well-developed surficial, interface, surface and subsurface karstic features that are open or filled with sediment. The formation of Ayn Majdoub doline is filled with saline water, which is attributed to the dissolution of a buried carbonate layer by fresh groundwater due to the drop of the Sea level and the associated groundwater levels. This is combined with epeirogenesis movements, which have caused the development of karstification to reach a depth of 130-150 m below present sea level in the Benghazi plain. Through this Karstic system, groundwater seeps from Benghazi Basin towards the Ayn Zayanah (The Spring) and then to the Blue Lagoon (The Lake) finally to the sea. Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1344 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1343 Geological, geomorphological and structural characterization features of Al Bordi area, Libya Al Mabrouk, Mahmoud Ali; Abou El Leil, Ibrahim M This study has been conducted on Al Bordy area, which lies between latitudes N31°48'16.51 N31°43'14.91and E25°00'18.09 E25°06'55.07 on the sea coast of eastern Libya, The area has specified geological features, where the different rock formation exhibit good exposures that give a clear view about the stratigraphic column. The exposed formations are Al Gaghbub, Al Faidiyah and Al Khowaymat. The target of study is to evaluate some characterization features e.g. lithology, stratigraphic analysis, fossil distribution, structural and tectonic setting. The technical simulation models and geographic information system (GIS) software have been applied to interpret some geologic structures such as faulting, fractures, cracks and folding as well as the effect of stresses on formation strata. The field observations and the obtained data revealed that the area has affected by variable geological factors and changes in depositional environments, in addition to tectonic movements that led to the formation of various structures such as anticline and syncline folds, normal faults and unconformities Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1343 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1342 Utilization of seismic attributes for structural pattern detection In Bualawn, Dor Mansour fields, Western Sirt Basin, Libya El-farsi, Mohammed N; El-Shari, Saad M An integrated approach to the study of fault patterns carried out in the complex geological structures of Bualawn, Dor Mansour fields by using multiple seismic attributes of 3-D seismic data. Each type of geological structure event usually generates a unique seismic signature that can be recognized and identified. This paper highlights the practical importance of analyze integrated attributes and interpret them within the context of an appropriate structural deformation. Many of discontinuity attributes such as variance, 3DEE (3D edge enhancement), ant tracking, chaos and structure smoothing have been selected to delineate fault styles and their displacement effectively, which cannot be fully delineated using seismic amplitude data. Conjugate growth faults in NW-SE and NE-SW direction, dipping toward SW with antithetic faults dipping in opposite direction to the growth faults and other minor faults. The faults were identified manually and then tested by discontinuity attributes. Fault system is represented by a fracture system comprising long en echelon seismic faults and several discontinuities. This system of en echelon faults was initiated by left-lateral wrenching movements. This wrenching system has been identified by negative and positive flower structure along the releasing and restraining bends. The current understanding that these faults are strike-slip faults despite the absence of extensive horizontal displacements along them as shown on different time slices. A periodic strike-slip movement along deep-seated basement faults have developed many structural features, such as horst-graben styles, which is the orientation of the transtensional movements linked to the Upper Cretaceous Succession Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1342 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1341 Biostratigraphy of Palaeocene to Miocene Foraminifera in Concession 65, SE Sirt Basin, Libya Abdulsamad, Esam O; Tmalla, Ahmed F. A; Bu-Argoub, Fawzi M Palaeocene to Miocene planktic and larger benthic foraminifera retrieved from ditch cuttings samples taken from 5 wells drilled in Concession 65, SE of Sirt Basin, Libya, have been studied biostratigraphically. This study indicates that the Palaeocene sequence is composed of a shale unit overlain by a carbonate unit. The shale unit contains a rich assemblage of planktic foraminifera indicating Early Palaeocene age (Danian Stage), which is equivalent to the planktic foraminiferal zones P1 and P2. The overlying carbonate unit is Late Palaeocene in age (Selandian-Thanetian) based on the occurrence of several planktic foraminiferal species of the planktic foraminiferal zones P3-P5. The recovery of few species of larger benthic foraminifers from this carbonate unit provides an additional evidence that it was deposited during the Late Palaeocene, corresponding to the shallow benthic foraminiferal biozones SBZ3-SBZ6, which correspond to the (SelandianThanetian) stages. The Early Eocene