The Quaternary development of tributary channels to the Nile River at Kom Ombo area,Eastern Desert of Egypt,and their implication for groundwater resources

The dry wadis ‘ephemeral channel’ constituting the main tributaries to the Nile River in Kom Ombo are structurally and tectonically controlled and exhibit complex drainage pattern. This complicated drainage pattern is inherited from the morpho‐tectonic evolution of the ancestral Nile River (‘Protonile’), which drained the Eastern Desert during the Middle Pleistocene. A digital elevation model derived from Shuttle Radar Topography Mission data is used to delineate the contemporary drainage networks and their catchments. Satellite images acquired during a flash flood event were used to validate the delineated watershed divides and flow pathways, particularly where the courses of dry wadis are interlocked. Currently, the westward flow of Wadi Abu‐Suberah is derived from a small area in the Eastern Desert, as the palaeo‐upper reaches of this wadi were captured due to tectonic movements along NW/SE and N/S faults by wadis in the Kharit and Elewa areas. The influence of these tectonic movements on groundwater distribution is also shown where the deep Nubian aquifer discharges its water into the Quaternary aquifer through fault planes. The northward flowing ‘Protonile’ main course has tectonically shifted from the Gallaba plain in the Western Desert, eastward to the current Nile River course. This shift has produced several cut‐off segments of the palaeo‐tributary drainage that was originally flowing westward towards the old ‘Protonile’ main course in the Gallaba plain. However, these segments have reversed their surface run‐off flow directions eastward towards the current Nile course; they could include potential groundwater resources, as their alluvium may be still recharged by the Nile River. Copyright © 2010 John Wiley & Sons, Ltd.     

Assessment of regional estimation error by canonical residual kriging

Various regional flood frequency analysis procedures are used in hydrology to estimate hydrological variables at ungauged or partially gauged sites. Relatively few studies have been conducted to evaluate the accuracy of these procedures and estimate the error induced in regional flood frequency estimation models. The objective of this paper is to assess the overall error induced in the residual kriging (RK) regional flood frequency estimation model. The two main error sources in specific flood quantile estimation using RK are the error induced in the quantiles local estimation procedure and the error resulting from the regional quantile estimation process. Therefore, for an overall error assessment, the corresponding errors associated with these two steps must be quantified. Results show that the main source of error in RK is the error induced into the regional quantile estimation method. Results also indicate that the accuracy of the regional estimates increases with decreasing return periods. Copyright © 2010 John Wiley & Sons, Ltd.     

River evaporation and corresponding heat fluxes in forested catchments

River water temperature is a very important variable in ecological studies, especially for the management of fisheries and aquatic resources. Temperature can impact on fish distribution, growth, mortality and community dynamics. River evaporation has been identified as an important heat loss and a key process in the thermal regime of rivers. However, its quantification remains a challenge, mainly because of the difficulty of making direct measurements. The objectives of this study were to characterize the evaporative heat flux at different scales (brook vs river) and to improve the estimation of the evaporative heat flux in a stream temperature model at the hourly timescale. Using a mass balance approach with floating minipans, we measured river evaporation at an hourly timescale in a medium‐sized river (Little Southwest Miramichi) and a small brook (Catamaran Brook) in New Brunswick, Canada. With these direct measurements of evaporation, we developed mass transfer equations to estimate hourly evaporation rates from microclimate conditions measured 2 m above the stream. During the summer 2012, river evaporation was more important for the medium‐sized river with a mean daily evaporation rate of 3.0 mm day^?1 in the Little Southwest Miramichi River compared with that of 1.0 mm day^?1 in Catamaran Brook. Evaporation was the main heat loss mechanism in the two studied streams and was responsible for 42% of heat losses in the Little Southwest Miramichi River and 34% of heat losses in Catamaran Brook during the summer. Copyright © 2013 John Wiley & Sons, Ltd.     

Neoproterozoic granites of Sharm El-Sheikh area,Egypt: mineralogical and thermobarometric variations

