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Belal S. Amireh Joerg Mutterlose Mazen N. Amaireh Tobias Puettmann Abdulkader M. Abed 《Arabian Journal of Geosciences》2018,11(15):425
Three sections from the Al-Hisa Phosphorite Formation (AHP) were measured in the southeastern desert of Jordan: Batn El-Ghoul, Nagb Etayyeg, and Zgaimat Al-Hasah. A fourth section, Wadi Arfa, is added from a previous work. The three sections differ from the typical AHP Formation in central Jordan by having highly reduced thicknesses, omission/non-deposition of the underlying formations, rarity of fossils, abundant sand, and their stratigraphic ages. A Paleocene-Early Eocene age, based on calcareous nannofossils, has been assigned to the AHP Formation of the sections studied in the southeast desert. This Paleocene-Early Eocene age is younger than the Early Maastrichtian age of the AHP deposits in central Jordan. The published ages of the phosphorite deposits in the eastern Mediterranean countries suggest a younging to the east due to an interplay between paleodepositional environments and plate tectonics (paleohigh formation). The minor phosphorite deposits of Turkey and Iran are not involved in the discussion because they were not part of the Afro-Arabian Plate or the later Arabian Plate. The abovementioned differences between the southeastern desert phosphorites and the central Jordan deposits are here explained by the formation of paleohighs on the Neo-Tethys seafloor during the Late Cretaceous-Eocene. These include the Sirhan Paleohigh where the southeast desert phosphorites were deposited. The formation of the highs was due to the compression associated first, with the subduction of the Afro-Arabian Plate, below the Eurasian Plate and later with their collision. 相似文献
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Ahmed H. Ahmed Shoji Arai Yaser M. Abdel-Aziz Moha Ikenne Abdellatif Rahimi 《Journal of African Earth Sciences》2009,55(1-2):92
The distribution of platinum-group elements (PGEs), together with spinel composition, of podiform chromitites and serpentinized peridotites were examined to elucidate the nature of the upper mantle of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. The mantle section is dominated by harzburgite with less abundant dunite. Chromitite pods are also found as small lenses not exceeding a few meters in size. Almost all primary silicates have been altered, and chromian spinel is the only primary mineral that survived alteration. Chromian spinel of chromitites is less affected by hydrothermal alteration than that of mantle peridotites. All chromitite samples of the Bou Azzer ophiolite display a steep negative slope of PGE spidergrams, being enriched in Os, Ir and Ru, and extremely depleted in Pt and Pd. Harzburgites and dunites usually have intermediate to low PGE contents showing more or less unfractionated PGE patterns with conspicuous positive anomalies of Ru and Rh. Two types of magnetite veins in serpentinized peridotite, type I (fibrous) and type II (octahedral), have relatively low PGE contents, displaying a generally positive slope from Os to Pd in the former type, and positive slope from Os to Rh then negative from Rh to Pd in the latter type. These magnetite patterns demonstrate their early and late hydrothermal origin, respectively. Chromian spinel composition of chromitites, dunites and harzburgites reflects their highly depleted nature with little variations; the Cr# is, on average, 0.71, 0.68 and 0.71, respectively. The TiO2 content is extremely low in chromian spinels, <0.10, of all rock types. The strong PGE fractionation of podiform chromitites and the high-Cr, low-Ti character of spinel of all rock types imply that the chromitites of the Bou Azzer ophiolite were formed either from a high-degree partial melting of primitive mantle, or from melting of already depleted mantle peridotites. This kind of melting is most easily accomplished in the supra-subduction zone environment, indicating a genetic link with supra-subduction zone magma, such as high-Mg andesite or arc tholeiite. This is a general feature in the Neoproterozoic upper mantle. 相似文献
