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Depositional environments and facies of the Late Triassic Abu Ruweis Formation, Jordan 总被引：1，自引：0，他引：1
The Abu Ruweis Formation is composed of carbonates, evaporites, and mudstones, with some locally developed pelletic, oolitic and stromatolitic limestones. The lateral persistence of bedding, the purity of the evaporite rocks, the alternating arrangement of marine carbonates and evaporites indicates periodic deposition in subaqueous conditions (salina). Petrographic investigations, X-ray diffraction analysis as well as chemical analysis have shown that the outcropping evaporite beds are mainly composed of secondary gypsum, with rare anhydrite relics. Five microfacies of gypsum were recognized according to their fabrics: porphyroblastic and granoblastic gypsum showing polarization texture, gypsum pseudomorph after anhydrite laths, and satin spar gypsum. The textures they display indicate a hydration origin of precursor anhydrite, which is in turn rehydrated from primary gypsum. Some of these anhydrites were formed as a result of replacement processes of the carbonate sediments associated with the evaporites, as evidenced from the textural relationships of the carbonate and sulfate minerals. The O18 content ranges from 1.45 to 8.38% PDB and the C13 content ranges from −1.52 to 4.73% PDB. Trace elements analysis has shown that the Abu Ruweis dolomites are rich in strontium (up to 600 ppm), and sodium (up to 835 ppm). The isotope composition and trace elements content, as well as the petrographic characteristics point to a penecontemporaneous hypersaline dolomitization origin for the Abu Ruweis dolomites. The evaporites were deposited during a regressive lowstand systems tract, whereas the carbonates were deposited under shallow water marine conditions during a highstand systems tract. The Abu Ruweis succession represents a relatively stable arid climate within a rapidly subsiding basin. Restricted conditions were provided by the development of beach barriers. 相似文献
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A. E. El-Haddad A M. El-Akraby I. S. Ismail A. M. Abdel Gowad 《Arabian Journal of Geosciences》2014,7(8):3011-3021
The present study represents an application of the 2D homogeneous function method to investigate the near-surface groundwater potentiality to the east of Qena town, Egypt. The homogeneous function automatically inverts first arrival refractions to derive a 2D velocity distribution, which involves seismic boundaries. A complex set of observed refracted traveltimes along four seismic profiles (12 spreads) is used to construct refraction velocity field section and structural section. Such sections allow viewing the complex layered structure and delineating its boundaries and faults. The interpreted geoseismic layers were traced, according to their own gradients and velocity ranges. The resultant models were successful in fulfilling the proposed objective, as they provide: (1) the required details on the delineation of the subsurface layers, where three geoseismic layers with different ranges of velocities were detected; (2) determination of the thickness and the inversion boundary of water-bearing layer; and (3) detection of normal and reverse faults with displacement of about 10–40 m and variable dipping directions. The obtained result was found to be completely compatible with the information gained from identified boundaries of the nearby borehole. 相似文献
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A. A. Bakheit G. Z. Abdel Aal A. E. El-Haddad M. A. Ibrahim 《Arabian Journal of Geosciences》2014,7(6):2165-2178
The study area lies to the south of El-Dakhla Oasis in the central part of the western desert, Egypt. It is limited by the latitudes 24–25°?N and the longitudes 28–30°?E. The main purpose of this work is the investigation of the subsurface structure and the delineation of the main structural elements at different subsurface levels. This study aims also to estimate the basement depth, the basement relief, and consequently, the thickness of the sedimentary cover. The study is based on acquired aeromagnetic data prepared by "La Compagnie General De Géophysique" for the Egyptian General Petroleum Company and Conoco (1977), geological information and results of previous studies in the region. The study involves the analysis for the aeromagnetic data and generating of reduced to pole magnetic map from which different magnetic maps are calculated. The calculated maps are first vertical derivative map and downward continuation map at depth level 400 m. Trend analysis technique is used to define the fault pattern affecting the studied area at different subsurface levels. It is applied to the reduced to pole magnetic map, the first vertical derivative map, and the downward continuation map at depth level 400 m of the study area. All results obtained from the interpretation process were combined together to draw the general view of the subsurface structures of the area. The NE–SW, E–W, and N–S trends are important surface and subsurface (basement) structural trends. This is attributed to the rejuvenation of movements on these old (basement) tectonic trends after the deposition of the sedimentary cover. Basement depth calculation from the aeromagnetic data is achieved using different techniques. The applied techniques included natural spectral analysis and Euler deconvolution. The depth values obtained vary from 400 to 1,700 m. 相似文献
