Forced folding of the neoautochthonous Late Cretaceous–Early Tertiary sequence at the western end of the Hatta Zone, Northern Oman Mountains     

Mohammed Warrak 《Arabian Journal of Geosciences》2010,3(4):369-393

At the western end of the Hatta Zone (the Jebel Rawdha area), Northern Oman Mountains, the neoautochthonous Late Cretaceous–Early Tertiary sequence (“cover”) lies with an angular unconformity on the obducted Semail ophiolite, Haybi Complex and Sumeini Group (“basement”). Structural analysis of the faults in both the basement and cover sequences has shown that they are similar in type and configuration to those that develop in a transpressional left-lateral strike-slip deformational regime (a restraining bend) that is characterised by the dominance of the dip-slip component over the strike-slip component. The WNW–ESE (P_o) faults together with the linking NW–SE (P) faults have divided the basement into elongated blocks. These blocks, in turn, are subdivided by transverse normal faults into horst and graben sub-blocks. The cover sequence is gently folded into a generally WNW–ESE-trending ‘Main’ folds and NE–SW-trending ‘Cross’ folds superimposed on them. These folds appear to be dominantly forced folds that developed as a result of repeated uplift and depression of basement blocks. Their trends correspond to the trends of the subjacent basement blocks. Hence, the Jebel Rawdha folds trend differently from other post-obduction major folds in the foreland region of the Northern Oman Mountains, such as the Hafit and Jebel Faiyah folds. Differences in stratigraphic thicknesses and lateral facies changes of the cover sequence within the blocks and sub-blocks indicate that the earliest differential movement of the blocks must have occurred during the early Maastrichtian, and the latest movement in post-mid-Eocene. Thus, pushing back the initiation of the post-obduction deformation in the Northern Oman Mountains to the early Maastrichtian.  相似文献   

Spatial distribution and contamination assessment of heavy metals in surface soils of Hassi Messaoud, Algeria   总被引：9，自引：0，他引：9  

Mohammed L. Benhaddya  Mohammed Hadjel 《Environmental Earth Sciences》2014,71(3):1473-1486

An increase in heavy metal pollution in the soils of Hassi Messaoud (Algeria) due to intense industrialization and urbanization has become a serious environmental problem. There are three large industrial complexes that have been established in the region of Hassi Messaoud for petroleum extraction field and refinery. The region hosts several industrial facilities which are the main sources for hazardous wastes. Surface soil samples from 58 sampling sites (systematically sampled; 1 × 1 km regular grid), including different functional areas in Hassi Messaoud, were collected and analyzed. The results showed that the average concentrations of Cu, Ni, Mn, Pb and Zn in soil of Hassi Messaoud were up to 13.17, 35.78, 121.21, 130.97 and 61.08 mg/kg, respectively. Ni concentrations were comparable to background values, while Cu, Mn, Pb and Zn concentrations were higher than their corresponding background values. Among the functional areas, the industrial regions displayed the highest metal concentrations, while the lowest concentrations occurred in rural soil. Principal component analysis coupled with cluster analysis showed that: (1) Pb and Zn had anthropogenic sources; and (2) Ni, Cu and Mn were associated with parent materials. Contaminations in soils were classified as geoaccumulation index and enrichment factor. Pollution index values of Cu, Ni, Mn, Pb and Zn varied in the range of 0.04–5.41, 0.46–2.49, 0.01–5.73, 0.62–152.9 and 0.09–53.01, with mean values of 1.32, 1.08, 1.26, 5.64 and 3.1, respectively. The integrated pollution index (IPI) of all the analyzed samples varied from 0.42 to 31.59, with a mean of 2.48, and more than 5.45 % of samples are extremely contaminated; 18.18 % are heavily contaminated; 60 % are moderately contaminated; and others are low contaminated. The spatial distribution of IPI showed that desert and rural areas displayed relatively lower heavy metal contamination in comparison with other areas.  相似文献   

Rock slope stability and design in Arafat–Muzdalifa area,Saudi Arabia     

Ali M. A. Abd-Allah  E. K. El-Sawy  El-Sayed Sedek Abu Seif  Abdelhamid El-Fakharani  Mohammed Amin M. Sharaf 《Arabian Journal of Geosciences》2014,7(10):4029-4042

The present contribution is a complete study extending before, during, and after the excavation of the mountain side that lying north of road 7. It includes slope stability analysis, rock cut design, and rockfall modeling for natural slope and rock cut face. Neoproterozoic granodiorite and biotite granite forming the slope body have medium to very high strengths. Mineral compositions and textures of these intact rocks control the strength values. These rocks are intensively dissected by fractures that are filled with montmorillonite and chlorite. The high plasticity and slippery nature of these filling materials represent the main problem that may face a rock cut designer because they damage the mechanical properties of these fractures. The problem begins with the selection of the rock mass classification that deals with the fracture fillings and extends during the stability analysis and the suggestion of mitigation and supporting measures. The rock masses building the natural slope are suffered by plane, wedge, and toppling failures. Therefore, two rock cut designs are suggested to avoid the hazards related to these failures and considering the construction cost as well. Rockfall modeling for the natural slope and rock cut designs was done to assess the hazards related to these falling of the blocks. The kinetic energy of falling blocks is represented on the roadway by the coverage distance and block rebound amplitude. Slope height has a positive effect on the values of these distance and amplitude, whereas the steepness of berm height has a negative effect on them. Coverage distance is a function to the location of rockfall barrier and to the width of road ditch, while the amplitude controls the barrier height.  相似文献   

