Sources and genesis of the Pleistocene gravelly deposits in Northern Kuwait     

F.I. Khalaf  I.M. Gharib  A.S. Al Kadi 《Sedimentary Geology》1982,31(2):101-117

The Dibdibba Formation is of Pleistocene age and consists of a fluviatile sequence of ungraded, often cross-bedded sand and gravels intercalated with minor sandy clay layers. It occurs in the northern desert of Kuwait as subparallel elongated ridges trending NE-SW. Structures and mineralogy of the Dibdibba deposits suggest that they have been derived from the basement complex of the northeastern area of Saudi Arabia as sheet floods and deposited in the alluvial fan of the Wadi Ar-Rimmah-Al Batin valley system. Floods transporting these deposits were intermittent; the gravelly bands were deposited during severe floods and the sandy beds during relatively quiet floods.  相似文献   

‘Total’ fabric of some till landforms     

Edward Derbyshire  Alan McGown  Amr Radwan 《地球表面变化过程与地形》1976,1(1):17-26

The distinction between clast-dominant, matrix-dominant and well-graded tills is important in view of the influence of texture on the definition and function of till fines. Till fabric includes a wide range of features of both primary and secondary origin including folds, thrusts, fissures (the macrofabric), disposition of clasts (the mesofabric) and organization of the matrix (the microfabric). The results of fabric analysis of pebble, granule, sand, silt and clay in small depositional landforms beneath currently-active glaciers are described. Deformation fabrics are distinguished in freshly deposited end moraines and flutes. The sand-size material in deformed till may or may not behave in the same way as larger clasts, depending on the degree to which the till is matrix-dominant. While clasts in saturated subglacial till tend to align themselves sub-parallel to the depositional surface, the matrix usually retains abundant pore spaces. With slow, unloaded drainage, clast fabrics appear to be little modified. Such material is potentially unstable and any subsequent increase in overburden and hydraulic pressures may cause slope collapse and flowtill development. It is concluded that examination of a wide range of fabric parameters provides a means of distinguishing tills of diverse origins and of assessing their potential instability.  相似文献   

Seismic design of RC and masonry buildings,by T. Paulay and M. J. N. Priestley,Wiley Interscience,New York, 1992. No. of pages: 744. Price: £56. ISBN 0-471-54915-0     

Amr Elnashai 《地震工程与结构动力学》1994,23(3):341-342

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Benthic foraminiferal turnover across the Paleocene–Eocene Thermal Maximum (PETM) event in Eastern Desert,Egypt     

Hassan A. Soliman  Nageh A. Obaidalla  Amr A. Metwally  Azza A. Mohamed 《Arabian Journal of Geosciences》2018,11(14):394

Benthic foraminiferal fauna are analyzed quantitatively and qualitatively at three stratigraphic sections in Eastern Desert of Egypt (Serai, Duwi, and Um El Huetat). These sections embrace the Paleocene–Eocene Thermal Maximum (PETM) interval which is represented by the occurrence of five distinctive beds. These beds constitute the Dababiya Quarry Member at the lower part of Esna Formation. The occurrence of them indicates an expanded and relatively continuous record across the P/E boundary. The organic-rich clay layer (bed no. 1 of the Dababiya Quarry Member) marks the start of the PETM event. This bed is characterized by the extinction of all benthic foraminiferal fauna except for the occurrence of rare agglutinated foraminiferal species. The presence of these species indicates an oceanic anoxic event at the sea floor. High concentration of phosphatic contents including fish remains occurred in the middle part of the PETM (bed nos. 2 and 3 of the Dababiya Quarry Member) with the continuous absence of benthic foraminiferal fauna except for few specimens at the top of bed 3. Bed nos. 4 and 5 of the Dababiya Quarry Member represent the upper part of the PETM and the initial stage of sea floor recovery. Low diversity and abundance of benthic foraminiferal taxa occurred within these beds, represented by Valvulineria scrobiculata, Lenticulina midwayensis, Loxostomoides appliane, and Siphogenerinoides eleganta. This phenomenon continues upward during the post-PETM event. The Paleocene velasco-type benthic foraminifera Angulogavelinella avnimelechi and Coryphostoma midwayensis species are extinct within the advent of the PETM event. The benthic foraminiferal assemblages at the studied sections are dominated by midway-type fauna with little representative of velasco-type fauna. The velasco-type species are represented with high abundance at Serai section and with low densities at Um El Huetat section, while at Duwi section, they rarely occurred. This suggests outer neritic-upper bathyal (150–400 m) setting at Serai section and mostly middle-outer neritic (50–150 m) setting at Um El Huetat and Duwi sections.  相似文献   

Estimating potential direct runoff for ungauged urban watersheds based on RST and GIS     

Farid Radwan  A. A. Alazba  Amr Mossad 《Arabian Journal of Geosciences》2018,11(23):748

Estimating the potential direct runoff for urban watersheds is essential for flood risk mitigation and rainwater harvesting. Thus, this study aims to estimate the potential runoff depth based on the natural resources conservation service (NRCS) method and delineation of the watersheds in Riyadh, Saudi Arabia. To accomplish this objective, the geographic information systems (GIS) and remote sensing technique (RST) data were integrated to save time and improve analysis accuracy. The employed data include the digital elevation model (DEM), soil map, geology map, satellite images, and daily precipitation records. Accordingly, the hydrologic soil groups (HSG), the land use/land cover (LULC), and curve number (CN) were determined for each watershed in the study area. The results of this analysis show that the study area can be delineated into 40 watersheds with a total area of 8500 km². Furthermore, the dominant HSG is group D, which represents about 71% of the total area. The LULC maps indicate four major land types in the entire study area: urban, barren land, agricultural land, and roads. The CN of the study area ranges from 64 to 98, while the weighted CN is 92 for the city. The rainfall-runoff analysis shows that the area has a high and very high daily runoff (35–50 and >?50 mm, respectively). Therefore, in this case, the runoff leads to flooding, especially in the urban area and agricultural lands.  相似文献   