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An experiment was carried out at Nahshala Farm, north west of Al-Ain City, U.A.E. during the 1998–2000 growing seasons, using six halophytes (Batis maritima, Distichlis spicata, Juncus roemerianus, Paspalum vaginatum, Salicornia bigelovii and Spartina alterniflora) and two levels of leaching fraction (0·25 and 0·50) under three irrigation salinity levels (10, 20, and 40 gL−1) in a randomized complete block design arranged in split plots. The purpose of the research was to apply the theory of crop salt tolerance on aboveground yields and agronomic characteristics of halophytes to determine their thresholds for salinity and to determine leaching requirements. The results indicated that the halophyte species tested can grow with minimum reduction in the growth potential at <20 gL−1of mean salinity of soil solution. Leaching fraction (LF) of 0·25 at the highest salinity of irrigation water (40 gL−1) was inadequate to attain the steady-state salt balance during the growth period, although the drainage salinity reached more than 90 g L−1. Furthermore, if the same level of LF is used for longer period, soil salinity under this high salt treatment will continue to rise, and plant growth may deteriorate. Leaching fraction of 0·50 is preferable if salinity of irrigation water was more than 20 gL−1and dry matter production is considered, although the amount of water use will be excessive 相似文献
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El-Haddad Bosy A. Youssef Ahmed M. Pourghasemi Hamid R. Pradhan Biswajeet El-Shater Abdel-Hamid El-Khashab Mohamed H. 《Natural Hazards》2021,105(1):83-114
Natural Hazards - Floods represent catastrophic environmental hazards that have a significant impact on the environment and human life and their activities. Environmental and water management in... 相似文献
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A. M. Youssef A. M. Hassan A. A. A. El-Haddad 《Journal of the Indian Society of Remote Sensing》2009,37(3):377-393
Different outcropping sedimentary rock units, ranging in age from Paleozoic to Miocene, can provide significant information
to understand the development of tectono-sedimentary evolution of the Sidri — Feiran area, southwestern Sinai Peninsula. The
aim of this research is to test the ability of Landsat ETM+ imagery for differentiating and mapping these units with the help
of Shuttle Radar Topography Mission (SRTM) and field investigations. For this purpose, true and false colour composite images,
image enhancement techniques (Principle Component Analysis and Minimum Noise Fraction), and 3D perspective views were applied
to the data and the geological-photo interpretations were carried out. 相似文献
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Ahmed M. Youssef Hasan M. Al-Harbi Francisco Gutiérrez Yasser A. Zabramwi Ali B. Bulkhi Saeed A. Zahrani Alaa M. Bahamil Ahmed J. Zahrani Zaam A. Otaibi Bosy A. El-Haddad 《Hydrogeology Journal》2016,24(3):625-644
Approximately 60 % of the 2,150,000 km2 area of Saudi Arabia is underlain by soluble sediments (carbonate and evaporite rock formations, salt diapirs, sabkha deposits). Despite its hyper-arid climate, a wide variety of recent sinkholes have been reported in numerous areas, involving significant property losses. Human activities, most notably groundwater extraction, have induced unstable conditions on pre-existing cavities. This work provides an overview of the sinkhole hazard in Saudi Arabia, a scarcely explored topic. It identifies the main karst formations and the distribution of the most problematic sinkhole areas, illustrated through several case studies covering the wide spectrum of subsidence mechanisms. Some of the main investigation methods are presented through selected examples, including remote sensing, trenching and geophysics. Based on the available data, the main causal factors are identified and further actions that should be undertaken to better assess and manage the risk are discussed. 相似文献
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