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31.
In this part we expand the indirect part of the planetary perturbing function by Smart's method, via Taylor's theorem. We neglect, in our expansion, terms of degree higher than the fourth with regard to the eccentricities and tangents of the inclinations. 相似文献
32.
The results of geotechnical explorations, engineering geological investigation (including laboratory and in situ tests) and
field observations have been used, along with borehole logging charts, to obtain the rock mass geotechnical data. Based on
the data, the rock mass along the Sabzkuh water conveyance tunnel route was classified by rock mass rating (RMR), Q-system
(Q), rock mass index (RMi) and geological strength index (GSI) (3 methods). A new series of correlations were established between
the systems based on the data collected from the study area. These relationships were then compared with those reported in
the literature, and two new relations were recommended. The classifications were utilized to calculate mechanical properties
(rock mass strength and deformation modulus) of the rock mass along the tunnel according to available empirical relations,
and to distinguish the upper-bound and lower-bound relations. 相似文献
33.
Sixty-five sediment samples and 25 water samples were collected from Al-Mujib reservoir, central Jordan, in order to investigate
the heavy metal and ionic contamination assessment. Therefore, to achieve this aim, water and sediment samples were collected
during winter and summer seasons (2007) from Al-Mujib reservoir and the areas surrounding it. The study shows that there are
elevated levels of SO4
2−, Cl− and Na+ in reservoir water, which might originate from anthropogenic activities in the reservoir catchment area. In addition, the
reservoir water has higher total hardness (TH) values together with high Ca and Mg contents. This might be attributed to pH
of reservoir water and the nature of the rocks exposed in the catchment area. The average levels of heavy metals in reservoir
sediments are Fe = 14,888.1, Cu = 17.8, Zn = 88.6, Ni = 38.7, Cd = 4.4, Mn = 337.9 and Pb = 6.1 mg/kg, which are lower than
that observed in Wadi Al-Arab reservoir, northern Jordan. The values of enrichment factor are Cd = 35.5, Ni = 3.02, Zn = 2.54,
Cu = 1.26, Mn = 1.2 and Pb = 0.57; these values indicate that heavy metals in sediments of Al-Mujeb reservoir have a different
anthropogenic incrimination inputs. The study showed that the sediments are polluted with Cd, relatively contaminated with
Ni and Zn and uncontaminated with respect to Mn, Pb and Cu. 相似文献
34.
Ali Hamdi ABU SALIM 《地理学报》2014,24(3):457-474
This study addresses the morphometric variables that determine the sediment yield in Wadi Al-Arja through the analysis of the impact of different morphometric characteristics along the course of the valley on its sediment yield, as well as the analysis of spatial and formal dimensions and morphologies of the basin and its relationship to the sediment yield. The study also addresses the size of variation in the volume of sediment yield of the river tributaries that make up the water network of the valley under the differences of its morphometric and hydrological characteristics. The study found several results, most notably: The classification of Wadi Al-Arja basin according to the hypsometric integral value (72.1%) within an uneven topography, which increases the force of the erosive activity and the size of the sediment yield if the basin was exposed to moist climatic periods. The study also showed the presence of convergence in the intra-spaces between the river tributaries in the water network. This increases the volume of water flows when these tributaries meet with each other and thus increasing their erosive ability and sediment yield.The study also showed the presence of marked variation in the sediment yield of the river tributaries depending on the differences in its morphometric characteristics. The results of the step-wise regression analysis confirmed the importance of the morphometric and hydrological variables, and plant coverage in interpreting the variation in the size of the sediment yield of the river tributaries of different stream order in Wadi Al-Arja basin, where these variables interpreted 43% of the total variation, with statistical significance less than 0.05. 相似文献
35.