Petroleum system analysis of the Khatatba Formation in the Shoushan Basin,north Western Desert,Egypt     

Mohamed Ragab Shalaby  Mohammed Hail Hakimi  Wan Hasiah Abdullah 《Arabian Journal of Geosciences》2014,7(10):4303-4320

The Middle Jurassic Khatatba Formation is an attractive petroleum exploration target in the Shoushan Basin, north Western Desert, Egypt. However, the Khatatba petroleum system with its essential elements and processes has not been assigned yet. This study throws the lights on the complete Khatatba petroleum system in the Shoushan Basin which has been evaluated and collectively named the Khatatba-Khatatba (!) petroleum system. To evaluate the remaining hydrocarbon potential of the Khatatba system, its essential elements were studied, in order to determine the timing of hydrocarbon generation, migration and accumulation. Systematic analysis of the petroleum system of the Khatatba Formation has identified that coaly shales and organic-rich shales are the most important source rocks. These sediments are characterised by high total organic matter content and have good to excellent hydrocarbon generative potential. Kerogen is predominantly types II–III with type III kerogen. The Khatatba source rocks are mature and, at the present time, are within the peak of the oil window with vitrinite reflectance values in the range of 0.81 to 1.08 % Ro. The remaining hydrocarbon potential is anticipated to exist mainly in stratigraphic traps in the Khatatba sandstones which are characterised by fine to coarse grain size, moderate to well sorted. It has good quality reservoir with relatively high porosity and permeability values ranging from 1 to 17 % and 0.05–1,000 mD, respectively. Modelling results indicated that hydrocarbon generation from the Khatatba source rocks began in the Late Cretaceous time and peak of hydrocarbon generation occurred during the end Tertiary time (Neogene). Hydrocarbon primarily migrated from the source rock via fractured pathways created by abnormally high pore pressures resulting from hydrocarbon generation. Hydrocarbon secondarily migrated from active Khatatba source rocks to traps side via vertical migration pathways through faults resulting from Tertiary tectonics during period from end Oligocene to Middle Miocene times.  相似文献   

Diagenesis in the Middle Jurassic Khatatba Formation sandstones in the Shoushan Basin,northern Western Desert,Egypt     

Mohamed R. Shalaby  Mohammed H. Hakimi  Wan Hasiah Abdullah 《Geological Journal》2014,49(3):239-255

The Middle Jurassic Khatatba Formation acts as a hydrocarbon reservoir in the subsurface in the Western Desert, Egypt. This study, which is based on core samples from two exploration boreholes, describes the lithological and diagenetic characteristics of the Khatatba Formation sandstones. The sandstones are fine‐ to coarse‐grained, moderately to well‐sorted quartz arenites, deposited in fluvial channels and in a shallow‐marine setting. Diagenetic components include mechanical and chemical compaction, cementation (calcite, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of calcite cements and feldspar grains. The widespread occurrence of an early calcite cement suggests that the Khatatba sandstones lost a significant amount of primary porosity at an early stage of its diagenetic history. In addition to calcite, several different cements including kaolinite and syntaxial quartz overgrowth occur as pore‐filling and pore‐lining cements. Kaolinite (largely vermicular) fills pore spaces and causes reduction in the permeability of the reservoir. Based on framework grain–cement relationships, precipitation of the early calcite cement was either accompanied by or followed the development of part of the pore‐lining and pore‐filling cements. Secondary porosity development occurred due to partial to complete dissolution of early calcite cements and feldspar. Late kaolinite clay cement occurs due to dissolved feldspar and has an impact on the reservoir quality of the Khatatba sandstones. Open hydraulic fractures also generated significant secondary porosity in sandstone reservoirs, where both fractures and dissolution took place in multiple phases during late diagenetic stages. The diagenesis and sedimentary facies help control the reservoir quality of the Khatatba sandstones. Fluvial channel sandstones have the highest porosities and permeabilities, in part because of calcite cementation, which inhibited authigenic clays or was later dissolved, creating intergranular secondary porosity. Fluvial crevasse‐splay and marine sandstones have the lowest reservoir quality because of an abundance of depositional kaolinite matrix and pervasive, shallow‐burial calcite and quartz overgrowth cements, respectively. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Compressive and Tensile Behavior of Polymer Treated Sulfate Contaminated CL Soil   总被引：1，自引：1，他引：0  

Ahmed S. Mohammed  Cumaraswamy Vipulanandan 《Geotechnical and Geological Engineering》2014,32(1):71-83