sequence is mainly barren anhydrites and dolomites with rare badly preserved nummulitids in the Ypresian. The Middle Eocene (Lutetian-Bartonian) limestones contain a nummulitic assemblage with variable species, including Nummulites gizehensis/Nummulites lyelli group, which represent the SBZ14-SBZ16 in the Lutetian and the SBZ17-SBZ18 in the Bartonian. The Late Eocene interval is dated on the presence of few reticulate medium-sized nummulitic species, including Nummulites fabianii, and assigned to the SBZ19. The lowermost part of the Oligocene sequence is attributed to the SBZ21 (Rupelian) based onthe occurrence of Nummulites vascus and Operculina complanata in the limestones. This is overlain by the SBZ22 (Chattian), as indicated by the last occurrence of Nummulites vascus and the first appearance of Borelis melo melo and Amphistegina sp. The uppermost deposits of the studied successions, which are mainly sandstones with hardly any fossils, belong to the Miocene Thu, 31 Jan 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1341 2019-01-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1340 3D Seismic to absolute acoustic impedance inversion of the Lower Devonian Tadrart Sandstone in Ghadames Basin, NW Libya Zeglam, Ahmed Ali M; El-Saiti, Belgasem M Darnah Formation at Wadi Ekhil in Daryanah- Al Abyar area, Al Jabal al Akhdar, Northeast Libya has been subjected to micropaleontological and biostratigraphical analyses based on larger foraminifera "Nummulites" which has largely used as a time marker in the Tethyan region (Circum-Mediterranean). Taxonomical measurements were performed during this study from which the following five species were identified, Nummulites gizehensis, N. lyelli, N. beaumonti, N. striatus and N. sp. The studied sections assigned to the i) N. gizehensis biozone Late Eocene "Late Lutetian" age due to the acme occurrence of the zonal marker species N. gizehensis; and ii) N. lyelli biozone Late Eocene “Biarritzian" due to the total range of the zonal marker species N. lyelli. The concerned nummulites-bearing sections of Darnah Formation indicate an inner neritic environment of bank settings as indicated by A/B ratio Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1340 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1339 Possible carbonate buildups in the Palaeocene sequence at the North-eastern margin of Ajdabia trough El-Shari, Saad M Analysis of the seismic section from the eastern margin of Ajdabia Trough has resulted in a detailed study of carbonate buildups in the Palaeocene sequence. The main significant features identified in the seismic stratigraphic analysis are isolated mound features within the sequence in the northern shelf area. However, occasional discrete mounds of more diffuse seismic character have been seen in the extreme north-eastern part of the area, in an SW-NE trending feature. Large mounded structure of more than 200 ms thick and is composed of discontinuous, chaotic reflectors has been identified. Evidence for similar mound characters exists at the north-eastern part of the study area. The isolated mounds are draped and onlapped by later Palaeocene sediments. The observed mounds in the Palaeocene sequence are interpreted as carbonate build-ups, which are usually mound-shaped biogenic deposits that display marginal onlapping reflections, whereas the overlying reflections drape the reefs, and the underlying reflections exhibit pulldown effect. This pattern may indicate growth of carbonate build up during the early Palaeocene time. From an exploration point of view, these features within the Palaeocene sequence probably contain the potential for stratigraphic hydrocarbon plays in the area Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1339 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1338 Classification of hydrocarbons trapping systems of the Ghadames and Murzuq Basins in relation to Gargaf high, West Libya Ahmed, Al Fasatwi Yahya The Ghadames and Murzuq Basins, West Libya, are major producers of hydrocarbons in Libya. The producing-bearing horizons of the two basins range in age from Cambro-Ordovician to Triassic. Reservoirs of Devonian and Silurian age are major producing horizons in the Ghadames Basin. In the Murzuq Basin, the main reservoirs are Cambro-Ordovician in age. The Silurian Tanezzuft shales are the main source rock of the hydrocarbons in the Ghadames and Murzuq Basins. The reservoir characteristics indicate that the hydrocarbons of the Ghadames basin have mainly accumulated mainly in combination and stratigraphic traps in areas close to Gargaf high, and in structural anticline traps in areas close to the centre of the basin. In the Murzuq Basin, hydrocarbons are trapped mainly in structural faulted traps. The distribution of oil fields in the Ghadames and Murzuq Basins appears to be confined to a regional trend, which reflects the close relationship between tectonics, sedimentation, oil migration and accumulation. Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1338 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1337 Gas detection technique in low resistivity pays of Lower Acacus reservoir, concession NC7A, Ghadames Basin, NW Libya Elmasli, Abraheem A; Mohamed, Ismaeil I Lower Acacus Member is one of the main reservoirs in the Ghadames Basin and it is composed of alternation sandstone and shale facies. It is characterized by low resistivity multiple stacked pays, making the hydrocarbon detection task difficult. To date, no real procedure has been found to correctly define the hydrocarbon in low resistivity intervals. Gas layers as an example could be defined using density and neutron cross-over, but in shaly sand reservoirs as in this case, the shale effect on the neutron log measurement is opposite to the gas effect making the detection of the gas zone by cross-over not valid. On the other hand, the sonic log is affected by the gas by decreasing the rock density, which leads to overestimation of porosity. This phenomenon shall help diagnose the gas presence in low resistivity reservoir. Using color editor of petrophysical software enables the subdivision of log curves into horizontal intervals with specific color or shade based on certain values. Intervals with DT (90-100 msec/ft), which corresponding to 25-36% porosity unit, are shaded red. Comparing production test results with high porosity zones (red shaded on logs) proved that they are gas producers. The advantage of this procedure is that it does not need any extra measurement or calculation; it is only a way of displaying the logs. It has been applied to different gas wells in Ghadames Basin, and it shows a good result. However, this procedure is not applicable to oil pays. 1 Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1337 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1336 The hydrocarbon source potential of the Paleozoic rocks of Ghadamis Basin Northwestern Libya Dieb, Moftah Ahmed Ghadamis Basin is an intracratonic sag basin and is considered as an important hydrocarbon province in the North African continent. In Libya, the Ghadamis Basin is located in the western part of the country and filled by Palaeozoic sediments and overlying thin Mesozoic-Tertiary sequences. The Palaeozoic rocks range from Cambrian to Carboniferous with a maximum thickness of about 12, 000 feet. They consist of alternating transgressive and regressive marine sandstones, shales, siltstones and, locally limestones. The present study, based on the ditch cuttings shale samples, investigate the bulk organic geochemistry, kerogen microscopy and thermal maturity. The geochemical results demonstrated the presence of various organic-rich zones within the Palaeozoic sequences. The Mamuniyat, the lower ‘hot’ Tanezzuft and the Awaynat Wanin formations are considered to have a good to excellent potential source and are particularly prospective hydrocarbon generation in the study area. The Tanezzuft formation is divided into an upper ‘cool’ shale and lower ‘hot’ shale based on the basis of high gamma-ray response in wireline logs and high organic carbon content (TOC). Generally, the Palaeozoic sequence has TOC values ranging from 0.5 to 21.4 wt%. Maturity data indicate that the Devonian shale samples are immature to marginally mature and that the Silurian and the Ordovician shale samples are mostly middle to late mature. Visual Kerogen examination showed that organic matter is comprised mainly of amorphous and palynomorphs components (Type II Kerogen) oil prone with some phytoclasts materials (Type III), gas prone. Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1336 2019-03-31T00:00:00Z https://repository.uob.edu.ly/handle/123456789/1335 Geochemical and mineralogical studies of the celestite bearing formations and associated sediments in Benghazi Formation, Ar Rajmah Group (Middle Miocene), Al Jabal Al Akhdar, NE Libya El Ebaidi, Saad K The study area is located in the northeast of Libya, in the areas of Benghazi city and Ar Rajmah village. The purpose of this study is to find out geochemically and mineralogically the source of strontium element. Also the distribution of strontium in allochems, matrix and cement in the Benghazi Formation of the Ar Rajmah Group. Celestite grade 88.3 % (SrSO4) occurs only in the Benghazi Formation at Benghazi Cement Quarry as geodic nodules in the Middle Miocene rocks. Detailed mineralogical and chemical data have been collected on the celestite and associated sediments using XRF, XRD, EPMA, SEM and DSC techniques. Authigenic celestite and strontianite minerals occur both as a cement and as a replaced by other fracture filling minerals such as anhydrite. However, carbonate skeletal grains have quite high MgCO3 contents, reflecting sometimes the presence of dolomite and brucite minerals. The average Sr/Ca ratio of coralline algae is 0.65. Echinoderm fragments have the highest value 1.31 of Sr/Ca and containing 0.47 to 1.8 mole percent of MgCO3 in the Benghazi Formation. Echinoid spines contain higher strontium contents than other echinoderm fragments. Some bivalves are replaced totally by apatite and had a very high absolute concentration of strontium. The high strontium- low magnesium contents and vice versa are related to the diagenesis, mineralogical nature of the sediments and organic remains. Celestite occurs mainly in sedimentary beds of the Benghazi Formation, adjacent to the evaporitic environment (gypsum/anhydrite) and near sites of intense dolomitization. Sun, 31 Mar 2019 00:00:00 GMT https://repository.uob.edu.ly/handle/123456789/1335 2019-03-31T00:00:00Z