Mamdouh F. Soliman Nageh A. Obaidalla Ezzat A. Ahmed Ahmed A. Ahmed Johannes Kurzweil 《Arabian Journal of Geosciences》2014,7(10):4079-4099
The Qreiya Beds that record the ‘mid-Paleocene event’ at Gabal Nezzazat occur within the Igorina albeari (P3b) Zone and constitute part of a 14-m thick shale succession that ranges in age from Early to Late Paleocene. They are composed of four alternating dark grey and brown shale beds, which are thinly laminated, phosphatic, organic-rich and extremely sulphidic. They are characterized by distinct enrichment and high peak anomalies in chalcophiles (Zn, Co, Ni, Cu and Pb) and organic association elements (V and Cr), especially within the brown organic-rich beds. It is concluded that these elements are incorporated into the phosphatic debris, sulphides and organic matter. In contrast, the grey beds are enriched in clay minerals and quartz. Clay mineral assemblages indicate alternating periods of warm/humid climate (high kaolinite) and dry climate (low kaolinite) during the formation of the grey and brown beds, respectively. The sediments of the Qreiya Beds yield lithological, biotic, geochemical and mineralogical data indicative of suboxic/anoxic marine environments as a result of high productivity and/or upwelling. The top metre of the succession below the Qreiya Beds is characterized by a progressive change from faunas dominated by praemurcurids to faunas dominated by Morozovilids, and by a progressive upward decrease in δ13Ccarb and δ18Ocarb values. The foraminiferal faunal change may reflect shallowing and warming preceding deposition of the Qreiya Beds. The change in isotopic values is inferred to be the result of surface weathering, fluvial input and diagenesis with no evidence of any primary change that could support presence of a hyperthermal event. 相似文献
36.
Mohamed Abdallah Gad DARWISH 《《地质学报》英文版》2014,88(1):196-212
The SEM-EDX technique was applied to investigate Au, and Cu+Sn alloyed grains in the mineralization of the Um Shashoba mine for achieving further understanding of occurrences, internal structures and microchemistry of Au and Cu alloys and associated minerals, and mineralization type. This study is aiming at the genetic history of ore-bearing fluid events, geochemical evaluation and exploration significance. The results showed that the mineralization could be considered as a single major episode generated by metamorphic mesothermal solution rich in sulfides and unsaturated respect to Au. It was differentiated into many stages; started with formation of auriferous pyrite that was pseudomorphed by secondary hematite, limonite and goethite. Three phases of Au alloy were precipitated, and Cu+Sn and Ag-rich alloys were produced respectively and followed by deposition of two generations of barren pyrite. Calcite and ankerite were crystalized, surrounded and partially replaced some of early formed minerals. Finally, barren muscovite recrystallized around and inside both later formed carbonate minerals that were free of any sign of Au in their structures. The processes of deformation, recrystallization, annealing, dissolution, remobilization and re-precipitation played the most important roles in the genetic history of the mineralization. 相似文献
37.
Prediction of Land Cover Change Using Markov and Cellular Automata Models: Case of Al-Ain,UAE, 1992-2030 总被引:1,自引:0,他引:1
M. M. Yagoub Abdallah Ahmad Al Bizreh 《Journal of the Indian Society of Remote Sensing》2014,42(3):665-671
The UAE has witnessed rapid urban development and economic growth in recent years. With its ambitious vision to become one of the advanced nations by 2021, planners and policy-makers need to know the most likely direction of future urban development. In this study, remotely sensed imagery coupled with cellular automata models were used to predict land cover in Al Ain, the second largest city in the Emirate of Abu Dhabi. Markov and cellular automata models were used for 1992 and 2006 to predict land cover in 2012. Land Use and Land Cover maps for the study area were derived from 1992, 2006, and 2012 Landsat satellite images (TM, ETM+). The models achieved an overall accuracy of approximately 80 %. A Markov model was applied for 2006 and 2012 to predict land cover in 2030. The results conformed to the general trend of the Al Ain Master Plan 2030. This study demonstrates that remote sensing, with the availability of free Landsat data, is a viable technology that could be used to help in the prediction process especially in developing countries, where data availability is a problem. 相似文献
38.