Calc-alkaline and alkaline intrusions of the late Neoproterozic form essential part of the Arabian–Nubian Shield. They were formed during the collision between East- and West-Gondwana. Sharm El-Sheikh area, Sinai, includes wide compositional array of these intrusions that can be considered as a case study. Variations in both tectonic and thermobarometric condition for granitic intrusions are studied. Four mappable granitic types are recognized namely monzogranite, syenogranite, alkali feldspar granites, and riebeckite-bearing granites. The monzogranite and the syenogranite of the study area are mostly I-type, whereas the alkali feldspar granite and the riebeckite-bearing granite belong to A-type granitoid. The calc-alkaline intrusions were formed in compressional setting due to decompressional melting of mafic lower crust. Partial melting and anatexing of crustal rocks are suggested to explain the protolith of the alkaline intrusions. The transition from the calc-alkaline magma to the alkaline one occurred as a result of the tectonic transition from compression regime to tectonic relaxation (extension setting) during the last stage of the Pan-African Orogeny. The amphiboles of the studied granites are classified as calcic- and alkali-amphiboles. The calcic-amphiboles are ferro-edenite while the alkali-amphiboles are typically riebeckite. Both amphibole types are of magmatic nature. Coexisting amphiboles and plagioclases are used to estimate the physicochemical parameters of magma crystallization. The syenogranite underwent temperature and pressure of formation range of 520–730 °C, <3 kbar. The alkali feldspar granite records 450–830 °C, <4 kbar, while the riebeckite-bearing granite records the lowest temperature condition among all varieties and estimate formation at 350–650 °C, <4 kbar.     

Epi- and endobiont faunal communities on an Egyptian Mediterranean rocky shore: species composition and their competition for space

The exposed calcareous rocky area of the Abu Qir Headland,east of Alexandria,Egypt which range from coarse grains,through pebbles,cobbles,and boulders to rocky platforms,was significantly colonized by sclerobionts(epibionts and endobionts).The epibiont species diversity was comparatively higher than that of endobionts.Epibiont communities included bryozoans(the anascan-grade cheilostome Bifiustra savartii),serpulid(Hydroides elegans,Spirobranchus cf.tetraceros,Vermiliopsis striaticeps and Protula or Apomatus) and spirorbid(Spirorbis) wormtubes,and balanoid barnacles(Amphibalanus amphitrite,Balanus trigonus,and Perforatus perforatus).The cheilostome bryozoan colonies,which developed extensive sheets,proliferated on the study rocky shore either encrusting the bioeroded basement directly,or encrusting other epilithic taxa,particularly balanoid barnacles and serpulid worms.Encrusters displayed a remarkable marginal competitive interaction(overgrowth and stand-off) for space on the study rocky shore.On the other hand,endobionts were not well represented on the studied rocky shore exposure.It was possible to identify three ichnotaxa:Gastrochaenolites,Maeandropolydora,and Finichnus.The findings documented represent a significant contribution to our knowledge of sclerobionts composition,sequence of their colonization and/or bioero sion,and their mutual relationships on the intertidal rocky shore of the Abu Qir Headland.     

Harmonic by harmonic removal technique for improving vibroseis data quality

In this paper, an improved method is presented to reduce vibrator harmonic distortion, one harmonic at a time and the method is illustrated with both simulated and field data. This method improves on the previous method that treated all the harmonics at once. The significant contribution in this procedure is a considerable reduction for the harmonics without any alteration for the weakest signals possibly present in positive and negative times. The core of the proposed technique depends on an accurate simulation for all the harmonics one by one existing in the positive and negative times of the data after cross‐correlation with the fundamental sweep and then subtracting the simulated harmonics from the original data using an optimization procedure. The steps and mathematical equations of the procedure are explained in detail in the body of the article in the section titled ‘harmonic by harmonic attenuation procedure’. Accordingly, a well‐developed procedure for enhancing the vibroseis data quality in both down‐ and up‐sweep data is illustrated. The procedure was tested on both synthetic and field data sets.     

Semial ophiolite veins of United Arab Emirates―A fluid inclusions study

Calcite and quartz veins in the gabbroic and dunite rocks of the Semial ophiolite (UAE) were selected for fluid inclusion analysis. The inclusions contain both aqueous low-salinity and hydrocarbon-dominated fluids. Mi-crothermometry data indicate that the aqueous fluids contain 0.22 to 1.45 equivalent wt% NaCl and occasionally contain traces of hydrocarbons. Homogenization to liquid occurred between 91 and 152℃. Modeling based on these fluid inclusion observations indicates that the trapping conditions of t...     

