Uranium mineralized fault zone at Wadi Um Gir locality,Central Eastern Desert,Egypt

The area of Wadi Um Gir, Central Eastern Desert of Egypt, is covered by Basement rocks of Late Precambrian age namely; the postgeosynclinal (Hammamat) sediments, intruded by a bostonite dyke of the younger postorogenic volcanics. The radioactive anomaly discovered at Wadi Urn Gir is a typical vein-type hydrothermal occurrence structurally controlled by a major fault which is among the youngest faults related to the formation of the Red Sea Rift Valley during Tertiary times. The net slip of this fault is determined by the orthographic projection method to be 260 m.Hydrothermal alteration is intense along the fault zone, and is represented by successive bands mainly of hematite, kaolinitic clays, carbonates, etc.The radioactivity is normally distributed in the fresh rocks with anomalous readings connected to the altered bostonite rock in the fault zone. The abnormal high radioactivity is found to be mainly due to secondary uranium mineralization, with a uranium content of 0.065%, and in a radioactive disequilibrium with slight deficiency of daughter elements which may be due to redistribution by the effect of ground water. The uranium mineralization is usually present as fracture-fillings or forming thin fissure veinlets mostly with hematitic alteration bands along the fault zone.Genetically; repeated movement along the major fault resulted in intense fracturing of the bostonite rocks and reopening of the tectonically related fissures. The fault provided an easy channel for the passage of the contemporaneous or immediately ascending uranium-bearing solutions. Subsequently, alteration of bostonite and radioactive mineralization took place in the secondary tension fractures. The physico-chemical conditions of the altered and sheared bostonite rocks afforded the favourable conditions for the deposition of uranium minerals carried by the hydrothermal fluids along the opened fractures.

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Zusammenfassung Das Gebiet »Wadi Um Gir« in der zentralarabischen Wüste Ägyptens besteht aus Basisgesteinen von Präkambrischem Alter. Es handelt sich um die postgeosynklinale »Hammamat«-Serie, deren Sedimentabfolge von einem Bostonitgang des jüngeren postorogenen Vulkanismus durchbrochen wird.Eine Radioaktivitätsanomalie wurde in »Wadi Um Gir« festgestellt. Sie bildet ein typisch-gangartiges hydrothermales Vorkommen und ist von einem Hauptbruch der mit der Entstehung des Rotmeergrabens verbundenen jungen Brüche bestimmt. Eine Berechnung der Sprunghöhe dieser Verwerfung mit der orthographischen Projektionsmethode ergab einen Wert von 260 m.Intensive hydrothermale Umwandlung der Muttergesteine kommt entlang der Bruchzone vor. Sie besteht unter anderem aus Successiven Streifen von hämatitischem, kaolinitischem und karbonatischem Material.Die Radioaktivität, deren Verteilung in den frischen Gesteinen normal ist, zeigt Anomalien nur noch im Zusammenhang mit dem umgewandelten Bostonit der Bruchzone, wobei die abnormal hohen Radioaktivitäts-Werte mit der sekundären Uran-Mineralisation (Urangehalt 0,065%) in Einklang stehen. Es besteht jedoch durch geringe Verarmung an gewissen Tochterelementen eine Gleichgewichtsstörung. Dies könnte auf die Umverteilung durch Grundwassereinflüsse zurückgeführt werden.Genetische Überlagerungen führen zu der Annahme, daß die wiederholte Bewegung entlang der Hauptbruchzone eine intensive Fraktur der Bostonitgesteine veranlaßt hat. Dies führte zur mehrfachen Öffnung der in Zusammenhang stehenden Spalten und damit bildeten sich Bahnen für die aufsteigenden, syngenetischen, uranhaltigen Lösungen.Die Anlagerung uranhaltiger Mineralien in den sekundären Spannungsbrüchen wurde durch die physiko-chemischen Verhältnisse des umgewandelten und abgescherten Bestonits gewährleistet.

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Nonlinear lateral interaction in pile dynamics

A model for pile lateral response to transient dynamic loading and to harmonic loading is presented allowing for nonlinear soil behaviour, discontinuity conditions at the pile-soil interface and energy dissipation through different types of damping. The approach is used to establish equivalent linear stiffness and damping parameters of single piles as well as dynamic interaction factors for approximate nonlinear analysis of pile groups. The applicability of these parameters to the pile-group analysis was examined, and a reasonable agreement with the direct analysis was found. The superposition technique may be used to analyze the response of small pile groups. Also, the dynamic stiffness of pile groups is greatly affected by both the nonlinear behavior of the soil and the slippage and gapping between the pile and soil. For a basic range of soil and pile parameters, equivalent linear stiffness and damping parameters of single piles and interaction factors for approximate nonlinear analysis are provided.     