Active tectonic morphology and submarine deformation of the northern Gulf of Eilat/Aqaba from analyses of multibeam data 总被引:1,自引:0,他引:1
Gideon Tibor Tina M. Niemi Zvi Ben-Avraham Abdallah Al-Zoubi Ronnie A. Sade John K. Hall Gal Hartman Emad Akawi Abdelrahmem Abueladas Rami Al-Ruzouq 《Geo-Marine Letters》2010,30(6):561-573
A high-resolution marine geophysical study was conducted during October-November 2006 in the northern Gulf of Aqaba/Eilat,
providing the first multibeam imaging of the seafloor across the entire gulf head spanning both Israeli and Jordanian territorial
waters. Analyses of the seafloor morphology show that the gulf head can be subdivided into the Eilat and Aqaba subbasins separated
by the north-south-trending Ayla high. The Aqaba submarine basin appears starved of sediment supply, apparently causing erosion
and a landward retreat of the shelf edge. Along the eastern border of this subbasin, the shelf is largely absent and its margin
is influenced by the Aqaba Fault zone that forms a steep slope partially covered by sedimentary fan deltas from the adjacent
ephemeral drainages. The Eilat subbasin, west of the Ayla high, receives a large amount of sediment derived from the extensive
drainage basins of the Arava Valley (Wadi ’Arabah) and Yutim River to the north–northeast. These sediments and those entering
from canyons on the south-western border of this subbasin are transported to the deep basin by turbidity currents and gravity
slides, forming the Arava submarine fan. Large detached blocks and collapsed walls of submarine canyons and the western gulf
margin indicate that mass wasting may be triggered by seismic activity. Seafloor lineaments defined by slope gradient analyses
suggest that the Eilat Canyon and the boundaries of the Ayla high align along north- to northwest-striking fault systems—the
Evrona Fault zone to the west and the Ayla Fault zone to the east. The shelf–slope break that lies along the 100 m isobath
in the Eilat subbasin, and shallower (70–80 m isobaths) in the Aqaba subbasin, is offset by approx. 150 m along the eastern
edge of the Ayla high. This offset might be the result of horizontal and vertical movements along what we call the Ayla Fault
on the east side of the structure. Remnants of two marine terraces at 100 m and approx. 150 m water depths line the southwest
margin of the gulf. These terraces are truncated by faulting along their northern end. Fossil coral reefs, which have a similar
morphological appearance to the present-day, basin margin reefs, crop out along these deeper submarine terraces and along
the shelf–slope break. One fossil reef is exposed on the shelf across the Ayla high at about 60–63 m water depth but is either
covered or eroded in the adjacent subbasins. The offshore extension of the Evrona Fault offsets a fossil reef along the shelf
and extends south of the canyon to linear fractures on the deep basin floor. 相似文献
39.
Terry L. Wade Yousra Soliman Stephen T. Sweet Gary A. Wolff Bobby J. Presley 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(24-26):2585
The concentrations of polycyclic aromatic hydrocarbons (PAHs) and trace elements were determined for surface (top 2 cm) sediment samples collected during the deep Gulf of Mexico benthos (DGoMB) study .These elements and compounds are known to be toxic to organisms at high concentrations and may affect biological communities. There is no indication of major anthropogenic input of the elements Be, Co, Cr, Fe, Si, Tl, V, K, Mg, Ca, Sr and Zn, based on normalization to Al. The concentrations of these metals in the sediment are a function of the relative amounts of trace-metal-rich Mississippi River-derived silicate material and trace-metal-poor plankton-derived carbonate. This is not true for the elements Ba, Ni, Pb, Cd, As, Cu and Mn, whose concentrations show considerable scatter when normalized to Al and a general enrichment. On a normalized basis, Mn is enriched 5–10 fold, Cu and Ni 2–3 fold and Pb 2 fold over Mississippi River-derived material. These enrichments are likely the result of remobilization of metals from depths in the sediment column where reducing conditions exist. The Ba concentrations at selected sites are higher than those of average clay-rich sediments, but are typical of sediments from near oil well platforms in the northern Gulf of Mexico. In the case of Ba, it seems likely that the enrichments, as high as a factor of 10, are due to disposal of oil well drilling mud. The Ba-enriched samples are from the three shallowest water sites in the Mississippi Trough (sites MT1, 2 and 3) and from site C1 and WC5. All are in an area of intense petroleum exploration and development. PAH concentrations are also elevated at MT1, MT3 and C1. The total PAH concentration ranged from not detected (ND) to 1033 ng/g with a mean of 140 ng/g. Even at the sites most enriched in PAHs and trace elements, the concentrations are not at the levels expected to adversely affect the biota. However, these predicted non-effects are based on research using mostly near-shore estuarine species, not on the indigenous species at the sampling sites. 相似文献
40.
Bouri Djamel Eddine Brahimi Abdelkader Krim Abdallah Arab Ahmed Najser Jan Mašín David 《Geotechnical and Geological Engineering》2022,40(4):1675-1692
Geotechnical and Geological Engineering - This paper presents a study on Chlef sand to examine the effect of fines content (Fc), relative density (RD) and initial conditions on the compressibility... 相似文献