Petrological and mineralogical characteristics of younger granites and pegmatites in the Wadi Haleifiya area,southeastern Sinai,Egypt

This study is concerned with the radioactivity and mineralogy of the younger granites and pegmatites in the Wadi Haleifiya area, southeastern Sinai Peninsula, Egypt. The area is occupied by metasediments, migmatites, older and younger granites. Most of these rocks, especially granites, are dissected by mafic and felsic dykes as well as pegmatites. The younger granites are represented by three main varieties: monzogranites, syenogranites and alkali feldspar granites. The monzogranite consists essentially of quartz, plagioclase, potash feldspar and biotite with minor musco-vite. Iron oxide, titanite, zircon and allanite are the main accessory minerals. Syenogranite is massive, medium- to coarse-grained and commonly exhibits equigranular and hypidiomorphic textures. It is made up essentially of potash feldspar, quartz, plagioclase and biotite. Iron oxides, allanite, epidote, titanite, and zircon are accessory minerals. The alkali feldspar granite consists mainly of perthite, quartz, alkali amphibole (arfvedsonite and riebekite), biotite, sub-ordinate plagioclase and aegirine. Iron oxide, zircon and apatite are accessory minerals, whereas chlorite and sas-surite are secondary minerals. The altered monzogranite and pegmatite recorded high radioelement contents. The eU reaches up to 120 (av.=82×10-6) in the altered monzogranite and up to 55 (av.=27×10-6) in the pegmatites. The high radioactivity in the altered monzogranite is due to the presence of thorite, uranothorite and metamict zircon. In the pegmatites, it is re-lated to the presence of uranophane, uranothorite, thorite, zircon, samarskite, monazite, xenotime, magnetite, ilmen-ite, hematite and rutile.     

Mineralogy,M-type tetrad effect and radioactivity of altered granites at the G. Abu Garadi shear zone,central Eastern Desert,Egypt

The G. Abu Garadi area is covered mainly by metasediments, alkali feldspar granites and stream sediments. The alkali feldspar granite is traversed by a major strike-slip fault trending in an N-S direction as well as two subordinate sets of faults trending NW to WNW for the first one and NE for the second one. These faults represent the shear zones affected by magmatic (syngenetic) as well as hydrothermal (epigenetic) activities causing alteration of the granitic rocks. The most common alteration features are albitization, greisenization and koalinitization. The mass balance calculations of the studied altered samples show enrichments in Zr, Y, Ni, U, Th and Ga and depletions in Zn, Sr, Nb, Ba, Pb, Cu and V. Only the greisenized samples exhibit a significant enrichment in Nb, ∑REE budget and pronounced lanthanide tetrad effect (M-type), especially TE1,4, while weakly expressed tetrad effects are for the other albitized and koalinitized samples. Mineralogically, the common accessory minerals in the altered samples include samarskite-(Y), betafite, uranothorite, zircon, fluorite and cassiterite. The greisenized granites contain high eU and eTh than the other altered types, where they are characterized by an assemblage of the radioactive minerals; samarskite-(Y), betafite, uranothorite in addition to zircon. The inter-element relationships between U and Th and also their ratios illustrate that the radioelement distribution in these granites is mainly governed by magmatic processes, in addition to post-magmatic ones. The distribution of chemical elements and the fractionation of some isovalents within the shear zone are largely controlled by the newly formed mineral phases. With respect to uranium mobilization, uranium migrated from the host alkali feldspar granites of G. Abu Garadi, while the shear zones acted as traps for the migrated uranium. Moreover, U migrated in the shear zone during greisenization and albitization, and migrated out during koalinitization.     

Temporal evolution of weathered cataclastic material in gravitational faults of the La Clapiere deep-seated landslide by mechanical approach

After a few years of research, the observation and the analysis of the deep-seated landslides suggest that these are mainly controlled by tectonic structures, which play a dominant role in the deformation of massif slopes. The La Clapière deep-seated landslide (Argentera Mercantour massif) is embedded in a deep-seated gravitational slope deformation affecting the entire slope, and characterized by specific landforms (trenches, scarps??). Onsite, the tangential displacement direction of the trenches and the scarps are controlled by the tectonic structures. The reactivation of the inherited fault in gravitational faults create a gouge material exposed to an additional mechanical and chemical weathering as well as an increased of leaching. The displacement of these reactivated faults gets increasingly important around the area of the La Clapière landslide and this since 3.6?ka BP. In this study, mechanical analysis and grain size distributions were performed and these data were analysed according to their proximity the La Clapiere landslide and times of initiation of the landslide by ¹⁰Be dating. Triaxial test results show that the effective cohesion decreases and the effective angle of internal friction increases from the unweathered area to the weathered area. The whole distribution of the grain size indicates that the further the shear zone is open or developed, the further the residual material loses its finest particles. This paper suggests that the mechanical evolution along the reactivated fault is influenced by the leaching processes. For the first time, we can extract from these data temporal behaviour of the two main mechanical parameters (cohesion and angle of internal friction) from the beginning of the La Clapiere landslide initiation (3.6 ka BP) to now.