Depositional environments of the Miocene-Pliocene siliciclastic succession,Al Rehaili area,north of Jeddah,Saudi Arabia     

Faisal A. Alqahtani  Mohammed Khalil 《Journal of the Geological Society of India》2015,86(6):706-716

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A hydrogeological conceptual approach to study urban groundwater flow in Bucharest city,Romania     

Mohamed Amine Boukhemacha  Constantin Radu Gogu  Irina Serpescu  Dragos Gaitanaru  Ioan Bica 《Hydrogeology Journal》2015,23(3):437-450

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Stable and radio-isotope analysis to determine recharge timing and paleoclimate of sandstone aquifers in central and southeast Libya     

Mohamed Al Faitouri  William E. Sanford 《Hydrogeology Journal》2015,23(4):707-717

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Short-term forecasting of groundwater levels under conditions of mine-tailings recharge using wavelet ensemble neural network models   总被引：1，自引：0，他引：1  

Bahaa Khalil  Stefan Broda  Jan Adamowski  Bogdan Ozga-Zielinski  Amanda Donohoe 《Hydrogeology Journal》2015,23(1):121-141

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Pan-African adakitic rocks of the north Arabian–Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt     

Mohamed A. Obeid  Mokhles K. Azer 《International Journal of Earth Sciences》2015,104(3):541-563

The Precambrian basement of Egypt is part of the Red Sea Mountains and represents the north-western part of the Arabian–Nubian Shield (ANS). Five volcanic sections are exposed in the Egyptian basement complex, namely El Kharaza, Monqul, Abu Had, Mellaha and Abu Marwa. They are located in the north Eastern Desert (ED) of Egypt and were selected for petrological and geochemical studies as they represent the Dokhan volcanics. The volcanics divide into two main pulses, and each pulse was frequently accompanied by deposition of immature molasse type sediments, which represent a thick sequence of the Hammamat group in the north ED. Compositionally, the rocks form a continuum from basaltic andesite, andesite, dacite (lower succession) to rhyodacite and rhyolite (upper succession), with no apparent compositional gaps. These high-K calc-alkaline rocks have strong affinities to subduction-related rocks with enriched LILEs (Rb, Ba, K, Th, Ce) relative to high field strength elements (Nb, Zr, P, Ti) and negative Nb anomalies relative to NMORB. The lower succession displays geochemical characteristics of adakitic rocks with SiO₂ >53 wt%, Al₂O₃ >15 wt%, MgO >2.5 wt%, Mg# >49, Sr >650 ppm, Y <17 ppm, Yb <2 ppm, Ni >25 ppm, Cr >50 ppm and Sr/Y >42.4. They also have low Nb, Rb and Zr compared to the coexisting calc-alkaline rhyodacites and rhyolites. The highly fractionated rhyolitic rocks have strong negative Eu anomalies and possess the geochemical characteristics of A-type suites. Trace element geochemical signatures indicate a magma source consistent with post-collisional suites that retain destructive plate signatures associated with subduction zones. The adakitic rocks in the northern ANS are generated through partial melting of delaminated mafic lower crust interacting with overlying mantle-derived magma. The Dokhan volcanics were likely generated by a combination of processes, including partial melting, crystal fractionation and assimilation.  相似文献   

Ionization State in PDR (IC 63 nebula)     

O.M. Shalabiea  K.A. Khalil  M.S. EL-Nawawy 《Astrophysics and Space Science》2004,289(1-2):77-93

We investigated the chemical evolution in IC 63 nebula, a photo-dominated region (PDR). The chemical structure and the ionization state depend directly on the intensity of the incident UV radiation. The electron density is also affected by the incident UV radiation. It decreases gradually with the increase of the depth in the cloud varying from 5.9×10^-5 at the surface to 9.6×10^-9 in the core. Ionic carbon(C⁺) dominates the electron density in the outer region while ionic metals and other ions (H⁺, CH₂D⁺, and HCO⁺) are the most dominant in the deepest region. Our results at A _V = 6.7 mag are in good agreement with observations except in the case of H₂S, where the calculated value is lower than the observed value by about two orders of magnitude.  相似文献   