Diagenetic and metamorphic history of the Umm Nar BIF,Eastern Desert,Egypt

The Umm Nar BIF was formed in a sedimentary environment. It is confined to an upper stratigraphic zone of pre-Pan-African metamorphosed shelf deposits. During the Pan-African deformational history, the BIF and the host metasediments were tectonically' overlain by ophiolitic melange succession. The metasediments and the mélange were subjected to a major folding phase and then thrust over the “Shaitian” sheared granite, prior to the intrusion of syn- to late- orogenic granitoids. The BIF is divisible into two main types: oxide-bands including magnetite and hematite, and oxide-silicate bands including magnetite, hematite and stilpnomelane. The associated gangues are quartz, calcite, epidote, garnet, plagioclase, graphite and muscovite. Rhythmic banding and lamination, cross-lamination and flaser structure are the most prominent primary features in the IF bands. The iron minerals and the associated gangue show a variety of textural aspects and microscopic interrelationships which indicate successive episodes of mineral accumulation and formation, involving deposition, recrystallization, blastic growths, overgrowths, replacement and deformations, during continuous burial and subsequent tectonic deformations. Editorial handling: DR     

A Conceptual Model of Field Behavior of Air Sparging and Its Implications for Application

The basic physics of air flow through saturated porous media are reviewed and implications arc drawn for the practical application of air sparging. A conceptual model of the detailed behavior of an air sparging system is constructed using elements of multiphase flow theory and the results of recent experimental work. Implications of the conceptual model on air sparging topics are discussed. The meaning of radius of influence in the context of air sparging is found to be ambiguous. The hydrodynamic effects of air sparging such as mounding of ground water and flow impedance are explored. Limitations on rates of remediation and operational strategics for improving sparging effectiveness are examined.     

Evaluation of alternatives for lowering the groundwater table in a village in upper Egypt affected by the construction of the New Naga Hammadi barrage

The Egyptian government is replacing the existing Naga Hammadi barrage, located across the Nile River some 450 km south of Cairo, with the New Naga Hammadi barrage (NNHB) to incorporate a hydropower plant and to improve conditions for river traffic. The new structure will lead to an increase in river water levels, both locally near the new barrage and upstream. The rise in river water levels will in turn result in changes in groundwater levels in the aquifer system up and downstream of the barrages. In this paper, an area is chosen, which is expected to suffer from a high groundwater table after the construction of the NNHB, to investigate the problem and propose alternatives for lowering the groundwater levels. The study area is a village called Bakhaness, with an area of 588 ha. It is located some 1.5 km upstream of the NNHB. A computer model (MicroFEM) has been used to simulate the groundwater conditions before and after construction of the NNHB. Alternatives for lowering the groundwater table are proposed, simulated and evaluated. The systems, which are assessed are a municipal sewer system, a system of perforated pipes in urban areas, and tile drainage with different values of efficiency in agricultural areas.     

Tectonic relationships of Southwest Iberia with the allochthons of Northwest Iberia and the Moroccan Variscides

The Iberian Massif poses a problem of relationships between its northwestern and southern parts. Suture terranes (ophiolites and high-pressure rocks) crop out in NW Iberia but only as allochthonous units, unconnected from their root zone. Sutures cropping out in SW Iberia are discussed in order to relate them to the unknown root of the NW Iberia allochthons. On the other hand, the Moroccan Variscides are very briefly presented with a view to propose their correlation with the Iberian zones. Particularly important is the transition from the Variscides to the Paleoproterozoic basement in Morocco, which is a key argument for palaeogeographic reconstructions.     

Development and evaluation of biodiesel fuel and by-products from jatropha oil

Biodiesel is an environmentally friend renewable diesel fuel alternative. Jatropha seeds can be a feedstock to produce a valuable amount of oil to be converted to biodiesel using transesterification reaction. Jatropha plant has been successfully grown in southern Egypt using primary treated municipal wastewater for its irrigation. Abench scale production of biodiesel from Jatropha oil (using methyl alcohol and sodium hydroxide as catalyst) was developed with methyl esters yield of 98 %. Biodiesel was produced on a pilot scale based on the bench scale experiment results with almost the same methyl esters yield of 98 %. The produced biodiesel was evaluated as a fuel and compared with petroleum diesel according to its physical and chemical parameters such as viscosity, flash point, pour point, cloud point, carbon residue, acid value and calorific value. The experimental techniques and product evaluation results show that such properties of the produced biodiesel are near to that of petroleum diesel. A mass balance representing the transesterification process is presented in this study. Glycerol of 85 % purity was produced and evaluated as a valuable byproduct of the process. Free fatty acids and sodium phosphate salts which have industrial interesting are also produced and evaluated.