In this study, the compressive and tensile behavior of polymer treated sulfate contaminated CL soil was investigated. Based on the information in the literature, a field soil was contaminated with up to 4 % (40,000 ppm) of calcium sulfate in this study. In addition to characterizing the behavior of sulfate contaminated CL soil, the effect of treating the soil with a polymer solution was investigated and the performance was compared to 6 % lime treated soil. In treating the soil, acrylamide polymer solution (15 g of polymer dissolved in 85 g of water) content was varied up to 15 % (by dry soil weight). Addition of 4 % calcium sulfate to the soil decreased the compressive and tensile strengths of the compacted soils by 22 and 33 % respectively with the formation of calcium silicate sulfate [ternesite Ca₅(SiO₄)₂SO₄)], magnesium silicate sulfate (Mg₅(SiO₄)₂SO₄) and calcium-magnesium silicate (merwinite Ca₃Mg(SiO₄)₂). With the polymer treatment the strength properties of sulfate contaminated CL soil was substantially improved. Polymer treated sulfate soils had higher compressive and tensile strengths and enhanced compressive stress–strain relationships compared to the lime treated soils. Also polymer treated soils gained strength more rapidly than lime treated soil. With 10 % of polymer solution treatment, the maximum unconfined compressive and splitting tensile strengths for 4 % of calcium sulfate soil were 625 kPa (91 psi) and 131 kPa (19 psi) respectively in 1 day of curing. Similar improvement in the compressive modulus was observed with polymer treated sulfate contaminated CL soil. The variation of the compacted compressive strength and tensile strength with calcium sulfate concentrations for the treated soils were quantified and the parameters were related to calcium sulfate content in the soil and polymer content. Compressive stress–strain relationships of the sulfate soil, with and without lime and polymer treatment, have been quantified using two nonlinear constitutive models. The constitutive model parameters were sensitive to the calcium sulfate content and the type of treatment.  相似文献   

The motion of artificial satellites in the set of Eulerian redundant parameters     

Mohammed Adel Sharaf  Mervat El-Sayed Awad  Samiha Al-Sayed Abdullah Najmuldeen 《Earth, Moon, and Planets》1991,55(1):21-44

In this paper, the connections between orbit dynamics and rigid body dynamics are established throughout the Eulerian redundant parameters, the perturbation equations for any conic motion of artificial satellites are derived in terms of these parameters. A general recursive and stable computational algorithm is also established for the initial-value problem of the Eulerian parameters for satellites prediction in the Earth's gravitational field with axial symmetry. Applications of the algorithm are considered for the two cases of short and long term predictions. For the short-term prediction, we consider the problem of the final state prediction of some typical ballistic missiles in the geopotential model with zonal harmonic terms up to J ₃₆, while for the long-term prediction, we consider the perturbed J ₂ motion of Explorer 28 over 100 revolutions.  相似文献   

A geochemical survey of thermal springs in western part ofRepublic of Yemen and their geothermometric characteristics     

HazaeaMohammed HUKe 《东北亚地学研究》2004,7(1):58-63

The high-mineral contents of some thermal waters are believed to have medicinal properties. Numerous spas and bathhouses might be built at these hot springs to take advantage of theses supposed healing properties such as skin diseases, rheumatism and so on. This paper is to find thermal reservoir and to classify the kinds of water. The majority of thermal springs are found discharging from igneous centers of Tertiary and Quaternary volcanic fields of the western Yemen (research area). Structurally these volcanisms are connected to N-NW faults that are parallel to the main Red Sea trend. Temperature and pH values of the thermal spring range 37℃-96℃, and 6.3-8.7 respectively. The Yemen/thermal waters indicate high variability in composition since they are ofNa (K) -CI, Na=HCO3 and Ca (Mg) =SO4 types, whereas the surficial waters have the typical worldwide Ca (Mg) -HCO3 composition. Different liquid phase geothermometers,such as SiO2, K^2/Mg and Na/K. Estimated reservoir temperatures ranging 70℃-140℃ perform equilibrium temperature evaluation of the thermal reservoirs.  相似文献   

Evaluation of the Flow Measurement Performance of Compound Sharp-Crested Over-Fall Weirs and Optimized Discharge Measurement in Data Scarce Areas     

Kassaye  Aklilu Alemayehu  Mohammed  Abdella Kemal  Angello  Zelalem Abera 《Water Resources》2022,49(3):402-412

Water Resources - The hydraulic relationships of flow through the weir of different common shapes were investigated in this study. The hydraulic performances of weirs were carried out...  相似文献   

Extraction and analysis of geological lineaments by combining ASTER-GDEM and Landsat 8 image data in the central high atlas of Morocco     

Abdelouhed  Farah  Ahmed  Algouti  Abdellah  Algouti  Mohammed  Ifkirne  Zouhair  Ourhzif 《Natural Hazards》2022,111(2):1907-1929

Natural Hazards - The present work focuses on using remote sensing techniques and geographical information system (GIS) to automatically extract lineaments in the southeast of Morocco, which is one...  相似文献