Prediction of satellite motions in the Earth's gravitational field with axial symmetry by the KS regularized theory     

Mohamed Adel Sharaf  Mervat El-Sayed Awad  Mona A. Banaja 《Astrophysics and Space Science》1987,133(2):339-353

In this paper, economical and stable recurrence formulae for the Earth's zonal potential and its gradient for the KS regularized theory will be established for any numberN of the zonal harmonic coefficient. A general recursive computational algorithm based on these formulae is also established for the initial value problem of the KS theory for the prediction of artificial satellites in the Earth's gravitational field with axial symmetry. Applications of the algorithm for the problem of the final state prediction are illustrated by numerical examples of three test orbits each for two geopotential models corresponding toN=2 andN=36. A final state of any desired accuracy is obtained for each case study, a result which shows the flexibility of the algorithm.  相似文献   

A geostatistically based approach to the identification of aquifer transmissivities in Yolo Basin, California     

Mohamed Aboufirassi  Miguel A. Mariño 《Mathematical Geology》1984,16(2):125-137

A geostatistically based approach is developed for the identification of aquifer transmissivities in Yolo Basin, California. The approach combines weighted least-squares with universal kriging and cokriging techniques in an overall scheme that (1)considers a prioriknown information on aquifer transmissivity and specific capacities of wells, (2)considers uncertainties in water level and transmissivity data, and (3)estimates the reliability of the generated transmissivity values. Minimization of a global least-squares function that incorporates calibration and plausibility criteria leads to a transmissivity map that shows a good agreement with pumping-test results.  相似文献   

Growth of the marsh elder<Emphasis Type="Italic">Iva frutescens</Emphasis> in relation to duration of tidal flooding     

Glen?B.?ThursbyEmail author  Mohamed?A.?Abdelrhman 《Estuaries and Coasts》2004,27(2):217-224

Iva frutescens is a common shrub at the upland fringe of salt marshes throughout the East and Gulf Coasts of North America. Within a marsh, its location and relative size are governed largely by the degree of flooding by seawater.Iva’s wide distribution and restricted location within salt marshes may make it a useful indicator of overall conditions of the marshes. This work was designed to provide basic information on the age and growth ofI. frutescens, especially as they relate to the degree of flooding that is needed in order to investigateIva’s potential as an indicator. Cross-sections of older stems (living and standing dead) from salt marshes in Rhode Island, United States, were examined in order to age stems and estimate their growth rate from cumulative increase in woody tissue. Most stems were six yr old or less, suggesting that aboveground structures live for only a few years. Stem diameter correlated with growth rate and aboveground biomass. Elevation at the root zone was used to estimate the duration that plants were flooded, which was negatively correlated with stem diameter. The most robust plants came from sites that were flooded only up to 6–7% of the total time during the growing season. No plants were found in areas flooded more than 30% of the time.  相似文献   

Événements panafricains dans l'Adrar Souttouf (Sahara marocain)     

Michel Villeneuve  Hervé Bellon  Abdelkrim El Archi  Mohamed Sahabi  Jean-Pierre Rehault  Jean-Louis Olivet  Abdel M. Aghzer 《Comptes Rendus Geoscience》2006,338(5):359-367

The Adrar Souttouf belt (Western Sahara) lies in the northern part of the Mauritanide belt and was considered as a part of the Hercynian Mauritanian-Appalachian belt. Recently the presence of a Panafrican protolith (595 Ma) was evidenced by the age of inherited zircons from an eclogitic unit and led to consider complex Panafrican events included in the Hercynian belt, as in the central and southern Mauritanide belt. Our new field survey completed by ten KAr dating (whole rocks and separate minerals) confirmed that multiphased Panafrican formations outcrop within the center of the Adrar Souttouf massif. Diverse events ranged from ca. 1000 to 500 Ma, some of them being indicative of an oceanic type environment and metamorphism. The 1000 Ma metamorphic event is recorded for the first time in the West African craton. A large Hercynian remobilisation is also evidenced. To cite this article: M. Villeneuve et al., C. R. Geoscience 338 (2006).  相似文献