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ABSTRACTGrowth in water use and threatened shortages of water have become increasingly important in the modern world system. Natural resources are exploited extensively by capitalist interests in industrially advanced nations, while the lower strata of the world system, the underdeveloped societies, are left with limited access to natural resources for their productive processes, particularly water resources. We contribute to socio-hydrological research by examining underlying socio-structural factors that play a part in the process of deteriorating conditions of global water resources. Drawing on a world-systems perspective, this study examines how socio-structural forces – world-system position, per capita beef consumption, per capita energy consumption, and urbanization – affect per capita water footprint, which includes an accounting of “virtual water” consumption. We find that per capita beef consumption and per capita energy consumption have significant positive direct effects, and the world-system position has a significant indirect and total effect on per capita water footprint. 相似文献
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The concentrations of six heavy metals (Fe, Mn, Ni, Cu, Pb and Zn) were studied in 11 hard and 4 soft common coral species
collected from Hurghada, Wadi Al-Gemal and Gola’an along the Red Sea coast to assess the differential abilities of corals
to concentrate and assimilate the heavy metals inside soft coral tissues and hard coral skeletons. These results reveal the
order of Fe > Zn > Ni > Pb ≥ Mn > Cu. Fe recorded significant high concentrations in mushroom (funnel) forms of the soft corals
at the different sites; 125.19, 101.71 and 90.44 ppm at Gola’an, Hurghada and Wadi Al-Gemal, respectively. The soft coral
species recorded the highest average concentration of Mn, Ni, Cu and Zn than the hard corals, which were 13.22, 16.05, 13.08
and 148.17 ppm, respectively. Generally, soft corals show higher metal concentrations than the hard ones; moreover, Hurghada
recorded a higher trend of metal concentrations in soft and hard corals than the other sites. The study concluded that many
biological and local environmental factors influenced the metal occurrences and uptakes in both coral forms such as, the exposed
surface area for metal uptake, turbidity, overlying mucus thickness and the ability of metals to substitute inside the crystal
lattice of the hard corals. 相似文献
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Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth's magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole.A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio(α*). Stable orbits are identified for various values of α*. The main parameters for stabilization of the spacecraft are α*and the difference between the components of the moment of inertia for the spacecraft. 相似文献
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On the Management of Ground Water in Coastal Aquifers 总被引：1，自引：0，他引：1
Abdel-Aziz I. Kashef Member NWWA 《Ground water》1971,9(2):12-20
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Muha Abdullah Al Pavel Sharif A. Mukul Mohammad Belal Uddin Kazuhiro Harada Mohammed A. S. Arfin Khan 《山地科学学报》2016,13(6):1085-1095
We investigated the effect of tree cover, forest patch and disturbances on tree species richness in a highly diverse conservation area of northeast Bangladesh. A systematic sampling protocol was adopted and 80 sub-plots from twenty five 1 ha plots were used for the vegetation survey. Linear regression analysis was performed to understand the effect of patch area, disturbances and tree cover on tree species richness. Ordination using Redundancy analysis (RDA) and Non-metric Multi Dimensional Scaling (NMDS) were also performed to explore the tree species compositional similarities along the stand characteristics gradient and locations of the sample plots. Our study revealed that, forest patch size has greater influence on species richness. Areas with medium level of disturbances have shown greater species richness. In constrained ordination the selected explanatory variables regulated the richness of common species. Our findings can be useful for better forest management and restoration of landscapes of conservation needs using ecologically important species. 相似文献
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Cement kiln dust (CKD) is the by-product generated from the manufacture of Portland cement. Disposal quantities of CKD in construction project are required to protect the environment. In the recent construction experience in the area of study at the last years showed that, ground and underground engineering on the soft soil are susceptible to various types of cracking in buildings and roads. The improvement of engineering properties of two disturbed soils by using CKD in different percentages (5, 10 and 20 %) was discussed in this paper. The results indicated that CKD additives increased the pH values and decreased the plasticity index in both types of soils under investigation. The maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with increasing the percentage of CKD in soil A. In soil B the MDD and OMC decreased. 相似文献