Short and Long-term Behaviours of Bored Tunnels in Port-Said Clay     

Mansour  Mohamed F.  El-Nahhas  Fathalla M.  Elshanawany  Amr M. 《Geotechnical and Geological Engineering》2021,39(6):4563-4580

Geotechnical and Geological Engineering - This study investigates the behaviour of bored tunnels in the Port-Said very soft to firm clay deposit in El-Tina Plain, north-eastern Egypt. Recent...  相似文献   

An improved method for estimating life losses from dam failure in China     

Mahmoud  Amr A.  Wang  Jin-Ting  Jin  Feng 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(8):1263-1279

Stochastic Environmental Research and Risk Assessment - A dam-break flood can cause catastrophic life losses due to the uncontrolled large amount of water. This paper aims to improve the estimation...  相似文献   

Worst scenarios of tsunami effects along the Mediterranean coast of Egypt     

Amr Z. Hamouda 《Marine Geophysical Researches》2010,31(3):197-214

Scenarios of tsunami effects represent a very useful technique for the definition and evaluation of tsunami hazard and risk for the Egyptian coast. This paper is an attempt to develop different worst scenarios of tsunamigenesis toward the Egyptian Coast for five segment localities along three different sub-regions (Hellenic Arc, Cyprean Arc and Levantine Coast) in the eastern Mediterranean Sea. These segments are the southwest Hellenic Arc, southeast Hellenic Arc, northeast Hellenic Arc, west of Cyprean Arc and Levantine. For each of them, the scenario takes into account a seismic fault capable of generating an earthquake with magnitude equal to or larger than the highest magnitude registered in that region in historical times. Then the ensuing tsunamis are simulated numerically, highlighting the basic features of the wave propagation and roughly identifying the coastal sectors that are expected to suffer the heaviest tsunami effects. The output data indicated that the first wave of tsunamis from different segments attacked the nearest reference localities (city located nearest each segment) along the Egyptian shore between 28 and 50 min after an earthquake. Tsunamis from these earthquake scenarios produced maximum run-up heights ranging from 1.7 to 9.4 m at the shore. A Beirut Thrust scenario (Levantine segment) included the fact that only a small portion of the fault extended out into the sea, leading to a small effective tsunami source area. In contrast, the southwest Hellenic Arc segment (as in the A.D. 365 earthquake) has high displacement (15 m) and a long extensional fault, forming a highly effective tsunami source area.  相似文献   

Paleozoic alkaline volcanism: geochemistry and petrogenesis of Um Khors and Um Shaghir trachytes of the central Eastern Desert, Egypt     

Moustafa E. Gharib  Mohamed A. Obeid  Ahmed H. Ahmed 《Arabian Journal of Geosciences》2012,5(1):53-71

The Um Khors and Um Shaghir trachyte (UKT and UST) plugs and sheets represent two conspicuous outcrops of Paleozoic alkaline volcanism in the central Eastern Desert of Egypt. The trachyte magmatisms erupted along the Pan-African NW-trending shear zone (302?±?15 and 273?±?15?Ma, respectively) and intruded the Late Proterozoic rocks of the studied area. The trachyte rocks consist mainly of sanidine, anorthoclase, albite, and quartz with a noticeable amount of aegirine?Caugite, aegirine, hedenbergite, and arvedsonite. The studied trachytes are moderately evolved in composition (with 62?C67.5?wt.% SiO₂) and exhibit a limited compositional range in most of the major elements. They are alkaline in nature and considered as silica-oversaturated rocks. The rare earth elements (REE) patterns are somewhat uniform and highly fractionated, being enriched in light REE over heavy REE and show prominent negative Eu anomalies. The UKT and UST are enriched in high field strength elements Nb, Zr, and Y, consistent with typical within-plate alkaline magmatisms of extensional tectonic regimes. They were generated through the fractional crystallization of mantle-derived magmas. Although the UST is younger than the UKT, they show approximately similar chemical compositional ranges of the most major and trace elements, with somewhat higher MgO, Cr, Ni, and Ba contents in the former. This may argue against the evolution of the UST via a continuous fractional crystallization of the residual magmatic melt of the UKT. Thus, the UKT and UST are genetically related but could be emplaced through two various magmatic pulses of the same parent source (i.e., asthenospheric mantle source) at different times. The ascending magmatisms were subjected to variable significant degrees of crustal contamination during their generation.  相似文献   

Kernel distributed residual function in a revised multiple order autoregressive model and its applications in hydrology     

Nesa Ilich  Amr Gharib  Evan G. R. Davies 《水文科学杂志》2013,58(12):1745-1758

ABSTRACT

This paper describes a new approach to fill missing data in hydrologic series. Based on a multiple-order autoregressive model, our algorithm represents the random term with an empirical distribution function that includes different parameters for the low, medium and high ranges of the modelled hydrologic variable. The algorithm involves a corrective mechanism that preserves the original statistical distribution of the series that are filled, while also eliminating the possibility of obtaining negative values for low flows. The algorithm requires multiple correlated hydrologic time series with sufficient data to permit accurate calculation of their statistical properties. It ensures that both the original statistical dependence among the data series and the statistical distribution functions will be preserved after the missing data had been filled. The model has been tested using 15 streamflow series in the Upper Bow River watershed in Alberta, Canada.  相似文献